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Outdoor Free Flight Forum => Catapult Launched Gliders => Topic started by: Pit on June 27, 2010, 06:21:48 AM



Title: CATAJETS: Design and Development
Post by: Pit on June 27, 2010, 06:21:48 AM
OK, everyone. Here we go. I have started this thread for everyone to post their "designs", drawings, trials and tribulations with profile scale or fully built-up catapult launch gliders.

Feel free to post everything, from ideas for that obscure aircraft, drawing up a plan or sketch, building it and teaching it how to fly. All info to the success or lack of, welcome. I see this as a neat, inexpensive way to get people of all ages and gender involved with something that they can more easily relate to (Hey, I saw something like that fly over the house yesterday!). It does not particularly have to be a jet, but should be WWII or later and possibly earmarked for conversion to jet power. "Secret" (ex. Luft 46, Skunk Works, Star Trek/Wars) aircraft that never flew, are fully "eligible". The emphasis is on FUN!

There is a similar thread on SFA on the glider forum "Frustrating Catapult Jets" that was well visited for some time, but has become dormant despite attempts by me to revive it. Lots of good info there, tho.

I'm in the process of chopping wood for the "Scorpion". I won't get much done today - Formula 1 race and the Germany-England soccer match are in the way ;D - but I should have the parts cut by tonight.


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 28, 2010, 08:15:15 AM
To get this thread going, I'll run through how I "developed" ::) the F-89 "Scorpion".

I found a suitable 3-view that was large enough to show panel detail. Some 3-views are SO small that they are useless when blown up to a usable scale, so a bit of judgment is needed as to WHAT you want. I "saved" it to my hard disk, in this case as a jpeg file (tiff of gif might be better as less resolution gets "lost" when enlarging). Importing the file into a graphics editing program lets you then modify the file to your hearts content.

I DON'T recommend MS Paint as it is too limited, but can do in a pinch. I use either TurboCad or Inkscape (highly recommended in that it operates with vector graphics). I imported the file to the "0" level and "traced" over it on level "1". A couple extra levels were added for complicated areas that might (and usually do, like spline and bezier curves) need modification. Once I'm satisfied with what is shown, I'll scale the "drawing" up to the size I want (can be done at the start with the imported file, if the resolution allows) and print a copy. You should have been "saving" your work while drawing ;).


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 28, 2010, 08:34:54 AM
Once I have a "hardcopy" of the plan, I make up cutting templates. Tack-gluing a "copy" directly to the wood is also a good way to make your kit, but I generally make a bunch of each glider, so it's templates for me.

I use all sorts of material for templates, but for these small planes, I have come to prefer cardboard from cereal boxes or the heavier stock from the back of paper tablets. The heavy grade manila folders are also very good. I use permanent gluestick to attach the rough-cut printouts to the card stock, and final trim with a scalpel and scissors. The edges are then sealed and hardened with CA and sanded smooth. Sometimes I'll give the complete template a coat or two of clear "whatever" for added protection.

Pictured are the finished templates for the "Scorpion". I left the tip-tank winglet "raw" for description purposes.


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 28, 2010, 09:09:18 AM
One thing I forgot to mention, is to check whatever 3-view you use AND whatever plan you print from a file, is to check for symmetry. Many times, the top view is a slightly different scale than the side view or one side of the wing is "different" than the other.

A printout can come out lopsided, but not immediately noticeable due to many factors - worn feed rollers, platen or "helping" the paper as it emerges from the printer. I caught the guy at the copy shop "helping" an enlargement of mine. He insisted that it didn't matter with the big machines, so we measured the copy and ran another WITHOUT "help". I did NOT have to pay for the second copy.


Title: Re: CATAJETS: Design and Development
Post by: PeeTee on June 28, 2010, 10:21:53 AM
Quote
one side of the wing is "different" than the other.

Pete

The old chuckie build trick is to only cut a template for one half of the wing. Draw a centre line on the wood, cut out one side, flip the template over and cut out the other side - obviously lining up both sides on the centre line. It's the thing to do for tails (stabs) as well. Pas de probleme and easy peasy as they say :D

Peter


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 28, 2010, 02:14:12 PM
You're right Peter. It's the way I'd usually draw up a plan, but it's been my experience with those fairly new to building from a plan, that trouble pops up with the flip & cut. Since I use the mirror function in my drawing program, I can rest assured that the original drawing is "accurate". The template can be cut either way.

Here are the major parts cut for my preferred building method. Results in a fairly lightweight, bombproof fuselage. The only real "heads up" is that both outer layers HAVE to be cut accurately! One CAN use a single piece of 1/8th and glue the fin/stab assembly afterward (definitely lighter), but the unit WON'T be as strong, however alignment is easier. Tapering the outer fuse laminations from the wing TE to the tailcone will reduce weight in the rear, requiring less noseweight.


Title: Re: CATAJETS: Design and Development
Post by: Warhawk on June 28, 2010, 04:00:35 PM
Pete,

With the discovery a number of months ago of the Jetex designs for jets, I wondered if the designs might be adapted to Catapult Launch. I haven't done work on trying one out, but maybe this winter...

I'd think that if you scaled one of the designs properly, built light where you could, and used the rubber strip / heavy thread catapult method, they might put in some interesting flights. Unfortunately, most jets are not that generous on wing area, so the glides will suffer, but there are a few exceptions, and if you could get the others to glide even a little bit, it might be a rewarding effort.

Justin


Title: Re: CATAJETS: Design and Development
Post by: danberry on June 28, 2010, 06:05:17 PM
I'll pipe in with some wisdom from Paul Grabskie, who has flown a BUNCH of JetCats.

Don't put the nose weight all the way forward. Go about halfway to the nose. It requires some more weight but cuts down on the inertial moment, which helps recovery.


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 28, 2010, 07:15:30 PM
I've looked at the stuff on Jetex.org. They've got some really nice plans and they shouldn't pose any problems whatsoever to convert. I choose my subjects based on wingspan/area. There are a number of good to great subjects out there which I simply "like" and I've chosen 8-10" spans for convenience. These are NOT intended to be world beaters, but the OKHA easily does 30 seconds or better and my F9F Cougar is getting better each outing with a flat plate 1/16" wing. Both are pretty close to scale.

The tip about the nose weight is a good one, probably the reason one of my attempts was so inconsistent. The F-89 has a VERY long (and pointy) nose almost requiring a more rearward ballast placement. I like to embed the ballast completely, using just enough clay for fine trimming.

If anyone else has a catajet in the hanger, this is the place to bring it (back) into the spotlight. Tell us what it is, how it flys (or won't), post pics - yadda yadda. There's just too much fun to be had with these puppies.

I've gotten the fuselage glued up and the major sanding done. The stab is simply resting on the doublers (triplers?) going up to the stab. These "fin base doublers" my not be necessary (they're sanded to almost nothing), but it's something I wanted to try. Tailplane is tapered to .025". The whole thing as shown is only 3.69 grams. The wing blank (2.5mm/.098") weighs 3.41grams and should finish out around 2.2gm or lighter (based on another wing of similar size/raw weight). I don't think I posted the span: 8.5 inches.


Title: Re: CATAJETS: Design and Development
Post by: BG on June 28, 2010, 07:29:09 PM
Hi All,
Here are my templates for my Mig 15 this jet is great if done light.... I have gotten a consistent 35 seconds out of this designs and many lift assist flights of over a minute.

Next I present my Hawker hunter plan.... this works as a cat jet (reduce the decalage to near zero-zero) and is great as a rapier jet (it took the best flight award at open scale).

Last... a prototype Mig 17.... I have not built one of these yet but I suspect it will go as well or better than my Mig 15.

enjoy.
B


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 28, 2010, 07:51:52 PM
Glad you've jumped in Bernard! It's your doing that's gotten me into this "mess" ;D.

What were, if any, trim quirks with the swept planform? I've gotten the Cougar to do almost everything well but near the end of the flight envelope, it suddenly pitches up and stalls -very small stability margin I'm thinking, coupled with a bodacious amount of side/fin area? I washed the tips out some more which required more nose ballast and that helped a lot, but the condition was still there - just not as severe. A bit more schnoz weight got it "almost" perfect, but a sand grain more or less was too much.

I'm trying boundary layer fences next (the full size needed them to cure low speed problems). Hopefully tomorrow (today).


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 29, 2010, 01:22:15 AM
I got the wing airfoil sanded, dihedral set, slot cut in the fuse, and the first sealing coat on & sanded. AUW is 7.25 grams with the CG at 50%. Worked OK for the still warm (indoor thermals?) bed test. This one will get some color with the basic F-89 red and silver finish, so the finished weight will be pushing the 8 gram mark.

I used the same airfoil that I put to my OKHA and Reichenberg gliders so I'm confident that it'll fly reasonably well.


Title: Re: CATAJETS: Design and Development
Post by: BG on June 29, 2010, 08:01:06 PM
Trim Quirks: Not really they all seem to go pretty well as long as you have ample washout in the wing (swept planforms need more washout apparently).

B


Title: Re: CATAJETS: Design and Development
Post by: lemuel on June 30, 2010, 02:18:57 AM
Pete, when you say airfoil, do you mean that you are specifically sanding a particular shape of airfoil? I just give the ones I have a high point at about 30% and make it look 'airfoilish'. Maybe I am doing something inferior? I also only use 2mm wood to make my wings.

regards
Matthew


Title: Re: CATAJETS: Design and Development
Post by: ArneH on June 30, 2010, 04:34:25 AM
Thanks Pete! This looks like a fun project for rainy summer days. I am not so familiar with CLG, so I have some basic questions: What do you use for Nose Weight on these small jets? And do you have instructions for a catapult? What rubber, length etc.


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 30, 2010, 07:22:58 AM
Pete, when you say airfoil, do you mean that you are specifically sanding a particular shape of airfoil? I just give the ones I have a high point at about 30% and make it look 'airfoilish'. Maybe I am doing something inferior? I also only use 2mm wood to make my wings.

These jobbies, being primarily "fun "models and relatively quick to build (unless u use my laminated fuz method - then 10 minutes more is required ;D), is the reason I didn't specify any particular airfoil. So anything that "works", will work. Natch', if you plan on the jet catapult comp, then you'll want to use the "competition" 'foil.

I use the "flat slope" from a 25-30% high-point to TE 'foil with a phillips entry (or upsweep) to a point 0.5-0.6mm up on the LE (2.5mm wing thickness). The LE to HP curve is an ellipse TLAR shape that is done with a small flat sanding bar (lazy way) or with a shaped bar (finicky way).

I also like to use 2mm wood for these jet models, but 2.5 (0,098425197") is all I have at the moment. The suggested 3/32" (0.09375") is less than 2.5mm so the choice is yours.


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 30, 2010, 08:17:19 AM
Thanks Pete! This looks like a fun project for rainy summer days. I am not so familiar with CLG, so I have some basic questions: What do you use for Nose Weight on these small jets? And do you have instructions for a catapult? What rubber, length etc.

Hi Arne,

For nose weight, I have (still) some sheet roofing lead that I got before it was placed on the "verboten" list. It's 1.5mm thick, and I use a 6mm paper punch to knock out consistent 0.37gm "disks". These are then embedded into a hole punched into the wood wherever it's needed with a 6mm o.d. sharpened brass tube, glued in with CA and then the cavity leveled with spackle (filler) if needed.

For a catapult, I use a hardwood dowel of at least 6mm (10mm is IMO better) with a loop of rubber between 150 and 240mm attached to the end. I use 1/8th Tan 1 for sport flying, 1/8 and 3/16 FAI Black for "serious" flying but HAVE used 160 x 6 BROWN rubber bands from the hobby shop or office supply store (hard to find now in my area :().


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 01, 2010, 01:09:16 AM
Pete,

Thanks for this thread... I've already gotten insight into why a couple of my planes wouldn't fly today when I took my bunch out to the park. My Ohka's are not performing fairly well...no where the time you get but very satisfying and fun for myself and the Grandsons.

Any insights on the tail-less Me 163A 15inch wingspan. Just tumbles... added weight to the nose still no satisfying glide. Will look at washout on the wing tips.

Working on a couple of new clg's for the future... Will have to try BG's birds as well. These things are a real treat and just take a short time to construct.

Regards
Sky9pilot
Tom


Title: Re: CATAJETS: Design and Development
Post by: JetPlaneFlyer on July 01, 2010, 02:09:24 AM
Tom,

On a tailless design 'tumbling' invariably means that the CG is too far back.. add more noseweight. Tailless models need a CG further forward the normal planes.

If once the tumbling stops the model just wants to 'lawn dart' then you need to bend the elevons (the control surfaces on the wing TE) upward. On a swept wing like the Me163 washout also works well but the elevons should do the trick on their own.

Bear in mind that on a flying wing a 'normal' flat bottom airfoil does not work very well.. Best to sand in some 'upsweep' at the TE to give a reflexed airfoil effect, also an airfoil with a well forward high point is best for tailless planes. If the airfoil is already carved then you might be able to steam some reflex in.. but movable elevons give a similar effect anyway.

Steve


Title: Re: CATAJETS: Design and Development
Post by: chunkymonk on July 01, 2010, 08:47:45 AM
I'm currently working on plans for DH100 Vampire (22.5 cm span), Yak 15 and A10 Thunderbolt (both 19 cm span)! If only work didn't keep getting in the way!


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 01, 2010, 08:56:35 PM
Steve,

Thanks for the input.... will cut out the elevons and add some wire from twist ties and set some upsweep to them. Also some more nose weight to see if we can get the Me 163 into the air.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 03, 2010, 07:24:13 AM
The F-89 is pretty much finished. I decided to pretty this one up a bit with one of the well recognized polished alu and red schemes. Haven't done any lettering or national markings yet - I'll wait till I see if she catalaunches. I think I have some decals that will fit - I have to draw the line as far as hand lettering goes.

With the "paint" (silver floral spray and an Edding marker) and my Techno-pens, I was able to approximate the chosen scheme. Backyard glides needed a bit more nose ballast, so now the beastie is at a nice FAT 9.3 grams - but, seems to have a fair glide.

I WAS planning to take it to the field this morning along with the Phantom Flash, but I didn't think I'd have time. I needed to get at least one GOOD flight with the PF for the cookup (got two before the wind got too strong :)). I'll go out again this evening after the Germany/Argentina World Cup match (if the beer level stays below eye level ;D).


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 03, 2010, 07:35:01 PM
Pete,

The Scorpion looks great. Glad to hear she's gliding so well. Haven't had a chance to get back to the park and will be out of town for about a week so no building or flying for a while. Started working on a Douglas D-558-1 Skystreak based on the old Comet plan. I am also working on a Grumman EA6B will keep you posted.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 04, 2010, 11:53:53 AM
Thanks Tom.

I was going to run to the field earlier and decided to give the Scorp another toss in the backyard. Wasn't a good idea :(. I recently "share" the yard with a sandbox, a massive wood-framed swing and a "hollywood" swing. The toss went clear across the yard, smack into the swing's main upright, taking off one of the pods, tailplane and popping the wing loose in the slot (and a nice dent on the leading edge). The high weight, resulting in a higher speed and energy really showed it's "bad" side.

One BIG caution must be made clear! Those big wing pods (or ANY form of tip tanks) MUST be absolutely square to the centerline, otherwise the aircraft will never trim out. This also means that, even with the pods parallel to the wing CL, the WING has to be perfectly centered an square. An easy alternative is to leave the pods/tanks off. In the case of the Scorpion, which has flown without the pods and is pictorially documented, it simply doesn't "look" right. The same applies to the F9F Panther. For this reason, I can't recommend a model with tip tanks (profile) as a first catajet.


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 04, 2010, 07:11:09 PM
I got to the patch late this evening just in time for the wind to die almost completely. I wanted to get two more flights with the P. Flash, but a repair failed, nixing those tries. The F-89 turned out to be a mixed bag.

The GOOD: It flys.

The NOT so good: A bit too much incidence, a severe rolling tendency to the right, the way I mounted the stab is NOT strong enough - the ONLY part that broke.

I was able to get the roll at least under control to where it only completed one rev, leveling to a fast but flat left turn, then breaking right. The right panel somehow ::) ended up heavier than the left. A bit of ballast on the left reduced the right roll and the glide is now in the correct direction (almost). Another stab break (four in all) and impending darkness made me switch models.

The Scorpion shows definite promise. A few minor changes and I'll have the plan ready for posting.


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 06, 2010, 04:49:58 PM
It's truly surprising what a tiny bit of imbalance will do to these smaller planes (I SHOULD know better - or lay off the beer ::)).  The right panel was 0.13 grams heavier :-X.

Laterally balanced, all added warps/tabs removed - except for the gurney strip on the bottom TE of the stab - and the puppy sails clear across the backyard 10 for 10. Before, it was not consistent getting maybe 50% glides that looked ok. Now, they don't look ok, they are GOOD (and fast). It appears that the Scorpion needs very little to NO neg. incidence on the tailplane (<0.5°) - the Phillips entry on the wing might be enough, possibly because the high stab location is above the wing downwash(?).

Hoping for calm tomorrow morning or afternoon. An evening outing is out of the question with the semi-final against Spain. Too bad the Netherlands squeaked by Uruguay (sorry, Wout).


Title: Re: CATAJETS: Design and Development
Post by: chunkymonk on July 09, 2010, 05:30:44 AM
Just a couple of quick photos showing my last 2 Models. The latest being a model of Burt Rutans Space Ship 1. Modified from the Ebenezer Plan by John Kay and scaled down to a span of 6"! Built in an hour sat around after work and test flights (by hand) went well last night. Plan will come soon.


Title: Re: CATAJETS: Design and Development
Post by: lemuel on July 09, 2010, 05:42:47 AM
Great designs Chunky! well done.

regards
matthew


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 09, 2010, 09:22:30 AM
Right on, chunkymonk! That's what it's all about! The Vamp looks like it has some flight rash(?).


Title: Re: CATAJETS: Design and Development
Post by: Willi_S. on July 10, 2010, 12:33:55 PM
Hello.

I have just cut out all the pieces for Bernard's MiG 15. Soon I will glue it together.

But one thing is not in BGs drawing: where should be the CG?

regards

Willi


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 10, 2010, 06:33:31 PM
Chunky,

Great looking models...love the Spaceship 1 and the Vamp. How do you hold them for launch?

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 10, 2010, 07:30:11 PM
After getting the F-89 flying very nicely today, I "had" to get that "one more flight" :-\

 It'll get fixed, with a smidge more dihedral. Gory details in the "went flying " thread.


Title: Re: CATAJETS: Design and Development
Post by: lemuel on July 10, 2010, 08:46:25 PM
Those catapult launch models are dangerous. They are usually the ones that you fly the most when you get to the field....

regards
Matthew


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 10, 2010, 09:13:56 PM
 ;D

The Born Loser and P. Flash only got 1 flight each. The rest was all catafull, culminating with the 5 minute + flight of the new Kitty Katze. The Cougar got the most out of the nice HOT weather.


Title: Re: CATAJETS: Design and Development
Post by: Willi_S. on July 13, 2010, 02:25:42 AM
Hello.

I finished my first catajet now - the MiG 15 according to BGs plan. It came out a bit heavy at 13.7 g flying weight.

On ask for giving me information about the C of G a few posts further up I didn't get any reply. So I found 'my' C of G by trial and error until the jet made a nice glide from a throw out of my hand with a slight tendency turning to the left. Then on to the first catapult launches. The model makes a nice corkscrew up with about 1 1/2 turns to the left. Then it rolls or loops into level flight. But then it behaves very strange! In 1 of 5 launches it gets into a nice left hand glide with a bit of wingdropping to the left. But every 'drop' is recovered and it glides on.

In 4 of 5 launches it rolls into level flight. Then the forward motion nearly stops and the model turns left into a very stable spin to the ground. No recovery from this spin at all. This happened very consistently in a row until 1 'normal' glide occurs. The next launches again ended in a spin. The spin is not fast but very stable.

I tried many rudder- and elevator trim settings but nothing really worked! Is anybody out there who can give me some advice what to do.

I'm an absolute newby to catapult launched gliders. I can make a control line stunt ship fly and I can set the trim for a F1A glider or an indoor rubber job but catajets are a mystery to me.

Kind regards

Willi


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 13, 2010, 08:30:08 AM
Hello Willi,

That is EXACTLY the same "problem" that I have (had) with the F9F Cougar. I have apparently solved the problem by adding (a scale feature) boundary layer fences (stall strips) to the wing about one third panel span on each side - the full-size MiG has them also. I just put them on the top surface (1/16th sq strips about one inch long), but it is probably better on top AND bottom. The plane now glides consistently.

Swept wing aircraft like to fly fast and LAND fast. Grumman found this out with the Cougar and added the fences to cure the slow speed handling problems - it also works for models. The fences "keep" the air on the wing. You might also add a very small amount of noseweight and a fair amount of washout to both wings.

Will you be coming to Lampertheim this Fall?


Title: Re: CATAJETS: Design and Development
Post by: Willi_S. on July 13, 2010, 10:03:39 AM
Hi Pete.

Thank you for your advice! I will try the wing fences immediately.

The outer wings had a fair amount of washout from sanding the wing profile. And I 'tweaked' in even more during the flying session.

I hope I will be in Lampertheim this fall. What about you and the Interscale in November in Nijmegen/Netherlands?

Kind regards

Willi


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 13, 2010, 10:30:57 AM
I'm hoping to make the Interscale meet, but with the luck I've had this year with trying to "plan" anything... I might even have something to fly (never flown indoors).


Title: Re: CATAJETS: Design and Development
Post by: JetPlaneFlyer on July 13, 2010, 10:41:20 AM
The flat spin on swept wing models often means you need to move the CG forward and add more negative on the stabiliser.. But this would make a catapult model 'loopy' so might be no use.

Washout and wing fences are also very good ideas. The problem is that on swept wings the tips tend to stall first and because the tips are behind the CG when the lift from a tip is lost the nose pitches up and the model rotates toward to stalled wing producing the familiar flat spin.

Steve


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 14, 2010, 01:16:01 AM
Willi... the Mig looks great.

JetPlaneFlyer and Pete... thanks for all the input and advice... still working on the Me163A. have cut the elevons out and added wire tie hinges so they are fully adjustable. Will begin adding weight to the nose to see if we can get her flying... thanks again for the advice... as Matt said, hard to fly the other planes when the catajets are around... they truly are addictive.

Thanks again guys,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Willi_S. on July 14, 2010, 03:08:48 AM
Hello.

I added wing fences to the MiG and did some more trying yesterday in the evening. The MiG now behaves much better in the glide, but the problem with the stallspin is not entirely cured! In 1 launch of about 10 it occurs again.
The greatest step forward brought a change in my launch routine. At first I launched nearly 45° upward and with a slight angle of the model to the right with all the power my rubber band would deliver. I changed my technique to launching nearly horizontally and the model banks about 80° to the right. Only 75% of the possible power of the rubber is given to the model.
Bingo! This works fantastic. After launch the MiG now proceeds a huge half loop and rolls to the left. This gives a very smooth transition and a nice fast glide with a wide lefthand curve. The times were consistently 15 to 16 seconds and few very good flights with 20 seconds or a bit more. The hights I reached I would estimate as 15 to 18 m. The flight times Pete or BG mentioned of 35 sec. or more were not possible for me.

If I altered the slightest bit in this procedure then there was a bad transition (even the above mentioned stallspin occurred) or the heights were bad or other not so nice things happened.

I have cut the parts for the next catajet in the hope that it becomes lighter and the flight times would be longer. It is based on the numbers of BG's MiG 15 but I changed the outline to look more like a mixture of the French Mystere fighter jet and a Sabre. When it is finished I will post a picture or two.

I have to agree with Matthew - those catapult launched models are dangerous! You can't stop launching and chasing!

Kind regards

Willi


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 20, 2010, 02:54:40 AM
Hello All,

Here's my latest project... the Douglas Skystreak D-558-1

Had a few hours free this afternoon and was able to cut out parts and sand the wing. I tried to sand a taper from root to tip from 3/32 to 1/32 then sand in an airfoil at the 25% point from the leading edge of the wing. Horizontal tail surface is 1/32 balsa. The fuselage is a sandwich of two outside fuselage shapes from 1/32 and a center core of 1/16 balsa with the grain vertical glued in four sections of approximately 3 inch sections and the fourth section includes the Vertical Stab and Rudder, not included on the outside forms. I gave the wing a 15mm dihedral with one panel lying flat on the building board and the opposite tip raised. The Wing was one solid piece that was scored in the center and cracked up to the 15mm and pinned and braced at the dihedral and then glued with thick cyano.

I haven't done any glide attempts with it yet will try tomorrow in the morning... will experiment with incidence starting with approximately 1 degree negative incidence on the horizontal stab.

I've decided to use the early NACA experimental white scheme, once the gliding trials are accomplished. It this is successful I post the plans for it with any corrections. Just got the rough drawing on 8.5 X 14 inch paper (Legal Size in USA)

Here's some pics.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 21, 2010, 06:02:20 PM
Hi All,

Trying to catch up on all the promised builds...Here's my mockup of the Natter at 8 inch span. Fuselage is amazingly large for this bird. I've tried to employ all the points that have been made in the various threads... Pete's sanding of the main wing tapering to the tips from the 3/32 root to 1/32 or a little thinner at the tips with the airfoil then sanded to a trailing edge 1/64 or there abouts. sanding the fuselage to a taper at the tail.

Hopefully I'll see some fair times with these latest models...

Pete your Reichenberg is next. Thanks to all for all these great models and the fun they bring.... now to the finishes/schemes

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: lemuel on July 21, 2010, 06:20:40 PM
Nice work on the natter! I have given mine away to my nephew and hope he gets some fun with it. The natter does fly but you need a really good day of thermal activity to get some extra lift. Good luck.

regards
matthew


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 23, 2010, 05:19:48 PM
Hi All,

I have done some more work with the Natter... Some glides in the front yard resulted in changing the incidence of the horizontal stab, adjusting the weight ballast on the nose. Once the proper amount of ballast is accomplished I'll take the clay off and weigh it and add some lead to the nose in drilled holes which will be covered later. It takes a pretty hard toss to get the little wings flying in this bird.

Here's the pics of the semi finished camo of black under surfaces and mottled grey topside. I used acrylic artist paints and drybrushed the mottled spots on the grey. I used two sizes of black sharpie pens and a white jell pen for the panel lines on the black surfaces.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: lemuel on July 23, 2010, 05:50:48 PM
Yes, she ain't no floater. It would thermal though I believe. Nice Job! you are an excellent painter/ finisher.

regards
Matthew


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 23, 2010, 06:44:20 PM
Matthew,

Thanks for the comments ... I'm looking forward to putting her on the catapult as soon as I finish the front lawn trimming. Should be fun with the fetchermites ;D :D :)

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 24, 2010, 03:03:02 AM
Hi All,

Got the Bachem Ba 349 Natter trimmed after adding approximately a negative 2 degrees of incidence on the horizontal stab and removing some ballast and with a hefty toss got her to fly across the lawn and into the neighbor's yard ...15 to 20 yards. I was pleased to say the least to see her glide like that. May do pretty well off the catapult.

While I was at it I got the Douglas D-558-1 Skystreak trimmed and she was suprising... with a negative 1 degree of incidence and a little less ballast on the nose she took off in a very flat glide and crossed the lawn the neighbors driveway and out into the street, broke off the toothpick hook but was really sweet to see.

The model was finished with Artist Acrylic paints thinned with water. Markings were made with photoshop and printed on thin mailing labels cut to size. The panel lines were fine Sharpie permanent marker. I borrowed Chris Starleaf's suggestion of using a straight edge cut from thin cardboard (cereal box) so that it can be bent over the fuselage.

Here's the finished Skystreak pics...Can't wait to get her on the cat. I think with the sanding of the wing as Pete suggested and tapering the fuselage even at the finished weight of 18.9 grams with ballast she'll fly...again I don't compete so just some local park flying will be quite satisfying. I find the painting pretty good therapy. If she flies fairly well...I'll post the plans on site.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: lemuel on July 24, 2010, 07:57:29 PM
Looks very cool!


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 26, 2010, 08:05:11 PM
Thanks Matt,

I got out for some flying today and was very pleased with both models.... the Ba349 Natter has great potential... got a good flight after a little tweaking of the ballast and the launch technique. She didn't like the full stretch of the cat rubber... would only do a huge loop. After backing off on the stretch a bit and angling the launch slightly off directly into the wind and a slight bank (I launch left handed) on the cat she climbed in a nice left hand spiral and then rolled out on top into a right circle with a very nice flat glide. I tried to time her with my sweep hand on my watch and got approximately 19 seconds. Was very pleased with this. I feel certain that I can break my 20 second barrier at the local park.  Unfortunately my Fetchermite tripped on the retrieval and broke the main wing off the fuselage... After repair and time to dry with cyano I repeated a flight of 18 seconds.  ;D ::)

The Skystreak D-558-1 still needs tweaking...I was only able to get a large loop...need incidence reduced on the horizontal stab. The glide was fairly flat with a little stall quickly recovered from. I thing the incidence correction of about 1/2 degree should cure this. Other wise I think she should start flying very well. I forgot the camera so no flight shots as of yet.

Thanks to Pete and the guys who have shared the building and trimming techniques on this and the related threads... I've learned a lot and have really enjoyed the flying and the Fetchermites have had a lot of fun as well.

I'm going to refine the Douglas Skystreak D-558-1 plans a bit more before uploading them to the plans site.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: BG on July 29, 2010, 12:50:56 PM
Hi All, Just back from 3 weeks in the high Arctic.

So Willi..... I think you need washout sir. I ended up with a significant amount of washout on both tips and mine flew fine without the fences (too lazy to put them on).

B


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 31, 2010, 06:01:02 PM
Got out late this evening for another test of the F-89. I was able to glue everything back together, this time with a bit more dihedral and NO warp in the left panel :-[. A couple of hand tosses into the tall weeds next to the main field made me remove some of the weight I had added to the left panel for turn. Another toss had me removing ALL of the weight :).

A light pull on my rattiest sling went nearly straight up - very slight tendency to"climb" but reduced to a 1/2 spiral thanks to the "airfoiled" fin. She transitioned slightly nose down but recovered at about 30 feet (lost maybe ten) and made two nice 70 foot circuits to a greased landing. Two more identical flights and I called it an evening. I'll try to get some in-flight pics tomorrow

I'll update the plan and get it posted within the next day or two. I DON'T recommend this model for starters - it HAS to be built accurately (or leave off the tip pods :P).


Title: Re: CATAJETS: Design and Development
Post by: Pit on August 08, 2010, 01:03:15 PM
Made another 2 3/4 flights with the F-89. I didn't change anything from the last outing. If anything was different, it was for the better with the first two flights over 20 seconds (22 and 26). The next 3/4 WOULD have been great had it not been for the boundary fence in the pit area.

The stab got literally blown off and a nice dent along the top of the port wing was the final tally >:(. Time WOULD have been over 30 seconds (WHAM at 29).


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 15, 2010, 12:03:55 PM
Pete,

Too bad about the "WHAM"...glad to hear you got her sorted out. Sounds like you had some great flights.

Look forward to the repairs and inflight shots.

Got inspired by the Lear Fan and made one up on Friday...What do you know about v-tails.  She would glide strait and level without any ballast ( I think because of the long nose moment) but as soon as the speed dropped off she would stall and snap into a spin. I haven't tried adding nose ballast yet just took her out into the front yard for trimming.

I will post pics as soon as my computer gets repaired....snafu with the modem ??? ::) :o :'(

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 16, 2010, 01:58:14 AM
Hi All,

Got the computer working again... Not so much the computer but the guy hitting the keys ::) :o :D

Here's a few pics of the Lear Fan 2100 catajet(fanjet) made from the only 3 view I could find on the net. The fuselage is almost the same length of the wingspan just a little longer. I took great pains to taper the wing from root to tip then sanded the airfoil with the apex of the foil at 30% of the chord. Roughly balanced at the 30% chord. The plane is short coupled but I couldn't resist the shape. Soooo sleek. Just looks very hot and fast.

As I shared with Pete... I get a stable glide as long as she has speed but as soon as she slows down the nose drops and she snaps into a tail spin and does the impression of a lawn dart. Didn't have time to experiment with adjusting ballast and incidence yet will share these as soon as time permits. Would appreciate any suggestions in regards to the V-tail set up and adjustments.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: danberry on August 16, 2010, 07:35:29 AM
I'm seeing a need for dihedral.


Title: Re: CATAJETS: Design and Development
Post by: Pit on August 16, 2010, 12:10:49 PM
I'm seeing a need for dihedral.

I agree. At least double what you have there. It might look a bit funky when compared side by side to a three-view, but it will make a world of difference. The Scorpion really tamed down with 50% more dihedral (looks 'orrible, tho).

Getting V-tails dialed in can be traumatizing, as ONE surface adjustment affects two directions. The only change that won't mess up two is incidence, UNLESS the unit is biased to one side..

A neat, good looking project.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on August 16, 2010, 08:12:52 PM
This is my son's F-15 catajet glider. It's a slightly modified kit from an Aussie company called Artmill who produce a line of "chuck glider" kits. It's 370mm long (now :-[ ;)) x 300mm w/span with almost 50mm dihedral :o :o. The kit wood is heavier than I'd like with printed detail on one side only. I have an F-5 to build with him also from Artmill.

As you can see, I've detailed both sides and the top and underside, plunged a canopy and dug up a side view of an F-15 driver for the cockpit, made pylons and missles, painted it and added decals from the ink jet. I know it's heavy but my boy loves it as it looks "real". The cat-hook is a straightened paper clip.

The catapult used for this model is made from 250mm of looped clothing elastic with a small split ring for hooking up to the glider. This gets it up to about 30-50' approx (depending on the wind) launched at around 45deg where it will either loop or just drop it's nose both into the trimmed r/hand glide that lasts for about 10-15secs. We have an unofficial glide of longer in still air that wasn't timed.

The F-15 has lots of landing rash, damage and MANY repairs, and it still flies. :o

Keep flying all
Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 16, 2010, 08:25:47 PM
Thanks for the input... Pete and Danberry... I'll give the wing more dihedral...I was thinking about this in prep for a stick and tissue rubber powered model. I really like the lines of this bird. FAAMAN ...love the F15. Glad to see the landing rash....just means she's been in the air. My grand kids love the catajets and they like them all painted up as well...me too.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 17, 2010, 12:59:19 PM
Pete & Danberry

Thanks for the suggestion of adding dihedral. I added 10mm more and she doesn't look too bad and she doesn't snap into a spin at the end of the toss. I think this may have accomplished the needed adjustment. Thanks. Now to add some paint...just can't seem to leave them just balsa. Will add pics and flight info later.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 20, 2010, 07:54:18 PM
Hi All,

Here's some pictures of the LearFan 2100 catajet. The suggested dihedral wound up being a total of 25mm and seems to have stablized the LearFan. I have not used the catapult yet, but have achieved a nice glide after adding some ballast on the nose and tweaking the left wingtip. I'm consistently getting a 25 to 30 foot glide with a pretty hefty toss. Got to have some speed to get her flying. Here's some pics...going to the park tomorrow...we'll see what happens. ;D

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on August 20, 2010, 10:35:21 PM
Cool Learfan Tom!! Hope it flys as well as it looks, cause it looks great!! ;D Have fun.

Neil


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on August 23, 2010, 09:59:03 AM
Here's a project I started on Saturday, it will be a catajet version of the Handley Page HP.115 from the Jetex website.

Printed out on A4 and taken to my local copy-place I got it enlarged 150%. Looked a good size at this enlargement for an unusual model to fly.

So the plans were transferred to balsa and then cut out. The fuse balsa is med-hard 2.5mm, the wing 1.5mm and the vertical stab 1.0mm.

The wing was assembled first, but I wasn't happy with how the end grain was exposed and probably easily damaged during "normal" flying so I modified the assembly by cutting 3mm from each L/edge and substituted 2.4mm thick med balsa 3mm wide as the new L/edge slightly rounding off the underside before gluing to the rest of the wing so that a slightly drooped L/edge can be sanded in when dry. I'm hoping that this will help the wing's aerodynamics work a bit better (ala F-102, F-106, Mirage) than the flat triangle on the plan. I'm trying to stick as much as possible to the plan without altering it too much so this is why I haven't added a "curved" slot in the fuselage for the wing and hence the leading edge alteration.

Cheers all
Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 23, 2010, 11:52:09 PM
Hi All,

FAAMAN....your delta looks great. I shall follow your progress with interest... I want to do the Convair Deltas F102 and F106 in the future.

Re: the Lear Fan it was an interesting day at the park... she is very sensitive to the smallest changes in trim. I made the above dihedral change and the dihedral is 25mm under one wing tip while the other panel lies flat on the building board. I like the painted finish but it did cause a slight warp in the left wing panel. This wasn't noticed until the second catapult launch. I must admit that this is one fast bird off the cat. On the first launch I stretched the rubber approximately 1/2 the tension of the rubber. I lost sight of the Lear right off the cat. She is soooooo fast that I had no idea where she went. After a five minute circuit around the field I finally found her about fifty feet in front and to the right of my launch stance. On the second launch at about a quarter of the tension at approximately 30 degree angle she did a sharp right rolling arc and did a lawn dart in the grass 40 feet in front of me. Upon closer examination I noticed the warp in the left panel. With a few tweaks of the wing panel twisting in the opposite direction the majority of the warp was removed. On the third launch with 1/2 tension she performed a nice big loop with a slight right bank and steep nose low glide. I removed some ballast from the nose and put a small pinch on the left wing tip top. Fourth launch at approximately a 45 degree angle at the same tension and she climbed out to about 40 feet and rolled out into a right banking turn and glide. I tweaked the left panel again and removed some more ballast from the nose of the Lear. One more cat and I was reward with a nice high launch and 15 second flight. So I decided I would add more stretch on the catapult. More as full cat launch! :o ::) What I got was a tight right rolling climb to approximately 50 or so feet. When she rolled out of the launch she was inverted and completed the down leg of the loop and then started a right glide across the field.... amazing how far this little bird got in 18 seconds. After a nice 100 yard stroll across the park between the trees I recovered the Lear. I'm thinking she needs to be about twelve inch wing span or so. Much easier to see on launch and hopefully not so sensitive to trim changes. I will continue to work with this model but will build a larger version as well. I will tweak the plans to show the changes I've made and post them in the plans sections with a few notes to the changes to achieve some satisfactory flights. This is no contest model and I am sure the paint keeps the times down. But I just like to see them painted. Going to see about some artist felt tip markers to get some schemes lighter on a model. Sorry for this being so long. Any insight others might have re: the flights and corrections I'd like to hear.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on August 24, 2010, 08:58:09 AM
Nice 115 Neil! Hope you can get it to catapult well - deltas and scale-type canards are NOT easy!

Way to go, Tom! Your point about a larger model is true - they are easier to see and trim for flight. Felt markers for coloring are a LOT lighter than paint, but have a number of disadvantages.

They don't like "sticking" to anywhere glue is, rub off without a sealing coat of clear and most sealing coats will make the color run. Airbrushing a sealant is about the only way to go. Rattle cans WILL work, but u have to "wave" the model thru the spray.

The best markers I have found are those used for overhead projectors or CD/DVD's (permanent) - they even cover glued areas but still show and I haven't seen any in day-glo colors.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 25, 2010, 12:01:16 AM
Pete,

Thanks for the input on the markers...I'll check out the arts and crafts store locally here to see what I can find. Thanks for the sealing info as well.

I got motivated to build a 50's jet instead of the EA6B...so here's the mockup of the McDonnell F2H Banchee. It has polyhedral on the wings of 15mm under each wing tip and the horizontal stab also has a dihedral of 25mm under one stab tip while the other panel is flat on the building board.

Here are a few pics of the mockup prototype.

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on August 25, 2010, 10:30:53 AM
Nice Banshee Tom, now all we need is an FH-1 Phantom !!!

Clear skies mate!

Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 26, 2010, 07:37:44 PM
Greetings All,

Have posted the plans for the LearFan... I do recommend enlarging the plans to a 10 or 12 inch wingspan. This little propjet is very fast. I've had loads of fun and she gets away very quickly. Longest cat launch is only 18 seconds but I had a long walk to retrieve her. Got to work on trimming a turn in the glide.

FAAMAN....the Banshee is one of my best hand launched glides yet. Have yet to catapult her. The FH1 Phantom is already in the plans stage. She should be as good as the Banshee. Will keep you posted. The banshee flew right off the board. She glided across the front lawn and into the middle of the street :o ::). Shall try catapult launch tomorrow.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on August 26, 2010, 08:44:02 PM
Tom, between you and Pete, and probably a few others, there won't be a jet or anything resembling one, that you won't have made into a Catajet. You Guys are prolific. :)

Caley


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on August 27, 2010, 10:53:13 AM
I am in possession of the AF MANUAL 355-10 which is titled aircraft recognition for the ground observer DEPARTMENT OF THE AIR FORCE, Dated April 1955.

My uncle Gave it to me when President Eisenhower terminated the Ground Observer Corps. He knew I was a certified Plane Nut so he wanted me to have this manual.

The planes of Canada and the United States are featured with a few others tossed in(like USSR AND GREAT BRITAIN)

One section features all jets which got me to thinking: Most feature pictures ,three views and Salient features. The IL-28 USSR Twin-Jet Bomber is only an artist's conception.

Why am I sending this one out? If you need something ask and if I have it in the book I will scan it and send it in.

The book is put together in a very easy to take apart fashion. Unscrew the 2 short bolts going thru to blind nuts .

Some pages are missing (C-99) another has torn corners (B-52).

It may be possible you need other aircraft from the book besides so it never hurts to ask. Remember the time frame of this manual covered all kinds of military aircraft and civil a/c as well as helicopters.


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on August 27, 2010, 11:19:28 AM
FlyAce, That's really kewl. My father, a Marine, gave me something similar when I was a single digit midget. It was a deck of cards that pretty much did the same. They were playing card sized cards apparently put out by the Marine Corps. But I don't have those anymore. :(

Caley


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on August 27, 2010, 05:05:53 PM
The Manual I was referring to measures 10 x 6.5 inches and about 1/2 inch thick. ::) :o ;D


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on August 27, 2010, 05:14:20 PM
Sounds like a typical Air Force manual. Big enough to be used to bomb with, if you use up all the rest of the bombs.  :D


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on August 27, 2010, 05:18:38 PM
MOST AF manuals would have been better if they included more pictures. I guess all the good photo's were already snapped up by other people.


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on August 27, 2010, 05:37:23 PM
I spent 24 years in the AF. I'm just glad I don't have to worry about such things now. But now, on with the catajets. Wonder what's next off the board?

Caley


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on August 27, 2010, 06:54:55 PM
I am currently working out the kinks of the Heinkel P-1077. Hand launch looks good but catapults act more spasmodic.

I am getting this one done in plain balsa . I will take a picture soon no matter what.


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on August 27, 2010, 07:11:05 PM
Interesting project. Kinda similar, but not like the V-1 and Okha. Similar idea though. Should be a very fast flyer.

Caley


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on August 28, 2010, 11:47:16 AM
I now have pictures ready to submit. I would like to add these without going thru my friend Curtis. Can the administrator give me help doing the set-up now?


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 01, 2010, 03:16:39 AM
FLYACE1946... sounds like you have quite a treasure there in that recognition manual.

Caley... too bad about the cards... those would be special also.

Well...I almost ruined the Banshee...got carried away with the paint. Warped the wingtip tanks and the horizontal stab strakes. They will be made integral with the wing on the next one. Too difficult to maintain alignment gluing them on later.

Well here's the Banshee, she has been trimmed since the paint and required additional ballast plus straightening of the right wingtip tank. As Pete pointed out with the F-89's tiptanks, they are quite sensitive in setting up trim and flight.

Here's pics of the F2H-1 painted up...Navy Blue from a rattlecan and the panel lines are white gel pen.

Regards,

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 01, 2010, 08:12:58 AM
Woo Hoo Tom!! ;D, looks great!! Anyone for Brubakers's Panther ala "Bridges At Toko-Ri" ?

Happy Flying

Neil


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 01, 2010, 08:54:49 AM
Got it! But not yet put together and probably won't paint it. Cougar already flys.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 01, 2010, 11:12:05 AM
If your interested, go to:

 http://www.windysock.net/windyindexALL.htm

go to the plans page and scroll down to July 2010, have a look at the Convair F-102 Delta Dart for jetex, wouldn't it make a wonderful catajet?? 8) ;D

Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 01, 2010, 04:55:06 PM
Tom, That's really quite a wonderful model. You're sure artistic. I need to get those pens so I can start trying to do panel lines. The lines sure make the model more realistic.

Caley


Title: Re: CATAJETS: Design and Development
Post by: olddog on September 01, 2010, 05:38:36 PM
Hi Tom: Great model and a pretty good shot of a future modeller. Is that the one designed by Bill Hannan and printed in SIG Modeller?

Ron


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 01, 2010, 06:03:05 PM
Thanks to all for the nice comments...

Caley... just a couple of sizes of Sharpie permanent markers "fine" and "medium" and a local Arts and Crafts Store (Michael's) for the white gel pen, in the scrap booking section, will get you started and then take a cereal box or FedEx box and cut a couple of strips of varying lengths and widths and your set. I even took a french curve to one piece to get the curved panel lines on one model. The flexibility of the cardboard works on the curved surfaces. I also use the cardboard to clear the felt tips from time to time as they can get gummed up with the ink some what dissolving the paint.

FAAMAN... Brubaker's Panther would be great...I'll have to build Pit's plan and paint it up.... won't get the flight times of Pit... because of the paint but he's already done the hard work to get them in the air. I'll check out the F102 because it and she and her younger sister, the F106 are favorites of mine.

olddog... Aiden is my youngest grandson 3 years old, "Fetchermite" loves flying the planes. We do that regularly in the mornings when the wind is calmer here. Usually get a delta breeze up the delta from San Francisco most every evening so don't usually fly in the evenings. Didn't know of the Hannan plan... made mine from a 3 view and photoshop. I usually take the 3 view into photoshop and scale it to the size I want and then duplicate it taking one half of all flying surfaces and reversing them and adding them to the opposite side to get exactly the same size wings. I also enlarged the horizontal stab and vertial stab and rudder approximately 20% to add more stability. Really following Pit's lead here. I've really enjoyed these models and get a great kick out of them. But I do need to get a tighter circle glide trimmed into them. Had to chance the LearFan quite a ways to retrieve it when the Fetchermites weren't along. My site is a local park and I use most of it up flying the 12 to 15 seconds I usually get from a cat launch. Great fun...jump in. I'll post my plans of the Banshee when she gets a few cat launches under her belt.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 05, 2010, 02:42:23 AM
My handley Page HP.115's main wing segment has been finished shaping, detail pics should show the leading edge shape as well as possible.

Keep flying!!

Neil


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 11, 2010, 01:30:08 AM
Some more progress for the HP.115 ....... ;D


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 13, 2010, 07:48:27 PM
FAAMAN... the HP115 looking great. Even a formed canopy for the profile fuselage... awesome. Looking forward to more pics


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 13, 2010, 08:02:11 PM
I just looked in Wikipedia on the HP115. Very interesting aircraft, originally towed to altitude and glided down, then fitted with one engine. There was a reference toward the bottom of the page that said that Boulton Paul P.111 was a comparable aircraft. I can see that it might also be a good subject for a CLG profile model.

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 13, 2010, 08:49:15 PM
Caley, check out this link to Jetex.org, http://www.jetex.org/scripts/yabb2/nph-YaBB.pl?num=1260554113, should answer your question, with a few tweaks of course.

Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 13, 2010, 09:41:23 PM
Neil, Ah!, Rapier powered. Roger always does such nice graphic work. My guess was good that the Boulton Paul would be a good flyer. Got too much other builds going on. I just mentioned it in case someone wished to do another CLG.

Caley


Title: Re: CATAJETS: Design and Development
Post by: JetPlaneFlyer on September 14, 2010, 02:08:40 AM
I just looked in Wikipedia on the HP115. Very interesting aircraft, originally towed to altitude and glided down, then fitted with one engine. There was a reference toward the bottom of the page that said that Boulton Paul P.111 was a comparable aircraft. I can see that it might also be a good subject for a CLG profile model.

Caley,

The HP.115 was never flown as a glider. It had the jet engine fitted from day one and used it on all it's flights. The HP.115 was built to test low speed handling of the highly swept delta wing as part of the development work for Concord. The proposal was originally for a glider but it was changed to jet powered before construction of the HP.115 was started.

The BAC 221 was developed to test the high speed regime of a Concord type wing.. The HP 221 would make a really nice cat jet ;)

Steve


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 14, 2010, 09:21:08 AM
Steve, Thanks for clearing up my mistake. I apparently mixed up what I read, not unusual.

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 14, 2010, 09:34:36 AM
Check out this site for a BAC221 research aircraft. It's in French but it's got v.good pics.

http://prototypes.free.fr/fd2/fd2-4.htm

Have fun!
Neil


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 14, 2010, 09:50:00 AM
Found this link too ..... http://www.nuricom.de/10000/index.htm


Title: Re: CATAJETS: Design and Development
Post by: JetPlaneFlyer on September 14, 2010, 01:12:23 PM
Here's a nice 3-view of the BAC 221


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 14, 2010, 05:43:39 PM
Ya'll keep coming up with the most unusual birds to model.... love the delta's will have to put them on the "to do" list.

Looking forward to seeing more.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 17, 2010, 05:10:18 PM
Nice Banshee Tom, now all we need is an FH-1 Phantom !!!

Clear skies mate!

FAAMAN... I had the Phantom in the works and here's a few pics of the mockup.... I like the polyhedral on the wings and seems to make her a bit more stable in the air. Glides pretty good across the living room so far. We'll see how she does outside on the cat. This one has wingspan of 8 and 3/4 inches. a bit bigger than the Banshee. Going to go with a Marine scheme dark navy blue and yellow.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 17, 2010, 07:11:37 PM
The Banshee s one of my old favorites that I've nearly forgotten about, another being the F-101 Voodoo. Just about all of the early jets were SUPER good looking, and you've done a good'n on this one.

I haven't had much time for the catajets lately in spite of the "good" building weather (read: crappy outside) with finishing some leftovers and getting a model fini for the upcoming contest (my first indoor) in November.

Hope the Banshee goes well on the sling.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 17, 2010, 08:46:30 PM
Sneaky Tom ;D. Your Phantom looks great to me, how much did you enlarge the tail feathers over the original? Betcha she goes real good "under power' from the cat. Cool colour scheme as most FH-1's were relatively plain in their finish.

This catajet 'thang' is getting out of control guys, even my kids are making suggestions as to what'll do well. They seem to like the weird ones 8) , here's two from them.

Enjoy, light winds,

Neil


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 17, 2010, 10:02:20 PM
In case your wondering, the straight winged beastie is a (Chance?) Vought F6U Pirate USN nightfighter, the swept wing one bird is a Republic XF-91 Thunderceptor USAF prototype fighter.

Cheers,
Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 17, 2010, 11:04:17 PM
Sneaky Tom ;D. Your Phantom looks great to me, how much did you enlarge the tail feathers over the original? Betcha she goes real good "under power' from the cat. Cool colour scheme as most FH-1's were relatively plain in their finish.

This catajet 'thang' is getting out of control guys, even my kids are making suggestions as to what'll do well. They seem to like the weird ones 8), here's two from them.

Neil... and Pit...

I guess I fit into the weird category... I've already downloaded the Pirate 3-view and planned to get it in the air soon. These catajets can be be cut out and in mockup form in just a couple of hours. I must admit I looked at the XF-91 but the wing design just makes me wonder about strength and flying ability...thin at the root and thick at the tips ??? what do you guys/girls think.

The tail feathers on the Phantom are enlarged approximately 20% using the TLAR engineering method (That Looks About Right)

I'm also working on a delta F-102 and a swept wing thunderjet F-84F.

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 18, 2010, 03:05:17 AM
This is getting nuts fellow flyers. My secret flight test facility in Western Sydney has ........ well ........ several, ah, ideas happening at present, nuf said ;D So you grabbed the Pirate Tom eh? Sounds to me like a fan of the early USN jets is growing in their .............. obsession? ;) ;) ;) ;) XF-91 would be fun, you could get plenty of washout in that "fat" wingtip.

By the way, went catajet flying this arvo, 5+ knots of wind, not good, we destroyed my son's Ta152H and badly damaged the F-15A. The Ta has been voluntarily retired by my son to be replaced by a new build one, the Eagle will be repaired and retrimmed to cure it's inability to recover from a stall in anything less than 40' !!!! Wind could also be a factor in this too.

My Reichenberg's first "powered" flights resulted in a violent loop with various versions of semi stall, and two instances of "hovering"!!! 8) She really doesn't like wind at all and I'm thinking she needs some more nose weight to control the looping tendency. If this doesn't help she may need the horizontal stab increased in area.

Cheers all,
Neil


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 18, 2010, 05:04:47 AM
Niel, a small increase in stab area won't hurt, but it sounds more like too much incidence. Try "breathing" in some down elevator - if that works, sand in a bit of an airfoil on the TOP surface of the stab (just a LITTLE bit at a time).

How are the hand glides? Most of my catajets (read: ALL) needed a pinch of extra nose ballast to work well off the sling, even though the backyard test tosses looked perfect (the long, floating glide into the far fence/street/neighbor's yard - needs more in the schnoz ;D).


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 18, 2010, 07:05:01 AM
Pit I think you just may be right, the backyard glides are longish (depending on wind strength) and relatively slow, so I'll be sorting elevator/stab first then adding approx 1g to the nose.

Most of the weight of my son's Ta152H (9.3g) was nose weight and it flew not badly at all today (or any other days either), even exhibiting some "penetration" into the wind (climbing, bobbing and dipping alternate wings) before turning and running with the wind (accelerating) and flying into the ground. It was one of these landings that killed it.

Soooo ......... seems you're on the right track mate, thanks for the confirmation of what I was thinking :) 8)

Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 19, 2010, 03:14:57 AM
Greetings All,

I used BG's plan for the Mig 15 catajet and got the parts all mocked up tonight. Thought I post a few pics...I used the scrap balsa I had available so the fuselage is made from stiff 1/8 balsa which I then sanded from the rear of the cockpit to the tailpipe tapering it down to approximately 1/16 inch at the rear. I then cut out the two wing panels from 3/32 inch balsa and sanded in the usual airfoil with the apex at approximately 25% of the chord from the leading edge. Tapering the wing panels from the root 3/32 to tip approx. 1/32 inch with the airfoil. I used the TLAR engineering on this wing. Tail surfaces are 1/32 inch stiff balsa. Wingspan is 11 1/4 inch so she is one of the bigger catajets I've made. Still deciding on the scheme. Here's some pics of the mockup.

I didn't review the posts that BG made with the plan he posted so I added 15mm dihedral on the main wing. Haven't tried gliding yet but looks to need some ballast on the nose first.

Calm breezes,
Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 19, 2010, 07:20:47 AM
Very nice Tom, looking forward to the finished product.

Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 19, 2010, 10:29:07 PM
Neil,

Thanks for the comments... still deciding on the scheme for the Mig 15... leaning towards a Chinese camo version I've found.

Here's the finish on the FH-1 Phantom... My oldest Grandson "Ethan" has already claimed it as his own... can't wait to get it out to the park to test the catapult, so far glides really nice.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 19, 2010, 10:35:36 PM
Hey Tom, Will you adopt me. I don't need much, just some balsa catajets. ;D Sure like all those catajets you're doing.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 20, 2010, 12:43:36 AM
Caley,

Consider yourself a part of the family... but you'll have to wrestle with the fetchermites for the Catajets ;D ;D ;) maybe I can make you a special one.... what do you want? 8)

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 20, 2010, 08:23:15 AM
Tom, LOL!!!!! ;D Nothing other than pics of the fetchermites having so much enjoyment. Their smiles are great.

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 20, 2010, 10:05:40 AM
Tom, brilliant looking FH-1, very cool 8). Love the colour scheme. The smiles on yer "fetchermites' are very familiar, my three get the same one's on their dials!!! ;D

I'm unfortunately waaaay behind with my own catajets :-[, managed to break the wings for my HP.115 yesterday :o >:(, started to build a new set differently to the first as I was having lots of trouble with warping with the original build style.

Caley, how about a purple or pink Reichenberg for you?? My daughters designed their own colour schemes, ......... don't know about kittens and Tinkerbell markings though??? ::)

Have fun all!!!! Keep up the great work Tom ;D

Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 20, 2010, 11:38:07 AM
Neil, Sorry to hear about the HP115. You'll get it streaking through the sky again shortly. Glad your girls are having fun with the models. I'm kind of partial to wild colours, though a purple or pink Reichenburg? How about lavender.  ;D Gotta have cartoon characters on your kids models. I did that with stickers on a purple Baxter Big Pussycat, and the girl who got it just loved it. Not sure if you have 99 cents stores or equivalent down under, but that's where I get the foil stickers. They come in cartoons, stars, smilies and all other kinds of things, and weigh almost nothing, though I guess they could have a little bit of effect on the flight of a catajet.

Look forward to more creations from the catapeople. :)

Caley with too much on her plate to build one. :(


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 20, 2010, 12:33:44 PM
Caley and Neil,

Thanks for the comments.... Love the smiles on the kids faces. Make building even more fun. My oldest wants to build something right now... Maybe we'll get something going so he can personally build it with white glue. Can't trust him with the Cya... I can just see fingers and hands and no telling what stuck together... HA HA. ;D ;D ;) ::) :o

Caley... good Idea about the 99cent store. We get them stickers and toys there all the time. I'll check out something for the catajets.

These catajets go together so fast its hard to get back to the other stuff I've got on the table. :'( ;D

Got to get busy with them though to finish up some cookups.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 20, 2010, 12:38:00 PM
Tom, I use Titebond on all my Catapult flyers. It seems to work just fine. The key is getting the glue joints flush. I think he might start with an HLG for practice. Even a poorly done one can fly a little. I built an HLG called a Dogchew, and am averaging about 8 seconds, which is probably just fine for a starter. And your youngster can probably throw harder than I can. :)

Caley


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on September 20, 2010, 07:49:45 PM
Can anybody show a picture of the FAC approved launching stick?


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 20, 2010, 08:04:50 PM
FlyAce, I'm not familiar with FAC, but generally the stick is 6x1/2 inch with about a 6 inch loop of 1/4 inch rubber for larger CLG's. My stick from Sting Aero has a loop of rubber 7 inches long. You would use 1/8 rubber for smaller models. I didn't know FAC did gliders. Interesting.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 21, 2010, 01:55:52 AM
Hey Tom, Will you adopt me. I don't need much, just some balsa catajets. ;D Sure like all those catajets you're doing.

Thanks All... I'll give the thinned white glue a try and see what Ethan (number 1 fetchermite) can do. Caley is the Dogchew a kit or a plan you used? Caley I put all the catajets together in one album on the Yahoo site here http://groups.yahoo.com/group/ffcookup/photos/album/1930304792/pic/list?mode=tn&order=ordinal&start=1&count=20&dir=asc
I've become a Catajet Addict... :o :o ::) ;D I believe it was Pete that said, "Fly the rubber powered planes first, before the CLG's or you never get them in the air". Tooo True ;D I just have too much fun with the fetchermites at the park with the CLG's.

Neil... was reviewing the thread after you mention of the F-15 and was wondering if the kit for the F15 is a current kit available online? Nice looking bird. Sorry to hear about the TA 152. Was it a CLG?

Hope to finish the Mig 15 tomorrow. Decided on a camo Chinese light green and Dark green over light blue. Hope it turns out ok. After rereading the posts on page 2 re: the Mig 15 I'm adding the wing fences initially.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 21, 2010, 07:49:17 AM
Don't say I didn't warn y'all ;)! Tom, I believe the F-15 can be gotten from PENN VALLEY (it's a West Wings kit). I have the F-18 (no longer in the lineup) that flys great as a chuckie, but is a disaster on the sling - I have NOT been able to get it tamed to work consistently. It's a pretty model tho.


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 21, 2010, 08:43:08 AM
Tom, I found the Dogchew plan on the internet. http://chuckglider.blogspot.com/2010/07/free-model-glider-plan-dogchew-6-tiny.html  I would imagine that you can size it up from six inches to a size that you'd like. I did mine at 6 inches so I could enter the Worldwide Tiny Gliders Postal. Maybe your youngster would like the throw one and you could enter him for fun. http://tinygliders.blogspot.com/

I went to the site you gave, but I need to be a member to view things. I kind of got away from those Yahoo Groups when one person kept bugging me about this or that.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 21, 2010, 04:31:04 PM
Pete...thanks for the info on the F-15 I'll check it out...you were sooooo right about these CLG's...I have a bunch of 3 views waiting in the wings for a redesign for Catajet plans. Not enough time. :'( ;D ;) I want to do the Canadian version of the CF101B...Vodoo should be a nice looking bird. Caught the real thing up in Sacramento at McClellan AFB when they would come through doing ECM training. Sometime they would be the bad guys and at other's they would be the interceptors while the U.S.A.F. guys were playing the bad guys.

Caley... sorry about the yahoo site and the bother you found there...thanks for the Dogchew info...have already downloaded the plan will enlarge to 8 inches and make up two kits for the fetchermites to build with the thinned Elmers titebond. Should be great fun. Also bought some "DayGlo" orange rattle can paint to highlight the tips of the wings like I noticed on Pete's and the other gliders. They (fetchermites) can add what they want to decorate...stickers etc.

I'll let you know how it goes.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 21, 2010, 05:32:32 PM
Tom and Pete, You don't know how hard it has been to resist building catajets along with you. I just don't want to move into my car when I want to go to sleep or eat. My place is getting a bit crowded. ;D

Tom, Glad you got the plan. Sure hope the kids can build them, with your help on the decalage and dihedral parts. Those probably will be the most difficult for them to do. Look forward to seeing each with a decorated Dogchew in their hands.

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 21, 2010, 09:15:29 PM
Tom, the F-15 is a chuck glider by Artmill, made here in Australia. I don't know what nor where Penn Valley is, and it's not the West Wings kit as the Artmill kit is only printed on one side (!!) although there is some passing simularities. You get to draw your other-side/underside. My son's F-15A has a canopy I vac-formed with a pilot and ejector seat i made, a pair of wing pylons with AIM-9 Sidewinder rails with AIM-9's made from wood. I couldn't sort a way to make sufficiently strong enough nor mount AIM-7 Sparrows to the fuse stations without having to replace them (or the fins) over and over ad nauseum ........... The model was a bit heavy even before paint etc and really needs some trimming. I trimmed it for long glides before adding details and paint. When finished flying characteristics were checked and she did good! :)

The Artmill Australia web site is under construction at present. They make several balsa kits types, free-sail sailing boats, stick & sheet rubber powered aircraft (my eldest boy flew one of these for years) and 6 chuck gliders, F-5E, F-4E, F-15E(?), F104, F-18A and Harrier. I've the F-5E to build for the boy now and thankfully he wants a USN Agressor (GO NAVY!!) scheme on it plus wing-tip AIM-9's and a centerline tank.

The Ta152H was a paper D/L HLG (chuck) I found along with a small Cub and a Canuck. I sanded some 0.8mm balsa sheet down to approx 0.5mm thick and got the kids to cut out the pics and glue them down (I had to create in Photoshop the undersides of the wings/tail), and surprise, they all flew!! ;D ;D The now retired Ta is repaired and will become a ceiling guardian in the boy's room after replacement with another Ta. He thinks they look "evil" 8)

Cheers all,
Neil


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 21, 2010, 09:48:55 PM
Just an idea all, and so we don't get too sidetracked off topic, does anyone support the idea of another thread to be started for........... CataPiston models or CataProp? :-[ Guess we gotta be careful of how we say CataPiston! ;D. As there are SOOO many other subjects out there to fly as catapult launched gliders that are piston/propeller powered. I think the natural demarcation line with aircraft is actually propeller driven vs jet driven. So CataPiston would have anything with a piston powerplant OR CataProp would include everything with a propeller be it piston or turboprop.

I thought this idea was worth a float on the forum and I hope I'm not causing problems with already posted turboprop Catajets, but as I said previously, I don't want to go off topic when I produce a "piston powered" catapult model. For instance, I've got 9, yes 9, MkXII Spitfire catapult models in the works for the family and they wouldn't be appropriate to show on Catajets. The Spit pic is of a "Root-Canal" version of the same MkXII Spits on my workbench.

PM or Email me if you like so we don't clutter this thread with babble on this question

Regards all,
Neil.
Cheers all


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 22, 2010, 07:51:25 PM
Neil,

Loved the pics of your collection...I started a collection thread because I didn't want to hijack this thread. Love the Spit...

Here's the Mig 15 finished up...not sure how to determine the CG on sweptwing birds... thought this would need a bunch of ballast on the nose....but tossed it in the living room at the back of the couch across the room...to my surprise is glided straight across the room with a shallow glide right into the back of the couch. I immediately took it to the front yard and gave her a toss and she flew across the yard into the neighbors front yard nice and flat with just a hint of right turn, which was into the gentle breeze blowing across the yards. Approximately 35 feet :o :o ;D Can't wait to get her on the cat. Here's the pics

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 25, 2010, 09:32:48 AM
Just spotted a B-52 Catajet in Yahoo Groups "Free Flight Cook-Ups" (FFCU). It's by member 'kittyfritters' and the two pics are posted in Photo Albums - Howards Hanger. It flew a 16 second competition flight from a FAC regulation catapult which is an 8" loop of 1/4" flat tan rubber.

I think it looks great, does anyone know if he is a member of this forum? It would be nice to get some first hand info and some more pics.


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 25, 2010, 11:40:22 AM
I don't think that Howard is a member here. He IS planning to post the plan on the Yahoo site as soon as he gets some bugs worked out. I have some contact with him, and as soon as I get more info, I'll post it here.


Title: Re: CATAJETS: Design and Development
Post by: High Point on September 25, 2010, 02:30:41 PM
What size sheet balsa is the fuselage and wings cut from; lets say for a 12" ws bird?

Thanks,
Curtis


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 25, 2010, 04:37:34 PM
You can get by with 1/8th. I prefer to laminate 2 x 1/16th to a central core of 1/32nd with the rear third of the center core following the fin sweep. This is for catagliders up to about 10" span. I also add doublers to the front if nose weight looks to be needed (note: the Suchoy [show us your collect...] came out VERY nose heavy).

For 12-18 inchers, I think 3/16 is a good bet.


Title: Re: CATAJETS: Design and Development
Post by: High Point on September 25, 2010, 06:29:01 PM
OK, thanks, I appreciate the info. I'm thinking of joining in with something.

Curtis


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 25, 2010, 06:38:35 PM
From the "Show us your collection ........ " thread I thought I'd add this quote from a post I did there to get the swing wing discussion on this thread:

"Tom, I think you'd find that the Grumman F-10 Jaguar would be a difficult and frustrating subject to fly with swing wings because the distance between the pivot points is very small, causing some large CofG movement probs, all the early swing wing aircraft had this prob 'till the engineers worked out that if they put the pivots further apart it reduced the CofG movement to manageable level. Just look at the planview distance between the pivots of the F-111, F-14, Tornado, Sukhoi Su-17, Su-22, Su-24, MIG-23/27, Tupelov Tu-22 Blinder and Tu-22M Backfire. The distance between these pivots are greatly exaggerated on some of the Russian aircraft, but it also further limits the CofG move."

If you look at the planview of the F-10, you'll see that to swing it's wings (increase the wing sweep) it has to change the actual position of the pivot point forward from the initial pivot position in the swept forward position (pivot point fully aft). The idea of putting the pivots out on 'gloves' or root extensions was to allow fixed pivots for the wings of modern swing-wing aircraft thus clearing up many of the probs, some serious, that these earlier swing-wings had.

Can't remember who asked, but this link will take you to an online Centre of Gravity calaulator ;
http://adamone.rchomepage.com/cg_calc.htm

Keep flying all !! ;D ;D
Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 26, 2010, 07:20:51 PM
Pit and Curtis...looked up the B-52 on the yahoo site. looks nice. One of the things that always facinated me with the real B-52's that flew around my home in Sacramento, CA...they climbed out nose low. I don't know if it was the large swept wing and the horizontal stab incidence or what but it was always kinda wierd to see them climb out with the tail higher than the nose.

Neil...thanks for the cg link... ;D

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 26, 2010, 08:24:31 PM
Tom, I got stationed at half a dozen bases with BUFFS. You're right about the odd way they climbed out. They also had a real odd way they landed in crosswinds, as they could end up with their tail and nose canted way off from the axis of the runway. The landing gear was designed to handle those crosswinds. I was communications support for those crews for probably 12 years. Will be interesting to see what a CataBUFF will look like.

Caley


Title: Re: CATAJETS: Design and Development
Post by: High Point on September 27, 2010, 06:10:18 PM
I've noticed in a lot of posted pictures not much wing dihedral (as best as I can see); how are the CATAJETS performing with the wings built this way?

Thank you,
Curtis


Title: Re: CATAJETS: Design and Development
Post by: danberry on September 27, 2010, 07:05:16 PM
Poorly. As though needed more dihedral. ;)


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 27, 2010, 08:06:20 PM
Tom, I got stationed at half a dozen bases with BUFFS. You're right about the odd way they climbed out. They also had a real odd way they landed in crosswinds, as they could end up with their tail and nose canted way off from the axis of the runway. The landing gear was designed to handle those crosswinds. I was communications support for those crews for probably 12 years. Will be interesting to see what a CataBUFF will look like.

Yeh, I saw one land at Mather AFB when they were stationed there and With the bicycle landing gear I couldn't believe the angle of the aircraft as it landed...the nose was at least 45 degrees off center line of the runway...but as soon as it touched down it squared up with the centerline. Really something to see. :o ;D 8)

I'm curious as to how the CataBuff would fly....a buddy who flew them told me the wingtip of the real ones flexed upwards approximately 18 feet. He had some really neat Red Flag stories to tell.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on September 27, 2010, 08:39:59 PM
Tom, I was stationed at Mather from 1983-1990 when they closed the unit down. :( I've never seen the tips flex up that far, but I guess they could if they are fully loaded with conventional ordinance. They could carry a lot of that stuff. I heard some really good stories also. One wasn't so pleasant for one crew who strayed inside Dreamland and were met and carted away by special agents upon landing. After that none would ever mention anything about that flight. I still wish I was up in the Sacramento area. Loved the area. Just say one of your creations over on the CATAPROP thread. Real nice.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 28, 2010, 09:23:18 PM
Caley,

Sacto is a nice area...we live there from 1977 to 1988. Did a lot of photographing the birds there and at McClellan and up at Yuba City/Marysville, Beale AFB. Got some nice pics of the real birds, SR-71s, U2C's and U2R's, B-52's at Mather and a whole bunch of types at McClellan...A10's, F-111's, F-106's, F-105's, C-130's, C-135's, F-105's and some British birds as well. Loved all the activity.

Yeah, I got a Cataprop on the other thread... my fetchermites have already claimed it as well... got some pics there.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 29, 2010, 08:24:36 PM
Been doing some research through my library and around the web (SFA, S&T, HPA etc) the past week or so looking for some answers in regards to our "launch loop", transition probs, stability and glide flight-path.

So firstly, the "launch loop" is caused by the "excessive speed" required at launch (causing huge lift coupled with the models inability to correct it's set trim for gliding) to get our models to a decent altitude therefore giving us longer glides. In all the references I've checked, including Hip Pocket, it seems that the tailplane (enlarged @ least 25% over scale) should be at 0deg with the wing root at no more than +0.8deg incidence with the appropriate amount of washout for your model. This washout should be started at -5mm root to tip as a starting point. Also, the amount of weight we use for trimming CofG to get a nice smooth glide across the yard is not enough. It seems that at least another 1/2 again as much weight is needed set approx 1/4 - 1/2 way back from nose weights before the CofG. This gets a little messy when a model with a short nose is created and the positions for the weights get a little close or even overlap (more a prob with single engine Prop driven designs).

The probs with transition after launch come down to a number of factors, including speed, inertia, wind direction & strength and obviously model design/trim/weight. From what I've read (in some cases reread 'cause I'd forgotten :-[) it seems we also need a little more dihedral than we've been using (scale models do not have enough for inherent stability in free flying). This modification coupled to the previous ones' mentioned above smooths the transition point.
I came across a thread in "Hand Launched Gliders" here on HPA that tightened the angle of incidence to +0.5deg (! :o), there was also a very good idea to sand an airfoil into the vertical stabiliser so it "lifts" opposite to the direction of flight thus turning without deflecting the rudder and causing form drag.

This is not by any means a comprehensive fix for our Catajet probs, nor is it the be all to end all on the subject. Any constructive input from those far more experienced and knowledgeable is more than welcome, and if I've got it wrong, I gave it a good try. Best way is to trial what I've found on test articles and test, test, test! ;D

Regards all, keep flying!!
Neil


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 30, 2010, 07:25:21 AM
Another thing to try (it actually works for some subjects - HAS been used for comp. C/HLG) is to sand in an airfoil into the stab (Neelmeyer or Clark-Y style) and mount it INVERTED at 0/0 decalage. Supposedly has a teeninesy bit less drag, but the airfoil has to be "just right" to lift just the right amount of "down" lift. I've tried it successfully, but prefer the neg. incidence route - less work.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 30, 2010, 09:53:56 PM
Poorly. As though needed more dihedral. ;)

Which models are you referring to? The Catajets that I have built have sufficient dihedral or polyhedral for a stable recovery after launch and roll out at the top and then proceed in a large 45 to 50 foot circle in a fairly flat glide.

I've found that the angle of launch has a lot to do with the effect of the full power launch. I have found that more balast has helped with dealing with the, as Neil says 10+G Loop. My F-94C has been the most successful of my designs so far with a nice high launch and glide that produces a consistent 19 second flight and a nice walk all the way across the park where I fly. If I tweaked for more performance I'd probably lose it where I fly. Still lots of fun and almost everyone who sees it stops to watch it fly across the park. The dihedral on most of my birds is 15mm under the wingtips and on the LearFan its 22mm with the V-Tail. Still sorting that one out. I don't know if this is appropriate but I use the same rule as for the rubber powered planes. I try to keep the tips above the trust line of the fuselage.

I've been doing most of my engineering on the TLAR style. So most is guestimation. I'm careful with the decalage of the wing and stab. I usually start with +1 degree on the wing and negative 1 degree on the stab. I leave room on the vertical stab to adjust the horizontal stab and use shims to get the glide I'm looking far. I try to get it just below the stall at the end of the glide. Then add a bit more ballast for the catapult launch. I usually try to add turn at the base of the vertical stab/rudder by tweaking the balsa with my fingers. :o ::) must be careful not to crack the balsa.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 01, 2010, 06:16:09 PM
Got the Catajets out this morning to do some flying...remarkable how the slightest warp in the structure affects the flight pattern. The FH-1 Phantom flys fast... needs to be larger which won't be a problem as the last flight (number 5 or 6) she caught a gust of wind on the launch which rolled her inverted... did her best to pull out but lawn darted and wound up in four pieces. Will rebuild larger. Was really flying pretty good but hadn't gotten to transition into the gliding circle. She would roll out on top start a large left turn and then straighten out and glide straight till she landed.

The F94C put in two good flight but the fetchermites wanted to do the new ones so we progressed to the Mig 15. This was a surprisingly good flyer. almost no ballast and she would rocket up on launch. When she rolled out she leveled off and flew straight ahead across the park. Still working on getting a shallow turn introduced. But she glides really well.

Natter was the showoff today... three really good flights very high and all the way across the park...forgot to time her but got a shot of her at altitude...

Lear Fan is still very fast...needs enlarging as well. Wind came up too soon and the fetchermites decided to run the bases at the ball park so we packed it in after the NoCal P40C caught a gust and did a wingover into the ground and then tried to relaunch...did a nice ground loop and destroyed itself on the rubber motor and prop beating into the ground. ::) :o ;D ;)

Will try again...
Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 01, 2010, 06:52:45 PM
Tom, Some great stuff. I always get a smile when you get your fetchermites in the photos. They just look like they're having so much fun, and I'm sure you're having fun watching them.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 07, 2010, 01:13:09 AM
Tom, Some great stuff. I always get a smile when you get your fetchermites in the photos. They just look like they're having so much fun, and I'm sure you're having fun watching them.

Caley,
They are a kick to watch. Especially as they hurry back to re-launch. I know one of them is going to fall on the model one of these days but that's half the fun. It is fun seeing them get excited when the planes take off and fly across the park. The noise they make as they chase them is priceless. ;D ;D ;D

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 09, 2010, 08:32:21 AM
Here's the latest on my HP.115. A new wing was built as the original looked more like a potato chip than a wing ..... enormous warp! >:( Assembly went ok but I had to make a second canopy blank as the first didn't work very well, got a good canopy to use from the second attempt.
 
The pilot and ejector seat were drawn by myself. The part of the ejection seat visible above the cockpit coaming was copied from a pic I found taken from squarely (well, close) beside the real HP.115 at the Fleet Air Arm Museum at Yeovelton England. The pilot and seat are made from layers of paper glued over some thin balsa (0.5mm) to give the details some "3D relief" and then painted with Humbrol enamels. 8)

The landing gear has been created with a paperclip (nosegear) and .3mm piano wire (mains) bent as per plan. I couldn't really leave them off as they are fixed on the full size beast and it wouldn't look right without them. So I'm using the oleo of the nose gear carefully bent as the catapult hook with a plastic kit wheel drilled and glued to the "hook", the main wheels are balsa with paper oleo pants.

I have to work on the flying control surfaces as both are warped ::) (more warping .... hmmm ..... may reflect on me ???) one bent up along the grain and the other has a steeply warped down trailing edge. >:(

My phones' camera is at it again, washing out the colour but at least you'll get the idea.

Cheers all, gentle winds,
Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 09, 2010, 07:26:34 PM
Neil,

Can't believe the detail you put in the cockpit of the catajet.  :o :o ;D kewl ;D

Did it understand that you plunge for the canopy? Slick Idea. "I like it!" as the Rocketeer said sitting on the edge of the pond after his first flight! ;D ;)

Keep me informed on the trimming ...I'm pondering an F102 and F106.

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 09, 2010, 07:41:26 PM
Tom, I built my own vacuum former a few years ago and I'm still learning how to do it well. :) I'll supply a pic of my first attempt canopy blank being used.

I'm glad you like the cockpit, it just adds something when it flies past and you glimpse a "pilot". 8)

Have fun and fly high!! ;D

Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 11, 2010, 06:02:21 AM
Tom, I built my own vacuum former a few years ago and I'm still learning how to do it well. :) I'll supply a pic of my first attempt canopy blank being used.

I'm glad you like the cockpit, it just adds something when it flies past and you glimpse a "pilot". 8)

Have fun and fly high!! ;D

Neil... your vacuform looks great. Very professional looking. I made one for the Koutney Cookup and it works well. I think yours is much bigger than mine. Mine is approximately 8 inch square.

I'll have to try a canopy on my next catajet. Does open up a lot of options.

Keepem flying,
Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 11, 2010, 05:31:36 PM
Everyone's neato CATAJets have finally tipped me to take the plunge. But I really don't know how things will go, as I am terrible at trimming these CAT Gliders, or HLG's. I thought I was beginning to see the light on how it was done, but have discovered that much of what I've done was blind luck, and l cannot figure out how I made one fly. LOL!!!!

Anyway, I am going to try a Heinkel He176. I saw one of these airplanes at a RC swap meet I attended this past Saturday. The gentleman took a three view and scratch built an EDF scale model that is just a work of art. He was waiting for the swap meet to finish so he could maiden it. I didn't get to stick around, as my friend was driving us around and he needed to move on to other chores.

I'm not even sure this is a candidate, but I will build it anyway, and try to do the scale markings as well as I can. If it will glide straight ahead with a gentle toss, I'll feel that as a victory.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 12, 2010, 08:20:50 AM
That ought to work ok as a catajet :). Just project the wing LE and TE to the fuz centerline to maintain the span. The stab looks close to 25% as is, but u could increase it a bit and the fin/rudder looks a bit small.

What size are u going for?

I've come to the conclusion that catajets UNDER 10" wingspan do NOT work too well. They CAN be made to fly decently, but require a huge amount of work. Most of my stuff has "grown" to 10-12", which has made trimming much easier.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 12, 2010, 09:20:13 AM
Caley, what a cool subject, I really look forward to the model. 8) 8)

Pit I agree with you, the catajets have to be bigger to reduce wing loading and slow their glide characteristics, the smaller w/span models events happen far quicker due to their higher loading and larger frustration factor !! ;D

Here's some pics of how I'm fitting my HP.115's elevons so I can adjust trim (being that deltas are difficult to trim), I've used the grain at 45deg so I can "droop" the tips without affecting the whole elevon. I've done a bit of research and it seems it'll help stave off tip stall like washout does, only not as efficiently as washout does, everything's a compromise in this hobby ;D

Cheers all,
Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 12, 2010, 09:39:38 AM
Pete, I imported the 3-View into MS Paint. It sized out at 6 inch wingspan, so I doubled that size. My view is that the tiny ones are too difficult to paint and detail. I'm keeping the tail feathers per the 3-View, and will make it a chuck glider. If that won't work, I'll slice off the tail feathers and enlarge things. The stab is embedded about 1/4 the way up the fin, so removing things will be easy. Because of the wood I have, paint will be all I add. I'm hoping that won't warp the wood like the Helmsman did. So far the paint hasn't caused warping on other models.

Parts are cut out. I just need to sand them and put it together. Not sure what the CG would be. It has a very long nose, so it probably won't require a lot of ballast.

Caley


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 12, 2010, 05:28:52 PM
Correction on the wingspan. It actually will be 8.25 inches. Somehow my Paint program burped and gave me an incorrect printout. I think what happened is that it remembered the size previously and printed that. I'm going to try 3/4 dihedral which is about three times what the 3-View shows.

Caley :-[


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 12, 2010, 05:46:03 PM
That ought to work ok as a catajet :). Just project the wing LE and TE to the fuz centerline to maintain the span. The stab looks close to 25% as is, but u could increase it a bit and the fin/rudder looks a bit small.

What size are u going for?

I've come to the conclusion that catajets UNDER 10" wingspan do NOT work too well. They CAN be made to fly decently, but require a huge amount of work. Most of my stuff has "grown" to 10-12", which has made trimming much easier.

Caley.... good looking choice. I think it has real potential.

I must agree with Pete.... 10-12 inches span will be the minimum for me in the future. They are much easier to trim and a whole lot easier to see off the catapult.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 12, 2010, 06:29:40 PM
I've got everything sanded. Well, I may sand the fuselage a tiny bit to give it a slightly curvy shape.

I think I'm going to do some computer work and do the graphics on tissue and cover. I know that adds weight, but I'm just trying to see if it'll even fly. let alone fly like the way, say Pete gets his to. I'm not really sure what the overall colour is. All there are online for pics are the black and white kind. I think it was just a prototype in basic aluminum colour, so I will probably do it in light gray.

Getting the stab and fin slot had to be done by slitting from the fin LE back. I'll fill in ahead of the stab once I get things glued correctly. I'll also be putting in micro pieces of wood below the stab along the fin to give some grip/support since I'm using 1/20 wood in those locations.

Note the flying surfaces (all) have sub fins and rudders, or whatever they are called. Getting those perfectly aligned is going to be a real pain. The scale model I mentioned earlier did not have these attached. I am wondering if there are several versions of this, those with these little sub thingies and those without. I might just leave them off, as they probably will create a tremendous headache trimming the model, which I am lousy at.

Pete, I did leave the fin the same size, but if the thing is getting a dutch roll or whatever you get with a small fin, I can always add a little with cardstock til I get it right, and then make another stab/fin of appropriate sizing.

I'm stil dubious about it actually being able to fly since it has such a short tail moment. This could be another flop like my U-2 which also had a shorter tail moment than I usually see in CLG's

Well, back to work.

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 12, 2010, 07:29:29 PM
Caley, had a look through my library on the He176, as far as all my refs and the web says, there is only 1 b&w image of the plane at Peenemunde, and debate rages over the actual scheme, there were no discernible markings as you've probably noticed. The popular scheme is aluminium (polished) fuselage with lt. grey wings, horizontal and vertical tail along with the landing gear, just have a look see the model pics I've found. I hope this helps with your project.

Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 12, 2010, 08:00:50 PM
Neil, I figured the colour was aluminum/silvery. I sure would like to do all that landing gear stuff, but that would be some kind of drag and make trimming a super problem. Wonder what those cages on the wingtips and stab accomplish? Landing stability? I've got some silvery enamel paint I could use, though, if my memory serves me the stuff looks terrible unless the surface is perfectly smooth. I don't have the patience for that. Light gray will have to do all over with panel lines.

I'm going to search for a large crafts shop that might carry the gel pens I've been waiting to get for doing panel lines while in Perris tomorrow. I would imagine a Staples outlet might have them. This CATAJET is kinda fun stuff.  :)

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 13, 2010, 12:57:08 AM
Caley

Look forward to seeing your bird come to life. For black panel lines I'd use the fine and medium point Sharpie Permanent pens. For the dark background scheme that need a light line I use the white gel pen the Michael's Craft Store has in their scrapbook section. Be careful with the gel pens they will smear till they dry.

Neil...you're a resource library all on your own ;D ;)

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 13, 2010, 07:15:22 AM
Tom, Thanks for the tip. I'll keep an eye out for a Michael's while in Hemet. Parts sit as was described until I gather these pens. I'm also going to look for paint that matches what Neil showed.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 14, 2010, 01:47:56 AM
Caley,

While surfing the net found this site with your Heinkle 176 didn't know if you'd seen it.

http://ww2drawings.jexiste.fr/Files/2-Airplanes/Axis/1-Germany/01-Fighters/He-176/He-176.htm

Hope this post works for you fairly nice three view of the He-176, but I'd still use the colors recommended by Neil.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 14, 2010, 09:20:15 AM
Just to add a bit of salt to the soup regarding the He-176, the info I've seen regarding all WW II German aircraft has indicated that NONE were ever tested, or even rolled out of the workshop, without a coat of paint - usually the grey. There was too much risk with a polished alu scheme, blinking away in the sun, during the war.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 14, 2010, 10:07:11 AM
Just a quick note on the HP.115, backyard test flights went well yesterday morning and this morning, so well that I bit the bullet and took the Fi103R and the HP to the park for some "aviating" even though there was a 5+knot breeze from the WNW.

The Fi103R is STILL frustrating >:(

The HP had some good results from some low power launches, so continuing to adjust the trim I got up the nerve to do a full power launch across the wind at 70-80deg, Whoo Hoo did it go :o 8)!!! Up approx 40-50 foot rolled right way up and flew 50m approx, quick and a bit "twitchy" but good. So I did approx 15 flights with ok results, so I came away reasonably happy. I still have to finish the trimming but I'm happy that I'm on the right path.

I'll try to capture some pics and video during test flights tomorrow so that over the weekend I can finish the detailing (..... and repairs :-[) and then paint.

Did I say this was going to be a quick note ........... ???

Cheers all

Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 14, 2010, 10:07:37 AM
Tom, I don't think I came across this site, but did see the pics in my picture browser. Not sure why I didn't follow the pics. Guess I was looking for a pic of the real thing.

Seems I may've picked the correct paint colour based on these new drawings. I picked out, or should I say, a very nice lady picked out Folkart Acrylic Metallic Aluminum. It's pretty close, though maybe a bit bright like Pete mentioned about bare metal.

I also picked up some gel pens and those pens that mark white on dark background. Thanks for the Michaels tip. They had one in Hemet, California.

Neil, Somehow I missed your creation, a delta wing!. Glad to hear it is showing good signs. Everyone beware! The skies will soon be filled with CATAJETS and CATAPROPS. ;D

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 14, 2010, 10:19:00 AM
Just a note on the He176, her first flight was in March 1939 with the first official flight 20June 1939, this being before the war taken in context with the only pic, I would think it was safe to say that alley fuse and grey everything else is correct for it's finish. I got this from the Luft 46 site page ...... http://www.luft46.com/prototyp/he176.html

I just love digging for info ;)

Cheers all!!

Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 14, 2010, 10:53:44 AM
Neil, You're a lot more dedicated than me. I just build. ;D This airplane, well, rocket, sure was an advanced design for the year they were doing it. I guess the Germans had a lot of people who thought outside the box. Just glad the people in charge didn't go along and use these designs.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 16, 2010, 03:54:59 AM
Neil,

Ran across this F102 solution to your delta leading edge. Its a conical camber leading edge made from a solid balsa stick 5/16 X 3/8 as long as your leading edge. The conical under camber is carved from root to tip with the root being a flat 1/16 then rolls down to 5/16 at the tip.

Here's a picture that explains it better. Remember its looking at the delta from the rear.

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on October 16, 2010, 02:48:21 PM
Hey everyone, I've been reading a lot of the posts on making the gliders from 3 view drawings but I'm not sure how you figure out where to place the center of gravity. The few gliders I've built F9F and F84 showed the c/g. Not sure how to do this if I try to make plane from the 3 views. Looking for any help I can get. Good flying to all.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 16, 2010, 03:37:55 PM
The way I've done it is to use regular catapult glider numbers. That is, decalage ~0.5° and balance point around 50-55% root chord. Hand glide tests should show a marked glide slope - NOT floaty across the yard and NO dive. THEN try a catalaunch with about 25% pull and see what the model does for starters. I start adjusting glide turn on the building board, sanding in camber on the outside (RIGHT side for left glide) of the fin/rudder. If it shows need for more turn , I add a bit of weight to the inside wing tip. If the transition is poor, I try a bit more rudder offset (or a temporary Gurney flap) near the base of the rudder.

Jets, with the generally short tail moment (short coupled) is not quite so "easy" as a purpose built endurance glider and a flat plate airfoil (as on my present F9F Cougar) present even more willies - a new "proper" airfoiled wing is in the works as is the straight winged Panther.

The whole thing is "cut and try" (and don't tell anyone about the failures ::)).

One thing I just did, as a result of the still occasional spin-in with the Cougar, was to trim the fin/rudder to almost scale size. I haven't had a chance to test the mod yet (weather uncooperative/rain). The next decent day will be devoted to catagliders/jets for the various Postals, so I'll let everyone know the outcome - this coming Wednesday looks promising.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 16, 2010, 09:34:17 PM
I agree with Pit...

I sometimes start the CG at about 30% of the wing chord on straight wings.... I just experiment with swept wings. Because these catajet aren't competition its just try to get the best glide out in the front yard before heading for the park.

Pit...any results on the F111?  Sure getting the itch to try that swing wing bird.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 16, 2010, 09:55:51 PM
>SNIP<
Pit...any results on the F111? Sure getting the itch to try that swing wing bird.

Not heard from Marty (Copbat) yet. He's been laying low since the Geneseo party.


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 19, 2010, 10:17:55 PM
Gents, The glider Heinkel He176 is almost done. Needless to say, detailing isn't one of my talents. The gel pen did more scoring of the wood than marking. Lines therefore got a bit icky. I didn't put the wheels on, but may make them for display setting. Colour is acrylic silver aluminum on the fuse. I couldn't figure out how to get a clear effect, so I painted it enamel silver on canopy and nose to simulate the glass. Not even close. Wings are painted again with acrylic with a mixture of medium gray, white and elm green mixed. Again, not even close to the photo example, but what the heck, maybe a fantasy version. I might size a bond paper pilot on the canopy to give it a driver.

Haven't CG'd it, but from what I think someone was saying, starting around 50 percent probably is a good start. It won't take a lot of nose ballast because of the long nose. Anyone have a good suggestion for a near invisible catahook? If nothing else, it may be a good five second chuck glider.

As you can see, the Allies have already winged it on the right wingtip. Not sure how that happened

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 20, 2010, 07:36:56 AM
Cool beastie Caley!! 8) Looks fine to me. Must've been winged by some marauding RAF Typhoons while on the ground, sneaky sods!!! ;D

Happy trimming and lite breezes,

Neil


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 20, 2010, 10:40:18 AM
Neil, Like I said, not very well decorated, but the best I've done so far. I had to add 1.3 grams of nose weight to balance. Test glides onto the bed are promising. May have to take a tad of the ballast off. When it slows, it noses downward. No testing outdoors until the rain quits, and the ground dries out.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Alvaro Sala on October 20, 2010, 11:20:31 AM
Caley
The bird looks very good. For an invisible hook I use acrylic.

May have to take a tad of the ballast off. When it slows, it noses downward.

What you describe sounds like stall. I would't take ballast, perhaps add some more...


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 20, 2010, 11:36:37 AM
Alvaro, Thanks. I decided to place the hook where the nose gear strut is shown on the three view. That solved that problem. If I decide to add the wheels, the strut is available for the nose wheel.

I did another test glide with the catahook on and it continued this time without dropping its nose. As for the nose in during first glides, it was a flat glide, and when speed bled off, it dropped its nose.

Caley


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 20, 2010, 04:27:00 PM
The icky weather has subsided, and I went out in the back yard to do test gliding. It's fine for a 10 foot glide, but with harder throws a disaster. It went in a curve into the ground and broke apart. I know I had plenty of incidence between the wing and tail, so not sure. Could very well be that I don't throw very straight. I've consistently thrown HLG's into the ground. :( Guess I will glue the thing back together, remove the lead weight and see if some kid would like it with the caveat that it doesn't fly. I think my designing days are at an end. The U-2 Spyplane and this one were total failures. Don't know enough about airplanes to design from 3-views. I'll just sit back and enjoy watching you experts have fun.

Caley


Title: Re: CATAJETS: Design and Development
Post by: High Point on October 20, 2010, 05:51:19 PM
Don't stop Caley; your little glider has inspired me even more and others too I'm sure. I have problems throwing also, except for short test glides, that's why a year or so ago I decided to just do CLG; more consistent launches. So get a sheet of paper and let your imagination run wild. I enjoy seeing your work.

Curtis


Title: Re: CATAJETS: Design and Development
Post by: Zack on October 20, 2010, 06:54:19 PM
Hi Caley,

Maybe you should go directly from soft tosses to catapult launches? I rarely test rocket gliders with hard tosses--I trim them with soft tosses and then see if they can take the full power rocket boost ;D

Zack


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on October 20, 2010, 07:01:13 PM
Hi Caley,
my old friend George Perryman had much to say but some of the things that stuck with me is follows:

1. Get out from the workshop to the Laboratory and fly for fun.
2. If it ever turns out NOT to be fun then I'll look elsewhere for fun. HINT it was always fun with George.
3. When you aren't having a fun day refer back to #1 above.

George really had a lot of fun and the rest of us did to when he was around.


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 20, 2010, 07:02:39 PM
I've YET to get a good "hard" toss to work on a catajet when gripping the thing on the fuz under the wing. What works for me on a "high power" toss is to grip the fuz FORWARD of the wing - like the nose grip of a low-wing rubber model.


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 20, 2010, 07:32:57 PM
Guys, I'm retiring from cata design. One reason it broke was that the gel pen made impressions as it laid down the lines on the fuselage. Where those lines are, is where the thing broke. And I was using too soft of wood anyway.

Pete, as I said, this puppy wasn't going to catajet up up and away. Too weak.

FlyAce, That gliding test was my first chance outside today due to it raining and being icky. The darn traitorous glider had it in for me. ;D

I'll make some big fat wheels like in the three view and make it a display model, waiting for the right kid to give it to.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 20, 2010, 07:50:09 PM
Nooooooooooooooo :o ;) Caley ;D

Don't let the little bugger get you down. Just try again. I agree with Pete... a hard toss is difficult with these little guys. If it will glide 10 feet with a medium toss just start light catapult launches and trim from there.

My experience of trying to toss these little guys hard has would up with most of them doing a lawn dart. As far as the gel pens go... forgot to tell you not to press hard... sorry :'( :-[ I just lightly drag the pen along a straight edge, usually several time to get a line on dark schemes.

Give it another go, girl ;) ;D

Tom


Title: Re: CATAJETS: Design and Development
Post by: danberry on October 20, 2010, 07:59:01 PM
Caley, one word. Dihedral.

That little plane ain't got any. Make it a 14" span and put 1 1/4" under each tip. That might be enough.


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on October 20, 2010, 08:03:35 PM
Tom, If I try again, I'll need to build another. The fuse broke pretty bad due to those lines. Probably would make a naked airplane first. :o That way I trick it into thinking it won't get prettied up. As those gliders I've prettied up first always destroy themselves. I guess they get mad at me for getting a smudge of dirt on them. :D

Caley

Dan, may not look like it has any dihedral, but for its size, which is an 8 inch wingspan, it probably has plenty at 3/4 inch. Indoor glides were rock solid laterally. Just wanted to drop its nose once speed bled off.


Title: Re: CATAJETS: Design and Development
Post by: danberry on October 20, 2010, 08:19:49 PM
Dropped it's nose..... needs dihedral. It needs more.
8" isn't big enough. Go to 14" and see a world of difference. Our 12" Beat The Vart gliders are almost out of control and they're designed to fly as cats. These things are squirrely. Build to a decent size.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 21, 2010, 12:52:43 AM
Dropped it's nose..... needs dihedral. It needs more.
8" isn't big enough. Go to 14" and see a world of difference. Our 12" Beat The Vart gliders are almost out of control and they're designed to fly as cats. These things are squirrely. Build to a decent size.

atta girl Caley...

Bigger span is easier to trim as Danberry says... that's why I'm going to enlarge the LearFan to 11 or 12 inches.... I think the reason the natter and ohka did so well at 8 inches is because they have a thick chord which makes it like a plank. All my birds have a tapered chord wing root to tip. You might try a bit more dihedral as an experiment. It helped my LearFan.

Just part and parcel of the catajet design and development. ;D ;)

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 21, 2010, 07:02:43 AM
Dropped it's nose..... needs dihedral. It needs more.
>SNIP<
All my birds have a tapered chord wing root to tip. You might try a bit more dihedral as an experiment. It helped my LearFan.
Just part and parcel of the catajet design and development. ;D ;)
Tom

And my F-89 "Scorpion"! Looks kinda weird, but it now flys.


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on October 21, 2010, 08:28:47 PM
I cracked the wing on the P-1077 and set it up with more dihedral. It will glide better already so maybe Saturday I will have it up again and it'll do better than 4 seconds,... I sure hope so anyway.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 23, 2010, 01:43:07 AM
FLYACE1946... good luck with the P-1077 on Saturday... hope to see pics soon

Casa c-101 aviojet... 9.5 inch span catajet ;D

I tried the trick that Neil used on the Piper and Aronca on the cataprops and did some Photoshop tweaking of a color three view and used thinner balsa and glued the paper over the balsa. The Fuselage was 1/16 balsa tapered nose to tail with another fuselage of 1/32 laminated to the 1/16 and the paper profiles glued to the outsides of the laminated fuselage. The wing was from 3/32 balsa tapered and sanded to the airfoil profile. Have yet to balance and try to glide it. Need to add my wire catapult hook on the nose as well.

Looks ok... but its kinda cheating.... plus I enjoy doing all the markings myself ;D :o ::)

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 23, 2010, 07:04:01 AM
Tom,
That looks really sharp! Did you do the printing on tissue? I did 2 "test" models with printed tissue finish (another Viggen) and one with a colored dope finish (two coats sanding sealer, then the 2 colors plus graphics). The fully printed tissue with a sealer coat was 2 grams lighter and looked better. I "owned" them just long enough to get them the flying patch the next day ::).


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 23, 2010, 08:31:52 AM
Very nice Tom, don't forget to varnish the model before you go to fly it, this will protect the printed finish. By the way, it was a Super Cub, Fleet Canuck and a FW Ta152H that were made with this method. Turns out strong and allows some pretty hefty "adjustments" to trim without cracking.

Cool build mate, have fun!! 8) 8)


Title: Re: CATAJETS: Design and Development
Post by: High Point on October 23, 2010, 12:50:51 PM
Tom, beautiful job on that little jet!

Curtis


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 23, 2010, 07:00:01 PM
Tom,
That looks really sharp! Did you do the printing on tissue? I did 2 "test" models with printed tissue finish (another Viggen) and one with a colored dope finish (two coats sanding sealer, then the 2 colors plus graphics). The fully printed tissue with a sealer coat was 2 grams lighter and looked better. I "owned" them just long enough to get them the flying patch the next day ::).

Pete... just printed it on bond paper... I thought with the bond paper glued to the thin balsa this would add stiffness to the balsa and be close to the larger size balsa and planes.

I found a colored profile "online" and combined the profile with a 3 view. I then used the sample color (eyedropper) in Photoshop to transfer the colors to the 3 view and added the additional markings. I enlarged the size to 9.5 inches. I'll have to finish the whole thing with some Krylon Clear fogged on at first to set the colors and protect the finish.

This was a plane that I really liked the looks of... apparently there is a Spanish Demo Team the "Eagle Squadron" with a nice silver, red and yellow scheme that is quite striking.... may have to build a larger one with about an eleven or twelve inch wingspan to see how it comes out.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 01, 2010, 07:53:47 PM
While some tissue is being "stain" shrunk on the frame for my P'nut wing, I cut a kit for the F9 Panther. I want to get the plan for the combined Cougar/Panther finished and uploaded ASAP, but the balance point and trim tricks still have to be determined for the straight wing cat. The weather looks to be going to He**, so I might get it built this week.

I got a chance to try a mod on the Cougar this last Sunday. Most of the "jets" I've chosen to do have a very large amount of side area aft of the wing. Coupled with a short tail moment, they've all shown some stability issues that I was able to minimize, but not really cure. I cut down the vert. stab to the SCALE size (I had increased the area about 8-10%), removed a bit of nose weight and had 10 of 10 successful flights with NO fall-off into a spin. I had thought that a bit more washout might be needed, but was not the case (1/8th on both sides). I might pop the wing off and replace with a 2mm airfoiled one to see what, if any, difference it makes - other than more weight. Flight times were in the 15-20 second range in cold/humid late afternoon air.

The Panther will get a REAL wing from the get-go.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 02, 2010, 12:42:12 AM
Pit,

Look forward to seeing the Panther.... sounds like you solved a lot of the problems.... I had been leaving the vertical fin and rudder scale from reading other threads and only enlarging the horizontal stab. Thanks for the update and notes on your progress... will help me in the future.

gentle breezes,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 02, 2010, 11:24:33 AM
The "kit" I've made has morphed to an exploded view. The wing is nearly ready for "covering" - Stanfoil sanded in and glued together. Wood used for the wing was the first 2.5mm sheet that I found with fairly consistant grain/density - didn't bother to weigh it. Same with the fuz wood - "A" grain that was fairly consistent through the three plys. I usually use 1mm for the stab, but had a piece of 0.8mm right in front of me that was the right size, so I used it.

The wing is stretched over the scale size, which is why it looks a bit strange, and I WON'T be using the tip tanks at first. The first pic shows how I splice the center fuz ply to get the grain optimized. Also visible is the recess for the basic nose weight - a 1mm x 6mm dia. lead piece. Once I get the fuz glued up, it'll get tapered from the 60% chord point to the tail. Hopefully, the embedded weight will suffice - a test glide with the thing slipped together was, as expected, tail heavy, but not excessively so. A second bed toss with ballast equal to the lead piece was just slightly tail heavy.

As I mentioned earlier, I plan on "covering" the model with blue "Japico" tissue and making the panel lines with a silver gel-pen. The under surface will be in the closest color to scale that I can get without having to work too hard (these are for quick FUN, remember ::)). I'm targeting 13 grams RTF - it's at 10 as shown.

If this kitty flys, I'll be making a box full for the next big swap meet in March (Lampertheim) - both versions ;D. OKHA production is also "progressing".


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on November 02, 2010, 01:55:35 PM
Hmmm, Pete that is very creative. Reminds me of the paper (cardboard) airplanes I made for some neighborhood kids. The fuselages were layers of paper with weight embedded between the layers on the nose.

Good luck on the production for the swap meets. I guess you are putting each together and at least test gliding to see how they go. The few gliders I made for the local kids were fright tested before they got them. Have fun!

Caley


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 02, 2010, 02:43:01 PM
Yeah, it's a policy of mine to not sell or even GIVE away a plane that doesn't fly (at least a little). Getting and KEEPING any interest in modelling - even with (B)ARF's - is largely dependent on the "success" of the venture. I don't just give the planes a test toss in the backyard, they have to pass a full blown flight. I also cant't take the time or afford to write up a "trimming" instruction sheet, though I SHOULD.

I usually have a couple of cata/tosser'planes along at the field just to hand out to anyone who shows enough interest to at least TRY a flight. The first one is a freebie, the next one they have to pay for OR they can have a free plan to try their own build. I make myself available for on the spot assistance - either at my cave or theirs.

So far, not too many takers :(.

I'm SERIOUSLY considering a move...


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on November 02, 2010, 03:21:31 PM
Pete, I think you do a lot more than what people understand. I think it is just that the new generations are spoiled and lazy, instant gratification types. To get a full trimmed to the hilt cata glider for free is unbelievable. I gave one to a youngster and he was so happy, spending what seemed hours launching and chasing. My problem is that it takes me so darn long to figure out how to put the correct warps in gliders to get them flying even the standard 20 seconds I usually manage. It is a black are I may never figure out, but still enjoy trying.

Have you tried an indoor cataglider design? I understand they are only a gram or two for six inchers and float for what seems forever. Maybe you can try that for your next indoor meet, if they have a glider contest part to their meet. Thanks for this and the other cata thread. I sure enjoy following things.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 02, 2010, 03:50:10 PM
I#d probably do a lot more indoor if I had an affordable venue. There are a lot of places here where one COULD fly, but as a loner the "rent" for the couple hours time ... I'd have to change my name to Rockefeller :(. There's a guy in Aschaffenburg (Dawn of Passion) who flys indoor at a Sporthalle, but I've only got one message from him in the last 3 years.

I DID connect with the indoor RC group in the next town (5 klicks), but they weren't to enthused with a FF floating around the one time I flew a trial run. Cost me 10 Euros for the 3 hour session.

That's why I'm SERIOUSLY considering a move...


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on November 02, 2010, 03:56:06 PM
Pete, All I can say is OUCH! on that fee. That's a lot for a few hours. Hopefully, if you move, you can find a nice place to live, and have that indoor venue for the icky winter months. Wish I could send everyone the relatively nice weather we have here, where I live.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 03, 2010, 11:59:52 AM
I was wondering why the fuz for the Panther turned out so "heavy"...

I had sanded the taper towards the tail, cambered the vert. stab, then slipped the whole works together and went outside for some glide tests. It needed a pinky tip of plasticine for a fair glide - depending on your pinky size, that's moderate to a lot.

Inside, I weighed the clay - 1.2 grams :o! Took everything apart to weight the components. The wing and stab were within "tolerance", but the fuz was 5.7 grams! This was without the clay, but with the 0.36 gm lead slug embedded in the nose (WHY is it rattling???).

This morning, I started cuttin a new one-piece fuz (this is the way most will likely build it) with 3mm (1/8th") wood. Boy, this stuff looks skinny - as if some 2.5mm got mixed with my 3mm stock. DOUBLE DOH!! My painstakingly cut/glued/sanded fuz was 3 layers of 1.5mm (1/16th") :-[! My laminated fuselages are "normally" 3 of 1mm :-[ ::), The lead disks are 1mm thick (rattle, rattle).

The "new" fuz with the 1.5mm fin/rudder already glued on weighs only 2.6 grams unsanded.

OH, well...


Title: Re: CATAJETS: Design and Development
Post by: Zack on November 03, 2010, 02:04:29 PM
Glad you sorted it out! That scale is sure useful for spotting mistakes. ;D


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 03, 2010, 03:51:20 PM
Glad you sorted it out! That scale is sure useful for spotting mistakes. ;D

That's a fact! Actually, I'll probably stay with the "fat" fuz just to work out the trim fine points (decalage, final balance point), and build a "proper" fuz for weight comparison. Fatty will go to an interested onlooker (IF it behaves ;D).

I did get to toss it around in the backyard a bit before the rain started. The glide is better than I at first thought (difficult to make coherent observations at 2 AM ::)). The amount of noseweight should be easy to reduce, as I think that the decalage is too much (cutting inaccuracies).

We'll see...


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 03, 2010, 06:17:03 PM
Pit,

Panther looks great. Should get some great glides with that main wing. Can't wait to try one out for myself. Liked the laminated fuselage. But I agree that most people will use the one piece 1/8 inch.

Tom


Title: Re: CATAJETS: Design and Development
Post by: ddock on November 05, 2010, 10:15:32 AM
Are there 'official' rules for wingspan and length. I see this event is going to be flown at the King Orange meet in December.I found Temco and Cessna T-37 plans (Larry Kruse)Dec. 82 M.A.

DDock


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 05, 2010, 11:00:37 AM
Are there 'official' rules for wingspan and length. I see this event is going to be flown at the King Orange meet in December.I found Temco and Cessna T-37 plans (Larry Kruse)Dec. 82 M.A.

THAT's a question I've been meaning to ask myself, tho any of the models/plans that are now sprouting like mushrooms can be scaled to fit whatever requirements there might be.

Check with the AMA rulebook, I think it's an "official" class there. Not sure about FAC.


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 05, 2010, 11:16:15 AM
Forgot that I have the FAC rulebook. It's an official class. Pic is the catajet rules. The AMA has no catajet class but I guess one COULD fly a jet in the catapult glider class - just DON'T expect to place ::).

Tom's models would get max points for color and markings (and probably detail) ;), but check out the HAMMER catapult allowable :o!


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on November 05, 2010, 11:42:30 AM
Pete, This is way kewl! Nice someone has catajets for comp. Are they serious about the amount of rubber for the launcher, or is that the max allowed. I know my catagliders would fall apart :o with two loops of 1/4 rubber tugging on them. Most of mine like one loop of 1/8.

Caley

Pete, PS - If I lived in your area, you'd have a customer for some of those models you're making to sell.


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 05, 2010, 11:47:49 AM
Caley,
PM me with your snail mail addy. Maybe Santa will be nice ;).


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on November 05, 2010, 12:09:22 PM
Naw Pete. Postage is astronomical from Germany. Find a deserving child, and brighten their eyes. I know that would make your holiday very enjoyable.

Once you experts get things mapped out, I might try building one of your creations. I don't know enough to design and build on my own, though my feeble attempts have been fun.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 05, 2010, 10:30:30 PM
Pit... great stuff with the Panther.... really want to do one of those....

Caley... pm me your snail mail address and I know Santa could find you from here!!! ;)

I think an F94C could fly at Perris ;D

Tom


Title: Re: CATAJETS: Design and Development
Post by: danberry on November 05, 2010, 11:50:48 PM
Denny, you need to get some jetcats built. They're more fun than WenMacs.


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 06, 2010, 10:40:15 AM
Couple more pics of the Panther. I've covered it with so-called JAPICO tissue, which is heavier than Esaki (just a tiny bit) but has a coarse texture much like 000 silkspan. I should have used my Guillow's blue as it is closer to the Navy blue and MUCH smoother, needing much less dope to make it stick and fill. In the first pic, the attached and "paneled" fuz already has two coats of GLATTFIX and is very rough to the touch even after a very light sanding with 600 grit.

The second photo shows the wing mounted. The sharp eyed among you will notice that the nose doesn't look quite right. I used the same template from the Cougar which has a slightly shorter schnozz and a slight lower bulge. The plan will show the correct shape for both. The wingspan on the Panther is the same as the overall length - on this model, I increased the span 1.25 inches keeping the tip chord "scale". This makes the wing appear even more out of proportion (I'll draw in a more "scaled" outline).

This "exercise" is more aimed at the FAC catajet rules where coloring, markings and detailing can bring in another 20 points. The wing is now covered, lined and doped. I was able to keep the AUW to 14 grams - addition of the tip tanks will bring the weight to 15. Not TOO bad for a 11 3/4" span profile scale jet.

Now to house-break the kitty...


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on November 06, 2010, 11:50:21 PM
Tom, Why don't ya try locating another youngster, possible future fetchermite for someone else, and award them one of your neat creations. All I know is that when I give away one of my little creations that I manage to get flying fairly well, and pass it on to a youngster, I get all kind of warm fuzzies watching them have fun shooting and then chasing.

Tom, I guess your weather has probably gone south also. I sure will miss those outings you talk about with your little fetchermites. I sure enjoy hearing about those escapades. And hopefully no more flattened models.  ;D

Caley


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 07, 2010, 01:03:23 AM
Just a note that the plans for the F9F "Cougar" and "Panther" have been uploaded and should be "approved" by this evening. I made a few major corrections to the Panther with the "correct" fuz shape and scale tail surfaces - they should be adequate as the slightly smaller stab on my prototype seems to work ok.


Title: Re: CATAJETS: Design and Development
Post by: Ratz on November 07, 2010, 01:09:19 AM
Done Pete.

Ratz


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 07, 2010, 02:00:58 AM
Done Pete.

Ratz

;D


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 08, 2010, 10:31:05 PM
Tom, Why don't ya try locating another youngster, possible future fetchermite for someone else, and award them one of your neat creations. All I know is that when I give away one of my little creations that I manage to get flying fairly well, and pass it on to a youngster, I get all kind of warm fuzzies watching them have fun shooting and then chasing.

Tom, I guess your weather has probably gone south also. I sure will miss those outings you talk about with your little fetchermites. I sure enjoy hearing about those escapades. And hopefully no more flattened models.

Caley,

I'll pass the F94C to another fetchermite.... Your right about the weather....been nasty up here, just cleared up today. But too wet to fly. I've been busy on the LearFan and on my latest cataprop.... Rutan Pond Racer. I like those weird looking birds.

Pit... I love the look of the Panther...I'll have to get the plan downloaded and start to work on my version.

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 09, 2010, 02:39:17 AM
I got a surprise last night while thumbing thru the Jan. 2010 issue of FM in the Small Talk column. A very nice pic of a 7 3/4" cataPanther that Bill Hannan did back in '67 and mention of one that was in the October '09 issue.

Ain't nuttin' really "new" other than mine may be bigger :-\.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 11, 2010, 09:19:39 PM
I got a surprise last night while thumbing thru the Jan. 2010 issue of FM in the Small Talk column. A very nice pic of a 7 3/4" cataPanther that Bill Hannan did back in '67 and mention of one that was in the October '09 issue.

Ain't nuttin' really "new" other than mine may be bigger :-\.

Pete,
How do you rate? I just got my December issue of FM.... I'll look forward to the Jan issue. Like you say.... nothing new under the sun! ;D ;)
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 12, 2010, 06:59:50 AM
The next issue is Jan. 2011 ::).

I haven't been able to afford a sub yet, maybe next year. A buddy gives me his when he's finished with it - sometimes I even get them "on time" ;D. Usually, tho, I get a huge stack, which takes a bit of time before I can get through them. I'll usually go thru a mag 2 or three times, 'cause I almost always miss some nice tidbit.


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 12, 2010, 12:32:19 PM
I cut a "proper" Panther fuz the way I described on the plan. What a difference! :o! The raw weight of the first "wrong fuz" was 5.3 grams, the "new" one 3.5. It might not need anywhere NEAR the nose weight of the first - maybe none. In any case, it'll be LOTS lighter.

I guess I'll call model #1 a Cougapanth (BTW, it flys. 1st catapull yesterday between squall lines - too much incidence, glide OK).

As I'm in the process of cutting a kit for the Jetco "Imperial" (build thread on RC Groups), I have to squeeze work on the catajobs in during breaks.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 12, 2010, 04:52:12 PM
Alright Pete.... I look forward to hearing how the new one performs... Sounds like your so busy you don't have time to get bored. That's Good!

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 13, 2010, 12:15:39 PM
Bored?!? I thought all that word meant was "drill a hole" - if that's the case, then I get a LOT "bored" :D.


Title: Re: CATAJETS: Design and Development
Post by: Maxout on November 13, 2010, 09:54:17 PM
Some interesting stuff here. I recently built this critter, a Miles M.52. Still needs color markings, but those will come later. When I can get the rubber to stay on the hook until the tension is gone, it does in the high 30's. Unfortunately, it has a tendency to let go prematurely, and that cuts a good 10 sec off. Regardless, thermals wonderfully. Span is only 7.5", too!


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 14, 2010, 01:01:13 AM
Great to see you here Josh! Your input is very welcome and needed - especially the taming of the beasties. That critter of yours looks to have nearly ideal proportions for a regular cataglider (maybe a bit more wing). High 30's is darn good time - my OKHA does only mid 30's with fair consistency (also sans paint).


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 14, 2010, 01:05:07 AM
Maxout.... outstanding... love the choice of plane... nice thick chord on the wing. Good luck with the hook/rubber setup.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Maxout on November 14, 2010, 07:37:35 AM
Maxout.... outstanding... love the choice of plane... nice thick chord on the wing. Good luck with the hook/rubber setup

Yeah... it had better improve soon... getting slapped by the catapult when it lets go REALLY hurts. :o


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 15, 2010, 05:33:31 PM
Maxout.... outstanding... love the choice of plane... nice thick chord on the wing. Good luck with the hook/rubber setup
Yeah... it had better improve soon... getting slapped by the catapult when it lets go REALLY hurts. :o

Yeah, kinda like in Jr. Hi. shooting the bow and arrow and getting slapped by the string...It's no fun.

Gentle breezes and soft landings,
Tom


Title: Re: CATAJETS: Design and Development
Post by: patternpaul on November 22, 2010, 08:39:21 PM
Hi all,

I have an A6 Intruder in the works. I will probably keep it plain for the first one and try painting the second one after I get all the bugs worked out.

Paul


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on November 22, 2010, 08:58:00 PM
Hi Paul, Welcome to HPA. Look forward to seeing and hearing about your creation.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 23, 2010, 10:53:15 AM
A warm welcome from me too, Paul. The A6 has been on my list for catajetting also, so I'm looking forward to seeing yours. I also follow the "fly and de-bug first" rule - usually with the result that I end up having so much fun with the plane that I never get around to "decorating" it, or someone begs it off me ;D.

Have FUN here, I know I do!

Pete


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 23, 2010, 03:39:58 PM
Hi all,

I have an A6 Intruder in the works. I will probably keep it plain for the first one and try painting the second one after I get all the bugs worked out.

Paul,

Ditto all the welcomes above.... Looking forward to the A6.... I've been looking at the EA6B now that their retiring her from active service. Look forward to pictures soon.

Tom


Title: Re: CATAJETS: Design and Development
Post by: patternpaul on November 23, 2010, 08:24:33 PM
I live in VA Beach, VA so I was used to seeing the A-6 and EA-6B all the time. Saw an EA-6B a few weeks ago flying past. Was a great sight. Hopefully I will get it done soon. Work and the Holidays are getting in the way. LOL Everyone on here has such great planes, I am almost embarrassed to post pics of anything I build. I have a bird glider I built for my daughter and will probably make a second one as CLG. That was does not fit into Catajet or Cataprop though. LOL

Paul

BTW, thanks for all the welcomes.


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 24, 2010, 01:14:16 AM
I live in VA Beach, VA so I was used to seeing the A-6 and EA-6B all the time. Saw an EA-6B a few weeks ago flying past. Was a great sight. Hopefully I will get it done soon. Work and the Holidays are getting in the way. LOL Everyone on here has such great planes, I am almost embarrassed to post pics of anything I build. I have a bird glider I built for my daughter and will probably make a second one as CLG. That was does not fit into Catajet or Cataprop though. LOL

Paul

BTW, thanks for all the welcomes.

Maybe start a new CATagory ::) for oddball designs. How about "catawhats?"?


Title: Re: CATAJETS: Design and Development
Post by: patternpaul on November 25, 2010, 11:50:04 AM
That was a good one. Also looks like I need to spell check before I send messages too. LOL Well, maybe proof read is a better way to put it.

I may have to look into making a new CATAgory. LOL Have no clue how though. Maybe CATAbirds? Would there be any interest if I did?

Paul


Title: Re: CATAJETS: Design and Development
Post by: Pit on November 30, 2010, 06:58:03 AM
Forgot to put up the pics of the "correct" Panther fuz. Again, it's the three layers - 0.8mm, 1.5mm and 0.8mm - with the center 1.5mm spliced at the fin LE to align the grain with the fin. It's about 2 grams lighter than the "CougaPanth"fuz at the same stage.

Right now, I'm playing with two Czech cataprop designs (J7W1 Shinden and a Zlin 526 AS) for a limited time cookup on SFA. Have to figure which one to do and then get the plan scaled and printed. Probably do the Shinden as designed (cataprop), then re-draw the plan as the jet version (IF it flys).


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on November 30, 2010, 08:15:12 PM
Pete,

Looking good with the new fuselage... Also looking forward to seeing your other birds for SFA.

Hope the Shinden flys well for you, I think I'd like to try one also.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 03, 2010, 04:52:58 PM
Hi All,

Finally started the F9F Panther from Pete's plan...great design by the way ;D

I made the fuselage from a center lamination of 1/32 balsa with the cross grain per plan. I then laminated two 1/16 balsa outside lamination that were tapered from nose to tail 1/16 down to 1/32.

The wing is made of 3/32 balsa tapered to 1/16 on the right wing and tapered to 1/32 on left wing. I hoping this will result in a nice left turn after she rolls out of the launch.... have to weight to see.

She is a bit heavy...art store balsa is a bit too heavy but its what I had on hand. All up weight now is 13.8 grams. I'm pleased with the glide so far. I think it looks promising. I don't know about the 30 seconds for SFA but should be able to get some decent glides.

Here's the pics so far....won't put paint and markings till I get my best glide. Gonna go for the Bruebaker F9F from the movie Bridges at Toko Ri Movie (un-sure of the spelling) ???

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on December 03, 2010, 06:31:07 PM
Tom, Looks great, and the Fetchermites are probably saying the same thing. :) Did they get their ears lowered? Sure looks like sparse growth upstairs.


Title: Re: CATAJETS: Design and Development
Post by: dosco on December 03, 2010, 07:09:33 PM
As I'm in the process of cutting a kit for the Jetco "Imperial" (build thread on RC Groups), I have to squeeze work on the catajobs in during breaks.

The Panther is one tasty plane.

What is the URL for the Jetco thread you mentioned?


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 03, 2010, 08:43:41 PM
Tom, Looks great, and the Fetchermites are probably saying the same thing. :) Did they get their ears lowered? Sure looks like sparse growth upstairs.

Caley... they've already tossed it in the front yard... as you noticed their daddy gave them a buz cut... wasn't suppose to be that close but the attachment on the clippers wasn't on tight and a slip to the scalp made the buz necessary ;D :D ;) But it grows back fast.

They really like this one... spent over a 1/2 hour in the front tossing it. The didn't want to come in...had to break it before we could come in. Working on their throwing arms.

Tom ;)


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on December 03, 2010, 09:46:59 PM
Tome, I guessed they would have their little mitts on it sooner than later. Hope they didn't break it. And you Guys never have to work on your throwing arms. I think that part is genetic. :D Since they don't like pink, then do one in blue and call it the Blue Buzzard. :o

Caley


Title: Re: CATAJETS: Design and Development
Post by: Pit on December 04, 2010, 03:34:08 PM
As I'm in the process of cutting a kit for the Jetco "Imperial" (build thread on RC Groups), I have to squeeze work on the catajobs in during breaks.
The Panther is one tasty plane.

What is the URL for the Jetco thread you mentioned?

Eduardo, from Colombia, is WAAY ahead of me on his build. He has an advantage in that his primary interest is with vintage gliders ::). The thread is HERE (http://www.rcgroups.com/forums/showthread.php?t=1336967).


Title: Re: CATAJETS: Design and Development
Post by: dosco on December 05, 2010, 08:15:20 AM
Quote
Eduardo, from Colombia, is WAAY ahead of me on his build. He has an advantage in that his primary interest is with vintage gliders ::). The thread is HERE (http://www.rcgroups.com/forums/showthread.php?t=1336967).

Thanks for the link. That is a veritable forest of balsa. Wow. I like it.


Title: Re: CATAJETS: Design and Development
Post by: Pit on December 06, 2010, 06:53:56 AM
I have uploaded a revision to the F9F Panther plan. There is a scaling error, resulting in a too-wide root chord and trailing edge. It's an easy fix, but I corrected the plan. The corrected copy will be noted in the Gallery as "F9D Panther (revision 1)".


Title: Re: CATAJETS: Design and Development
Post by: Pit on December 06, 2010, 01:48:11 PM
Since we've still got lots of time for the "limited time" CU ;) over on SFA, I threw together a F9F Panther to test a "proper" model of my plan. The "CougaPanth" was to test the wing, but looks really weird with the stubby Cougar fuz.

Weight came out fair at 9.4 grams without finish, and I used 1.5mm for the stab instead of the 0.8-1mm specified necessitating a bit more nose weight. The CougaPanth is a heavyweight at 14.9 grams, but flys surprisingly well. I expect the Panther to finish out around 12.5. This model has the corrected wing shape (plan has been amended).

Glide test to the bed has been successful ;D :D.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 07, 2010, 02:56:51 PM
Pete,

Your Panther looks good. I've had some good trimming sessions in the front yard since the rain stopped. I used some sanding sealer and that's all she'll get till I time her hopefully later today. The sun has come out and I hope the park has dried out so there aren't any big puddles.

Got inspired and finally brought out the plan I've been working on since September. The F6U Pirate. I was going to build a 10 inch wingspan model but the fuselage would have be gigantic. The final beta plan is printable on 8.5X14 which give a wingspan of almost 8 inches (7 7/8 inch) with a 10.5 inch fuselage. Makes for a large plane with a lot of side area. She required 1.5 grams of ballast all hidden in the nose ballast compartment. She glides well now and with a tweak of one of the auxiliary fins on the horizontal stab the right turn was removed. Hope to put it and the panther on the cat today.

Here's a couple of pictures.... more with finish later.

Tom


Title: Re: CATAJETS: Design and Development
Post by: lemuel on December 07, 2010, 04:44:56 PM
Nice... you guys are getting awesome at these..


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 07, 2010, 09:56:17 PM
Nice... you guys are getting awesome at these.

Thanks Lemuel...

Had a problem with the incidence on the Panther. Couldn't seem to trim out the major loop under catapult power... Added additional weight to the nose and seemed to get more climb less loop. I decided to give her a max cat launch and didn't notice a cracked tiptank. This caused a left roll that lawn darted under full power...you can guess the result... :'( :-[ ::)

Sheered off the tail and destroyed the tail and the tiptanks were shredded. OOPS I think she can be saved but 8.9 seconds was a far cry from the 30 second goal. Oh well the fetchermites will love playing with this rebuild. A new Panther is definitely necessary. :o ;D ;)

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on December 07, 2010, 10:08:22 PM
Wow Tom, Is that the crash and burn site circled around the model. Talk about carnage.  ;D You can bet that your FMs will vie for the refurbed airframe. Those two are future fighter pilots. The faster the better. Maybe even astronauts which is even faster. :D

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 09, 2010, 03:59:00 PM
Wow Tom, Is that the crash and burn site circled around the model. Talk about carnage. ;D You can bet that your FMs will vie for the refurbed airframe. Those two are future fighter pilots. The faster the better. Maybe even astronauts which is even faster. :D

Thanks Caley... and yes they like to go fast... I'm always having to tell them to stop running in the house ;D. They do like airplanes and flying them. I got them some styrofoam gliders at the Dollar Store the other day for stocking stuffers... They will love flying them till they break them into little pieces.

Working on the Vought F6U Pirate right now... then the repair of the Panther.

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on December 19, 2010, 09:42:08 AM
Hey Tom

Planning to start on your F94 plans. How did the 1/16 wing work out. Did you use a hard balsa for the wing. This winter plan on doing the FH1 and F2H. Love the older jets.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 19, 2010, 05:00:36 PM
Hey Tom

Planning to start on your F94 plans. How did the 1/16 wing work out. Did you use a hard balsa for the wing. This winter plan on doing the FH1 and F2H. Love the older jets.

The F94C is one of my better flyers brings in consistent flights of 19 to 20 seconds. The wing is more like the store bought gliders we used to get for a dime or quarter when we were kids. It works very well. I haven't tried to make a shaped wing with it yet. Good luck with the 94... I'm with you and I do enjoy the early jets. Hope to have the F6U worked out soon. When I get her trimmed and all the specifics worked out I'll try to post that plan as well. Looks promising so far.

Please post pictures of your progress to keep us informed.

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on December 19, 2010, 05:15:39 PM
Hey Tom

Are the vertical and horizontal also 1/16 balsa. Just started cutting the fuselage today going back down as soon as laundry is done

Brian


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 21, 2010, 02:52:19 PM
Hey Tom

Are the vertical and horizontal also 1/16 balsa. Just started cutting the fuselage today going back down as soon as laundry is done.

Brian,

Sorry I didn't note it on the plan... all vertical and horizontal stabs are stiff 1/32 inch balsa (hobbyshop artcrafts store stuff) Seems to hold up well and is not as heavy as the 1/16 hobbyshop balsa used in the rest of the bird. This one has been a pretty good flyer for me and flew right off the board with few trimming tweaks.

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on December 26, 2010, 11:02:14 AM
Hey Tom

Here are some pic's of the F94 from you plans. Right now she's 5 grams. Still need to put the clear dope on then paint. Have to wait till spring gets here for tests. Hope to have better luck than the last model I made. It stayed inverted at the top of the loop then lawn darted. Did not get the chance to fix that problem. Next up is the Phantom and Banshee. Will post as the get father along.

Brian


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on December 26, 2010, 11:35:56 AM
Brian, very nice. I sure like jets, especially the ones from the 50's.

Caley


Title: Re: CATAJETS: Design and Development
Post by: danberry on December 28, 2010, 10:27:46 PM
Hey Tom

Here are some pic's of the F94 from you plans. Right now she's 5 grams. Still need to put the clear dope on then paint. Have to wait till spring gets here for tests. Hope to have better luck than the last model I made. It stayed inverted at the top of the loop then lawn darted. Did not get the chance to fix that problem. Next up is the Phantom and Banshee. Will post as the get father along.

Brian

It needs dihedral.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 29, 2010, 04:28:34 PM
Brian,

Looks pretty good. As Danberry suggests, it might need a bit more dihedral. I forget just what's on the plan but 20mm or 25mm should be minimum.

Tom


Title: Re: CATAJETS: Design and Development
Post by: danberry on December 29, 2010, 05:55:01 PM
It needs more than a bit more.


Title: Re: CATAJETS: Design and Development
Post by: Pit on December 30, 2010, 09:03:53 AM
Just for comparison, I had 30mm (15/side) on my 9" Scorpion and it WASN'T enough!. It now has 45mm total and works fine.


Title: Re: CATAJETS: Design and Development
Post by: pubguy on January 03, 2011, 11:44:36 AM
Some new pictures of the new builds. With three coats of dope on each the F94 comes in at 6g the F2H at 9g and the FH1 at 8g. Now if I can go easy on the paint. All three are built per the instructions. Test flights will tell the story. Made changes to the other F2H added more dihedral. Waiting to test it out. Gotta love winter its a great time to build.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on January 04, 2011, 02:40:55 AM
Brian,

The models are beautiful. I look forward to hearing about your trimming and flying. Keep up the good work. Hard to beat the 50's and early 60's jets.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on January 06, 2011, 05:35:07 PM
Brian,

Looks pretty good. As Danberry suggests, it might need a bit more dihedral. I forget just what's on the plan but 20mm or 25mm should be minimum.

I guess it can be confusing in regards to dihedral and polyhedral. I haven't added each side together on my plans when it comes to dihedral or polyhedral. I mean "X" amount of dihedral on one side if its listed. I try to usually give an illustration of the dihedral or polyhedral on the plan with the amount listed in the illustration. Wingtips at or slightly above the normal thrust line of the fuselage. I know this will open another can of worms re: thrustline. For me it's a central pitch line through the fuselage nose to tail.

Here's a typical picture for the dihedral and polyhedral. Not to scale/nor are the lines exact... just a quick sketch.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on January 11, 2011, 12:38:44 AM
From the "Show us your collection ........ " thread I thought I'd add this quote from a post I did there to get the swing wing discussion on this thread:

"Tom, I think you'd find that the Grumman F-10 Jaguar would be a difficult and frustrating subject to fly with swing wings because the distance between the pivot points is very small, causing some large CofG movement probs, all the early swing wing aircraft had this prob 'till the engineers worked out that if they put the pivots further apart it reduced the CofG movement to manageable level. Just look at the planview distance between the pivots of the F-111, F-14, Tornado, Sukhoi Su-17, Su-22, Su-24, MIG-23/27, Tupelov Tu-22 Blinder and Tu-22M Backfire. The distance between these pivots are greatly exaggerated on some of the Russian aircraft, but it also further limits the CofG move."

If you look at the planview of the F-10, you'll see that to swing it's wings (increase the wing sweep) it has to change the actual position of the pivot point forward from the initial pivot position in the swept forward position (pivot point fully aft). The idea of putting the pivots out on 'gloves' or root extensions was to allow fixed pivots for the wings of modern swing-wing aircraft thus clearing up many of the probs, some serious, that these earlier swing-wings had.

Can't remember who asked, but this link will take you to an online Centre of Gravity calculator ;
http://adamone.rchomepage.com/cg_calc.htm

Keep flying all !! ;D ;D
Neil

Guys and Gals,
Been thinking in the off time with the Dash 8 on the Scale FF Thread, about the F111 and was surfing the web and on the RCGroups RC they have a foam F111 from a Japanese site. It was quite intriguing. Here's the link: http://momo-machine-works.seesaa.net/category/557895-1.html

I'm giving the F111 some real thought about construction for a nice 12 inch extended wingspan with some kind of rubberband extension after cat launch to altitude.

By the way Happy New Year and I hope all had a great Holiday season.
Tom


Title: Re: CATAJETS: Design and Development
Post by: Dave Andreski on January 24, 2011, 12:37:27 AM
I'm considering this one. Requires a forward grip?

Dave Andreski


Title: Re: CATAJETS: Design and Development
Post by: Tmat on January 24, 2011, 01:15:53 AM
Here's a typical picture for the dihedral and polyhedral. Not to scale/nor are the lines exact... just a quick sketch.

Yes, poly just means "many" or more than one dihedral break. But you do realize that both dihedral set-ups you showed are not equivalent right? (I'm sure you do). Tip rise is not an accurate indication of dihedral effect.

Good thread!

Tmat


Title: Re: CATAJETS: Design and Development
Post by: Pit on January 30, 2011, 01:54:03 PM
Had a chance to get to the field today to do some more testing with the F9F(x) CougaPanth. I had made a couple more very minor adjustments with decalage and noseweight, and now have the beastie pretty well trained. It's gotten very consistant with times rarely under 20 seconds and one at 43. Conditions were 0° C, wind @ 1-2 meters/sec with clear skies near dusk. The CG has been refined and I will add the change to the comments section in the Plans Gallery. I was even able to get some video of two flights, the last one was about 27 seconds - they'll be uploaded later.

I am now confident enough to take the Panther for the next outing - possibly Tuesday.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on January 30, 2011, 05:58:45 PM
Pete,

Sounds great... look forward to video... I don't have that capability, but really enjoy the work of those who do!

Haven't been able to get out to fly lately. Working on a 10 inch F4D Skyray from a jetex plan... will post later.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on January 30, 2011, 08:26:39 PM
Here's the vid of the CougaPanth. The transition is actually MUCH better than what the video implies - very similar to the way my OKHA goes. The wing has NO tabs and might benefit a bit from one on the left panel. The launch elevation is now up to about 75° and 45° bank (right).

http://s304.photobucket.com/albums/nn194/staubkorb/FF%20Gliders/?action=view&current=CougaPanth-01.mp4


Title: Re: CATAJETS: Design and Development
Post by: chunkymonk on February 01, 2011, 12:09:22 PM
I haven't got round to building much lately but have been working on a few plans.

Currently in the pipeline I've got Burt Rutans SS1, Fouga CM8 R9,8 - Cyclope 1, Su27, DH100 Vapire, Yak 15, DH Sea Vixen, Starship Enterprise (from the Enterprie series), Canberra, Victor, Avro Arrow, Vulcan, Viggen, A10 Warthog, Hawker Hunter...

Should keep me going for a while!
 ;)


Title: Re: CATAJETS: Design and Development
Post by: Pit on February 01, 2011, 03:11:49 PM
I've done the Viggen and Vulcan. The Viggen is a fair flyer and got better when I increased the wing and foreplane areas, and mounted the foreplane as an auto surface. The Vulcan is a good flyer when it decides to play, then quits when tired ::). NOT that it's inconsistent, it'll start the day with 4 or 5 good flights, then simply STOP flying ???!

Also made a Su-24 "Fencer" and made a mistake by adding doublers to the front. Due to the LOOONG nose moment and near non-existent tm, I had to sand ALL of the doublers off - still haven't got it sorted. According to MODELAR MAGAZINE, where it was published in '84, it is a good flyer. I think the SU-25 "Frogfoot" would make a good catajet if the tailplane is enlarged (only ONE fin to worry about).

As for a SU-27, my FA-18 has a very similar layout except for the canted fins. Flys ok as a chuckie, but on the catapult it's a dog.

You've definitely a nice list! Let us know how it goes and...HAVE FUN!


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on February 19, 2011, 06:57:27 PM
Hi all,

Been away from the Catajet scene for a bit building the Dash 8 from Chris Starleaf plans.... Great plane. Needed a diversion for a bit to refocus and refresh the creative juices.... so here's my latest Catajet... from the Jetex site's plans for the F4D-1 Skyray by Douglas Aircraft. Most unusual plane with an "S" shaped airfoil of a flat sheet of balsa. Looks pretty good but unusual in layout. I figured if it worked with the Jetex 50 motor it ought to work as a catajet. I've gotten it to glide with approximately 11 grams of ballast in the nose. As per their instructions it does have a natural turn to the right which I'm working on to level it out some. Didn't document the build but here's some pics of the sealed airframe as I'm starting to paint on the markings. Going to pretty colorful. Here's what I shooting for and the work so far.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on February 19, 2011, 10:16:26 PM
After the F9F, the Skyray and the "Hustler" are my Delta favorites. See if you can find a Jet-X or the older Jetex (original). The plane, with the S airfoil might be a disappointment as a catajet - the speed envelope is too broad. But DO try it... might be surprised ;).

Great job on the build!


Title: Re: CATAJETS: Design and Development
Post by: pubguy on February 20, 2011, 05:37:26 PM
Tom the skyray looks fantastic. How big is the wing span. Looking forward to hearing how it flys.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on February 21, 2011, 11:28:01 AM
After the F9F, the Skyray and the "Hustler" are my Delta favorites. See if you can find a Jet-X or the older Jetex (original). The plane, with the S airfoil might be a disappointment as a catajet - the speed envelope is too broad. But DO try it... might be surprised ;).

Great job on the build!

Thanks for the comments.... I enlarged the PDF plans to 10.5 inch span which increased the number of balsa sheets for the wing construction in re: to the instructions from jetex. I believe the original plans were for an 8 inch version. I'll experiment with the catapult to see how she reacts with the "S" airfoil. Then I might make a more conventional wing version. I love this plane's looks and the delta planform.

Thanks,
Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on February 23, 2011, 07:31:39 PM
Finally had a nice night to test fly. Balanced the F94 Starfighter and FH1 Phantom. Both flew straight and true every toss. To bad tomorrow we're supposed to get 2 inch's of snow. Spring can't get here soon enough. Next up is the Banshee.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on February 24, 2011, 02:19:03 AM
Finally had a nice night to test fly. Balanced the F94 Starfighter and FH1 Phantom. Both flew straight and true every toss. To bad tomorrow we're supposed to get 2 inch's of snow. Spring can't get here soon enough. Next up is the Banshee.

Sounds like great results. Here in No California we don't face the snow of others, but we have had our share of rain and wind... even some hail last week for a couple of minutes "pea size". At first thought kids were throwing gravel at the building. ;D :o ;D

Good luck with the banshee. Next nice day gotta get them together and retry them all at the park. I still need to put schemes on the Panther and the Pirate. Almost got the Skyray painted, coming along nicely. Show us some pics pubguy.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on February 25, 2011, 09:39:09 PM
More work done on the Skyray...

Got a little impatient with the painting and as you'll notice on the wingtips, applied the orange over the white base coat before it had completely dried. Crazed the finish a bit but still acceptable to me, beings I don't compete. Just me and the fetchermites. Still have to shape the ballast for the nose slot you'll see on the left nose area. Weather hasn't been nice enough to try glides and launches yet outside... just make noises around the building room. The fetchermites help make the flying noises with very little encouragement.

Will post flight results as soon as the weather permits.
Here's the pics....

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on February 25, 2011, 09:51:39 PM
Looks great Tom. Sorry to hear your weather problems are persisting. We've had ok days, but wind crops up whenever I try to get out and fly. Of course, that's kind of normal, here where I live. And rain, then snow is on the way.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on February 26, 2011, 03:43:06 AM
Thanks Caley,

The weatherman said possible snow in the valley tonight.... Not suppose to happen in the valley here in No. CA. It's really cold outside... duh ;D ;D ::) ;)

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on March 03, 2011, 06:59:57 PM
Just posted a link that may be useful to you guys on the Cataprops thread.

Neil


Title: Re: CATAJETS: Design and Development
Post by: pubguy on March 03, 2011, 07:10:52 PM
Tom love the looks of the Skyray. Just test flew the FH-1. had nice long glides with at part power. Looking forward to getting out to my normal field to really let it go. Was so happy with the Phantom I tried the F94. I have some trimming to do on it. Nice fast launch then it dives at the peak of the launch. I think it may just need a shift in the balance then it shouldn't try to lawn dart. The next one up is the F2H just need to get around to painting the base coat first. Your Plans are working out great Glad I got into this end of the hobby. Good flying to all.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 04, 2011, 10:21:20 PM
Pubguy.... great to hear you're enjoying the catajets... funny how these little planes can generate soooo much fun and joy of flying. If you fly other models be careful how many catajets or cataprops you bring with the other models...you may wind up just flying the catajet/cataprops. Glad the plans are working out for you. Always nice to hear some else is having success with them.
ENJOY ;D 8)
Tom


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 08, 2011, 12:35:10 PM
Well I've just started an Aero L-39 Albatros... I haven't done one of these for quite a while, so I'd appreciate any pointers.

This one is going to be the pretty blue scheme shown in the pic below - hand painted finish I expect.

The scale is 1:44 - wing span is 8.5" and the profile just prints out on a sheet of A4. I'm just working off a printed 3 view so no plan as such. The fuse is 3/16" and the wings are hardish 1/16". It probably wont be a light model!

I was going to put 1 degree negative incidence on the tail (does that sound ok?) but I might do adjustable elevators for easier trimming. The original has a little dihedral (3.8 degrees on the bottom surface) so I'll give it four degrees... that's a slight increase over scale considering no taper in wing thickness for the model.

Any tips on how to do discreet nose weight would also be welcome...

I couldn't resist a posed shot even at this early stage!

Jon


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on March 08, 2011, 02:34:09 PM
Hi Jon, I really like this subject. A very neat airplane. I don't know a lot about incidences. I usually guess, or ask like yourself. But one degree in the stab sounds like a lot for a cata anything. I think I've read more around 1/2 degree, but this is where the experts will have to leap in. I don't wish to throw you astray.

As for the nose weight. Many are doing a ply fuselage of 3 sheets of 1/16. with the nose area of the central sheet being hollow. Weight is placed in the hollow and then faced by the surface sheets. I would think that you could even make the central sheet set off by 45 degrees or so to make the fuse stronger. Somewhere in this thread or in the cataprops thread are examples of this.

Guys, I love watching this thread. I think is is really kewl. Wish I had the patience to do what you'all are doing. But my trimming abilities are rotten when it comes to these leetle speedie airplanes.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 08, 2011, 02:46:05 PM
Thanks Caley!

I put the fuse and wing on the scales and it was 7g :o so I've changed track a little - cut most of the sheet out in lightning holes and sheeted it with cross grained 1/32". it may not be much lighter but at least I now have somewhere to put the nose weight.

Jon


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on March 08, 2011, 03:18:41 PM
Jon, I don't think your weight is bad, at least compared to what I've built. I get the idea that if you can keep to one gram per inch of wingspan or under, you're doing ok. Hey Pete, you are the resident expert. What is a good weight target?

Caley


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 08, 2011, 03:28:15 PM
Caley,

That's 5oz/ft sq. in old money... ;D

Seems quite a bit to me? For such a tiny span... I haven't measured my wing area yet but they're pretty small - It's quite a high wingloading on the original.

Jon


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 08, 2011, 04:22:31 PM
The way I've done it is to use regular catapult glider numbers. That is, decalage ~0.5° and balance point around 50-55% root chord. Hand glide tests should show a marked glide slope - NOT floaty across the yard and NO dive. THEN try a catalaunch with about 25% pull and see what the model does for starters. I start adjusting glide turn on the building board, sanding in camber on the outside (RIGHT side for left glide) of the fin/rudder. If it shows need for more turn , I add a bit of weight to the inside wing tip. If the transition is poor, I try a bit more rudder offset (or a temporary Gurney flap) near the base of the rudder.

Jets, with the generally short tail moment (short coupled) is not quite so "easy" as a purpose built endurance glider and a flat plate airfoil (as on my present F9F Cougar) present even more willies - a new "proper" airfoiled wing is in the works as is the straight winged Panther.

The whole thing is "cut and try" (and don't tell anyone about the failures ::)).

One thing I just did, as a result of the still occasional spin-in with the Cougar, was to trim the fin/rudder to almost scale size. I haven't had a chance to test the mod yet (weather uncooperative/rain). The next decent day will be devoted to catagliders/jets for the various Postals, so I'll let everyone know the outcome - this coming Wednesday looks promising.

Here's Pits suggestion on incidence on the horizontal stab from a previous post. I suggest that anyone new to the site review the previous post, a lot of good info is already posted.

A lot of this for me is trial and error. Still lots of fun. Can't wait for the weather to get better so the fetechermites and I can get back to the park for some more CLG activity.  ;D ;)

Tom


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 08, 2011, 04:48:31 PM
Cheers Tom. I was re-reading the thread for this kind of thing but hadn't managed to find this post, thank you.

I'm afraid I haven't built this type of model for a few years and somehow this flurry of activity passed me by until now! I seem to have had my head buried in other parts of the forum... It's rather exciting to see so many cool projects!


Title: Re: CATAJETS: Design and Development
Post by: danberry on March 08, 2011, 07:14:46 PM
The Albatross needs dihedral.

Put the nose weight about halfway towards the nose.


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 09, 2011, 07:35:49 AM
An update on the F9F "Panther". CG is now at 28mm from the leading edge and the incidence is 0.3° (wing: 0°; stab: -0.3°). The sucker flys GREAT (10.3 grams)!! NO flights have been under 20 seconds using the 1/8th slingshot at half pull, and a few with the "GOOD" black FAI 3/16th - again at half pull - were close to 50 seconds in late evening air.

A problem that I had at the beginning of the F9F series was over-elevation (Cougar, CougaPanth and Panther). The CougaPanth, lead sled that it is at 16.5 grams, now flys consistent 20-30 seconds


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 09, 2011, 08:17:13 AM
Pete - those times are awesome!

I understood the incidence needed to be minimal to prevent looping but had still overestimated...

I've changed track a bit - I decided the Albatros might be a little heavily loaded for the moment so I am now doing a North American FJ-1 Fury. It has a reasonable amount of dihedral and a good wing area. I will come back to the Albatros at some point though...

Here are a few pics so far. The fuse is 1/8" with 1/32" doublers for the nose area. The little 'hatch' should alow me to adjust the nose weight...

Jon


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 09, 2011, 08:38:54 AM
That's a neat one! What span are you building it to? A minor suggestion - add a bit more chord to the stab (more area) - the short tail moment will almost require more area there.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 09, 2011, 10:06:22 AM
Thanks! It's coming along...

The span is 9.2 inches - scale is 1:50.

The tail plane shown is just the 'stick fixed' half as I was planning adjustable elevators with wire hinges... (probably unnecessary!) The area of the whole stab is increased to about 120% over scale.

Jon


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 09, 2011, 12:45:41 PM
It WILL need about 15mm dihedral per side - even tho it makes the plane look a bit funky. Not so sure about the adjustable elevators.

At the speeds these kitties get to right off the sling, you're liable to get blow-back on ANY "adjustable" surface plus the added weight of hinges is exactly in the wrong place. To correct the decalage on my F9F's, I used a razor saw to cut directly under the stab, the depth of the surface. By re-gluing, closing the resultant gap (small), the change was near perfect (I had used CA for the original join - DUCO/AMBROID/527 would have been better and MUCH easier to effect changes).


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 09, 2011, 01:03:13 PM
It has 10mm each side at the moment, which is a bit more than scale. (The pic above shows the wing before the dihedral.) I could do more if that's not enough? The vertical stab area is relatively small, though the dihedral in the tailplane works against spiral stability a little too.

The hinges should be stiff enough - I'll be using wire from a cable tie. And not too heavy hopefully... we'll see - it's going to be a bit of an experiment. They work very well on free flight rubber models but as you say they have nothing like the acceleration..

Edit: just measured and it's 11mm per side! :D


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 09, 2011, 02:55:09 PM
Don't think you'll need to worry about the vert. stab. There is a heck of alot of side area in the fuz, so if it dutch-rolls, you can always glue on a TE extension. The dihedral MIGHT be enough.

Try to test fly it BEFORE going wild on the decorating (if possible ::)). It's easier on the psyche to make changes prior to the final finish.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 09, 2011, 05:39:58 PM
I was thinking the small vertical stab was a good thing in this case - to avoid spiral instability. Its a fairly 'conventional' lay out for a jet really.

I was thinking along the same lines so Ive done a super quick 'proof of concept' using the original wing but a 'disposable' fuselage. It weighs 8 grams with noseweight. The stab is just slightly negative. The glides across the living room were a success - no tuck under anyway and no spiral instability (although that doesn't mean much at this stage) I'll try it with the cat tomorrow hopefully...

As this is a development thread, I thought it might be worth sharing an idea I used with my old catapult spitfire: I was trying to get an accurate measurement of it's speed in straight and level (for Reynolds number purposes).

What I did was put the model on the side board (a table would do) and used a piece of string on the cat hook - pulling the string down over the edge of the sideboard you could get a pretty consistent launch. By measuring the distance and averaging the times it took (to hit the window!) I was able to get an accurate speed for it.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 09, 2011, 06:34:02 PM
Nice Yak....

You beat me to the FJ-1 Fury... it was on the list.

Looking good.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 10, 2011, 03:17:30 AM
Sorry Tom... :-\


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 10, 2011, 07:27:17 AM
I've decided to follow your advice Pete: I'm concentrating on the flying side of things for a while, before I start firing hours of work at the scenery!

Here's a couple more, still in the mock up stage. SIAI Marchetti S.211a (8.7" span) and Fouga Magister (12.7") both at 1:38 scale. Just simple profile models done with CA, blu-tack for nose weight and minimal sanding...

I will try the S.211a with no dihedral first - I reckon it might just work with the high wing mounting. The Magister has a lot of lateral area forward so will be interesting!

Jon


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 10, 2011, 12:47:35 PM
It was rather windy (15-20 knots) so I took the catajets to the park to do some running ;) Results were inconclusive because of the wind...

The Fury was coming off the cat very nicely but didn't transition too well, not much recovery from a dive - I was going to try a little less nose weight but bust it before I could.

The S.211a test glided ok but I had built it with too much rudder offset. It went well off the cat but again didn't recover well. A bit of 'up elevator' had it looping. It seemed quite sensitive to nose weight too - I shall try it again with a little bit of dihedral. The few times it got into a glide ist spun and/or tumbled so maybe the vert stab needs increasing too.


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 10, 2011, 01:33:02 PM
Did the spin/tumble occur late into the glide phase or right after transition?


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 10, 2011, 06:11:01 PM
Hard to say because of the wind - It was very dependent on the nose weight... I'd imagine it was linked with the CG being too far back on some flights.

There wasn't much glide... And definitely a flat spin not spiral dive. It seems to have a bit of spiral stability in spite of no dihedral - sweep and high wing help a bit I would think.

It was really hard to see a consistent pattern though. I'll try again on a better day.

The Fury goes like it's on rails now.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 12, 2011, 06:22:23 AM
Well I tried again - I increased the vert stab areas to see if that would help, the Fury by about 120% and the S211a by a lot more maybe 160%.

I've been doing little vertical flights in the garden to watch the stall and recovery characteristics. Both models seem to do a kind of tail slide and flat spin.. although it's not consistent. They both seem ok at first but if the yaw gets too much the fuselage sides start acting to flip the model. In a gust or stall the high angles of attack and yaw act strongly on the fuselage, you can see them trying 'knife edge flight' at some points of the stall recovery.

I then took both to the park - still windy though...

The Fury broke early in the trimming process so might need a little more incidence to stop it lawn darting. With less nose weight it was still spinning but with more it was diving. I would think I need a little more up elevator and a slightly greater static margin to give me a larger 'sweet spot'?

As it was busted, I cut a chunk of the nose off to see if the forward lateral area was the problem... Unsurprisingly glides in the garden showed it handled like any other sport chuckie... very stable and straightforward stall recovery.

The good news is that the S211a is spirally stable with no dihedral... not very stable but not bad. With the large increase in vert stab area it still spun during transition once or twice but recovered and glided well. The problem was that it lost a fair bit of height so was down to 30 feet or so before it got into a stable glide. Adding dihedral might help speed up the recovery here...

I then tried ballasting the S211a (with a few grams of blu-tack) and the results were impressive: much higher off the cat obviously but interestingly less spin problems and faster recovery. Unfortunately the glide ratio is obviously worse.

These models need very little nose weight to balance... which makes me think that the mass distribution along the fuselage could be causing issues with inertia... this can definitely affect stability in any aircraft, reducing the size of the sweet spot between dutch roll and spiral instability. Ballasting the S211a seemed to improve things. It would also have brought the CG down below the wing so perhaps some minor 'pendulum' benefits there too.

My conclusion so far is that the problem is a large forward lateral area and possibly the inertia problems mentioned... I might be missing something obvious though (too small a static margin?)... Both models are absolutely fine off the catapult, the problems seem to be with the transition and glide. I might just need more dihedral of course... Anyway I'm going to keep trying!

Jon


Title: Re: CATAJETS: Design and Development
Post by: danberry on March 12, 2011, 09:41:31 AM
Dihedral.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 12, 2011, 11:16:48 AM
Thanks Dan... I'm sure thats a factor but I don't think it's the whole story.

I re-glued the S211 wing in with a chunk of dihedral and it hasn't stopped the spin on recovery... even seems to have dutch roll now on the garden glides. :-\ ... I think I'm possibly suffering from some sweep issues - the same as Willi' s Mig on page 2. When it flies it flies well. I might have a go with stall fences (the original has them) and washout...

If it is just a stall/spin issue that would explain why the ballasting (change in moments of inertia) had such a positive effect. Mass placed away from the CG (eg tip tanks) also tends to flatten a spin and slow/impede recovery into a spiral dive.

The Magister has just been finished with a fair bit of diheral ... and also has the same problem!

I'm going to start measuring the centre of lateral area of each of them to see if there's any correlation.


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 12, 2011, 03:43:41 PM
Take the tip "tanks" off the Magister and use them for display. I've found that unless they're PERFECTLY square to the fuz, they act like rudders causing ALL sorts of strange behavior.

The swept wing NEEDS more washout than a "normal" wing and the drastic increase of the fin area sounds like TOO much. Case in point: The first models of my F9F (both the Cougar and Panther) had only 10% increase in the fin. Spiral instability ++. I cut the area back to SCALE size and now have two (well, actually 3 with the CougaPanth) that fly beautifully! Had them out today for 8 hours of FUN!

Lesson learned: if the size of the tail surfaces LOOK ok, TRY it.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 12, 2011, 04:48:24 PM
Flew the Magister and the S211a this evening (the Fury is now beyond repair >:() I didn't bother with the tip tanks because of their vulnerability. Less wind today, which was good too.

The S221a does recover from unusual attitudes a little faster with dihedral... no surprise there but there's still a problem with spinning sometimes. I got probably 10 seconds max out of it. It's well busted now too so I shall make another incorporating the next developments.

The Magister flew better than expected - I started out with quite a bit of dihedral and it was very stable, slight dutch roll even. It was less predictable off the cat (V-tail I suppose) but once I had it worked out I was able to get a fast barrel rolling transition and good glide. The only problem was once it spun: that was it - 7 or 8 turns before the nose showed signs of dropping by which time it was in the grass. But as long as it kept flying, it was really good. This one didn't like being ballasted much though. (Perhaps the extra CL demanded of the thin wings?)

I think the main problem is bad stall characteristics with sweep, taper and very low Reynolds numbers on the skinnny chord wings. The other thing is that once spinning I think the wide fuselage is blanking the wings and delaying recovery. I do think the large forward lateral area and mass distribution/inertia are factors in poor recovery too.

The other problem is not being able to see other people's flights when you fly alone - I'm not sure what I might be doing better! :-\

So I shall try a Cataprop with a short nose for comparison, plus continue with the jets and try more washout and stall fences. I'm also thinking of trying something with LEX'x (Leading Edge Extensions) to see if that helps blanking during stall recovery. I also plan to do more high wing jets - Id like to get something flying well with minimal dihedral and I'm pleased with the S221a in this regard...

Anyway I'm enjoying the process! Pete, If you feel my ramblings are hijacking your thread please say and I 'll start something parrallel in Aerodynamics maybe ;D

Thanks
Jon


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on March 12, 2011, 05:30:34 PM
Well Yak at least you gave it a try.Don't stop trying. I had similar problem with my P-1077. I gave it down elevator and started launching it banked to the right at about 45 degree angle. I may have helped it be better by adding right on the left rudder while keeping the right rudder straight. It does help having some experienced flyers close by to help trim these but just keep notes on what it does, what correction you made, and the results. Remember make just one change at a time . I am no expert on trimming cat gliders but Mr Lee Campbell the owner of Campbells Custom Kits in Indiana is very helpful if you have no one else to ask.


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 13, 2011, 09:46:42 AM
Definitely NO hijack! The successes AND failures and all points leading up to either are EXACTLY what is intended with this thread.

I'm going to make a "real" wing for the swept COUGAR - it's presently a simple flat plate with some thinning at the TE and a cambered LE and a swipe of upsweep. It DOES spiral in occasionally (1 in ~15) which I have traced to an improper launch. It HAS to fly off the top - does NOT tolerate a flop-type transition. OTOH, the PANTHER can be launched at about 80° with a 45° bank and does a roll-flop. I got a flight vid of the Panther yesterday, but not of the launch - no one there had the experience to catch a catalaunch so I did my own filming. It'll get uploaded sometime in the next few days (new camera - have to figure out how everything works ::)).

I'm also working on a strap type, wrist mount for my camcorder for true point-and-shoot vidding.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 13, 2011, 10:20:23 AM
Cheers Pete! Looking forward to seeing that: I'm tempted to build a Panther from your design as a comparison.

The Magister also has to fly off the top.

I experimented with adding tissue strips doped onto the wing of the S221a (the only bit that survived) to warp in a bit of wash out. I ended up with wash in (!) but at least I know it works.

I'm also going to try something bigger to see if the increased chord helps...

Jon


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 15, 2011, 04:00:30 PM
Great stuff guys.... I'm learning lots.... the V-Tail is a challenge. Still working with the LearFan in that regards.

Haven't been able to fly due to weather...

Regards,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 15, 2011, 05:06:58 PM
Your Learfan looks very cool Tom!

I used the flying surfaces off the S211a and added them to a stick of balsa for a 'standard' cattie... Flies amazingly well compared to the CATAJET version :-\ but then there's a lot less weight and drag and no 'fuselage effect'.

Jon


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 16, 2011, 03:13:57 PM
Your Learfan looks very cool Tom!

I used the flying surfaces off the S211a and added them to a stick of balsa for a 'standard' cattie... Flies amazingly well compared to the CATAJET version :-\ but then there's a lot less weight and drag and no 'fuselage effect'.

Thanks Jon,

If you'll note on the Mig 15 I did of BG's mig plans I had the instability you mention until I added the 1/64 ply fences on the wings and this aided greatly to the stability. I'm still working on the incidence of the horizontal stab. Under full launch power I keep getting a hugh fast loop unless a greater angle of launch is added. I plan to decrease the negative incidence by slicing with a razor saw and raising the incidence just a "smig" (a highly technical term) ;D :D ;)

Tom


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 16, 2011, 03:19:42 PM
Cheers Tom - stall fences are the next thing on list for me to try. I think I have possibly gone too much the other way.. they might need a smidge more incidence.

How did you get on flying the Casa c-101 by the way? It looks a similar layout to the SIAI Marchetti S211a, in terms of forward area anyway...

Jon


Title: Re: CATAJETS: Design and Development
Post by: pubguy on March 20, 2011, 12:48:23 PM
Hey Everyone

Well here is my first attempt at building a clg from scratch. The build went ok. The test glides were very unstable. I'm thinking of making the wingspan around 8 to 10 inches.Right now wingspan about 6 inches. And I think more dihedral. The test glides showed the planes habit to spin. Could not get a good glide. Hope to start a rebuild in a week or two after other projects get finished.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 20, 2011, 01:05:33 PM
Cool Pubguy!

Is it a Super Sabre? I've also had a lot of spin problems - I think because of the sweep and the fin effect of the forward fuselage.

My latest (cataprop) is a SIAI Marchetti SF260 (no sweep, small area forward) and it doesnt have any of those issues.

Let us know how it goes!

Jon


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 20, 2011, 07:20:42 PM
The F100 Super Sabre looks great. It is quite close coupled (distance between the wing and horizontal stab) this may be part of the problem. I believe the F100 had wing fences as well on the real bird. double check this with me....might try more dihedral as mentioned.

Haven't flown the Casa 101 yet got side tracked with stick and tissue birds.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on March 20, 2011, 08:01:01 PM
Tom, I keep learning things in this thread. I finally got the curiosity to look up what a wing fence is. Strange looking structure. Now I know what it is and I think what it does, which is preventing a whole wing from stalling. I guess it divides up the wing into parts blocking airflow. Never can translate into my words. Found this in Wikipedia.

Caley


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on March 20, 2011, 09:25:45 PM
Hi all, just thought I should add my 10cents worth,

The idea of wing fences is to stop the 'outward' drift/flow of the airflow over the top of the wing straightening it, as the fast moving air "drifts" along and off the end of a swept wing (the greater the sweep the greater the flow) creating low speed control problems AND hi-speed instability (all a loss of lift and maneuverability really), the underside airflow "drifts" into the fuse in the opposite direction to the top flow, these differential flows plus the differential pressures above & below the wing tip are the base causes for wing tip vortices (drag). Not a good thing for a high speed aircraft, but greatly magnified in a Catajet due to the model spending most of it's time airborne "unpowered", gliding, where it's highly susceptible to these effects, robbing performance and stability.

The top flow basically needs to be anchored/restricted in place, and not allowed to drift too far, see the Mig-19 and it's enormous fences as an example.

The thing is, if the REAL plane being modeled has wing fences, so should the model, powered or not.

Happy flying
Neil


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 21, 2011, 06:32:52 AM
I agree with all of that... but one of the results of the spanwise flow is 'spanwise stall propagation' as Caley said.

Swept wings tend to stall first at the tip anyway. But any stall tends to quickly spread along the wing because of the spanwise flow, and very soon you have one wing flying and the other one not :o No wonder the result is a spin.

The 'Boundary Layer Fences' prevent the stall propagating and keep the tip flying. Saw tooth leading edges are a similar thing. Although with those it is the vortex created that 'fences off' the tips.

Jon


Title: Re: CATAJETS: Design and Development
Post by: dosco on March 21, 2011, 04:11:15 PM
Hey Everyone

Well here is my first attempt at building a clg from scratch. The build went ok. The test glides were very unstable. I'm thinking of making the wingspan around 8 to 10 inches.Right now wingspan about 6 inches. And I think more dihedral. The test glides showed the planes habit to spin. Could not get a good glide. Hope to start a rebuild in a week or two after other projects get finished.

The direction of the grain for your wings and vertical stabilizer is unusual. Any reason for that?


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on March 22, 2011, 09:27:06 AM
Thanks YAK, I forgot that bit :-[ :-[, absolutely correct :)

Another Russian jet with fences ....... 3 on each wing ....... the Mig17.

Cheers all

Neil


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 22, 2011, 11:03:22 AM
I've just spent a bit of time reading through the SFA 'Frustrating Catapult Jets' thread more carefully. The reports of some posters on that thread seems to confirm my feeling that the large forward area of many jets is the real problem, although sweep probably plays a part. I had the same issue to some extent with the straight winged FJ1 Fury...

I think that if yaw gets beyond a certain point the angle of attack is great enough to cause divergence in yaw.. ie no recovery. In fact with the rearward CG necessary in CLGs there may be very little stability in yaw at all. It doesn't show up off the catapult generally because the aoa is very small at that point. On my S211a the massive increase in fin area made a difference but even so it still spun off if yaw got too great.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 22, 2011, 06:17:53 PM
Great stuff guys....
Can't wait to apply some of this on my next outing.... No rain this morning but predicted tonight and tomorrow.... Had to work this morning.... that's life..... ;D ;)

Happy Landings,

Tom


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 22, 2011, 06:38:10 PM
Take the CASA Tom, I want to hear how it flies! :)

Jon


Title: Re: CATAJETS: Design and Development
Post by: pubguy on March 22, 2011, 06:55:53 PM
Hey Dosco

The fuselage is one piece decided to try it that way. As for the wing, goof on my part. Guess I wasn't paying to close attention to grain. Going to try fences and see what happens soon

Brian


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 23, 2011, 08:44:01 AM
A quick (and dirty) way to prevent wing fold on launch for "Wong Wai Gwain" built catawings is to glue/dope/attach a length of tissue (pref. Esaki) to the top AND bottom of the wing - grain SPANWISE. Width of the strips should be about 1/4 the chord, top strip at the LE (creates a bit of turbulation)n, bottom - down the middle


Title: Re: CATAJETS: Design and Development
Post by: dosco on March 23, 2011, 09:12:16 AM
Hey Dosco

The fuselage is one piece decided to try it that way. As for the wing, goof on my part. Guess I wasn't paying to close attention to grain. Going to try fences and see what happens soon

No problems, I wasn't attempting to be critical. I was wondering if I may have missed something.

Probably not a bad way to go to build a test vehicle.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 23, 2011, 10:05:59 AM
I do this for the fuselage/fin on a quick model... but I cut a slot and CA a tooth pick in across the grain. You can see it on the Fury in post #301. Everything else on the model broke except the fin!


Title: Re: CATAJETS: Design and Development
Post by: pubguy on March 23, 2011, 07:03:18 PM
Hey Everyone

Will try the idea of covering with esaki paper. No body missed anything it was just a off build day. Normally I would have the grain going the other way on the wings. Hope to add the wing fences this weekend work permitting. Looking for a set of 3 views for a F4 Phantom or a F3D Skynight does anybody have a idea were to look.

Brian


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on March 23, 2011, 07:19:37 PM
Brian, Here's a Wikipedia thing on the Skynight. It has a shadow three view that might help http://en.wikipedia.org/wiki/F3D_Skyknight  And another link http://en.wikipedia.org/wiki/F3D_Skyknight

Caley


Title: Re: CATAJETS: Design and Development
Post by: dosco on March 23, 2011, 07:20:24 PM
http://www.fas.org/man/dod-101/sys/ac/f-4.gif

http://www.the-blueprints.com/blueprints-depot-restricted/modernplanes/modern-f1-f8/f_4_phantom-20095.jpg


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on March 23, 2011, 08:27:20 PM
Brian I hope these help. I've got masses of 3-views. Do you want Navy/Air Force F-4's (radar/missiles only) or F-4E/EJ/F with the gun? Or maybe one of the RF-4's?

Neil


Title: Re: CATAJETS: Design and Development
Post by: dosco on March 23, 2011, 09:33:58 PM
Brian I hope these help. I've got masses of 3-views. Do you want Navy/Air Force F-4's (radar/missiles only) or F-4E/EJ/F with the gun? Or maybe one of the RF-4's?

Boeing 727-200?

Or you only have fighters? ;D


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 24, 2011, 07:09:16 AM
Brian, the Sykknight looks like a good candidate for a catajet - fairly small forward area, reasonable tail moment arm, shoulder wing. Look forward to hearing how that one goes.

I had thought of doing the F4 myself, still rather a large forward area but all that dihedral in the wing tip panels should be good for transition.

Jon


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on March 24, 2011, 07:47:40 AM
You mean these 727's? ;) Have fun!! :) :)

Calm winds,

Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 24, 2011, 12:21:37 PM
Great activity guys,

Look forward to seeing the new models...

Weather is just not cooperating here.... wind gusting to 45mph and rain...the one clear day I had to work.... so no flying this winter yet.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on March 24, 2011, 12:24:26 PM
Tom, Its got to get better eventually, weatherwise. And you cannot afford to be stuck inside forever because the fetchermites are probably starting to get hanger rash from bouncing off the walls.  ;D

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 25, 2011, 07:39:19 PM
Tom, Its got to get better eventually, weatherwise. And you cannot afford to be stuck inside forever because the fetchermites are probably starting to get hanger rash from bouncing off the walls. ;D

Caley.... you are soo right... I made a couple of peanut Vagabonds on the indoor thread and the fetchermites have already broken one throwing it around the house.... they will glide across the room with no problems at all...they love it. But gotta get them outside soon. Looking forward to that nice sunny calm day for a lot of flights. Seems the CLG's always take the time from the rubber powered one's they are a lot of fun.

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on March 25, 2011, 08:09:00 PM
Tom, I can't wait for new photos of the mites with those beaming smiles. I just love the kids enthusiasm.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 27, 2011, 06:24:50 PM
Hey Everyone

Will try the idea of covering with esaki paper. No body missed anything it was just a off build day. Normally I would have the grain going the other way on the wings. Hope to add the wing fences this weekend work permitting. Looking for a set of 3 views for a F4 Phantom or a F3D Skynight does anybody have a idea were to look.

Brian,

I haven't tried this one yet but here's plans for several catapult launched models including the F4B with free downloads: http://www.e-aeromodelismo.com.ar/Planos/Histart-mano.htm you might want to check them out... I don't read Spanish but with the aircraft titles it's clear which are which.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Zeiss Ikon on March 27, 2011, 09:39:35 PM
I haven't tried this one yet but here's plans for several catapult launched models including the F4B with free downloads: http://www.e-aeromodelismo.com.ar/Planos/Histart-mano.htm you might want to check them out...I don't read Spanish but with the aircraft titles it's clear which are which.

Look at the "motor goma" for "rubber motor" airplanes. Once in that section, "Ala Alta" is high wing, "Ala Media" is mid-wing, "Ala Baja" is low wing. Most of the rest are self-explanatory.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 28, 2011, 04:47:25 PM
Thanks Zeiss Ikon... appreciate the clarifications

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on March 30, 2011, 07:56:17 PM
Well guys put the F-100 on hold for now and started on the Skynight. Here is the start of this project. The F-100 attempt will start up in a week or two. I will hopefully have more luck with it. Picked up some good ideas reading past posts.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on April 07, 2011, 01:59:14 AM
Well guys put the F-100 on hold for now and started on the Skynight. Here is the start of this project. The F-100 attempt will start up in a week or two. I will hopefully have more luck with it. Picked up some good ideas reading past posts.

Pubguy... skyknight is looking good. What's the wing span?

Look forward to more posts ;D
Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on April 10, 2011, 11:34:05 AM
Update on the F3D It is now all together and ready for test flights if the weather ever cooperates. It is pretty tail heavy. Hoping for the best. Started back on the F100. I think the wings are the problem. Updates soon.


Title: Re: CATAJETS: Design and Development
Post by: danberry on April 10, 2011, 12:09:37 PM
Where's the dihedral?


Title: Re: CATAJETS: Design and Development
Post by: pubguy on April 10, 2011, 07:31:59 PM
Hey Everyone
The wing span is 9 inches. The pictures don't show it but dihedral was set at 25 mm. Next time I'll get a picture more from the front. The weather still has cooperated so no test flights as of yet. Good flying to all.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on April 13, 2011, 01:00:37 AM
Hey Everyone
The wing span is 9 inches. The pictures don't show it but dihedral was set at 25 mm. Next time I'll get a picture more from the front. The weather still has cooperated so no test flights as of yet. Good flying to all.

Brian,

The skyknight looks great... should be a good flyer. If you run into any stability problems, as danberry suggested, an increase in dihedral may be called for. But give her a try first. You may want to add doublers to the nose to offset the tail weight and I've been using them to cover the splitshots as well.

Long flights and gentle landing,
Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on April 21, 2011, 06:12:22 PM
Chuncky.... great stuff... look forward to seeing more and reports about flying...

Went flying last minute... and just grabbed the box of catajets and off we went... great day but a bit windy... constant breeze of approximately 5mph with some gusts to 10mph. Flew them anyway. The fetchermites had a great time. Gotta find a better way to store the models between flying. Acquired a few warps that took some retrimming. Re-kitted a couple of them, the BG's Mig 15 and the Natter .... but that's part of the fun... they lawn darted ::) :o

Also met a couple of boys while flying and they had their first experience with catajets... I think they may be joining in on the building and flying fun.... their mom said it looks like a great thing for dad and the boys to do.... Here's a few pics of my fetchermites Aiden with the Okha and Aiden with the F94C Starfire and the two brothers Rion the older brother and Marley.

More later...

Tom


Title: Re: CATAJETS: Design and Development
Post by: crashcaley on April 21, 2011, 06:21:30 PM
Tom, I've been waiting for so very long to see the kids having fun. Glad the weather is starting to improve, though based on the photos, still looks a tad nippy. Very happy to hear you might get a couple more out with you. Who know, word may get out and you'll have a whole slew of others out for weekly fun.

Caley


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on April 22, 2011, 03:37:54 AM
Nice one Tom. More wind = more exercise for the fetchermites! ;D


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on April 23, 2011, 06:06:07 PM
Nice one Tom. More wind = more exercise for the fetchermites! ;D

Yak...you're right. they did a lot of chasing and then were ready to pack it in. Broke two birds but repairs have been made. Hope to get the Casa C111 in the air soon.

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on June 05, 2011, 05:16:30 PM
Finally had a with no rain or winds averaging 20 + mph. Took out my winter builds and am happy to report all are back safe and sound. I finally got the F2H to work they way it was intended right side up not upside down. The FH1 and F94 were solid flyers once I got the balance and tweaking done. Hand pretty long flights with those three the F3D Skyknight does fly ok. Big arc on launch then in to a straight glide. Idid manage to hit the only sign at the field but no damage done to the wing.  All in all a good day out. Looking forward to the next weekend of good weather.  Good flying to all

Brian


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on June 08, 2011, 06:02:10 PM
Take the CASA Tom, I want to hear how it flies! :)
Jon

Finally got out to fly...the CASA flew great...right into the top of a 35 foot tree.  No chance of retrieval.  Sooo another CASA will be built.  Several lawn darts today.  Apparently my Fetchermites like to fiddle with the clay on their way back from landing site to launch site.  So the trim kept being off.  I couldn't figure it out till I observed the Mites on their way back to me with the planes. HA HA ;) ::) ;D

Funny how small amounts of balast removed or mashed on a different place on the aircraft will affect the flight patterns.  I just gave the Mites a briefing on the effect and we had some great flights after that.  The Phantom and Banshee worked very nicely.  Also the LearFan put in some nice 20 second flights.  But the wind came up and rather than risk another lost in the trees (got the orange Ohka out with the help of a young guy with a good arm and a couple of full water bottles).  so all in all a great day inspite of the wind.  Too bad about the CASA.  Another will be made soon.

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on June 08, 2011, 06:32:00 PM
Hey Tom

Even the young ones need to have some fun. Bet they keep you on your toes.

Brian


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on June 08, 2011, 07:26:27 PM
It's amazing how little a change in the weight distribution is needed to alter a glider into a lawn dart! My H.P. and the Fieseler have taught me patience and not to grossly change the position too much at a time. Maybe I'll finally get them flying in a consistent way when I get the time.

Fair winds,
Neil


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on June 10, 2011, 04:32:11 PM
Take the CASA Tom, I want to hear how it flies! :)
Jon

Finally got out to fly...the CASA flew great...right into the top of a 35 foot tree.  No chance of retrieval.  Sooo another CASA will be built.  Several lawn darts today.  Apparently my Fetchermites like to fiddle with the clay on their way back from landing site to launch site.  So the trim kept being off.  I couldn't figure it out till I observed the Mites on their way back to me with the planes. HA HA ;) ::) ;D

Funny how small amounts of balast removed or mashed on a different place on the aircraft will affect the flight patterns.  I just gave the Mites a briefing on the effect and we had some great flights after that.  The Phantom and Banshee worked very nicely.  Also the LearFan put in some nice 20 second flights.  But the wind came up and rather than risk another lost in the trees (got the orange Ohka out with the help of a young guy with a good arm and a couple of full water bottles).  so all in all a great day inspite of the wind.  Too bad about the CASA.  Another will be made soon.

Tom

Good stuff Tom, glad it was a success (pre-tree anyway!)

I've also found it important to use very small adjustments for nose weight... I'd imagine its because the combination of low tail incidence and rearward CG, means a very small Static Margin... and sensitivity to CG movement as a result. Plus the long noses on most jets means a small weight increase is a still a big moment increase.

Jon


Title: Re: CATAJETS: Design and Development
Post by: pubguy on July 04, 2011, 03:40:12 PM
Had a Great day of flying today. Finally got all the gliders to work perfectly. Even managed to make the DC9 fly. That one was always stubborn. Im guessing but most flights by the end of the day were around 15 to 25 seconds. The F94 would have been longer except for the tree which snagged it in flight. Luckly the tree gave it back a few minutes later.  All returned home safe and sound after some field repairs.  Happy flying to all.

Brian :)


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 03, 2011, 11:05:40 PM
Brian,

Glad to hear about your catajets flying so well...they sure are lots of fun...even the stubborn one's are a fun challenge to make them work...then what a thrill when it starts to fly and glide coming off the top ;D ;D ;D 8)

Been busy with the stick and tissue models and son moving into the building room so relocating the building table.  Decided to try my hand at a 3D catajet from the cookup at SFA...Douglas Skyrocket D-558-2, 6.25 inch wingspan...still need to add hook mount and canopy before covering...from the plan on the jetex site/ Croslley I believe... here's the pics so far...

gentle breezes,

Tom


Title: Re: CATAJETS: Design and Development
Post by: marcelop on August 04, 2011, 05:47:44 AM
 :o
wow! no rapier?no prop? catapult????? wow!!!it is posible the okha (the rapier version) fly in this way too????
sky9...wow!!!!
congratulations!!!


Title: Re: CATAJETS: Design and Development
Post by: Pit on August 04, 2011, 08:56:37 AM
Nice looking model,Tom!  You sure are a fast builder!

Marcelo, there should be no reason that the Okha would not work.  Steve even recommends a catapult hook to help the launch.  For a FULL catalaunch you WILL need to reinforce the hook mount and grip location to withstand the stress of the catarubber at full stretch.  I'm doing (sloooowly) some minor mods on my F-105 for the same reason.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 04, 2011, 01:35:07 PM
As Pit says...doing some reinforcment for hook and still working on the tail for launch holding for the catapult launch...will keep you informed  8)

Thanks for the comments...

Marcelo...I was thinking of the Ohka as well, will see how this works out and maybe try the Ohka....great potential... ;D ;) 8)

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on August 26, 2011, 12:42:38 PM
Hi all,

Just an update...got the D-558-2 Skyrocket tissued and painted but had the tissue grain turned the wrong way and she looked like a starved horse.  Couldn't stand the look so I stripped off the tissue and repaired some broken stringers/longerons.  Much more acceptable now...will post pics soon.

Tom


Title: Re: CATAJETS: Design and Development
Post by: JPRIZZ on September 02, 2011, 02:44:38 PM
Hey All, these all look so great. Can't wait to try some of these out for my Little guys.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 13, 2011, 12:27:31 AM
JPRIZZ,

Go for it...you'll have fun and your fetchermites will too...you might want to check out the pole launcher HERE (http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=7886.30) for the littleones....I haven't tried it yet for my guys but look very promising...

Tom


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 15, 2011, 02:38:07 PM
Well I finally finished another project that allowed me to get back to the D-558-2 Skyrocket by Douglas Aircraft....

I hated the original tissue and paint job, so stripped it all off, repaired several of the stringers that were sagging (a bit too light/soft balsa)...Got here retissued and sealed with Future Floor Polish...
Did a pretty good job and no overpowering smell like the dope....Just used a rattle can of gloss white for the final finish.  Made tissue decals with Microsoft paint program and applied with glue stick.

Here's the pics of the finished 3-D fuselage (not profile) Catajet...

Tom


Title: Re: CATAJETS: Design and Development
Post by: lemuel on September 15, 2011, 09:20:04 PM
I have a bachem natter that has no rapier motors.. Maybe I should do what you have done?


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on September 15, 2011, 11:10:28 PM
Very nice Sky!! ;D


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on September 17, 2011, 12:20:34 AM
Thanks Faaman...

Matt...I was thinking of building an Ohka like this for Catajets as well...

Tom


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 15, 2011, 06:26:43 AM
Hey guys, been a while but I thought I'd let you in on some "on again - off again" reasearch that I've been doing for a while now (in amoungst other things) to attempt to solve the "10G launch loop" our gliders suffer from off the cat.

I'm curing it by basically giving the horizontal stab changeable incidence using the difference between the high speed off the cat compared to when the model slows reaching "altitude" to control a change in angle. IE at launch the angle of the stab is 0 deg + held by the high speed airflow and when slowing as it reaches altitude the angle reduces to, for instance -0.5deg to keep the nose up for glide. It uses a small surface (made from coke can alley) protruding from the vertical stab flat to the airflow that reaches all the way down (inside the stab) to the horizontal stab at the "hinge" (think of slab stabs) with a small spring surface that resists the stab going into 0+ deg but is overcome buy the airflow at launch, at normal flight speeds holds the angle at the required -0 deg angles for glide.

Almost got it beat I think, but it does seem to be a airframe by airframe problem, that is the degree of anglular movement, the size of the "drag" surface and the amount of "spring" must be tested for each model.

So seeing that we're probably heading toward full stick and tissue Catajets (and Cataprops) there is even more room for this small bit of engineering.

Hope you find this interesting and maybe informative, post your thoughts ..........

Cheers all
Neil


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 15, 2011, 01:07:05 PM
Neil....

Interesting stuff...got any pics of the process???  Sounds like something I need to look into...

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 15, 2011, 04:01:16 PM
It is a viable thing.  I did something similar about 6 years ago with my first catajet (SAAB J-37 "VIGGEN") on the canard.  It worked pretty well, but I didn't really follow up on it.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on October 15, 2011, 05:42:42 PM
No, no pics as yet, I'm a bit of a perfectionist and if I don't think it looks good I won't publish pics. Really I just don't want to be embarrassed by my poor prototyping and building skills .... ::) ::)

Yes Pit something like that, but in the vertical, had some surprisingly ( :o ;D) good results at first but then something changed and it went a bit pear shaped  :-[. And yes mine was originally on the outside of the vertcal stab but it was too hard to stop the arm vibrating/flapping and causing some real mayhem at first. Then I decided to bury the arm in the V.stab and just have the small "tab" poking out the top, this changed things remarkably.

I've less time for muckin' round doing reasearch now as my work hours have been increased (new owners - 10hour workdays - 0500 start >:() and we're in the middle of renovating a big peice of our house plus other type of modelling (plastic) and teaching my son to build his Minicraft Typhoon (his first model) ....... so as I get it tied down and actually making the effects predictable ...... it's gonna take some time.

Neil


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 16, 2011, 08:42:09 AM
TIME... another nasty four letter word ;D.  That's  the reason I let up where I did.  I did determine that the system "works" reliably, but only with a thin music wire spring.  Aluminium was only a bit lighter, but FAR less reliable and fatigued quickly.  The wire on the VIGGEN is 0.3mm x 60mm and the weight was not even considered as the model needed nose weight anyway, but it IS very light.

The pearing out sounds like something was "hanging up", OR the launch "pull" was not enough allowing the stab to kick in sooner.  I get similar behavior when my FAI "black" shooter breaks and I have to resort to the TAN I rubber sling.   


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on October 18, 2011, 11:45:03 PM
Neil...sounds like your plate is full ;)

Pit...does the wire pull the canard up??? Not clear on just how it works?

Soon as I get the two projects done I'll have to look at the catajets again...

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on October 19, 2011, 09:51:38 AM
The wire "holds" the canard down.  Airstream at launch overrides the spring till the airspeed starts to bleed off.  It's VERY entertaining during the tests to find the sweet spot (playing with the length of the wire is the easiest way to find the "correct" amount of holding force).

Canards work backwards from normal stabs.  TE down = climb, so you want to negate that tendency at launch.


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on October 19, 2011, 03:49:12 PM
Verry interesting stuff guys ,I have been lurking about and absorbbing some of the info here !!
Keep up the testing so we all can get better planes glideing about for the youngsters !!
George


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on January 10, 2012, 12:24:46 AM
A couple of years ago I designed this B-52 glider.  Although somewhat larger than the typical catajet, it flies quite well and looks quite realistic in flight.  The plans are in .pdf format and may be downloaded from the Files section of the Minute_models group on Yahoo.

http://groups.yahoo.com/group/minute_models/files/B-52%20Glider/ (http://groups.yahoo.com/group/minute_models/files/B-52%20Glider/)


Title: Re: CATAJETS: Design and Development
Post by: Pit on January 10, 2012, 04:50:38 AM
SHEESH!  Thanks for the reminder, Howard.  I cut the parts of that when you sent me the prelim plan WAAY back then - and then I got sidetracked... :-[

Pete


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on January 11, 2012, 03:07:31 AM
Howard,

The BUFF looks great...hope to checkout the plans soon....in the process of moving so all my building for a while will be vertual....

Tom


Title: Re: CATAJETS: Design and Development
Post by: robunos on February 29, 2012, 04:57:38 PM
Meant to do this sooner................................... :-[

Recently posted over on RC Groups :-

A Phantom :-

http://www.rcgroups.com/forums/showatt.php?attachmentid=4637580&d=1329376332

and a Harrier :-

http://www.rcgroups.com/forums/showatt.php?attachmentid=4647390&d=1329713507

the page link is here :-

http://www.rcgroups.com/forums/showthread.php?t=1534053&page=16

The Harrier shows the use of a ground catapult. I've come across several references to these in various books and magazines I have.
Does anyone have any experience with them?


cheers,
         Robin.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 02, 2012, 01:15:33 PM
Thanks for the links Robin...have you built any of these?  If so please post some pics...

Tom


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on March 05, 2012, 05:43:23 PM
Thanks for the links Robin...have you built any of these?  If so please post some pics...

Tom

I, and some other people in the Blacksheep Squadron, have built the Phantom from B. Mallet's plans in the November 1994 AeroModeller and it flies quite well.  One note: make sure that the grain orientation on the wing and stabilizer follows the leading edge (see the tail), not chordwise as shown in the plan.  The glider will be less fragile and fly even better.

Howard


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 06, 2012, 12:39:29 AM
Howard....


Thanks for the insight on the grain...gotta build the Phantom soon...one of my favorite jets...

Tom


Title: Re: CATAJETS: Design and Development
Post by: flyfac on March 06, 2012, 01:49:01 PM
The wire "holds" the canard down.  Airstream at launch overrides the spring till the airspeed starts to bleed off.  It's VERY entertaining during the tests to find the sweet spot (playing with the length of the wire is the easiest way to find the "correct" amount of holding force).

Canards work backwards from normal stabs.  TE down = climb, so you want to negate that tendency at launch.

Very interesting. 

Based on your experience with canard CLGs, what's emerged as the best incidence setting for the canard during the glide phase?

Scot


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 06, 2012, 06:02:11 PM
The wire "holds" the canard down.  Airstream at launch overrides the spring till the airspeed starts to bleed off.  It's VERY entertaining during the tests to find the sweet spot (playing with the length of the wire is the easiest way to find the "correct" amount of holding force).

Canards work backwards from normal stabs.  TE down = climb, so you want to negate that tendency at launch.

Very interesting. 

Based on your experience with canard CLGs, what's emerged as the best incidence setting for the canard during the glide phase?

Scot
Now I have to dig the thing out of the pile and measure it ;D.  It was more of a "cut-and-try" effort rather than any mathematical wizardry.  I'll get back when the deed is dood.

Pete


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on March 08, 2012, 01:26:04 PM


Very interesting. 

Based on your experience with canard CLGs, what's emerged as the best incidence setting for the canard during the glide phase?

Scot

My experience, with a model I have been working on, is that 6 degrees incidence, the main wing being zero, gets a good glide if the canard is relatively small, less than 1/10 the wing area, and the incidence (decalage) decreases as the canard area gets larger relative to the wing. 

Of course, there has to be some method, like Pete's wire, of reducing it to zero for a cat launch.  I've seen several canard cat gliders that are set up for good launching with zero/zero decalage and they have very good launch characteristics, in fact they go higher than any conventional gliders I have seen, but they all loose too much altitude before establishing a good glide angle.  Pete's idea sounds like a good solution.  (Easier than mine, anyway.)


Howard


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 08, 2012, 03:32:19 PM
Measured the incidence at 5° glide (TE down) and the slot allows the angle to go to 0° at launch.  As Howard mentioned, it does get up there on  launch, but I still don't have the transition really "nailed".  It's OK, but the shot has to be near perfecct or it'll do funny things going over the top.

On the Viggen, I increased the areas of the main-plane AND the canard over the size shown on the plan, which reaklly helped improve the overall performance without ruining the appearance.  I've seen a Vary-Eze that did well as a cataglider (more usefull wing) that I may try.


Title: Re: CATAJETS: Design and Development
Post by: robunos on March 08, 2012, 04:46:26 PM
Catties are a new departure for me, so no hardware at present. I'll probably build the Phantom, thanks for the tip about the grain direction on the wing, but I think the Harrier is a bit over-engineered, with the hollow fuselage and all, however I do like the use of thin ply for the tail surfaces...
At the maoment, my main interest in in 'models of models', as I mentioned in the cataprops thread, so I'm concentrating on those at the moment...

cheers,
         Robin.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 08, 2012, 05:03:24 PM
The ply seems a bit overkill to me - I normally use 1/32 balsa for tailplanes and sometimes 1/16" for fins on this sort of thing :o Although maybe the underfin would need to be tougher.

I think it would fly ok with no dihedral but I've found getting them to transition is tricky without it  :-\


Jon


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on March 08, 2012, 07:07:10 PM
Measured the incidence at 5° glide (TE down) and the slot allows the angle to go to 0° at launch.  As Howard mentioned, it does get up there on  launch, but I still don't have the transition really "nailed".  It's OK, but the shot has to be near perfecct or it'll do funny things going over the top.
...


Have you tried launching with the model about 105 degrees to horizontal?  I mean leaning a little backwards from straight up.  I was having trouble with the Vampire F.1 I am working on until I launched it leaning backwards with my back to the prevailing breeze.  The result was a straight up climb with a good roll out at the top.

Just a suggestion.


Title: Re: CATAJETS: Design and Development
Post by: flyfac on March 09, 2012, 02:16:14 AM
Pete & Howard,

Thanks for the feedback on canard incidence.  Looks like 5-6 degrees would put me in the right ballpark.

Here's a 3-view of the aircraft I'm looking to convert to a clg. 

Best,

Scot


Title: Re: CATAJETS: Design and Development
Post by: flyfac on March 09, 2012, 02:20:31 AM
Quote
The result was a straight up climb with a good roll out at the top.

That's an impressive bit of photography!  How many tries did it take to capture the glider in the shot?

Scot


Title: Re: CATAJETS: Design and Development
Post by: Pit on March 09, 2012, 05:02:38 PM
I built a similar model - the J7W1 Shinden.  Off the shooter, it does a nice series of loops, but has a fair glide.  tried to trim the "loop" out and it wouldn't glide at all.  Methinks the canard is too small, even tho it is considerably larger than scale.  NO auto surface on it.

It's now awaiting a wider canard.


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on March 09, 2012, 05:44:18 PM

That's an impressive bit of photography!  How many tries did it take to capture the glider in the shot?

Scot

That was the first shot.  The guy who took it is just that good!  I didn't know he had taken it until he handed me the print.  Here's one I took of the glider close up.  (Picture quality reduced to meet attachment requirements.)

Howard



Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on March 09, 2012, 05:53:48 PM
Cool! Love the Vampire Howard!

Jon


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 24, 2012, 06:39:54 PM
Just catching up after the move....

Great looking jets Howard and I love the pic of the launch catching the Vampire.... 8)

I've gotta build a couple of jets for the fetchermites when we get back to them in June...thinking about a F-14 from Marcelo...

Tom


Title: Re: CATAJETS: Design and Development
Post by: spooler41 on April 08, 2012, 12:36:47 PM

   I've almost forgotten about catapult launch stuff. The last ones I can remember building was about 60 years ago, '53/'54. One of my best flyers was a 12" span" Nater". Looks like I may have to take a new look at this. I could use a few hours of simple builds and simple flying fun.
       Thanks for the reminder.
                                                 .................Jack


Title: Re: CATAJETS: Design and Development
Post by: Pit on April 08, 2012, 02:10:44 PM
!!URGENT WARNING!!

Scale type cataplanes can be SERIOUSLY addicting!

Do NOT expect to get any other forms of flying accomplished if the outing is started with these beasties!!


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on April 10, 2012, 08:48:00 PM
Pit... ;D ;D ;D ;D :o BEEN THERE, DONE THAT...GOT THE T-SHIRT :D ;) 8)

Tom


Title: Re: CATAJETS: Design and Development
Post by: rpendzick on April 10, 2012, 09:37:03 PM
Has anyone tried a swing-wing? Here's a few pix of my off-scale F-111 test bed.
have fun
Rick


Title: Re: CATAJETS: Design and Development
Post by: Pit on April 11, 2012, 08:59:20 AM
I've been itching to try a true "swing-wing" - either the 111 or one of the Russian jobs.  Have you gotten the swing function to work reliably yet?  if so, HOW?  Looks like you have a button timer in the nose...

Tom...
Got a pic of the T-shirt?


Title: Re: CATAJETS: Design and Development
Post by: rpendzick on April 11, 2012, 01:23:37 PM
I grew up next to the Calverton Grumman plant. While working in the potato fields, F-111Bs and F14s flew overhead. I've tried many swing wing versions and nothing worked. A few weeks ago I saw the Swinger plans in Meccano Mag 2/68. The pivot points are in a different place (not scale). As soon as I saw it - I knew it was the answer.

The wings snap forward and lock up against the fuse. Note: fiberglass the wing holes or the wing will give way along the balsa grain.  I also suggest not gluing the pivot pin in the top/bottom plate. Then you can change wings easily.

The release timer is my own design. First note the "Launch Pins" on each wing. When the wings are swept back the launch pins meet at the cutout in the fuse. I found monofiliment fishing line slides the best. I get 2-4 sec. delay after launch, then the wings snap forward for glide. I played with many different ways to string it. I finally hit on the simplest way. Just tie one end to a launch pin - thread through a center eye - out to the timer - back through the eye - tie to the other launch pin.

lots more photos and how-tos (link to Meccano plans) at my site:
http://hobby.eyeonentry.com      click on Swinger 111

note: I'm working on a scale F-111B

Trimming these Jet Cats is tricky!

have fun
Rick






Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on April 11, 2012, 07:45:20 PM
Rick....great links and you site is GREAT!!!!

Really appreciate this swing wing info....been wanting to do an EF-111A  and an F-14 Tomcat....

Post some pics of you stuff here also....

Tom


Title: Re: CATAJETS: Design and Development
Post by: rpendzick on April 11, 2012, 10:30:53 PM
Tom
One more important change from the Meccano plans. The slot through the fuse for the rubber band is in the wrong place. Move the slot back to line up with the bottom plate.
The rubber band swings the wings forward AND pulls on the button timer. The trick is to get them to work together. The plan's slot position has a maximum rubber stretch with wings swept back while in the forward position the rubber is too weak to hold the wings firmly forward. If you make the rubber shorter ie stronger, the timer goes off too soon. I was getting 1.0 - 1.3 secs.
So I found the middle ground position. The new slot position has the minimum difference in rubber stretch. By adjusting the length of the rubber loop you can get a consistent 2.0 - 2.5 secs. I start with a long loop and keep making shorter and shorter knots. The wing has a strong pull on the Tiny Rotary Timer, it makes 3/4 of a revolution in 2 secs.
Another benefit, the rubber band does not get caught in the swing mechanism and it is not as visible, kinda tucked under and out of the way.
Have fun
Rick




Title: Re: CATAJETS: Design and Development
Post by: pubguy on May 12, 2012, 04:21:28 PM
Hello Everyone

 Its been awhile since the last post. So here are some pictures of the latest build. If the flying goes good tomorrow I plan on building the longer F version. Glide test were really good so I have high hopes for it. If we survive the rest of the markings will go on. Looking to build a F4G and A7 or F8 or all of them. Well Happy Landings to all.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on May 12, 2012, 04:28:35 PM
Very nice! Does it have any dihedral?

Jon


Title: Re: CATAJETS: Design and Development
Post by: pubguy on May 13, 2012, 01:46:15 PM
Hey Jon
 
The F100 has aprox. 7mm at the wing tips. Had a great day at the field today. The F100 will need some work as it would swap ends at the top of the launch then lawn dart straight in. Shifting the weight around changed very little. Need to look into it and see what can be done for next flights. If anyone has a idea I'm all ears. Remade the Tiny Dip from lite balsa went from 14g down to 7g and averaged 15 sec. flights with a few 20 and 30 sec. flights. The best was when martin decided it was flying to close and attacked 3 or 4 times. No injuries to plane or bird. All other models flew great except the F94 today. It works better with a breeze.  All in all a great day. Looking for the next chance to get out.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Pit on May 13, 2012, 06:13:54 PM
More dihedral and washout (what is the span?).  If the real plane had boundry fences, add them to the model.  My F9f Cougar did the same shenanigans till I made the aforementioned mods - now flys fairly consistant 20-30 seconds.

Pete


Title: Re: CATAJETS: Design and Development
Post by: pubguy on May 20, 2012, 03:54:36 PM
Worked on a few new projects this weekend should be ready for dope and paint Mon/Tues. The P40 is the first attempt for the piston work. Hope to test fly this week. Will post other pics on Cataprop. site soon. The yellow dip had its wings replace with lite balsa wings since I built the orange one out of lite balsa and had better flight times. The tail feathers are heavy balsa so if it doesn't fly any better I will change them out also.

Brian


Title: Re: CATAJETS: Design and Development
Post by: ddock on May 28, 2012, 09:00:42 AM
Cat-Jet Guys,
Going through my Dad's old Aero Modelers (JULY 1963) and found a full size plan for an 'Arbalete'(Swiss jet) flying wing catajet.I don't have a scanner but would be happy to copy and send to someone who would put it in the plans file if it is legal.
D Dock


Title: Re: CATAJETS: Design and Development
Post by: Pit on May 28, 2012, 09:36:25 AM
Here is a small three-view of the beastie...


Title: Re: CATAJETS: Design and Development
Post by: pubguy on May 28, 2012, 12:42:46 PM
Update on the F100. The boundry fences helped out the flight after it swaps nose to tail. Next step will be washout on the wings and another test flight. Then it will be more dihedral. Had great flights on the Krazy Kat ounce some weight was added. Looks like it will be blast on a calmer day. Its to bad the winds stated to pick up and gust. I was hoping to be out longer. 


Title: Re: CATAJETS: Design and Development
Post by: pubguy on June 03, 2012, 02:08:59 PM
Have an  update to the F100 saga. Finally got out to the park. Winds were around 9mph give or take. Added the dihedral to the wings and some balance weight under the wings. Had a number of satisfactory flights. Now its a question of balancing for the wind conditions. Flights weren't as good when the wind was down as compared to a breeze. But I am happy with the way it is improving that I will now put the finishing decals on to make it look better. Thanks Pit for the helpful hints.

Brian


Title: Re: CATAJETS: Design and Development
Post by: ddock on June 06, 2012, 10:48:00 AM
Catajet,
Found a second Catajet in an old Aero Modeler...Vulcan...May 1965.
Denny


Title: Re: CATAJETS: Design and Development
Post by: Icarus on June 14, 2012, 04:15:04 AM
Hi everyone,
Here's a picture of my Fi-103R made from plans on this website, which I was put onto by FAA man when I was looking for a project last year for the autistic boy I was teaching at school. My student got a real buzz out of building his version - I have attached a photo of his too. His didn't fly that well (he made a number of modifications one day while I was at lunch that saw to that!) but I have managed to get about 25 seconds out of mine and a nice steady glide path. It glides best with a launch just above horizontal.
I am at a new school this year and have just got a couple of boys with learning difficulties to build an Fi-103R. We launched it last week on the school oval at lunchtime and they became instant heroes. It flew better than I expected straight off and they are perfectly happy with 15 seconds flight starting with a loop and including some unpredicable inverted flight...
Anyway, I now have about 4 students building the Fi-103R and a couple of Phantoms and one wants to start on a Skyray from the Jetex website. I'm gonna have to start making up basic kits to get them all started!
Seriously, any other teachers out there have probably realised the education potential of these planes, best thing is you get to play too! The kids get to learn building skills and the patience to get it right and they get something they value for their trouble.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on June 15, 2012, 12:04:58 AM
Great stuff Icarus,

Thanks for sharing the story with us and good luck with the new flock of birdmen ;)  Just a note the Skyray from the jetex plan is quite large,if my memory is correct. You may want to ruduce the plan size to 8 inches span. Will still leave a pretty good size model. Pete's Panther on this site is another good model.  The Phantom may be a bit more of a challenge to trim.

The guys will love them regardless.... ;D enjoy and thanks for your efforts with the "Paddawan learners"...

Tom


Title: Re: CATAJETS: Design and Development
Post by: Icarus on June 15, 2012, 03:06:30 AM
Hi Tom,

Thanks for the kind words. Yes, I haven't told them how big the Sky Ray actually is, have just shown them the reduced plan. I'm not sure how the wing will act at about 8" with no dihedral - have you tried it?
I have been wanting to build the Phantom myself so have been keeping a close eye on it to make sure it's being built right, luckily the builder is one of the more patient kids so he should be prepared to do what it takes to trim it. We'll see...

One boy has started building the Panther but seems to have lost interest - that sometimes happens when they realise that it's not an instant thing. I'll have to chase him up.

By the way, it's not just boys - some girls are building them too.

My own current project is a P-80, just can't seem to get the trim right. 15 seconds on the stopwatch is best so far!

Cheers,

Richard


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on June 15, 2012, 03:18:49 PM
Icarus,

Great you've got some girls involved also...they'll enjoy this as well.  Sometimes they have more patience than the boys.  My full size Skyray didn't work out too well as a catajet.  Takes a hefty size rubber to launch and was a bit much for my grandsons, should work well as a smaller catajet.  They preferred the smaller planes. I've seen a Concord model with the same wing setup that is 8 inch wing span that was reported to fly well (just noted it's in the gallary plans section).  The Okha is a very good flyer,and was what got me started in the catajets, link: http://www.hippocketaeronautics.com/hpa_forum/index.php/topic,3731.0.html , and my F-94C flew well with just a 1/16 flat sheet wing.  Just make sure the tip tanks are aligned parallel to the fuselage or there will be trim problems, same for the panther's tip tanks....

Good Luck and keep us posted with the progress.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 16, 2012, 06:35:34 AM
The Panther has turned out to be a pretty good flyer - tho I haven't really done much the last year.  One thing I DID try - mostly to avoid the trim problems of mis-aligned tip tanks - was to make the three dimensional and from the lightest foam I could get my mitts on.  "Scale" sized, and only about 0.5grams for the pair.  Really adds to the effect, with no trim problems.  Glued them on with a dot of canopy glue.

They DO take a beating, tho...

Pete


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on June 16, 2012, 01:28:52 PM
Pete,

Thanks for the update...I'd thought about foam for the tiptanks...got any pics???

I must admit I've been away from the catajets also...about time to do a couple more...
Tom


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 16, 2012, 04:59:16 PM
Unfort. no picts of the tanks.  They don't last very long (but longer than the profile ones), and one is somewhere in the head high wheat field - deciding to play hide-and-seek.  My gliders are presently "buried" somewhere in my work-cave.  I've only had one chance to do ANY FF, and that was last month, when the tank went AWOL.  Nothing but wind, rain and unseasonable COLD!

I've been hoping to get  the "BUFF" by kittyfritters done for this "summers" jetting, but won't be able to do much till next week.


Title: Re: CATAJETS: Design and Development
Post by: pubguy on July 04, 2012, 09:06:06 AM
Hello Everyone

Well the winds in the mid-west finally calmed down enough to get out and fly. Had Great success with the F100. After all the adjustments suggested by Pit things were working pretty good. The final adjustment came in the launch. Instead of launching at say 45deg. right I leveled the launch and it never swapped nose to tail again.  The last flight that day had me running about 200yds to retrieve it. It was a great day.

Brian


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 04, 2012, 11:58:31 AM
Glad you got a chance to get out flying Pubguy....I'm getting inspired to get some new birds built and to get out flying again.

Tom


Title: Re: CATAJETS: Design and Development
Post by: Icarus on July 06, 2012, 12:12:22 AM
Here is one result of this morning's flights. The first flight of the day, the normally reliable F103 does a half roll to the left straight in to the ground. I have attached a picture of the park where I was flying - of course the F103 had to hit the compacted running path, not the grass!

I also tried the Sky Ray in 8 inch span version, too much lift, it just wants to loop off the cat and then glide slowly to the ground, maximum flights about 5 seconds.

The Phantom from the plans on this website was better, but has a strange habit. With only a little nose weight it flies well off the cat, then as it slows it hits a speed where it gently stalls and falls out of the sky like an autumn leaf. (At least there are no hard landings!). Add just a little nose weight and it transitions at about the same point into a shallow dive - graceful, but doesn't make for flights of any duration.

Any suggestions why? I've tried to add washout but not sure it works with the Phantoms wingtips.


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on July 06, 2012, 06:34:30 AM
A lot of the catajets are suceptible to this behaviour, I think its because the flat forward fuselage is acting like a fin - on a built up model it would have less effect. As long as the model flies straight it doesn't notice but a small yaw is quickly exacerbated.

Is it snapping off in to a deep stall and fluttering down or does is drop a wing and spin down? The former is often due to a lack of fin area or too much forward fuselage area as above. The model becomes unstable in yaw.

The second is an asymmetric stall (aka tip stall) so washout, wing fences, sawtooth leading edges will all help. Wash out will also have an effect on the decalage so you might need a bit extra incidence in the tail. Wash out certainly tamed my swept and tapered wing P.1127 which had similar problems.

It may also just be that you need to fine tune the CG position with really tiny amounts of noseweight. On some of mine I've found as little as 0.1g makes a big difference.

Keep plugging away with it though  :) Tom will probably have some more specific trimming tips too...


Jon


Title: Re: CATAJETS: Design and Development
Post by: marcelop on July 06, 2012, 07:17:26 AM
hi folks!!! i send a special edition of "lupin"magazine, with 4 new plans of catajets.hope see soon in the plan gallery
enjoy!

marcelo and the JV44 school of ff of uruguay


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 07, 2012, 01:03:51 AM
Icarus....

Jon gave you some great information....

The Skyray might respond to a small gurney flap on the trailing edge of both elevons towards the wing tips that can be adjusted in small increments.  With the Skyrays "wave" airfoil you may be getting too much up elevon.  So a bit of down with the flaps may tame the loop tendency.

Just remember that it's very important "small" adjustments are made.  With that cat launch small deflections of the surfaces (elevators, rudders/fin etc.) causes big responses immediately.  I would encourage you to keep records of the adjustment...will help immensely.

Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on July 08, 2012, 11:45:04 AM
Here are the pictures of the F100 and my Skyknight. Both now perform really good. You can see they have had a few flights before adding the final details.  Next step is to make a F version of the Super Saber.


Title: Re: CATAJETS: Design and Development
Post by: Icarus on July 08, 2012, 07:37:24 PM
Hi Jon and Tom,

Thanks for the advice, I'll let you know how it all goes. One thing you need a lot of with these little planes is patience! Still, if they flew perfectly off the board that would take all the fun out of it, wouldn't it. ;)

Richard


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on July 09, 2012, 06:04:52 AM
...One thing you need a lot of with these little planes is patience! Still, if they flew perfectly off the board that would take all the fun out of it, wouldn't it. ;)...

Too right!

Lovely jets Pubguy  8) I like how you've done the intakes on the skyknight.

I flew my Hawker P.1127  off the catapult the other night. I had built it (in about 5 minutes  :-\) as a test glider for a rubber powered version and I didn't expect it to do very well as a catajet. But I was pleasantly surprised at how well it did. It has 7 degrees of anhedral so it doesn't exactly transition but it did get quite high and recover enough for a short glide. Only 8-10 seconds I reckoned, but it has some novelty value.

I'm tempted to build one as a dedicated catajet...


Jon


Title: Re: CATAJETS: Design and Development
Post by: Balsa_Hacker on August 25, 2012, 03:16:59 PM
Built a Saab viggen 37, and after numerous lawn darting (and nose rebuilds!) got it dialed in and out to the local High School.

Really happy with 7+ seconds. Not much compared to most folks on here, but with such a HUGE delta wing and front canards (and over built!) wasn't really ideal for my first attempt at catapult launching!


http://airplanesandrockets.com/airplanes/viggen-mar-1973-aam.htm


Title: Re: CATAJETS: Design and Development
Post by: tom arnold on August 25, 2012, 09:31:11 PM
I, too, have built the Viggen out of the American Modeler mag and have had a ball with it after getting it trimmed out. But, just like your experience, it really is not a floater and I cannot imagine why. It has a LOT of wing area and it is all "useable" due to the canard being the trimming surface i.e. no reflex is needed like on many delta wings. So why the modest flight times? I realize it has a low aspect ratio but so does a Fike and look what it does. I don't know and hope one of our aero engineers can shed some light on this mystery.


Title: Re: CATAJETS: Design and Development
Post by: Pit on August 26, 2012, 06:17:58 AM
I got fair duration (20-28 seconds) from most of my Viggen models built from the plan in Flying Models, but I had added dihedral to the main wing.  Duration went up when I increased the areas of BOTH surfaces and "hinged" the forplane to flatten out at launch, springing (thin wire) to the glide position as the wash diminished.  The American Modeler plan is a bit more "scale" with the mainplane in the "correct" location.  Maybe a new build is in the cards.  The Viggen IS responsible for getting me into this catajet mess (was my first one) ::).

I'll have to try the dihedralled foreplane...

Pics and description HERE (http://www.hippocketaeronautics.com/hpa_forum/index.php/topic,472.msg4311.html#msg4311) staring at msg #11


Title: Re: CATAJETS: Design and Development
Post by: Balsa_Hacker on August 26, 2012, 06:10:19 PM
I get really cool flight paths out of it, covers lots of ground.


I moved the hook fwd, at put a nice "TLAR" airfoil on front canards.

Next mods I am thinking of is putting some pseudo flaps on the main wing to help with descent recovery.



Title: Re: CATAJETS: Design and Development
Post by: pubguy on August 29, 2012, 07:20:02 PM
Hey Jon

Here are some early pictures of the build that may help. Its still needs some tweeking. Next time I may add more dihedral and see what happens.

Brian


Title: Re: CATAJETS: Design and Development
Post by: lekovic on October 29, 2012, 09:32:21 AM
Hi all! My catajets and catapult scale plans collection: http://depositfiles.com/files/59xs07yec Enjoy!


Title: Re: CATAJETS: Design and Development
Post by: rpendzick on June 25, 2013, 08:36:19 PM
Here is my latest F-111b swing-wing JetCat. It's has taken me 2 years and 5 different major rebuilds. I've got a box of drawings.

This one is 8.5in closed, 17in open, length 17.75in. Sweeps a scale 16deg to 66deg. (I think the real F-111  maxed at 72deg, but the Navy F-111b could "over-sweep" for storage on aircraft carriers.)

have fun
Rick


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on June 26, 2013, 02:54:11 AM
Very cool F-111B (?)  8), must've been a lot of R&D involved to get it right.

Do you have any flight pics or vids? 100 out of 100 for effort !!!!


Title: Re: CATAJETS: Design and Development
Post by: rpendzick on June 26, 2013, 07:55:40 AM
Trimming the F-111b is tricky. Your high speed launch is swept back with a rear CG and then 3 seconds and then forward sweep for glide mode. You have all the crazy trimming issues as you would for a fixed wing JetCat but in two modes. This new version has 1.25 in. dihedral in glide mode, that helps. All previous versions were flat wing. You can also insert stops to change the forward wing sweep angle. (ie. sweep = dihedral) I'm starting at a forward sweep of 10 deg (scale takeoff was 16 deg). If I need more stability I'll sweep it back another 5 deg or so.

Still more R&D to go - You don't appreciate good model designs until you try and do one yourself and I'm a slow learner. Skip back a page or so to see a year old post - 3 versions ago. It kinda looks like a pancake.
The Swinger plans in Meccano Magazine 2/68 changed my life.
http://pdfmm.free.fr/6802.pdf

have fun
Rick


Title: Re: CATAJETS: Design and Development
Post by: Monz on July 04, 2013, 06:49:16 PM
"hinged" the forplane to flatten out at launch, springing (thin wire) to the glide position as the wash diminished. 

Hi Pete, do you maybe have a pic of three of this setup?


Title: Re: CATAJETS: Design and Development
Post by: Pit on July 05, 2013, 07:15:09 AM
"hinged" the forplane to flatten out at launch, springing (thin wire) to the glide position as the wash diminished. 

Hi Pete, do you maybe have a pic of three of this setup?
I can't find the original photos that I had, but here is where I posted them - starting with a brief description in reply #9.

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=2370.0

Pete


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on July 05, 2013, 07:02:17 PM
Great stuff lately.... gotta try the swingwing!!!!

Tom


Title: Re: CATAJETS: Design and Development
Post by: rpendzick on April 26, 2014, 11:01:34 AM
Never Give Up - latest F-111b

The biggest problem with my swing-wing design is that it broke before I could get it trimmed to fly well. So I'm keeping what works and changing what doesn't.
WORKS - the basic geometry and wing release system. After 3 years I think I have this right.
DOESN'T WORK - too fragile, too heavy, not enough lift.

I now have built up wings, this saved some weight, gives a lot more lift, and it flies slower. The built up wings should be less of a problem on launch with the wings swept back. I also added an inch to the wingspan (the F-111b had longer wings than the USAF version). I have a few more tweeks, bigger pivot dowel to distribute the load (drilled out the pine dowel to a 1/16 wall - If I'm lucky the dowel will break before the wing.) , redesigned leading edge from the fuse to the wing shoulder and I'm using 1/64 ply to support the top and bottom plates. Wingspan is 10.5" closed, 18" open.

So far I've have tossed a pinned up version in the back yard, just to see the glide and incidence settings are close. So far I'm happy.

You never know - one of these days I might just show up with a plane that works.

have fun
Rick



Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on April 30, 2014, 11:53:04 PM
Just keep plugging away at it guy ,I hope you get it working so I can play with one with a better chance to have it work because of your
determination to get things right !!
George


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on May 01, 2014, 04:24:10 AM
rpendzick...great stuff!  As the old saying goes, "If at first...."  I know you'll succeed!  Ditto what Dimeflyer said!
Tom


Title: Re: CATAJETS: Design and Development
Post by: pubguy on September 01, 2014, 02:02:40 PM
Hello Everyone
Its been awhile but here is my latest CATAJET. It took awhile to get it balanced and flying good. Nice high launch with a bank to the right and a smooth transition to a right turning glide. She is no light weight 17.8 grams. But what a flyer. Made the plans from a drawing in a book of John Bell designs and 3-views. Will eventually build another one and correct the mistakes of this one. Until then lots of good flights coming up. The red tips were added after the first test flights as it was to hard to find the plane sometimes.


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on September 03, 2014, 08:14:33 PM
great looking F4FII
I had some fun times in NAM watching them drop Napalm canisters on some tanks with red stars on them !
 Really not fun - it was scary as all heck because if they did not stop the tanks I would not be here today !!
George


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on September 03, 2014, 10:16:11 PM
Has anybody done one of these as the F-22 Raptor? Just wondering. Let me know how if you have any ideas.


Title: Re: CATAJETS: Design and Development
Post by: Pit on September 04, 2014, 08:24:12 AM
I have a DEPRON® test vehicle based on the F-22/F-35, but I haven't had decent enough weather to give it more than a few tosses in the backyard. It's tiny at about 5" span and was a buggar to get flying (at present NO dihedral), but did finally get it to glide reliably.  I'm hoping to build one with an 8 or 10" span for catajet postals.


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on September 04, 2014, 09:37:18 AM
Pit thanks and keep us posted on the progress.


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on September 04, 2014, 09:32:31 PM
Pit
have you ever seen Dr. Ninamia paper gliders I'm not sure if I spelled his name proper ?
I have put some of the first set he put up to the public together for my Daughter and Son years ago
and have wondered if they might work if we enlarged them and made them from foam , I always
get detoured by wife from doing a test of them in foam because she is afraid I will spend to much $ on
the project so she makes me go to the wood shop and build some thing for the house so I will forget
about the gliders !!


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on December 07, 2014, 07:08:10 PM
Has anybody done one of these as the F-22 Raptor? Just wondering. Let me know how if you have any ideas.
Has anyone designed a model with a profil;e fuselage? I can't help but wonder how the twin fins can be attached. I really want one to fly in FAC Jet Cat Glider event. I have a Raptor t- shirt as well as a Raptor cap.


Title: Re: CATAJETS: Design and Development
Post by: Pit on December 08, 2014, 10:50:20 AM
Here are a few photos of the foamy Raptor.  It's all 2mm thick foamboard, probably Depron® cored, and all the parts fit on an A4 sheet (about half of a standard sheet of  US paper).  As I mentioned, it DOES fly but was not quite so kid friendly to get there.  Alignment is critical, and getting the tabs thru the slots was a bear - a kid (and many an adult) would probably destroy it.

Decalage is designed into the "kit", but I found that it still needed a bit of "up" elevator.  The intake strakes are set with the front on line with the wing LE, but the area at the LE is above providing a bit of camber.  All tabs remain, providing a tremendous amount of drag, but may actually provide for a bit of stability as long as they are kept aligned.

I'll try to get an 8" span sketched up this week and a proto build done.


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on December 08, 2014, 07:50:15 PM
Thank you for the response. This looks mighty nicely done. I'll be watching for further developements. Will you be using balsa on the 8" span version ?

Very nicely done Pit


Title: Re: CATAJETS: Design and Development
Post by: Pit on December 09, 2014, 05:36:15 AM
Thank you for the response. This looks mighty nicely done. I'll be watching for further developements. Will you be using balsa on the 8" span version ?

Very nicely done Pit
I can't take credit for this one.  It's a 1:1 copy of a commercial Chinese product that I bought/stuck together for my neighbors' kid.  Scanned the graphics and made my own foamboard.  I've a bunch of the "noseweights", left over from trashed foamy toys - almost perfect balance.

My larger version will be balsa.


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on September 10, 2015, 02:54:31 PM
After five years my venerable B-52 cat glider finally won the contest it was designed for.  I made a few modifications, increased the stabilizer area and gave it slightly more dihedral, which gave it a bit more floaty glide.  It was a quite windy, 100 plus degree day, and the B-52 has good penetration which blew the competition around so I was able to win with a 26 second flight.  There was a wet spot on the field which had quite a downdraft over it.  A couple of flights my glider went through the downdraft and started a well developed spin which made two or three turns and recovered to a nice glide!  I will re-post the plans after I revise them to the current standard.


Title: Re: CATAJETS: Design and Development
Post by: wyshynski on December 16, 2015, 04:05:24 PM
My first attempt at a jet CLG: F2H-2N Banshee. I have a new appreciation for those who design from scratch, especially FF scale kits. Immense amount of effort, just based on what it took to create this simple CLG from 3-views. Some test glides in my backyard, leading to blob of clay at the tail, leading me to think the regular version of the Banshee would have been a better starting point.

Best,

James


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on December 16, 2015, 08:15:14 PM
Jets are not normally good gliders as full scale aircraft so it takes some fiddling to get them to be an Hlg or clg
in a small scale , the only model I found that took very little fiddle time was Niamyas white wings F15 Eagle in the smaller
 scale paper planes kit . that I have never found again and would like to be able to remember how to build again because
the manual and parts sheets was destroyed in an garage fire a long time ago !  :'( :'(
 George


Title: Re: CATAJETS: Design and Development
Post by: wyshynski on December 17, 2015, 05:40:13 PM
Thanks George.

J


Title: Re: CATAJETS: Design and Development
Post by: Pit on December 19, 2015, 03:18:13 AM
I got my F9f Panthers flying pretty reliably - without too much trouble - at 12" span.  I couldn't get an earlier version at 8" to work.   The Banshee is very close to the Panther layout so it might do OK.


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on December 19, 2015, 03:25:58 PM
The Banshee looks pretty nice.  Good luck with her!  I got my FH-1 Phantom to fly pretty good.  Nothing near Pit's Panther but lots of fun.  Guess I'll have to get building some more Catajets!
Sky9pilot


Title: Re: CATAJETS: Design and Development
Post by: wyshynski on December 22, 2015, 10:00:40 AM
Thanks all, will see once it stops raining here in Atlanta

James


Title: Re: CATAJETS: Design and Development
Post by: DHfan on January 29, 2016, 11:45:59 PM
F22 Raptor Catajet  10 inch span

Nothing fancy.  Very stable flyer.  Stiff structure, a little difficult to warp in the trim.

I have a book of Semi scale glider plans from Starcraft?  Karl Geis is the name I am remembering.  A lot of fun, good flyer.  I tried to do the design in the same style.
Plans have been uploaded to the gallery.



Title: Re: CATAJETS: Design and Development
Post by: DHfan on January 30, 2016, 12:43:32 PM
That middle line didn't make much sense.
F22 Raptor Catajet  10 inch span
...
I have a book of semi scale glider plans from Starcraft, Karl Geis is the name I am remembering.  The designs were a lot of fun, good flyers.  I tried to do the F22 design in the same style.


Title: Re: CATAJETS: Design and Development
Post by: HoveToo on January 31, 2016, 04:52:38 AM
That looks like an interesting start into catajets (for me) - thanks for posting the plan.

Can you provide dimensions for the wing mount as there is no scale bar on the plan.

Ian


Title: Re: CATAJETS: Design and Development
Post by: DHfan on January 31, 2016, 08:51:56 AM
I measure 3.0" long, (across the grain), and 2.86 wide.  Another way to look at it is that the wing Mount width should be 2x the width of the inlet pieces, which is slightly more than 2x the forward edge of the horizontal stab pieces.  Similarly the length of the Mount is the length of the wing root edge minus the length of the side of the fuselage part of the horizontal stab, plus a little (<1/16") for clearance between the wing TE, and the stab LE.

Having said all that, my suggestion is to cut out a set of paper templates and fit them together per the layout in the lower left corner. Trim the templates so they fit flush and square.  There needs to be a little (<1/16") clearance between the wing and horizontal stab flying surfaces.

On the vertical stabilizers sand in the lean angle to the bottom edge to get a good glue joint. Same for the wing roots and the dihedral. Those butt joints need all the help they can get.

Thanks for the question.  It got me looking at the plan from another perspective.  I'll re-post it with improvements, (like separating the vert stab pattern from the fuselage pattern, duh!).

Mike


Title: Re: CATAJETS: Design and Development
Post by: HoveToo on February 01, 2016, 04:05:47 AM
Thanks for the extra guidance Mike. I have a box of CLGs that need repairs this morning (frozen ground and sub optimal landings) but that should give me time to cut some new wood.

Cheers, Ian


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on February 01, 2016, 05:51:11 PM
Good to see the F-22 in this. Just might build one someday.


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on February 02, 2016, 02:11:02 PM
Made a modification to my B-52 cat glider...increased the elevator area.  Took first at the Black Sheep Squadron picnic, back in September, with a 26 second flight, not it's best (but good enough that day), and I have some other ideas that may make it fly better and make it easier to build.  When I get the original plans on my system I will edit them and post in the Plan Gallery. 

Changed computers, a while back,  and the backup with the plans is on a 3.5" floppy disk.  Fortunately, I still have the old computer out in the garage. I just have to find the time to re-install it and boot it up.


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on February 02, 2016, 07:51:59 PM
What is the wingspan on that winning B-52 ?


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on February 03, 2016, 02:56:17 PM
What is the wingspan on that winning B-52 ?

The span is 16 inches and it's patterned after an early model with the tall tail. The photo is pre elevator area increase.


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on February 03, 2016, 06:43:37 PM
I thought it might be a D model B-52. Saw a lot of the D and G model while serving on Guam between June 1972 and June 1974. They were amazingly noisey especially during takeoff.


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on February 05, 2016, 05:48:10 PM
K.F.
Fantastic C.L.G. Guy !
George


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 14, 2016, 10:38:44 PM
I've been flying Jet Cats for a little while and really like them as opposed to CLG's but both are FUN...I'm flying a Jet Provost right now and so far it has been the best flyer for me. The short nose does the trick but you pay a penalty with weight in the nose. So I got around that by building it light, 3/32" sht. fuselage, 1/16" sht. wing and tail feathers, spray acrylic colors. Working on a Macchi MB-326 trainer right now and another Provost and decided to put 2 ribs in each wing panel because the 3/32" sheet wing just wasn't generating enough lift. I wetted the panels, Ace bandaged them to a form and when dry, and after glue sticking the ribs to the plan, added cement and pinned the whole shebang down. I did cyno 1/16" square basswood to the leading edge before I wetted it. I suppose a 3/16" sheet wing would work better but I'm put off with the weight penalty. I have heard of people using built up wings and will try that next. Way, way, way back in the late 70's Dennis Norman built a very large B-52 for Jet Cat and it blotted out the sky. He stuck a pitch fork in the frozen sod, added about 20 grams of Pirelli and let it go ! Reminded me of the BUFF's I saw in Okinawa when I was passing through going home from NE Asia...


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on February 17, 2016, 01:35:34 PM
I have a problem (maybe it is solved) . On my latest XP-84 I need to figure out a way to install the vertical stab at the rear and top of the aft fuselage. How do you cut the slot ? I keep trying different approaches and just never am happy with the results . The no.11 blades always follow the grain or a wood file just won't get the slot done straight. The rear slot is cut but the glue has done the trick so that the assembly is now installed straight. Maybe you can remember the time when you suffered with getting  the slot done easier and will tell us since I know I will be doing other similar jobs in the future. Thanks for any assistance.


Title: Re: CATAJETS: Design and Development
Post by: Audax on February 17, 2016, 02:23:25 PM
On my latest XP-84 I need to figure out a way to install the vertical stab at the rear and top of the aft fuselage. How do you cut the slot ?

Hi Ace,  I don't cut a slot.  The vertical tail is just glued on top of the fuselage, and it stays put for me. 

If you think you need a beefier mounting, you can add a couple of small balsa strips at the base of the part, and sand them to make a sort of a fairing.  That will increase the gluing surface.  But honestly, I don't thing you need it except in cases where the stab is mounted higher up in the vertical tail.  In that case, some extra stiffness is helpful. 

The pic shows my Arsenal VG90 (prior to painting) with the tail butt-glued on.  It's flying pretty well, and has suffered no damage in the test flight program...so far.  Rich


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 17, 2016, 03:30:59 PM
I also just glue the fin on the fuselage and/or stab...on higher mounts, I integrate the lower portion of the fin into the fuselage material...I use cyno for everything except when I slid the wing into the fuselage and there I use Titebond for a stronger joint...I try to pick 'planes where I can just glue the stab on top the fuselage, typically 1/16" sht. stabs and fins and hard 3/32" for fuselages...I'm talking about 16" span models, but 18" to 20" wing span models would go up a notch in size...I've tried 3/16" & 1/4" wings but I think you've got to make 'em light, maybe even built up?...Rudy Kluiber treats them like HLG's and has great luck doing that
and they get very high in a spiral on launch just like HLG's...the hardiest models to fly well are the ones with swept back wings, a lot of set up dynamics going on there and not much of a return in performance if that is what you are going after. I'd love to build one and the number of 'planes to choose from is huge.


Title: Re: CATAJETS: Design and Development
Post by: Pit on February 18, 2016, 09:03:45 AM
All of the catajets I've built have had the fuselage done as a three layer laminate with the center - usually 1.5mm - oriented to optimize the grain for the fin/rudder.  The outer  "cheeks" using 1.5mm or even 1mm and 0.8mm (depending on the model size) run the full length, grain horizontal, and usually get the area aft of the wing tapered.  On some, I was "industrious" enough to make cutouts in the inner lamination rear end for weight/mass reduction.  My catajets usually have a max span of 12 inches.

Stab and wing slots, if required, get done on a milling machine now.


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 18, 2016, 11:22:13 AM
wow...a milling machine?...the only machines I use are a small drill press I got from airline miles rewards accumulated and a 12" band saw I've had for ever that I use for cutting out prop blanks...but why not?...I haven't tried 12" span JetCats 'cause I'm still stuck in HLG mode of doing things and clumsieness is my strong suit.
I do want to try a swept wing model but the Saab Tunan I did build didn't work out...I like early jets a lot and straight wing models appeal to me for their bonus of better flying qualities. I'd also like to try a more 3 dimensional type model like the rapier powered ones...maybe a Hawker Hunter, Gnat or EE Lightning. I'm trying to stay away from deltas and tailless but their are some nice modern jets too...F-22, F-35 and that guppy-looking jet that lost out to the F-35...


Title: Re: CATAJETS: Design and Development
Post by: Pit on February 18, 2016, 03:11:46 PM
The milling machine's not mine, but I only have to walk (run?) 20 meters to use it practically any time I need it.  Guppy looking one???


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 18, 2016, 04:04:23 PM
Yes when the US was considering the Joint Strike Fighter, 2 companies submitted candidates and the one that lost had a perculiar guppy looking nose or maybe  a whale shark nose...


Title: Re: CATAJETS: Design and Development
Post by: skycafe on February 18, 2016, 04:37:58 PM
Boeing X32


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 18, 2016, 10:16:04 PM
Yep...I got a 3-view of it today so I'll try a 3-dimensional of it with all the photo's I found on line...it's about as ugly as a 90 year old in a Speedo...don't know whether to do the anhedral wing or give it a smidge of dihedral?...but maybe it's time to try a slightly built up wing...it's just for S**TS and giggles anyway and why not?...even though I still have 2 or 3 models on my list to build this winter, I'm having fun again and if anyone tells you JetCats are easy-peasy, they aren't paying attention...


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on February 18, 2016, 10:52:18 PM
That's the thing about Catajets!...They're highly addictive!!! And if you take some with your Stick and tissue birds to the field the S&T models will stay in the box as you tweak and fly the Catajets!  Enjoy. 

Here's the picture of the "Guppy".
Sky9pilot


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 19, 2016, 06:17:53 AM
That's also why my buddy and I take bungee gliders with us...they are more addictive that JetCat's...it's amazing how much flying you can do in an hour with Catapult's and bungee's (same goes for E-36)...


Title: Re: CATAJETS: Design and Development
Post by: Pit on February 19, 2016, 11:36:46 AM
That X32 is one UGLY mutha'!

This version is much cuter ::)...


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 19, 2016, 01:12:28 PM
Yeah, I saw that one earlier...any thoughts you guys about using slight dihedral instead of anhedral?...has anyone built any kind of model with wing anhedral?...The magazine SAM-35 Speaks in England runs a column on Rapier/Jetex models and occasionaly a Jet Cat plan. Might be a good place to dig for info and ideas...


Title: Re: CATAJETS: Design and Development
Post by: Pit on February 19, 2016, 02:46:02 PM
check out the JETEX (http://www.jetex.org/) site, too.


Title: Re: CATAJETS: Design and Development
Post by: Audax on February 19, 2016, 07:25:31 PM
...has anyone built any kind of model with wing anhedral?

Haven't tried it yet on a genuine Jet Cat, but I have a couple of related items that may be of interest. 

One of my flying buddies built the BAC Lightning from the Aerographics kit.  It's 12" span and set up for either Rapier or Rubber power.  The plan calls for a flat wing, but my friend put in a quarter inch of dihedral to be safe.  He said it was over stable, but he got it going well enough to take home a plaque from the FAC Nats in Peanut Scale.  I watched it fly, and it was steady in the air, except the wings rocked back and forth on the whole flight.  The designer, Peter Smart, told him that it works best with a quarter inch of anhedral.  I've got the kit, and I'm gonna try it that way.  If I get real nuts, it might be fun to stick a hook on the nose and try it as a Cat glider.   

Last year I thought that a Hawker Harrier might be worth a try as a Jet Cat, but before I butchered any balsa, I slapped together a White Wings version.  Most of those WW things go at least fairly well, and it allowed for easy adjustment to the di/an hedral angle at the field.  It's pretty tiny so I don't know how much weight you can give the results, but man, it was a bear to get going, and touchy as all get out.

   


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 22, 2016, 07:51:07 AM
a pic of the last 2 JetCat's....


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on February 22, 2016, 11:44:04 AM
Those look terrific. How did you finish those. I have to spray my Jet Cat XP-84, my Flip HLG and then spray on my Whistler HLG designed by my old friend George Perryman. I have a can of Deft Clear Wood Finish and then will use something else for the proper colors.


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on February 22, 2016, 06:31:07 PM
I use Design Master spray Acrylic colors because they are thin and don't smell too long if you dry them with a hairdryer after each coat...usually 2 coats color (LIGHTLY) and then 1 mist of Matte clear... I don't use dope except on prop blades...I have used spar varnish but I don't like that color of finished wood for models...just another weird thing about me....I would use Litecoat dope if I could get it but the hobby shop won't even order it or stock it because the majority of people are R/C flyers...and they don't use dope/tissue/rubber/balsa...


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 15, 2016, 12:52:02 PM
isismk2... your jets look fantastic.  I've really gotta build some more catajet!!!
Sky9pilot


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on March 15, 2016, 01:09:45 PM
Thanks but the building could be better...just built a 14" span Gloster Meteor in the "Yellow Peril" color scheme and am still thinking about that X-32 and a F-16 in prototype colors...you can't have too many Cats because they don't last long enough


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on March 15, 2016, 04:50:44 PM
Thanks but the building could be better...just built a 14" span Gloster Meteor in the "Yellow Peril" color scheme and am still thinking about that X-32 and a F-16 in prototype colors...you can't have too many Cats because they don't last long enough

You are so right.  They do get abused because they are so much fun to fly.  My fetchermites (grandsons) love em and sometimes in retrieval get too rambuncious in racing each other to the planes, and you can imagine what happens then!!! :o ;D ;) 8)  Just give the opportunity to make some new one to fly!
Sky9pilot


Title: Re: CATAJETS: Design and Development
Post by: skyrocket on March 15, 2016, 10:15:53 PM
Yup...I enjoy building, even the dreaded cutting out of ribs...boring and tedious...but once done, everything else is a breeze...


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on August 28, 2016, 02:54:34 PM
Finally made the time to upload the plans for my B-52 cat glider.   Waiting for administrative approval.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on August 29, 2016, 12:21:47 AM
Good lord, that's the first update I've received from here for over a year :o :o
Cool BUFF Kittyfritters :) :)


Title: Re: CATAJETS: Design and Development
Post by: Coops on April 19, 2017, 04:27:14 PM
Excuse thread necromancy!

As a complete novice I've just built two catajets. First, the West Wings kit of the Eurofighter Typhoon.

(http://img.photobucket.com/albums/v108/Coopdevil/IMG_1399x_zpsb7jh6tkn.jpg)

This is supposedly suitable as a chuck glider but...

(http://img.photobucket.com/albums/v108/Coopdevil/IMG_1392x_zpslxmu8n0i.jpg)

...it flies like a brick. Square section wing, no dihedral on the delta. The canard has anhedral but there's not much surface area there. So I've added a hook with an eye to catajet-ing it. Not tested as a catapult glider yet as I'm waiting for some proper rubber to arrive - at the moment the only catapult I have is from one of those toy Air Hogs foam glider things.

(I've made the hook by supergluing a bent pin into the wood with the pinhead clipped off. Will this be adequate? As a novice I've genuinely no idea.)

Also built up the Sabre Dog catajet from the plans in the May 1953 issue of Aero Modeller. A quick Sharpie pen job was supposed to be copying a Pakistan Air Force aircraft but then afterwards I belatedly realised that it was totally the wrong type of Sabre. Should the glider actually work I'll probably repaint it in a proper F-86D scheme.

(http://img.photobucket.com/albums/v108/Coopdevil/IMG_1400x_zpsetikscgh.jpg)

Coop


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 19, 2017, 05:12:14 PM
Hah!  I was just looking through this thread earlier this week.  Sand an airfoil in that Eurofighter's wing, canard and fin and it'll probably fly a lot better.  I learned that with some WWII sheet WestWings gliders - it really made an amazing difference.  If the small canard won't give you enough lift for a good glide you can also bend the trailing edge of the wing up a little.

The pin will probably work for a very light catapult - if it bends you can glue a wedge of balsa in front of it for reinforcement.

I've been working on a Supermarine Scimitar for catajet - see pics.  Camping with the cub scouts this weekend, so I probably won't get it finished and flying until next week. 

Two weeks ago a gentleman got a 57-second flight from a profile B-57 jetcat at the Gainesville Spring Warmup FAC meet!

Your Sabre-Dog looks like it should fly well.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 19, 2017, 05:29:46 PM
That sure is a sweet looking jet cat Mike.


Title: Re: CATAJETS: Design and Development
Post by: ZK-AUD on April 19, 2017, 06:12:22 PM
Mike, I've never taken these things particularly seriously but that's a very nice piece of balsa bashing.  Your example makes me wonder why they need to be profile at all.  I'm guessing that some weight is desirable for penetration / inertia etc so why would a fully carved fuselage not be a nice thing to do?  By the way are you a Cub leader? I'm a Scout leader over here.


Title: Re: CATAJETS: Design and Development
Post by: ZK-AUD on April 19, 2017, 06:16:53 PM
Hey, just thought of something - why not spring load that hook to retract flush while we're at it?!  These could be quite serious scale models....


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 19, 2017, 07:03:42 PM
I'm impressed by your Scimitar as well Mike - nice work. 

Quote
...it flies like a brick. Square section wing, no dihedral on the delta
I agree with mike - sand an airfoil into the canard and wing. Keep the airfoil fairly sharp at the LE with a very small nose radius, about a 20-25% local chord high point and straight taper to the TE which only needs to be around 0.8mm thick.

These small models need thin airfoils with fairly sharp LE's.

The CG on these cat gliders will probably need to be a fair way back towards the tail.

I have done a depron cat version of the Sabre and it flew well.

Kiwi Mike - I work with a local Air League Squadron and they are an aviation minded equivalent of the Scouts. Small world.

Happy Flying

John


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 19, 2017, 09:11:13 PM
Well it's only been nine or so months since the last post :o and I've been purely building scale non-flying models I was pleasently surprised at this sudden spurt of posts ;D

Coops we gotta have 'novices' in the hobby or it will die :o :o Welcome aboard!!! ;D ;D
That Typhoon's not a bad start from a kit it just needs some serious work. Firstly sand in a rounded leading edge to the wing till you get a nice airfoil shape to the leading edge, sand the trailing edge down from the top surface only to get a fine trailing edge. The canards should be sanded with a rounded symmetrical leading edge and carefully thinned trailing edge. Round the leading edge of the vertical stab symmetrically and thin the trailing edge. These actions will remove form drag and smooth the airflow considerably. Next gently slice the underside of the wing trailing edge outboard flaperons and gently bend them up to approx +1mm and glue them to hold the position, gently bend the wing tips down at the leading edge to create some washout (twist). This delays the onset of tip stall and pitch up into a full stall. Round off all the flat sheet edges (except for any forward facing intakes and aft facing exhausts) as it makes the balsa a bit more resilient to damage (it also removes weight ::).

Great F-86"Dog", don't forget a bit of washout (negative twist from root to wing tip) to stave off tip stall and smooth all edges as I said above. Don't touch the chin intake it's meant to be 'flat'. I look forward to you posting test flight results ;) 8)

MKelly, 57 seconds!!! :o That's amazing!! :o 8) You got a pic of the model?
Your Scimitar (love the choice of subject) is a very ambitious and beautiful piece of work 8) 8) I just hope those beautifully formed intakes don't act like a set of heavy deployed speed brakes and create huge drag. They may steal initial speed off the catapult and shorten your flight considerably. Also as the nose comes up as it slows the intakes may speed the model into a stalled condition due to trapped air in those intakes. Reason I'm mentioning this is I tried 3D intakes etc on a CATAJET Buccaneer (12" wingspan) only to fail for the above reasons, and after a long and involved conversation with an mate who's forgotten more about aerodynamics than I know that was the conclusion. In the real aircraft there are engines in there providing thrust, and when they stop working they become pure drag hence the 'flying brick' monika for jets with a flame out. The ducts are responsible for the same thing, wouldn't have thought it but. . . hey who am I to argue ??? I actually hope I'm wrong and your Scimitar will fly, and well at that as it really is beautifully done 8) 8) Just remember weight and drag are the enemy >:(

ZK-AUD, CATAJETS and CATAPROPS need to be mostly profile as that's the whole idea of the designs. Simple sheet balsa flying models launched by catapult that with a bit of gentle tweaking can be made to really preform in the glide. Weight and drag are the enemy with these models and you do not want to go 'too far' overboard with "correct 3D" details or operating bits as it's all weight and ultimately drag. You can obviously finish your models however you wish at the scale size of your choice just do not add too much weight and remember to test fly when you finish to see if there has been any changes to your models' flight characteristics. Just remember that the proportions in side elevation and plan view used in your model must be very close if not exactly the same as the actual aircraft you are modelling as a CATAJET. There are modellers out there that have to catapult launch their "Stick and Tissue" Rapier rocket motor powered models as a glider due to the unavailability of the rocket motors to power their models. They obviously must be careful with their models as it is easy to crush structure when pulling back for the cat launch but one thing that holds true, they must be light.

OZPAF, great advice on sanding wing shape ;) CofG is approx 1/3 the chord from the leading edge depending on the CofG rules of your chosen wing plan form and the actual balance point of your model (you want it to be slightly nose down for a CATAJET or CATAPROP when balanced on it's CofG). If you put the CofG back too far you risk having a model that does the 20G death loop off the catapult ending in a "sudden unplanned air/ground interface" that usually damages or destoys your model and sometimes injuring yourself also. I've never used depron so i cannot comment on it's flying characteristics.

Cheers all and happy flying ;D ;D
Neil 8) 8)
 


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 20, 2017, 09:07:04 AM
Thanks all, the Scimitar has been a fun build.

Mike, I am a Tiger (7-year-old) den leader.  Fun stuff - never having been in scouts before I'm learning just as much as the cubs.

John, rather than scouts I was in Civil Air Patrol as a young teenager, sounds like a similar organization to your Air League.  I had a lot of fun and that time did a lot to set up my subsequent career in the Air Force.  When my kids gets older I may get back into that if they show interest in it.

Neil,  thanks for the thoughts on the Scimitar.  The nacelles are 1/4" sheet - enough to give the impression of depth but hopefully not so big as to completely spoil performance.  The intakes are carved fairly shallow, again just deep enough to give the look. I'll watch out for the stall characteristics you warn of.  Might be interesting to make another without the nacelles and compare performance.  Weight is not too bad, just over seven grams before any decoration.  Balance is pretty close already so I don't anticipate adding much noseweight, should be able to keep the finished model under 10 grams.  The stab is adjustable so that I can play with balance and decalage to see what gives the best flights.

Unfortunately I didn't get any pics of the B-57.  It was a simple sheet model, profile fuselage and nacelles, looked like about 10" span.  There were two at the meet, both flew well although one had some trouble transitioning from very impressive launches into a good glide.  The 57-second flight was in windy conditions.  Pilot got a great launch and each turn from upwind to downwind recovered most of the launch altitude keeping the model in the air for an impressive time and distance.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: Crabby on April 20, 2017, 11:39:49 AM
Pit, a most compelling subject....Mike, have you tried turning the scouts on to a simple cat jet? Guys are always talking about drawing the young kids into the hobby, and few succeed. Marcelo is one, but he is stupendously atypical.  I bet a simple and well behaving cat jet presentation will hook a few... Keep it simple, and no "Kelly masterpieces"  Just saying. Great subject Pit!


Title: Re: CATAJETS: Design and Development
Post by: Coops on April 20, 2017, 01:14:30 PM
Thanks for the advice re airfoil profile chaps, I'm going to practise on a few 1/8" pieces of sheet first before hitting the completed Eurofighter model.

Beautiful work there Mike, gorgeous stuff!

On the subject of profile vs full fuselage - the thing that has attracted me to catajets in the first place is that I know I can put together a profile model from conception to completion in a short enough period of time to not get bored with the project. And I tend to be a real butterfly when it comes to subject models (I had this problem when I raced slotcars too) so being able to find a cool looking 1:1 prototype and know it won't be six months, and more importantly another 200 lovely looking cool aeroplanes that I discover in the interim, before it's finished is a huge plus to me.

Coop


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 20, 2017, 02:00:58 PM
Crabby,

Yes!  We had a glider night last fall for the full pack - the boys had a great time putting together and flying simple sheet gliders, including some simple distance and looping contests.  We also had a remote control night last month featuring helicopters for the boys to fly (as well as ground vehicles to drive) and demonstration of indoor RC aircraft.  My son has continued to fly the gliders and is getting started on a Guillows built-up profile rubber model (will be his second one).

Mike


Title: Re: CATAJETS: Design and Development
Post by: ZK-AUD on April 20, 2017, 04:29:57 PM
Pit, a most compelling subject....Mike, have you tried turning the scouts on to a simple cat jet? Guys are always talking about drawing the young kids into the hobby, and few succeed. Marcelo is one, but he is stupendously atypical.  I bet a simple and well behaving cat jet presentation will hook a few... Keep it simple, and no "Kelly masterpieces"  Just saying. Great subject Pit!

We have an air-minded troop with many of the families and leaders having strong aviation connections, and with me being involved it will be no surprise that we include an aeromodelling activity in the programme every year!  Usually we go with something called the Airsail Mantis which is a stick and sheet rubber model.  I get Avetek to laser cut them for me and select the wood myself so that we get really good flights of up to a minute in the local school hall.  Previously I had the kids cutting them out but it took too many nights to get them built and flown.  Over the last 10 years I have done over 500 Mantii with Cubs Scouts and school groups.  I also did Hangar Rats with a group of the more intelligent Scouts last year.   Oh we also did Tiny Bees one year - the little Mark Bees rubber all sheet biplane that appeared in Aeromodeller back in the 90's.  Cat jets are a good idea that we could have a go at this year - I have a couple of interesting plans in the cupboard - an F14 that came out in Aeromodeller and a an F111 with swinging wings that came out in Popular Mechanics in the 60's


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 20, 2017, 06:24:39 PM
What about the delta wing on a Skyray ? How much sanding is possible on a wing that is 1/32 sheet balsa to begin with. A few months ago I had a lot of fun with an A4 with no sanding needed and the only reason I went to a bigger jet cat was to be able to keep it in sight. The more balsa broke off the wing trailing edge allowed better flying. Don't know what happened to that plan.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 20, 2017, 07:06:02 PM
Hey Flyace, I've an A-4 "E" I think CATAJET plan 10" (?) wingspan somewhere around. If I find it do you want me to post it!


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 20, 2017, 09:11:51 PM
Allen,  minimal sanding on the Skyray wing - just round the leading edge and maybe a slight bevel on the trailing edge.  The slot in the fuselage will form the airfoil and reflex the trailing edge.  I don't think I did much sanding at all on the small one I built as a teenager.

Mike


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 20, 2017, 11:20:30 PM
Hey Flyace, I've an A-4 "E" I think CATAJET plan 10" (?) wingspan somewhere around. If I find it do you want me to post it!
Sure would like to see that one. Please do post it.

Thanks


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 20, 2017, 11:22:17 PM
Allen,  minimal sanding on the Skyray wing - just round the leading edge and maybe a slight bevel on the trailing edge.  The slot in the fuselage will form the airfoil and reflex the trailing edge.  I don't think I did much sanding at all on the small one I built as a teenager.

Mike
Thanks for the advice Mike. Getting mine cut out Friday morning. Nice shade of blue overall except the windshield.


Title: Re: CATAJETS: Design and Development
Post by: Crabby on April 21, 2017, 12:10:43 AM
Bill Dean did an excellent Skyray in his book...it has a reflex wing and is a fabulous cat jet. I made a dozen of them for my wife's day care one year and they had a blast till one of 'em got hit in the forehead... :'( ;D but these little people were getting major air with 'em!


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 21, 2017, 10:34:27 AM
Crabby,

That's the one Allen is building.  Here's it's larger cousin, Bill Dean's 10.5" span Jetex Skyray converted for jet cat. Fun flyer, very fast, but not really competitive - don't think I've ever gotten more than about 12-15 seconds out of it.  The smaller one may do better.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: Bredehoft on April 21, 2017, 11:49:00 AM
I have a question:

I built an Avro Vulcan (similar planform).  It had a similar sheet wing with an S-shape.  It would glide relatively well.  But I could not get it to catapult as it would simply loop.  The question is:  how do you get a flying wing delta to launch AND glide?

thanks,

--george


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 21, 2017, 01:11:39 PM
George,

The Skyray has the same sort of behavior, and that is what (I think) keeps it from putting up competitive times.  I've tamed it somewhat by bending down the outer panels of the wing (essentially taking out the trailing edge reflex in all but the boat-tail area near the fuselage).  Even with that, I get best results by launching downwind with the model banked almost 90 degrees left with less than 45 degrees elevation.  If done right, the Skyray does a climbing turn around into the wind, which pushes the model out of the loop and into a left turn resulting in a downwind glide.  When this works, you can get over 10 seconds, otherwise you're typically down in about 8.

I suspect that the model built per plan has too much reflex, generating flights just like you get out of a conventional model with a forward CG and too much negative incidence in the tail - the faster you go, the more the model pitches up (until you either stall or loop).

I've been thinking about gradually cutting slots in the boat-tail next to the fuselage to relax some of the reflex, adjusting balance as I go to preserve glide.  I think this should make the model less speed-sensitive in pitch and allow converting the launch energy into altitude rather than aerobatics.

I'd be most interested in other folk's thoughts on this.

Regardless, I've had a ball with the Skyray - the flight performance doesn't make for competitive duration, but you get some spectacular flybys!

Cheers,

Mike



Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 21, 2017, 06:39:53 PM
That's one good looking Skyray 8) 8) 8)


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 21, 2017, 06:53:02 PM
Quote
I suspect that the model built per plan has too much reflex, generating flights just like you get out of a conventional model with a forward CG and too much negative incidence in the tail - the faster you go, the more the model pitches up (until you either stall or loop).

Yes I think this is  the problem. I had a fun Depron cat glider with elevons and I had the same problems. Perhaps a bit more experimentation - reducing the 'Up Elevator' and moving the CG back may have helped but delta's have a very small margin of stability as they are so short coupled.

I suspect you would need minute movements of the elevons accompanied by changes in the Cg of a millimetre at a time!

John


Title: Re: CATAJETS: Design and Development
Post by: frash on April 21, 2017, 08:41:43 PM
Handley Page 115 (mikewight) as found in Outdoor Jet Power in the HPA Plans section is a very long narrow delta. Does this configuration gave a larger sweet spot for CG and trim?

Fred Rash


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 22, 2017, 07:52:35 AM
(http://i246.photobucket.com/albums/gg90/FAAMAN/Aircraft%20Modelling%20Projects/Catajet%20Profile%20Gliders/Handley%20Page%20HP_115%20delta%20wing%20reasearch%20aircraft/HP.115%20First%20Time%20on%20Its%20Langing%20GearS_zpstmcwztrk.jpg) (http://s246.photobucket.com/user/FAAMAN/media/Aircraft%20Modelling%20Projects/Catajet%20Profile%20Gliders/Handley%20Page%20HP_115%20delta%20wing%20reasearch%20aircraft/HP.115%20First%20Time%20on%20Its%20Langing%20GearS_zpstmcwztrk.jpg.html)

This is my HP.115 built from the Jetex plan as a CATAJET (it's actually fully painted and finished but it's put away at present so no update pics) and it flies very well on occaision, CofG shift is no very far, approx 4-5mm fore and aft from the CofG. It does have the tendency to 20G death loop :o :o if overpowered off the cat and can be very sensitive to elevon trim movements, all depends on the day and the longest flight has been 26 seconds.

Cheers all
FAAMAN 8) 8)


Title: Re: CATAJETS: Design and Development
Post by: Coops on April 23, 2017, 12:43:22 PM
Finally got the chance to go out and have a morning's flying yesterday. The F86D flies beautifully, once I'd sorted the technique of the cat launch I was getting some very long and slow steady glides. Great isn't it when you first get to watch it fly properly? The cat is only a thing from an Air Hogs toy with every Briton's favourite source of big rubber bands - the stuff the postman drops on the pavement! Now I've got some proper rubber I need to source a proper handle and get some decent height. Unfortunately my hook "solution" of a bent and clipped dressmaking pin superglued into the fuze doesn't work it's nowhere near sturdy enough and works loose after a few launches. Needs work.

It's not a catajet but I did play with one of these at the same time.

(http://ca.airhogs.com/images/uploads/AirHogs_Disections_RIP_FORCE.jpg)

Absolute rubbish as it just rolls and nosedives, until a spark of inspiration struck me and I tried launching it upside down. It then rapidly does an inverted half-loop and sets off on a long glide. I found this interesting and suspect it's because the wing has a really high angle of incidence (the stab is level). I think it may be designed to loop off the cat, so the inverted launch allows it to be the right way up at the apogee of it's flight. I might have learned something useful from this toy that I can take forwards to future gliders.

Coop





Title: Re: CATAJETS: Design and Development
Post by: flyfac on April 24, 2017, 01:58:08 PM

Has anyone built a catapult jet with a canard configuration?

If so, I'd appreciate feedback on the incidence used for the canard surfaces, if only as a starting point for further tweaking.

Thanks,

Scot Dobberfuhl
Forest Grove, OR


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 24, 2017, 07:38:04 PM
Flyfac page 16 of this thread has a Viggen done by Pit, there are several posts on this subject ;)


Title: Re: CATAJETS: Design and Development
Post by: Hepcat on April 24, 2017, 08:47:01 PM
response to #525

George,
To stop the delta from looping you have three options; put a long fuselage on it with a tailplane on the end, use radio control or make it big enough to carry a pilot.  I hope that doesn't sound rude, it was meant to be humorous.  I think there are certain aspects of aeroplane design that are a sine qua non and to flout them is a waste of time.

Putting aside my School Marm attitude for a moment I have to confess that I have dim recollection, probably from 1950,60, of a craze for catapult deltas with large elevators held in the up position with rubber bands.  The reports were that they were strong to withstand the speed, and therefore heavy and launched with the most powerful catapult they could manage. I hope they don't come back again.  I think they would be capable of killing people and animals and certainly lose more flying sites.  However automatic elevators used with common sense shouldn't be any more dangerous than present F1A, B and C models!  I wonder if a 'damper' timer could be rigged to go off reliable at a few seconds.
John


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 24, 2017, 10:43:23 PM
I did finish the small one and it hand glides across the house. Hope to catapult it tomorrow so I can keep it in sight. Sure looks nice so far.
Nose down in the turns-Just thought of the old saying, not exactly earth shattering.

Allen

Allen
Crabby,

That's the one Allen is building.  Here's it's larger cousin, Bill Dean's 10.5" span Jetex Skyray converted for jet cat. Fun flyer, very fast, but not really competitive - don't think I've ever gotten more than about 12-15 seconds out of it.  The smaller one may do better.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: flyfac on April 25, 2017, 12:57:33 AM
Thanks FAAMAN.  Exactly what i needed.

Best,

Scot


Title: Re: CATAJETS: Design and Development
Post by: flyfac on April 25, 2017, 01:34:09 AM
I read a bit further and was embarrassed to discover my own posts discussing the very same question I'd posed earlier today.  Guess it pays to revisit and review these longer threads sometimes . . .

Scot


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 25, 2017, 10:30:20 AM
Taking a few minutes here to allow the glue to dry on the fin for the F4D Skyray Mike mentioned. It broke of cleanly so will be back in the air in a few minutes. Does climb and turn nicely but still needs some more adjustments, I hope very few. Is fast too so I might be using too wide a strip of rubber. Might adjust down in that department too. Make a loop of 1/16th.

Allen


Title: Re: CATAJETS: Design and Development
Post by: Bredehoft on April 25, 2017, 11:46:02 AM
response to #525

George,
To stop the delta from looping you have three options; put a long fuselage on it with a tailplane on the end, use radio control or make it big enough to carry a pilot.  I hope that doesn't sound rude, it was meant to be humorous.  I think there are certain aspects of aeroplane design that are a sine qua non and to flout them is a waste of time.

Putting aside my School Marm attitude for a moment I have to confess that I have dim recollection, probably from 1950,60, of a craze for catapult deltas with large elevators held in the up position with rubber bands.  The reports were that they were strong to withstand the speed, and therefore heavy and launched with the most powerful catapult they could manage. I hope they don't come back again.  I think they would be capable of killing people and animals and certainly lose more flying sites.  However automatic elevators used with common sense shouldn't be any more dangerous than present F1A, B and C models!  I wonder if a 'damper' timer could be rigged to go off reliable at a few seconds.
John

I get your humor.

I had thought about a flexible reflex, also.  You mention a DT - that is an option (I know some have used DTs on jets to trigger swing-wings - Rick Penzick).  I also think back to what I know Cat Glider jockeys do indoors with foam and thin balsa training edges that flex out of the way on launch and then resume their position when air pressure reduces.  That's a lot of work and experimenting!

--george


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 25, 2017, 05:34:29 PM
Taking a few minutes here to allow the glue to dry on the fin for the F4D Skyray Mike mentioned. It broke of cleanly so will be back in the air in a few minutes. Does climb and turn nicely but still needs some more adjustments, I hope very few. Is fast too so I might be using too wide a strip of rubber. Might adjust down in that department too. Make a loop of 1/16th.

Allen
It really made a difference when I took the clay from the trailing edges and instead put in washout on each wing tip and using the clay on the nose really makes a big difference. The 1/16th loop gets it going and so does the 1/8 th loop. I lost it three times since bare balsa wood blends so well with the grass around here. The Skyray is now all white to aid in locating in flight and on the ground too. More testing to follow after it dries and the nose weight is re installed. This little thing really scoots.

Allen


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 25, 2017, 11:53:57 PM
Quote
I also think back to what I know Cat Glider jockeys do indoors with foam and thin balsa training edges that flex out of the way on launch and then resume their position when air pressure reduces.

This would probably be the best way to go. Now you mention I'm surprised some one hasn't tried it to give a good launch without a loop followed by a glide.

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 26, 2017, 11:20:55 PM
Scimitar is ready to fly - forecast looks good for tomorrow.  As usual, I've overdone the decoration, weight is now 9.5g balanced.

Wish me luck...

Mike


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 27, 2017, 12:18:56 AM
Superb!!! ;) ;)
May you have lite winds and lotsa success!!! 8) 8)


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on April 27, 2017, 11:48:42 AM
MK...Scimitar looks fantastic!  Ditto what FAAMAN said!!!  Lots of air and beautiful glides.

Been away from this thread and there are some fantastic looking models that have been posted lately!  Nice work and great inspiration.  Gotta build me a new catajet soon!!!
Tom


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 27, 2017, 06:22:10 PM
Nicely finished Mike. happy launches.
John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 27, 2017, 09:52:06 PM
Thanks - didn't get to launch it today, home with a sick kid.  Test glides in the yard show promise.  Still dialing in the stab and may need a smidge of noseweight as hard stalls can lead to a quick departure from controlled flight.  Sweepback and washout seem to be working as long as the nose stays down and the airspeed stays up.

Mike


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 28, 2017, 12:54:43 AM
Sounds like you need noseweight, be cautious of changing your decalage angle.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 28, 2017, 09:01:43 AM
You are correct sir.  .2g of clay on the nose and all is well.  Made a medium-power launch at the local schoolyard and barely landed inside the fences - need to take it to a bigger site.  Looking really promising...


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 28, 2017, 09:35:20 AM
Now I am really sure you might have a contender when we get someone else to go to Jet catapult locally. I sure hope we can find another flyer soon to take an interest. GOOD Work MIKE.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 28, 2017, 06:02:34 PM
Yahoo MK 8) 8) 8)


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 29, 2017, 01:36:48 PM
Took the Scimitar out this morning to our normal flying site.  Only got in two launches in 10+ MPH winds.  First one had good height but looped over the top.  Banked it a little more right for the second launch, got a great climbing turn with nice rollout on the top, flew the entire length of our flying field downwind, turned west and ended up between fences at the field boundary.  Handled the wind very well.  Retrieved it intact and decided to declare victory and save the model for calmer days or bigger fields.  This one is a screamer!


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 29, 2017, 06:37:21 PM
It was a real thrill to witness the two flights. It really did well, got us both scared and I think the flock of birds noticed it too.



Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on April 29, 2017, 06:58:36 PM
Outstanding!! 8) 8) Any photos? ;)


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 29, 2017, 07:15:25 PM
Not yet but hope to get an action video asap.


Title: Re: CATAJETS: Design and Development
Post by: Coops on April 30, 2017, 06:22:54 PM
Spent this evening assembling the Aero L-39 Albatross I'd been planning for a while although I've still got some final sanding to do. I had no printed plan for this one, just re-sized sections of a three view in GIMP for the templates for stab, fin, and fuze. The wings were just eyeballed based on what looked about right. 10" wing span, 3/4" dihedral under each tip. 1/16" sheet all around, the fuze is laminated to 1/8", 1/4" in the width where the intakes are.

(http://img.photobucket.com/albums/v108/Coopdevil/aero1_zpswt0kzij8.jpg)

(http://img.photobucket.com/albums/v108/Coopdevil/aero2_zpsx7aktcrl.jpg)

(http://img.photobucket.com/albums/v108/Coopdevil/aero3_zpsvxfbfldu.jpg)

(http://img.photobucket.com/albums/v108/Coopdevil/aero4_zpsfttcbalx.jpg)

I've made life easy for myself by copying a couple of the Reno air racers which gives me the excuse to leave off the fiddly wingtip tanks.

(http://img.photobucket.com/albums/v108/Coopdevil/66_L-39_Albatros_VH_IJC_True_Blue_Reno_Air_Races_2014_photo_D_Ramey_Logan_zpsnpwh9msz.jpg)

(http://img.photobucket.com/albums/v108/Coopdevil/25_plane_Violated-1024x727_zpshlyau0zv.jpg)

It's a great feeling when you start sanding and feel it taking shape and becoming smoother and smoother under the fingertips isn't it? I'd never really done any woodworking before getting interested in gliders and now I understand how therapeutic it can be. I actually enjoying the sanding whereas previously when I've needed to do some for household DIY it's a just a chore!

Coop


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 30, 2017, 09:50:31 PM
Good-looking jet, Coop!  Let us know how she flies.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: MKelly on May 05, 2017, 04:37:25 PM
Finally had a free day with some good weather to try out the Scimitar.  It flies nicely - big barrel roll on launch, fast flat glide down.  You've got to keep your eyes on it or you'll lose it.  Tricky to get max height on the launch, not enough bank or too much angle up and it loops over the top, loosing hard-won altitude.  Best timed flight of the day was just over 25 seconds, most flights were 15-25 seconds.  Should be able to wring a little more out of it as launch technique improves.

The swallows at the field get quite concerned when the Scimitar is in the air - video at:

https://www.youtube.com/watch?v=SSCXqGVAqog (https://www.youtube.com/watch?v=SSCXqGVAqog)

The Scimitar is just a dot in the videos - you can find it by following the swallows...

Thanks to Allen Shields for taking the vids.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on May 05, 2017, 07:18:01 PM
OUTSTANDING!!!! 8) 8) 8) 8)
Congrats on the Scimitar ;) ;)


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on May 05, 2017, 09:42:12 PM
Ditto what FAAMAN said....she's a beauty!
Tom


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on May 06, 2017, 05:03:21 PM
I like your work and congrats on a great plane !
George


Title: Re: CATAJETS: Design and Development
Post by: MKelly on May 07, 2017, 09:24:28 AM
Thanks!  This has been a neat little exercise.  Doing this plane again (which I probably will) I'd enlarge the stab a little less (current model is 175% to get a tail volume of .65) and put a lighter finish on it (paint and markings added 2 grams on a 10-gram model).  Sanding washout into the wings combined with the sweepback provides more than enough stability to get away with a flat wing (no dihedral).  The catapult hook needs to be just a bit longer, and the bottom of the hook needs to be rounded off - I've cut the rubber on both my 3/16" and 1/4" launchers flying this plane.

The good on this is that it climbs out better than any jet-cat I've seen, and although very fast it glides flat enough to get reasonable duration.  It also flies very well in the wind, although you've got to keep a close eye on it as it goes far downwind very quickly.

I didn't test fly it without the wing fences, so I don't know if they had any real effect good or bad on flights.

There are more of these low-aspect-ratio jet cats in my future...

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on May 08, 2017, 10:11:35 AM
Another way to make them lighter is by cutting some of the balsa from the wing and then replacing the missing wood with good quality tissue. Some success with that knife is always nice. This suggestion is for your future jets. Not the Scimitar.


Title: Re: CATAJETS: Design and Development
Post by: Coops on May 09, 2017, 02:59:26 PM
I discovered this little microjet today - the SubSonex JSX-2, all 18' wing span of it and immediately thought "Catajet". Following by thinking "err... I'm fairly certain I've run out of 1/16" balsa sheet..."

Nice parallel TE and LE on the wing so easy to cut out, and high visibility bright yellow colouring.

(http://img.photobucket.com/albums/v108/Coopdevil/JSX-2_3-view_zpstvmmhssb.jpg)

(http://img.photobucket.com/albums/v108/Coopdevil/SubSonex_N241SJ_First_Flight_2330x_zpsbq4gcdp2.jpg)

(http://img.photobucket.com/albums/v108/Coopdevil/SubSonex_air-to-air_8382x_zpswzfif2q7.jpg)

(http://img.photobucket.com/albums/v108/Coopdevil/SubSonex_1870%201_zpsyftbxkvi.jpg)

Sonex are so helpful to aeromodellers, they even add a diagram in their brochure to tell you how much of the pilot should be visible...

(http://img.photobucket.com/albums/v108/Coopdevil/3_zpsqrmuz07v.jpg)

I tried to attach the small brochure here (1.65MB) but apparently we can't attach PDF so here's the link instead

http://www.sonexaircraft.com/subsonex/SubSonex_Brochure_032816-web-optimized.pdf (http://www.sonexaircraft.com/subsonex/SubSonex_Brochure_032816-web-optimized.pdf)

A certain future project here.

Coop


Title: Re: CATAJETS: Design and Development
Post by: MKelly on May 13, 2017, 05:24:48 PM
Sonex looks interesting, Coop - build it!

Did some jetcat flying today with my family - son had a ball with the Skyray.  He did learn the hard way to keep his right arm away from the body while launching - I'd warned him but he got distracted while mom was videoing a launch and got a nice scrape across his right cheek.  After a few moments he was back to launching again.

I flew the Scimitar some more today - early morning flights went very well, but when I came back to the Scimitar a couple of hours later it wanted to launch high then spiral in.  Not sure what changed, managed to get it back to a decent glide but performance remained kinda unpredictable.  Still thinking this through...

Cheers,

Mike



Title: Re: CATAJETS: Design and Development
Post by: OZPAF on May 13, 2017, 06:23:38 PM
If it was a warm day( certainly looks warm ) it may have developed a slight warp in the wing or tail.
It looks like you and your son had fun anyway.

John


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on May 13, 2017, 07:43:29 PM
Great pics!!
Agree with OZPAF wing warp from the hot day could cause the unstable flying characteristics,
Light winds mate ;)


Title: Re: CATAJETS: Design and Development
Post by: MKelly on May 13, 2017, 11:11:05 PM
Thanks!  Agree on the warp - the Scimitar had been sitting in the sun and it looked like the right wing had lost a bit of washout.

Mike


Title: Re: CATAJETS: Design and Development
Post by: Bredehoft on June 28, 2017, 09:20:45 AM
my latest JetCat

(http://volareproducts.com/wp-content/uploads/OhkaProcess17.jpg)

--george


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 28, 2017, 09:24:22 AM
my latest JetCat

(http://volareproducts.com/wp-content/uploads/OhkaProcess17.jpg)

--george
You will LIKE it!


Title: Re: CATAJETS: Design and Development
Post by: dohrmc on July 03, 2017, 07:53:33 PM
Here's my little Brit fighter sold to the Swiss. Flies pretty well. I have made several mods and it is doing very well.


Title: Re: CATAJETS: Design and Development
Post by: FAAMAN on July 04, 2017, 12:15:24 AM
That's a very nice Vampire ;)


Title: Re: CATAJETS: Design and Development
Post by: dohrmc on July 06, 2017, 10:12:56 PM
Thank you. It is a nice kit from Retro RC. Laser cut, everything fits. Highly recommended, as it has a good glide.

It's most likely too heavy to be a winnah, so I am using it to learn to get it as high as possible on launch and then have a decent transition. I'm close, but no cigar yet! Still, it will reliably do 20 seconds +\- a couple, so with some tweaks, it should do ok for our local contests.

I have never paid much attention to this event, but now am going to put a little more focus on it.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 18, 2018, 01:52:24 PM
Finished up a 17" span Me-262 jetcat this morning, now waiting for the winds to die down here long enough to trim it.  Designed by Henry Toews from Canada and cut by IronMike.  Finish is printed tissue, graphics are adapted from flight simulator skins found on:  https://www.asisbiz.com/Me-262.html (https://www.asisbiz.com/Me-262.html)

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: tross on April 19, 2018, 12:26:36 PM
This is so cool Mike. :)
Is it me, or is the quality of build and finish on this one way above the norm for a catajet?

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 20, 2018, 12:40:04 AM
Wild! Neat way to go.

John


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on April 20, 2018, 12:19:50 PM
Very nice cat jet  have you tested it yet ?
George


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 20, 2018, 12:47:01 PM
Thanks all.  It's been too windy to wring it out yet.  I did one test glide in the back yard - it flew well enough that I didn't want to do that anymore!

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on April 20, 2018, 12:53:15 PM
That is a good thing -yes !
George


Title: Re: CATAJETS: Design and Development
Post by: Yardman Jeff on April 20, 2018, 02:51:29 PM
Love  the  262   8)

These CLGs look like fun !


Title: Re: CATAJETS: Design and Development
Post by: Dimeflyer on April 20, 2018, 06:01:57 PM
Yardman Jef
hey are indeed ! since I developed a bit of arthritis in my neck I have found them the easiest air Plaines to fly with out worrying about needing to look up a lot , if I do that I will fall over with a dizzy thump on my head ! ;D :-\ Be well and stay safe All !
George


Title: Re: CATAJETS: Design and Development
Post by: Yardman Jeff on April 20, 2018, 07:25:53 PM
Saw a few that interested me at the retro rc site.
Any other sites offering a kit?

My Hillbilly thinking went to a Guillow's HLG lying about, spare rubber bands, and woodland sticks.....
or just recalling being a kid again..lol

HLG at a birthday party were given out as party favors by Billy's "Crazy Uncle Ted". He taped pins to the nose and made games of pop the distant balloon. Winners received rubber powered stick and sheet airplanes. After the B-Day Cake he cut nose notches in a couple HLGs and launched them with a homemade slingshot.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 22, 2018, 12:55:30 PM
Had a break in the wind last night and got some trimming in on the Me-262.  Very stable and repeatable, only stuck it in the trees twice...

https://www.youtube.com/watch?v=-fq532gZ7fA (https://www.youtube.com/watch?v=-fq532gZ7fA)

Mike


Title: Re: CATAJETS: Design and Development
Post by: Yardman Jeff on April 22, 2018, 03:20:52 PM
 8) Thanks for the video. That looks like fun !
 That 262 looks sturdy and stunning well constructed and finished off.

I can see myself having fun like that. How should I get myself started? A kit would be the easiest and quickest way.





Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 23, 2018, 05:17:28 AM
Thanks for the video mike. Your ME262 flies well and seems pretty consistent.

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 23, 2018, 11:55:57 PM
Did a bit more trimming on the Schwalbe today:

https://www.youtube.com/watch?v=XO6eSeYRn-0&feature=youtu.be (https://www.youtube.com/watch?v=XO6eSeYRn-0&feature=youtu.be)


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 24, 2018, 07:14:11 AM
Interesting transition Mike - but it seems consistent and doesn't seem to lose much height. A little loop at the top of the climb and then into it's glide pattern.

John


Title: Re: CATAJETS: Design and Development
Post by: flydean1 on April 24, 2018, 09:25:42 AM
Downside to your excellent colors and markings--It will be difficult to find in tall grass after a long flight where you don't see it land.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 24, 2018, 10:33:01 AM
Downside to your excellent colors and markings--It will be difficult to find in tall grass after a long flight where you don't see it land.

Very true - I chose the scheme with the yellow numbers and rear fuselage stripes so I'd have at least a prayer of finding it in the grass...

Interesting transition Mike - but it seems consistent and doesn't seem to lose much height. A little loop at the top of the climb and then into it's glide pattern.

Yes - I think it could do with a bit less negative incidence on the tail.  I measured 2 deg after it was built.  Flights have shown that it needs a pretty shallow launch, anything over 10-20 deg elevation results in it coming over the top too fast with subsequent roller-coaster glide.  Launching with 10 deg elevation and about 90 deg right bank gives a very repeatable transition.  If (when) I build another one I'll probably set it up with an adjustable stab and see if I can get more performance out of it.  That said, I'm pretty happy with this one...

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 25, 2018, 08:52:55 PM
Perhaps a conventional 0-0 setup or just a slight decalage would work looking at it's present transition.

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 26, 2018, 02:11:55 PM
Thanks John - I was thinking about trying a Gurney under the TE of the left stab next time out - would reduce the effective incidence differential and would give a little more rolling moment to keep the inside wing up in the glide.

Mike


Title: Re: CATAJETS: Design and Development
Post by: tross on May 13, 2018, 10:24:41 AM
Mike,
Did you chalk the back of your tissue, or something other?
Flight test complete and am ready to cover (but in a holding pattern). ::) ;D

Thank you. :)

Tony


Title: Re: CATAJETS: Design and Development
Post by: MKelly on May 13, 2018, 12:43:14 PM
That looks nice Tony!  I have had a couple flights in the back seat of Vipers - quite a machine.

No chalking on the Me-262 tissue - the only thing I did was color the back side of the yellow numbers and white insignia with a white Prismacolor pencil. The balsa provides a nice light background for the printed tissue.

Your hook is pretty far back because of the intake - does that have any effect on launches?

Mike


Title: Re: CATAJETS: Design and Development
Post by: tross on May 13, 2018, 01:13:21 PM
Thanks Mike I'll try that. :)

No not at all.
We're about 35% in front of the approximate NP FWIW.
Straight up no worries. ;D ;D ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: tross on May 20, 2018, 09:15:25 AM
Another F16, rev 2. ;D
Launches straight up then transitions to a nice stable glide.
3.8 grams flying weight with a thin solid wing.
Flaps are soft grain and lower in the transition.

Tony


Title: Re: CATAJETS: Design and Development
Post by: tross on May 20, 2018, 07:25:56 PM
Try not to judge.
This is how it is after a day of yard work. ::) ::) ::)
Tried to keep it within sight in the video.
Once I launch above the tree height it takes off down field. :o

Should I be building this bigger than 8" WS?
I know the serious cat glider folks wouldn't be caught dead with a 2.5 AR jet cat,
but any insight is appreciated just the same.

https://youtu.be/GTvCBNw0Gtk

Thanks.

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on May 20, 2018, 09:20:51 PM
That's a pretty good transition Tony. Neat. I tried a 16" F16 some years ago and I was launched on a high start - in this case a light rubber catapult with a length of string - approx. twice as long. I can't remember where the pan came from. It had a elevator which kicked up after the launch - supposedly. I couldn't eliminate the loop but it glided well.
I like your idea of flaps - they seem to work well.

Cheating with the dihedral :) - but very sensible.

Yes - go bigger.I think you could probably move the CG a bit further back as well in small amounts to improve the glide - don't adjust the elevator or flaps - the transition is good as it is.

What a nice large private model airfield :)

John


Title: Re: CATAJETS: Design and Development
Post by: tross on May 21, 2018, 09:39:17 AM
Hi John,
It's a nice patch of grass for sure thanks. ;D
Too bad I can't fly the F16 there.
We're currently sending it up from the middle of that corn field. :o

These are just half launches choked up on some trimming rubber (using my thumb for a stick!)
Launch angle to the side a little and less power made it happen lower so maybe you could actually see it transition.
We tried to film the actual flights, but it was too high.
Even at 4 grams, the jet can climb. :o

I think you could probably move the CG a bit further back as well in small amounts to improve the glide - don't adjust the elevator or flaps - the transition is good as it is.
I'm finding raising one of the flaps just a smidge helps with that.
The very last part of the transition seems to need it where it is (8%?).
The flyable (CG) range is kind of tight, is that also the case with your models?

So maybe 12", or 16".
I'm not sure, what is standard/common for outdoor CLG?

Thanks again, any input is appreciated.

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on May 21, 2018, 07:10:11 PM
It was quite some time ago Tony and I was just starting into HLG's then on a long learning curve. I would have been happy with a transition like that. Mine always looped and then went into a glide.

Providing it doesn't stall on the glide - moving the CG back in very small amounts ( pinhead of plastiscene at a time) should not affect the transition but trim the nose up a bit on the glide. The amount of nose weight removed is not enough to upset the stability, and this is why the transition and climb stays the same. At least this is what I have noticed with my CLG's.

I think 18" WS may be getting close to a upper limit as it will take too much power to launch past this point.

I have another one hanging around - but it is destined to become a whip control line model. It's glide is unusual. It has no dihedral and it yes the CG range for a good glide is small. When it stalls it often goes into a high alpha descent - self DTing :)

Have fun - why not on the beautiful grass field? Not Yours?

John


Title: Re: CATAJETS: Design and Development
Post by: tross on May 21, 2018, 09:51:18 PM
Ha. Yeah, it's mine. I get to mow it too. ::)
Just too close to the model eating trees..

Thanks again for the tips.
I'm sure I'll need some more. ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: DerFlieger4 on May 22, 2018, 11:57:12 PM
Dear Pit,
I built your F9f Cougar last weekend (have yet to fly it, as the winds have been beastly lately) and my interest in "Catajets" has been ignited. I imagine creating a suite of the early 50s and 60s jet agers, but I have a question. How does one determine the CG when creating a plan?
Thanks,
Der Flieger


Title: Re: CATAJETS: Design and Development
Post by: MKelly on May 27, 2018, 01:26:22 PM
Did a bunch of jetcat flying last Thursday trying to get them tuned up for the June FAC meet in Gainesville TX.  Trimming changes were limited to micro-adjustments on the noseweight, mostly played with launch elevation, bank angle, and azimuth relative to the breeze. 

https://www.youtube.com/watch?v=r3Q0muu1-3w (https://www.youtube.com/watch?v=r3Q0muu1-3w)

The Me-262 consistently flew 17-20 second flights, with some getting up over 30 sec when the transition hit just right and the air was helping out.

The Scimitar was more challenging, typical durations between 10 and 20 seconds.  By increasing the launch elevation to near vertical with the model almost inverted I got it past stalling (and sometimes spinning) at the transition and got some great height followed by a fast, sweeping 30-second glide. 

Great fun.

Mike


Title: Re: CATAJETS: Design and Development
Post by: VictorY on May 30, 2018, 01:08:24 PM
Nice. I had some fun in the relatively calm winds of the last few days. :)


Title: Re: CATAJETS: Design and Development
Post by: tross on June 04, 2018, 10:48:00 AM
Awesome Mike,
Looks like one of them took a run at you... ;D

Just a short update on the F16.
This is version 5. ::)
8" span.
The wing is .03" wood and just slides through.
The other parts mate up to hold everything square.
Cut time is less than 30 min., build time about the same.
No dihedral. 8)
Has a nice glide at 2.95 grams all up in light wind, using .07" rubber for the launch.
I'll try to get some video of the glide.

Tony


Title: Re: CATAJETS: Design and Development
Post by: Crabby on June 04, 2018, 11:34:10 AM
Nice Tony.! For a split second I thought I was seeing the SR-71 Blackbird at pic 3. I love jets and can’t wait to see you fire the F-16! Gonna keep the eyes on this post


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 05, 2018, 03:53:47 AM
Very nice Tony. What Re did you run the airfoil analysis at ?

John


Title: Re: CATAJETS: Design and Development
Post by: tross on June 05, 2018, 08:36:32 AM
Thanks Crabby, I've been eye-balling the SR-71 also but not sure I could do it.

Sorry John, that was 15k.
I've attached a 15-50.
In reality it's just a .03" wing with the shape shown in the first image.
The glide is magical, but getting it above 20 ft is tricky so rev 6 is drawn.
Back to flaps on the wing as shown, and I'm adding some flex in the back as well.

Tony


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on June 05, 2018, 09:59:18 AM
That's some lovely work on the F-16's Tony, very pretty!

In reality it's just a .03" wing with the shape shown in the first image.
The glide is magical, but getting it above 20 ft is tricky so rev 6 is drawn.

Curved plate foils are really good at low Re in the glide but poor at low alpha/high speed in the ping  :-\ because of the flow separation on the lower surface at high speed. From an analysis point of view you want to be seeing low drag around zero CL.

The secret for tiny CLG models (non scale that is) is a thicker wing that you would expect - 1/8" on an 8" span. Something like 5% thick. This gives you enough camber for the glide but no undercamber (Check out BE5017VN and BE5017FB)

Not sure if this would work for you because thicker wings are heavier. If you can get flaps to work consistently that may be the way to go.

Jon

(https://static.rcgroups.net/forums/attachments/6/3/7/9/5/2/a9852193-75-BE5017FB.jpg)


Title: Re: CATAJETS: Design and Development
Post by: tross on June 05, 2018, 10:48:40 AM
Hi Jon,
I hope all is well.

I did start a solid wing version.
5% thick. Beautiful piece of 1/4", 4 lb wood.
Sanded down the thickness to the specified dimension, used some cnc templates.....
Took all evening to hand cut and sand, and it weighed 3 grams.

That's as far as I could go.
3 grams is the target AUW.
It also didn't fit into the 30 min cut, 30 min build criteria I have set.

I took a look at the thinner .03" wing compared to the 5% thick wing, and I've attached that below.
At high speed with flaps the thin wing profile would be different, but I didn't create a profile.
And of course, my actual wing doesn't look like what's in xfoil.
Your suggested wing would no doubt return better numbers. :)

I've had some luck with flaps on previous versions.
The glide wasn't as nice as this latest model with the thin under camber however.
So maybe I can get a good balance on this next version.

Thanks for responding, as you know I'll take all the help I can get. :)

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 05, 2018, 08:24:45 PM
I agree with Jon re the camber in the airfoil. I also noticed that you have a fairly forward CG and the decalage is considerable for a CLG on the launch.

I would suggest removing the negative incidence in the tail and wing and relying on the flaps only to provide camber and decalage on the glide. If possible moving the CG back to get a glide with minimum flap deflection would help although with such a short tail moment this may require a larger tail for stability, which would be a pity as it is a nice looking model.

Also score the underside of the flap hinge area to reduce the stiffness of the hinge.

It is easy to see why the older vintage jets are more popular with their longer tail moments.

Well good luck with this Tony.

John



Title: Re: CATAJETS: Design and Development
Post by: tross on June 06, 2018, 08:40:50 AM
Thanks John, who needs luck with you folks around? ;D
I'm trying to keep these short, but maybe the comments will help someone along the way.

The cnc desktop cutter makes short work of these, and I wouldn't be able to build one right after the other without it.
I've attached a picture of all the parts cut for the next version to see how simple it is.
Wing flaps and rearward parts are soft balsa. Flat horizontal part of fuselage incidence removed.

You're right of course, the scale moment/volume is an issue.
Along with the form. I'm ok with it, it's a worthy opponent.
The wing is ok as the 2% thick 4% camber for this one.
The cl in the glide is noticeably high,
it keeps the loading down, and is easy to fabricate.
We wouldn't be caught dead with it on a normal glider of course, but this is far from that.
Maybe it's the one and only advantage this plan form 3.15 AR has.
The wing is only .03" thick so I probably can't cut into it.
At 3 grams, it's held together with chewing gum as it is.

I would suggest removing the negative incidence in the tail and wing and relying on the flaps only to provide camber and decalage on the glide.
Tried that. Once it transitions and gets situated in the glide it's a nose-low attitude.
I won't elaborate, but we need the nose to come up a little.
One would think less margin, less longitudinal dihedral, less flaps would do it but it won't glide there.
Well, your models would.
The last 2 versions were all about trying figure out what it needs to glide, and really nothing to do with the
launch. I had to take a step back get that handled first.
These next couple will be more about getting a flat 0-0 at the launch and then opening up to the glide step up.
I have a few ideas on how to get that done.

Maybe I could just find a really small pilot. ;D :) :D ;D

Thanks again. Any and all comments welcome. :)

Tony

PS. I've attached a picture of the solid wing.


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 06, 2018, 09:35:09 AM
One of the problems with these flap gliders is ensuring the flap hinge has the minimum of friction so that it will actually move up enough on the launch.

How about trying to hinge it with a narrow - sat 3- 4 mm wide strip of say magic tape, instead of gluing it to the fore part of the wing.

You could also possibly hinge an elevator at the tail so that when the flaps blow up the elevators blow down on launch.

I had a larger F16(about 16" WS) many years ago - from the AMA mag I think, and it was launched on a longer catapult attached to a stake in the ground. It had a blow down elevator that worked some of the time. It had a nice glide but looped on the launch - the elevator didn't blow down too much. A stiff hinge kills it.

Happy launching and gliding.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on June 06, 2018, 09:59:49 AM
Hi John thanks.
It has been fun. :)
I'm getting plenty of exercise. ;D

I must have stumbled on a way to get the flaps to blow flat.
There's been a couple of times they stuck flat to the side of the fuselage.
So I know they're getting there.
It's super thin 4lb wood, not good for much anything else.

You could also possibly hinge an elevator at the tail so that when the flaps blow up the elevators blow down on launch.

Yes. That's where we are now.
Too stiff and it loops. Not stiff enough and it disintegrates on launch.
Maybe just build it similar to the wing, only in reverse.

Thanks again,

Tony


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on June 06, 2018, 10:32:34 AM
Tony,

Have you tried just a flat section? Poor in the glide obviously but may get you height instead?

Jon


Title: Re: CATAJETS: Design and Development
Post by: strat-o on June 06, 2018, 01:40:05 PM
Quote
I'm getting plenty of exercise

Pretty sure that fetching models is the best exercise there is!


Title: Re: CATAJETS: Design and Development
Post by: VictorY on June 06, 2018, 04:04:35 PM
Mechanical flaps with a spring/damper of some kind? I have a few lightweight ideas. You could tune the spring and the damper for overall resistance and time of transistion. :)


Title: Re: CATAJETS: Design and Development
Post by: flydean1 on June 06, 2018, 04:17:40 PM
Tony I'll take all that 4 lb wood you want to get rid of. ;D ;D


Title: Re: CATAJETS: Design and Development
Post by: tross on June 07, 2018, 07:57:39 AM
Lot's of walking strat-o..... ;D

Hi Jon, thanks.
It's mostly flat.
I've attached a picture.
Obviously not the flying attitude but hopefully shows how thin and flat it is.

I had a long session last night and came up with a set up that is working for both launch and glide (pic #2).
Launched it into some nice air and had some good flights.
Of course, in the spirit of science, I had to see how much it would take before it shredded on launch.
Found it. :o

VictorY, Thanks so much for the comment as nothing is off the table for jet cats. :)

Dean,
Stop by and we'll pick something out from the stash.
Most of what is in this pile is 5 lb. Some 6, and a fair amount of 4. Half of the block is under 5.
I'm addicted to balsa, always adding to the pile, and will never use it all. ;D

Thanks again.

Tony


Title: Re: CATAJETS: Design and Development
Post by: tross on June 08, 2018, 07:33:03 AM
I'll just call this another version since I've lost track of how many there's been. :D

We've increased the wing incidence by .5° and flattened out the horizontal fin by 1°.
This increased the flap chord some, and with a reduction in longitudinal dihedral we've moved the cg back.
It has a nice glide, and this should improve the launch.
Needs sanding.

Tony


Title: Re: CATAJETS: Design and Development
Post by: BG on June 08, 2018, 11:04:48 AM
Nice looking F16s. One thing you might find to be of interest. I would actually move the nose weight much closer to the CG. Yes this means using a lot more weight to get her balanced but it should result in a significantly better recovery because the moment of inertia will be significantly reduced relative to the stab moment. Perhaps one get the treatment and the other keeps the weight upfront?? Could make for a revealing experiment.

B


Title: Re: CATAJETS: Design and Development
Post by: tross on June 08, 2018, 12:43:08 PM
Hi Bernard,
Thanks for the tip. :)
I was putting a blob of clay on the bottom just under the cg a few models back.
It was transitioning right at the top of the climb like a circus act.
Then it shot across the yard and logged in a tree about 50 feet up.
We found it on the ground the next day. :'(

It didn't dawn on me to try moving it around a little.
The model in the back is retired, but I'll still give it a try for sure. :)

Thanks again,

Tony


Title: Re: CATAJETS: Design and Development
Post by: Pit on June 08, 2018, 03:54:40 PM
Mechanical flaps with a spring/damper of some kind? I have a few lightweight ideas. You could tune the spring and the damper for overall resistance and time of transistion. :)
I used a piece of guitar string (0.009) on the canard of my Viggen to push down on glide but was light enough for the surface to "blow" up during launch.  Worked.

On the F-16, the only real issue would be getting both surfaces balanced with the springs near the root of the flaps (mounted on the top surface and curved so that they force the flaps down).  Hinge the flaps with tissue or Scotch "Magic" tape along the entire length.  A down stop will likely be needed.


Title: Re: CATAJETS: Design and Development
Post by: frash on June 08, 2018, 08:55:29 PM
I like your fine wire spring. Years ago for F1H towline gliders (aka A-1 in US then), I used a fine wire for the hinge and as a torsion wire spring to move the rudder to the glide position. That is all the detail that I remember. I copied someone's idea from a magazine.

Olbill and other flyers of bunting low-ceiling cat gliders probably have tried this already for their very light indoor gliders.

Fred Rash


Title: Re: CATAJETS: Design and Development
Post by: tross on June 08, 2018, 10:39:51 PM
Hello Pete, and Fred.
It's good to hear about those good ideas from you guys. :)
I'm having some real fun with this.

In tonight's trimming I was able to remove most all of the negative stab (John)
And basically glued the flaps flat for a flat wing (Jon)
I just managed to get started on the rearward ballast when the lights went out (BG)
Thanks for the suggestions fellas. :)

Fast. That's the word for it now.
Still flying well, but it's cookin'.

I ordered a knock off 4k go pro cheap, so we'll see if we can't get that going. ::)

Thanks again.

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 10, 2018, 03:54:15 AM
It's given you quite a few hours of entertainment Tony.

Version infinity-1? :)

John


Title: Re: CATAJETS: Design and Development
Post by: VictorY on June 10, 2018, 11:46:18 AM
I used a piece of guitar string (0.009) on the canard of my Viggen to push down on glide but was light enough for the surface to "blow" up during launch.  Worked.

On the F-16, the only real issue would be getting both surfaces balanced with the springs near the root of the flaps (mounted on the top surface and curved so that they force the flaps down).  Hinge the flaps with tissue or Scotch "Magic" tape along the entire length.  A down stop will likely be needed.

I was picturing a titanium torque rod linking the two surfaces with a cam lobe in the center, riding on a leaf spring. Or you could just use the torque rod and a torsion spring on one surface. But this is getting complicated for cat launch models that someone wants to knock out quickly. :) I use a carbon rod for a leaf spring on my rc hlg elevator, and just have one tiny string of ultra lite test Spectra going to the servo for a pull line.


Title: Re: CATAJETS: Design and Development
Post by: tross on June 17, 2018, 10:43:42 AM
This one.
Version infinity minus 1. ;D
This one has good behavior and I would like to file a report with a few pictures.

Launching hard and level with the horizon, the flight path is straight with little change in altitude.
As the model begins to slow down, it gains elevation slightly and turns left into a gentle but flat glide.
Launching at higher speed at any angle to the horizon results in a similar pattern.

There is very little nose ballast on this model with no wedges or twists in the horizontal tail.
Although it would appear that this version incorporates flaps, the wing sections are not intended to flex and are stiff.
I have been putting in considerable left rudder, and as a result spend much less time in the corn. ;D :) :D ;D

All of the versions built have flown well enough in a stiff breeze.
Although this version is no exception, a warm evening with a gentle breeze shows off its low sink rate and the launch is more consistent.

I've had some success with durability as of late.
The wood is stiff, but not brittle @ 5.5-6 lb, c-b grain cut from .04" stock wood.
The final wood thickness as assembled is .03"

The AUW is 3.25 grams.
The rear section of the fuselage follows a line from the front nose point to the middle of the rear, and I consider this line the datum.
The front section of the fuselage does not follow the datum.
The wing camber is ±3.75% at 40% with some washout at the tips, and is set up around 2.5° from datum.
The horizontal tail makes up the remaining 4.25° total.
The CG is 45% at the root.

The wing seems to take most of the trim input at high speed launch, as the tail starts to take more of an effect near the end as the model speed decreases. Too much tail input causes a loop at launch. Finding a balance was a (the) challenge.
Both wings and horizontal sections are set at equal angles for each side, with the exception of a small amount of wash in left wing center.
Although small adjustments have noticeable effects, the stiff wood holds trim well.

I really appreciate the advice and encouragement.
Each version has given up little secrets along the way, and I am happy with the end result.

Thanks also to Peter (Pit).

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 17, 2018, 07:38:13 PM
Well that's a good reward for your determination Tony. Perseverance to the power of infinity-1.

What seems to be happening may be a unique result of the cambered wing. It actually has quite a bit of camber and this I suspect is providing a strong pitching moment(nose down) - particularly at high speed. The low CL at high speed is able to counter the nose down effect of the pitching moment due to the aft CG. As the speed drops and the CL increases - the nose rises until it reaches equilibrium at the trimmed gliding speed.

It looks like you may have found a way to improve the performance of Catajets. Good one :)

The disadvantage is that with camber comes high drag at speed - with the consequent low CL required.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on June 17, 2018, 11:35:03 PM

It looks like you may have found a way to improve the performance of Catajets. Good one :)
I wouldn't say that, maybe just F16 cat jets that weigh 3 grams... ;D

This model isn't bunting, but the model before it was for sure.
Both 4% camber wings, but that one had no incidence along the datum.
The bunt was impressive.
The PM is still there of course, just more balanced with the set up.

I've flown a 2% camber and a couple of flat wings, with different incidences. But the drag savings in the climb wasn't as noticeable as the reduction in the quality of the glide. 3 grams doesn't fly fast for long regardless me thinks. I guess I'll keep trimming for the glide and deal with the climb.

I managed to solve the little rise at the end of the climb today by increasing the negative stab slightly and adding a little ballast. It was just stalling at that high point. This really helped with elevation transition. I had decreased the negative a little for a while, but wasn't having much luck.

This isn't over. I'll keep chasing the dream.
If you're looking for me I'll be in the front yard. ;D :) :D ;D

Thanks John.

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 18, 2018, 02:15:38 AM
On point that I didn't mention Tony was that obviously the negative incidence on the tail is helping to balance the nose down pitching moment of the wing.

I feel that it would translate to a larger heavier model but possibly as the size increased the extra height from the increased weight would start to outweigh the minimum sink?

Anyway thanks for all the feedback - it's an interesting exercise.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on June 18, 2018, 10:30:02 AM
Hi John thanks.
I'm with you. Any change in size and weight would most likely require a do-over.
I have observations to share but it lacks glamour.
A side effect of this project, I've lost about 6 lbs truth told. :o
Took my nose out of the books for a while and didn't even realize it was happening. ;D

Thanks again.

Tony


Title: Re: CATAJETS: Design and Development
Post by: tross on June 20, 2018, 08:26:51 AM
The set up for this model is more conventional.

The flat bottom wing was cut from 1/16" wood with an incidence (from datum) of 1.75°.
The first screen shot shows the angles. The total is approximately 2.5°
Where as the last few models would be well suited for the front yard or a gymnasium (I'm calling them "Front Yard Fliers" :)), this
one clearly is not. :o

The balance of the parts are .04" 5.5lbs. wood and feel stiff.
The AUW is 4.5 grams.
The wing plan design was taken from the last version and again appears to have flexible flaps.
During initial trimming this part of the wing can be adjusted slightly but I am careful not to get carried away.
At these speeds, even the smallest of adjustment has noticeable effects.
The glide is fast but enjoyable to watch.
The Camber at the root is ±.75% and would be approximately 1.5% at the tip.
As the previous high cambered thin-winged models flew like hang gliders, the speed of this model looks the part of a F16.

I have removed the nose reinforcement and cut a hole in the vertical section of the nose to house the ballast.
The previous test subject is passing on advice to the new recruit..... ;D :) :D ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: Duncan McBride on June 20, 2018, 09:08:51 PM
Supermarine Attacker.  First jet with the Fleet Air Arm.  Nice moments, we'll see how she goes.  My first attempt at inkjet decals.


Title: Re: CATAJETS: Design and Development
Post by: PaulBrad on June 20, 2018, 10:53:44 PM
Looks really nice Duncan. What is the wing span and weight of the finished model?

Paul Bradley


Title: Re: CATAJETS: Design and Development
Post by: Duncan McBride on June 21, 2018, 07:41:53 AM
Thanks, it's 15.5" span.  Heavy at 24 grams.  If it shows promise I'll try another and get the weight down some.  The color is a first try at spraying cheap craft acrylic and that added more weight than I would have liked.  Easy to spray with a cheap Harbor Freight airbrush and water to clean up, just need to watch the buildup.


Title: Re: CATAJETS: Design and Development
Post by: tross on June 21, 2018, 08:51:20 AM
Well it's a beauty. :)
The weight seems alright for that size, isn't it?
If you didn't say it was your first go on the decals I wouldn't have guessed it.

Tony


Title: Re: CATAJETS: Design and Development
Post by: tross on June 24, 2018, 12:45:02 PM
Although camber, incidence, stab mounting and flap shape are all slightly revised on this latest version of the
F16, sanding was the topic of the day....
A .02" slices the air better than .04" go figure. ::)
I have a screen shot that should show some of the revised details below.  :)

We also have a trimming video.

The wind is a steady 5mph or more, and the morning grass is wet.
The trees block the wind, and in the last flight you will see the model make it's way out into the
breezy part of the flying field (front yard) and gain some altitude. Launching above tree top level in
these conditions just sends it either into the trees or onto the house. ::) ::) ::)
I've learned to start the process with thin rubber and light pulls to see if there are any issues
before moving up to a more powerful launch.
In the first 2 flights I'm just circling it about to see if it rotates out into a glide.
I notice a trend however wait until after the 3rd flight to make the adjustment.
Once I see how the glide starts after the transition I take off just a pin head of clay per my
instructions, and the model is off to a nice little glide.
Any adjustment other than adding or subtracting a little ballast gets a start over. ;D

https://youtu.be/JL7JtoelzKg

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 24, 2018, 08:10:13 PM
That's nicely sorted now Tony. It must b fun trying to locate it if it lands in the cornfield.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on June 25, 2018, 08:01:06 AM
Hello John,
If you mean a high speed launch doesn't loop around and hit me in the back of the head then yes, the puncture wounds are starting to heal. :D

This version does take an 1/8" rubber full pull without committing suicide, and we'll keep going up in rubber thickness until we destroy it. Here is some dead calm glides from the evening. https://www.youtube.com/watch?v=VCvL6NEhTQI

It's a weather vane in the gusty winds. 8)
Sorry about the quality here, my super confuser wouldn't let me save it in HD. ???
The second flight in this video is what happens when launch height is above tree top level.
https://www.youtube.com/watch?v=Ny7pX8CiCYY
The corn is 8-10 feet tall already, it's hard to find the model, and it's scary. :o

It's doing ok for what it is, but there will be a couple more built.
So if you have (or if anyone has) any suggestions by all means don't be shy.
These are simple and fast to build and I have a few more things I want to try.
Bernard's suggestion is somewhat implemented. I'm  sanding the top of the fuse to paper, and leaving the bottom as .04"
This shifted some of the inertia down and stiffened up the pull at the same time. ;D

Of course it will also need a paint job, and we should start thinking about a larger version.

Take a look at the pictures. I'm sure the 3rd has already been (over) done but would probably be a good front yard flier as 6-8".
Not an official vote, but comments welcome.

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 25, 2018, 06:57:00 PM
The U2 wings would be very small in chord at 6 - 8", however and may not be stiff enough for any sort of power perhaps. I think that might be more of an issue than the low Re.

What about the good ol Warthog? Probably overdone as well but nice layout from a glider point of view.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on June 25, 2018, 10:33:04 PM
Hi John,
I think the U2 glider I saw had a noticeable wider than scale chord.
The A10 would be cool, but the back end gives me a little pause thinking of the launch.
Zero-ing out a Black Bird would be a neat trick. ::)
I guess if its just for front yard fun it would be ok. ;D

For the F16 this evening I finally got around to a suggestion of yours.
With the stab set to zero negative and CG @ 50% (at the root) the glide is similar.
Even though this aft balance has the rudder adjustment a little sensitive, the change in launch is noticeable.
Who knew. :D

Tony




Title: Re: CATAJETS: Design and Development
Post by: OZPAF on June 26, 2018, 07:20:02 PM
Glad it helped :) However I think the real secret of your success with the F16 may be the cambered wing.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on July 01, 2018, 03:16:13 PM
I think you're right.
It has a nice glide. :)

I finally stopped hem-haw-ing   ::) around and sketched up the next little jet yesterday, then put it together last evening.

I was thinking it might look silly profiled like the F16, but it's fine.
It needs a finish of course. Probably a light coat of paint and maybe a couple water-slides sprinkled on.

The initial trim flights look promising, and I'm not really sure what I was concerned about.
A dozen or so flights and it was in there.

The wind was a little brisk during the session, but it handled it ok.
This unit shoots up like a rocket with 3/32" rubber :o :o, and could probably be enlarged. ;D

6" span, 3.6 grams.

https://youtu.be/RmpEEHmILf8

Tony


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on July 01, 2018, 07:54:50 PM
Good flyer tross


Title: Re: CATAJETS: Design and Development
Post by: tross on July 01, 2018, 09:54:06 PM
Thanks Flyace,
I had to move the CG forward a little for calm conditions.
The updated flying weight is 4 grams.
The climb out is fun to watch and the glide is smooth.

Tony


Title: Re: CATAJETS: Design and Development
Post by: Maxout on July 02, 2018, 01:41:49 PM
Well guys I've been dragged kicking and screaming back into jet cat models. And now I've got a laser cutter to speed the process along. I'm starting to reach the point of being able to do stuff with the laser than I can't do with a knife or even a saw.

Don Deloach challenged me to build this design as the possible ultimate jet cat subject. Well didn't work out quite that way, I had to enlarge the fin a lot to make it fly, but it does fly very well indeed now.

If you want to ultimate in ease of, well, everything, you can get a kit for it here: http://jhaerospace.com/product/focke-wulf-fw-p-1-scale-catapult-glider/


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 02, 2018, 08:48:18 PM
Another tree magnet Tony :) Nice flights and it looks the part.

John


Title: Re: CATAJETS: Design and Development
Post by: PaulBrad on July 02, 2018, 11:36:21 PM
After reading about FAC Jet Cat models I have been bitten by the bug. It has been a while since I have flown any catapult gliders so I have much to re-learn. Size being the first page in my learning book. I elected to go with a 17" span model. My thinking being that a model that size is closer to the size of models I have flown in the past.

I also was not sure how important earning bonus points would be. Knowing that FAC Jet Cat models tend to have less performance than a pure duration model, I felt any bonus points earned would help this newbie in the event. For that reason I selected the Me 262. One bonus point is awarded for each engine not contained in the base structure of the aircraft.

Provided are a couple of photos of the finished 17" span model. I ballasted the nose to generate a CG location calculated using the Tail Volume method. With the ballast added the all up flying weight is 16 grams.

I have completed the hand glide trimming phase and am now waiting for some suitable weather to start trimming with catapult launches. Hopefully it will survive that phase so I can fly it in the U.S AMA Free Flight Nationals coming up in several weeks.

Paul Bradley


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 03, 2018, 07:20:24 AM
Very pretty Paul. Have you looked at the vids a few weeks back on this thread, of Mike Kelly's ME262 flying?

John


Title: Re: CATAJETS: Design and Development
Post by: PaulBrad on July 03, 2018, 04:12:03 PM
John - It was that video and Mike's model that had me take the plunge. I am basically following in his foot steps but using my own structural design. I sure do hope I can get mine to fly as well as his.

Paul Bradley


Title: Re: CATAJETS: Design and Development
Post by: MKelly on July 03, 2018, 04:57:16 PM
At 16g your Schwalbe should fly quite nicely!  Mine weighs about 25g.  To give credit where it's due, the short kit I built from was designed by Henry Toews and "productionized" for laser cutting by IronMike.  I fiddled with the wing rib configuration and beefed up the nacelles (thus the somewhat portly flying weight).

Look forward to your flight reports Paul.

Mike


Title: Re: CATAJETS: Design and Development
Post by: tross on July 05, 2018, 01:19:53 PM
It looks like a flier Maxout, the stab doesn't look big.
Glad to hear you have a laser cutter now, it will no doubt speed things up. :)

That's a nice looking cat jet Paul, they should give you plenty of extra points. :D
Your wing design is just standard stick and tissue?
Very cool.

Hi John yes. I fly them straight at the trees until they get bored and give up. 8)

The first few iterations of the SR-71 flew fine as long as there was a breeze.
Trimming in calm conditions highlighted it's inability to self correct in pitch.
I made a couple of voodoo modifications, but was just putting off the inevitable.

The new model is bigger, and with an 8" span it's nearly 16" long. :o :o
There's a slight rise in elevation or climb out at high speed.
The transition is smooth and the glide is very stable.
It's a slower glide now for obvious reasons (see pic).
But as the nose lowers the on-coming wind encounters the smaller outboard elevons and we see a nose up correction.
If the nose starts to rise in the glide and then starts to slow, the on-coming wind is deflected by the larger inboard elevons.
The degree of launch bunt/loop is a balance of the four elevons as a whole.
The outboard elevons control the roll at high speed effectively, and can turn the model in the glide with a neutral rudder.
Tilting the model over at launch with a half pull of 1/8" rubber, the model rolls out at 40 ft. and heads straight for the corn.
Turning in the glide eats duration as expected.
Very little ballast is required.
Weight for this larger version is 6.8 grams.
The weather looks nice for the weekend, so I may stop down at the school to let it loose. ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: MKelly on July 05, 2018, 01:36:29 PM
Very cool Tony.  If you get a chance to stretch it out at the schoolyard please take video!

Mike


Title: Re: CATAJETS: Design and Development
Post by: tross on July 05, 2018, 10:37:15 PM
Hi Mike thanks.
Of course. Always taking some video if possible. ;D
I'm still a little hesitant to let it rip completely.
Just trying to stay out of the corn. ::)

https://youtu.be/Zvn4mSZfPlI

Tony


Title: Re: CATAJETS: Design and Development
Post by: tross on July 07, 2018, 04:10:41 PM
Those flights are hard to see. :P
Here are a couple low launch flights that circle back around (which is nice, less walking). :)
This set up would probably work well enough for any type of SR-71 free flight model. 8)

https://youtu.be/-jHW3hKCz9w

May I ask what type of airbrush paint you guys/gals are using for these?
I have a couple of options but would appreciate suggestions.

The slow trim is a little strange for a jet, so I set everything back to zero and trimmed minimums for a faster glide.
It climbs higher and flies faster but the duration is about the same.

https://youtu.be/eWKIFRWDiFs

Cat Jet fliers might get a kick out of this next video.... ;D :) :D ;D

https://youtu.be/5DLD8rtTKTM


Tony


Title: Re: CATAJETS: Design and Development
Post by: LASTWOODSMAN on July 07, 2018, 04:48:54 PM
Great videos Tony !    :o :o   I really enjoyed them.    Now I know what a lawn dart is, in the truest sense of the word .... that SR-71 Blackbird catajet not only finishes like a lawn dart, it actually looks like a "lawn dart" going in.   :)

LASTWOODSMAN
Richard


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 08, 2018, 12:39:42 AM
Fancy treating your $ 1 to the power of - billion balsa SR71 like that Tony. ;D lots of fun for very little money except time.

What would Kelly Johnson say? :D Cheaper than wind tunnel testing.

Thanks for your vids

John


Title: Re: CATAJETS: Design and Development
Post by: tross on July 09, 2018, 08:27:38 AM
Thanks Richard. Much appreciated. :)
I think the next time it darts in I'll just leave it there.
It would make a fitting snow gauge for an aero modeler. ;D :) :D ;D

Kelly Johnson would say I'm a nut job John. ::)
SR-71 and glider in the same sentence just sounds weird.
It's only been about a week and I've found it to be surprising easy to fly.
I made a design change that added 5 seconds (30%) to the average duration.
More of a left turn roll out, less of a loop.

The third launch is the highest.  :o
I put an evening calm wind launch in there for the record.
Spent some time on the roof, in the trees, and out in the corn but it was a good day of flying. ;D ;D ;D

https://youtu.be/QD89062aPQE

Tony


Title: Re: CATAJETS: Design and Development
Post by: Bigbandito on July 09, 2018, 02:15:03 PM
Beautiful plane and great flights. I wouldn’t have thought it possible. Thanks for sharing.


Sent from my iPhone using Tapatalk


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 09, 2018, 08:34:02 PM
Well done Tony.

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on July 09, 2018, 09:00:44 PM
Very cool Tony, what's next?  XB-70, maybe an Ekranoplan?

You're making me want to do another jetcat.


Mike


Title: Re: CATAJETS: Design and Development
Post by: tross on July 10, 2018, 12:48:53 PM
Absolutely Mike, you should build another one. :)
The Valkyrie would be a neat trick.
Although I'm on the fence a little about dealing with a canard, it might be a plus.

Thanks for the reply Bigbandito. Much appreciated. :)
These little planes are something else. Crazy fun. :D

As well for you John. :) I see now why this is a thing.
I lost it in the corn last night but it was near retirement.
Part of the deal.

Tony


Title: Re: CATAJETS: Design and Development
Post by: Maxout on July 11, 2018, 11:29:19 AM
It looks like a flier Maxout, the stab doesn't look big.
Glad to hear you have a laser cutter now, it will no doubt speed things up. :)

It's turned into a consistent flier. Flights are mostly in the mid 30's when I'm not doing stupid stuff. Even then it usually pops into a nice glide at thermal catching altitude (I normally fly in the evenings so those are rare).
https://www.youtube.com/watch?v=XlxRz9kRsmU&t=2s

I'm enjoying your SR-71 efforts. Would love to make a kit of that bird but Lockheed is really nasty about requiring licensure of these things. Maybe I'll try something silly like an XB-70...


Title: Re: CATAJETS: Design and Development
Post by: tross on July 12, 2018, 12:56:46 PM
It looks like a fun jet Maxout. :)
Very cool and nice paint job (what kind of paint is that BTW  ::)).

I hope you get some time to draw up, and kit, a delta.  ;D
Unfortunately, I could use a bigger yard... :D

Tony


Title: Re: CATAJETS: Design and Development
Post by: Maxout on July 17, 2018, 12:36:13 PM
It looks like a fun jet Maxout. :)
Very cool and nice paint job (what kind of paint is that BTW  ::)).

It's just the rattle can stuff. I put down a coat of clear dope and then painted it. It's not a super heavy coat of paint. The splinter type camo definitely makes the model look less simple and plain.

I hope you get some time to draw up, and kit, a delta.  ;D
Unfortunately, I could use a bigger yard... :D

I might tend to do such a thing... ;)


Title: Re: CATAJETS: Design and Development
Post by: tross on July 17, 2018, 04:05:17 PM
Thanks Josh.
So just a coat of sealer or dope, and some enamel is common for these then. :)
I like this one next.
Pretty, isn't it? ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: MKelly on July 17, 2018, 04:37:35 PM
You going to do it with the asymmetric wing Tony?


Title: Re: CATAJETS: Design and Development
Post by: tross on July 17, 2018, 04:45:39 PM
With lots of pin holes..... ;D
It'll probably be this version, which I think was the original set up..

tross


Title: Re: CATAJETS: Design and Development
Post by: tross on July 29, 2018, 09:28:39 PM
I think you might get a laugh at the "cat" in this cat jet video Peter (Pit). :)
Just a couple of low powered glide trim flights.
No tail, no worries... ;D :) :D ;D

https://youtu.be/qZJY8cpxZac

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 29, 2018, 09:38:46 PM
The cat liked it Tony.  :) He didn't see it coming on the second flight - It must be stealthy :)

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on July 29, 2018, 10:03:21 PM
More incredible stuff, Tony!  That looks really stable, and very cool - the split ailerons (drag rudders?) seem to be very effective.  Would you consider posting your plans in the gallery here?

I posted this over in the "What did you do airplane-wise today" thread, but thought some of the folks here might like it - got a 2+ minute thermal flight out of the Me-262 jetcat this morning:  https://www.youtube.com/watch?v=o724ae5QLyU&t=36s (https://www.youtube.com/watch?v=o724ae5QLyU&t=36s)

Not all that much to see on the video as it drifted quite a distance from the launch point.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: tross on July 30, 2018, 08:00:58 AM
Thanks Mike.
It launched right into one and then searched for another. :o :o
That was awesome. :)

I appreciate the suggestion but the plan is just a balsa wing.
Unfortunately, I wouldn't be able to express the mechanics of flying tail-free on a plan. :-[
Good eye as always, drag yaw. 8)

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 30, 2018, 08:38:26 PM
I didn't check this out thoroughly yesterday Tony and missed the split aileron/drag rudders that Mike mentions. Very clever. I agree it does look quite stable and the drag rudders look powerful. Do get interaction between the drag rudders and the elevons on top?

Very nifty plots as well - the airfoils have a very defined low drag sweet spot. Interesting. Keep the wing loading low and stay near the sweet spot.

Using the laminations to show the cockpit detail is innovative too.

Good stuff.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on July 31, 2018, 02:37:40 PM
Hi John,
From the field notes.
The upper and lower elevons are blended equally and not effective for ailerons.
The CG is set directly on the AC, and too much drag from the drag rudders results in a behavior typical of aft CG.
Without sufficient drag the plane wanders in yaw.
Roll is sluggish but effective utilizing the mid-span elevons, and the gust attenuators need to stay along the airfoil profile.
Any elevon lowered below the airfoil profile results in unstable behavior at increased airspeeds.

You're spot on for the light wing loading.
The outer panels are utilized for pitch stabilization and don't contribute to lift. Unless it's upside down. ;D :) :D ;D
Lift roll illustrates the situation.  :o
With an AUW of 6 grams, only 35 in² of the total 46 in² of wing area accounts for lift, and the result is an approximate loading of .2 gr/in².

The structural engineering department has stepped in and suggested a wing upgrade. 8)

When the sweet spot has been trimmed in it just floats along. ;D

Thanks again,

Tony


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 31, 2018, 08:22:47 PM
Thanks for the details Tony. The span loading chart from Lift Roll is I suppose what you would expect from a flying wing. It does empathise that the pitch stabilizing elevons should be situated at the end of the wing to ensure a reasonable CL for the main section of the wing.
A bit like an extreme Bell shaped distribution.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on July 31, 2018, 09:22:11 PM
No problem John, :)
Expected for a free flight glider maybe, but not so great I know. Terrible on purpose. :P
The entire outer panel is used for holding the wing section up at 2°as the outer elevon doesn't have enough yank (and is draggy).
The outer elevon would of course help with any slight pitch adjustment but would also affect the yaw trim which is sensitive.

Tony


Title: Re: CATAJETS: Design and Development
Post by: Maxout on August 07, 2018, 12:56:56 PM
Well folks, Steven Wrigley has topped everything, and I do mean everything. At my suggestion, he drafted up the most insane Jet Cat model ever and sent me the laser files to test it out. Ladies and gentlemen, I present to you the Caspian Sea Monster!

Yes, it flies.
https://www.youtube.com/watch?v=nB0ddLulmrU&t=6s


Title: Re: CATAJETS: Design and Development
Post by: MKelly on August 07, 2018, 02:23:15 PM
Awesome!  Is it 15 bonus point on that thing (5 for canard and 10 for all the engine pods)?

Mike


Title: Re: CATAJETS: Design and Development
Post by: dslusarc on August 07, 2018, 02:31:50 PM
That's awesome. I smell a new potential FAC rule in the making if this one starts to win. :)


Title: Re: CATAJETS: Design and Development
Post by: Maxout on August 08, 2018, 08:09:40 AM
Awesome!  Is it 15 bonus point on that thing (5 for canard and 10 for all the engine pods)?

Mike

I forgot about the canard. The way the rules are written, you get points for any "pods" on the aircraft, so the wingtip pontoon/stabilizer thingies also count. So 17 BP. Probably the most of any jet cat model to date.  ;D

The proposed Beriev Be-2000 would have been a close contender.

That's awesome. I smell a new potential FAC rule in the making if this one starts to win. :)

The bonus point rules were tweaked a couple years ago so that they are only added once. Back when they were added to each flight it made a big difference.

This model is more for cool factor than anything else, and I feel like it has achieved that goal in spades. I've got many other jet cat models that fly far better, and I don't have nearly as much fun flying them. Ironically, they were all harder to trim, too.  :-\


Title: Re: CATAJETS: Design and Development
Post by: dslusarc on August 08, 2018, 12:05:52 PM
Josh,

How big is that one in your video? Span, length, aporox weight?

Don


Title: Re: CATAJETS: Design and Development
Post by: Maxout on August 08, 2018, 02:24:35 PM
Its an 8" span, roughly 20" long. Didn't weigh it, but maybe 7-8g? Not flying outdoor competition actively is really liberating about not having to weigh things.  ;D ;D ;D


Title: Re: CATAJETS: Design and Development
Post by: VictorY on August 09, 2018, 08:27:06 AM
Would missle carrier tubes add more points? LOL


Title: Re: CATAJETS: Design and Development
Post by: dslusarc on August 09, 2018, 09:48:58 AM
Its an 8" span, roughly 20" long. Didn't weigh it, but maybe 7-8g? Not flying outdoor competition actively is really liberating about not having to weigh things.  ;D ;D ;D

Thanks. Was thinking of one for next year's Indoor contest in Michigan. My FAC rule comment was more along the lines of it not being considered an "airplane" in the sense that it was never meant to fly out of ground effect.


Title: Re: CATAJETS: Design and Development
Post by: Maxout on August 13, 2018, 01:00:10 PM
Thanks. Was thinking of one for next year's Indoor contest in Michigan. My FAC rule comment was more along the lines of it not being considered an "airplane" in the sense that it was never meant to fly out of ground effect.

A valid point, but something that could be defeated with any honest CD. The aircraft had greater than a .25:1 thrust:weight ratio at max load, so it would fairly easily fly out of ground effect, and indeed there have been comments made that the pilots had a great deal of trouble keeping the aircraft at optimal altitude--it wanted to FLY!

Also most of the Russian Ekranoplans demonstrated OGE (out of ground effect) flight, it's just that they weren't optimal in that flight regime.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on December 10, 2018, 06:24:00 PM
Been playing with the Bill Dean Jetex Skyray as a catapult glider.  The plan has a lot of reflex at the trailing edge boat-tail area, which made the model loop spectacularly at launch.  My son loved it, but the loops did nothing for flight duration.  Over several flying sessions I carved and shimmed out pretty much all of the reflex, which let me get rid of a chunk of lead in the front end and pretty much cured the looping.  Flight times have gone from 8-10 seconds to 15-20 seconds, with occasional longer flights from good launches or good air.  It'll never be a world-beater, but it's a lot of fun!

Video from today at:

https://www.youtube.com/watch?v=YXf-P1z-s4U&feature=youtu.be (https://www.youtube.com/watch?v=YXf-P1z-s4U&feature=youtu.be)

Mike


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on December 10, 2018, 08:13:05 PM
The flying session was the best and even with my Skyray vastly improved too. A REAL HOOT. Very happy with the results. Just wish the ME-262 was as much fun but still trying.


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on December 11, 2018, 12:27:24 AM
What a well finished Catjet!. That's good going I would think from a small delta wing model.

John


Title: Re: CATAJETS: Design and Development
Post by: Stuondrums on December 11, 2018, 01:58:36 PM
Hi folks, noob to the forum here. Some amazingly well flying models! Really good work folks - I am going to have to have a go myself again now.
A few years ago I had a (very brief) attempt at an EE Lightning - about six inches span with almost scale  anhedral. The thing insisted on flying inverted so I went back to flying my RC mustang ( I was on holiday ) I am going to have another go at that, possibly enlarged a little with a flat wing and see what happens. After seeing some of this really cool stuff I may even treat it moderately seriously and try a cambered wing.
On a related but side issue, back when I was a kid in the UK ( Oxford) in about 1972 the local model shop ( Oxford Model Centre in St Giles' ) sold small, injection moulded plastic catapult launched EE lightnings that flew spectacularly well, anyone remember anything like that?
Also, at about the same time there was a fairly advanced for its time mag/comic aimed at the younger reader called Speed and Power. 12p a week and you got loads of articles about things that were, er, fast and powerful. (And an Arthur C Clarke story every week) it had a section called Model spot thta was largely concerned with encouraging and stimulating creativity: scratch building from plans they provided you got a pretty good result from their instructions for an XB70, an F16 ( built with a mix of balsa and cartridge paper, though you could use all balsa I guess ) and a superb set of F111s with various different levels of wing sweep from 1/16 balsa, designed very much like Bill Dean's Skyray - with a fair bit of reflex. They would do quite magnificent loops on launch and fly with varying degrees of speed or duration depending on which of the three you had built.
These of course are nowhere near as scientifically approached as what's going on here - especially from Tross, Maxout and Mike, but fun nevertheless.

Right then, Lightning F6 and a Swift next, I think. And possibly even seeing if I can copy that 262...

Cheers folks.


Title: Re: CATAJETS: Design and Development
Post by: kittyfritters on December 20, 2018, 10:22:30 PM
(This FAC Jet Catapult event was also reported in the Events section.)

FAC report courtesy of Hugh Langhans, FAC Chapter 69 Adjutant.  (With a bit of editing, KF.)


An FAC contest was held at the Grassy Knoll on Sunday, December 9. It was scheduled for Dec. 2 but was blown out based on weather forecast of high wind. The forecast for Dec. 9 was also not so good, but I did not want to postpone the events again, and we lucked out. The wind did not start to show up until 10:00 AM and we were done by then. We did not have enough entries for Pearl Harbor and we started an FAC scale event but people left at about that time because of concerns about wind.

This may be the last event held at the Grassy Knoll. There is an alternate site south of the RC field that is larger than the Grassy Knoll and has fewer trees. Jim Alling lost a P-30 at the top of a tree on the far side of the grassy Knoll and we are always getting models out of trees in that location. So far we don't have a snappy name for the new location. perhaps Urban Undergrowth?

The Profile Jet Catapult event had four entries. They were Bill Watson with an XP-89,Hugh Langhans with a Grumman Cougar, Don smith with a Gloster Meteor and Howard Littman with a B-52. An  initial trim flight with the XP-89 resulted in damage which was soon repaired. The initial launch of the Panther resulted in a big loop that came around and hit me knocking off the front of the tip tank.

Bill's XP-89 had both the best times (one flight of 30.1 seconds!). It also had the highest score for color, details and craftsmanship. Howard was second with his B-52, Don smith third with the Gloster Meteor and Hugh Langhans fourth with the Grumman Cougar (sic Panther). The Cougar (sic Panther) had a best time of 4 seconds, but hey, it flew!

KF


Title: Re: CATAJETS: Design and Development
Post by: flydean1 on December 20, 2018, 11:28:13 PM
Panther was straight wing.  Cougar was swept wing on same general fuselage.  Both were F9F's with different dash numbers.


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on December 24, 2018, 02:58:26 PM
If you want a hint on a SNAPPY NAME think of some place like Area 51 maybe due to strange developments or just give a geographic location referring to a nearby landmark. FWIW


Title: Re: CATAJETS: Design and Development
Post by: tross on May 06, 2019, 07:11:17 PM
That's a nice report Howard.
I like all of those models. ;D

Here is my effort so far this season in the catjet category.
An 11 inch wing span F16.

A general outline of what I have built has been uploaded to the plans gallery (thanks Ratz)

This video has build pics and a couple of decent flights.

https://www.youtube.com/watch?v=m-6Yshy6fmY

It's been a fun project. :)

I hope everyone is doing well.

Thanks again.
T


Title: Re: CATAJETS: Design and Development
Post by: skycafe on May 06, 2019, 07:34:52 PM
Wow, that glides pretty well!  Good job.


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on May 06, 2019, 08:08:42 PM
Great flying F16 Tony. I'm surprised that the curved wing launches so well. That glide is very impressive.

Hope you are all doing well.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on May 07, 2019, 01:01:07 PM
Thanks skycafe.
I appreciate the comment.
I also like the glide. :D

All is well my friend. :)
It gets up ok.
I like how it mossies' along up there. :o :)

One can build it without the curve of course.
No worries there. ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: Sky9pilot on May 07, 2019, 04:43:27 PM
Tony...great F-16! Loved the video...I'm definitely going to have to build one.  I haven't been able to get mine to glide like that!!!!  Fantastic job!
Tom


Title: Re: CATAJETS: Design and Development
Post by: tross on May 08, 2019, 04:07:42 PM
Thank you Tom, I'm glad you enjoyed it. :)
My bet is your jet flies just awesome. ;D :) :D ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: Yak 52 on May 08, 2019, 05:40:48 PM
Looks great Tony, pretty large for that weight - well done!

Jon


Title: Re: CATAJETS: Design and Development
Post by: tross on May 08, 2019, 08:16:17 PM
Hi Jon thank you. :)

Right. Good catch. ;D
Pretty thin.
Thickness slightly less than what I have shewn on the outline.
.23 g/in², if you only account for the wing.

It can be built using conventional catjet-style wood thickness.
The outline is builder's choice. :)

Tony


Title: Re: CATAJETS: Design and Development
Post by: Starduster on May 10, 2019, 09:34:11 AM
OK, you guys are just having WAY too much fun without me, so I thought I'd throw my hat in the ring and try my first Catajet.

As the XB-70 has always been one of my favorite airplanes, this is as good as place to start as any.

I had already done a laser kit (offered by Bob Holman Plans) for the Competition Models B-70, I simply scaled the CAD down 50% to get a B-70 with a 10.375 inch wing span. There are a couple modifications, one being the rudders now have tabs that fit into slots in the wing, and the curvature of the bottom of the rudder follows the curvature of the wing.

A couple pictures are shown of the airplane before paint. I'm going to give it a light coat of white.

This being my first Catajet, I am not sure where to place the rubber hook, but I was thinking a little forward is best so that the airplane does not pitch up at launch. I put the paper-clip hook under the canard. It's epoxied with fiberglass reinforcement, so I'm hoping it will take the stress.

The airplane, before paint and decals weighs 18.6g. Probably heavy by most standards, but I'm not looking to win any contests, just getting in on the fun!

I'm submitting the 3-sheet drawing to the plans gallery, so if you need a quick project, have at it, and please let me know how yours flies. The uploaded file will also have a decal sheet.



Title: Re: CATAJETS: Design and Development
Post by: MKelly on May 10, 2019, 09:45:21 AM
Very cool - I'll be looking for that plan to hit the gallery.  I was quite surprised how well the delta-winged Bill Dean Skyray flew as a jetcat once the reflex was taken out of the trailing edge.  Flyace1946 has one that also flies well.  I built a roughly 6" span XB-70 glider while in school, but it was much too heavy for its size and glided about like the space shuttle.  Yours looks very good, and isn't really all that heavy.  For comparison my 11" span Skyray weighs just short of 19 grams and will do 20-30 seconds if I get the launch right.

Tony, the F-16 flight videos look great - quite a nice glide on that one.

Mike


Title: Re: CATAJETS: Design and Development
Post by: Starduster on May 10, 2019, 02:17:51 PM
"There she is, all bridled and saddled..."

Just about ready for first flight.


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on May 10, 2019, 02:24:08 PM
Looks Great. Have fun ok? Make some in flight videos if possible.


Title: Re: CATAJETS: Design and Development
Post by: tross on May 11, 2019, 10:02:35 PM
That's just perfect Rich and thanks for the plan. :)
I really like the finished look. Waterslide decals?

Regarding the F16 development,
I've raised the flaps a small amount.
This in turn has flattened out the glide angle and slightly reduced drag as expected.
A more coordinated turn during climb out, and a smooth transition. 8)

A cool day for flying (55°F/13°C) with a light 3-5 mph breeze.

https://youtu.be/CpHppg13CQ4


T


Title: Re: CATAJETS: Design and Development
Post by: Starduster on May 13, 2019, 10:45:35 AM
That's just perfect Rich and thanks for the plan. :)
I really like the finished look. Waterslide decals?


You are welcome, pleased to share with this community. I have not had a chance to test fly my XB-70 as yet.

I went to my local FEDEX Office store and got the drawing and decal sheet printed on 8 1/2 X 11 clear "sticky back" (label sheet). I then simply peel and stick the parts onto the balsa sheets and cut right through the plastic. The decals are also just cut out and peel and stick.


Title: Re: CATAJETS: Design and Development
Post by: hkybob on July 01, 2019, 10:23:47 PM
I'm gonna build this little 7" Skyhawk for my son, plans show a flat wing, any benefit from trying to give it a airfoil ?
Thanks


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on July 03, 2019, 08:39:45 PM
Quote
any benefit from trying to give it a airfoil ?
It will help a little and also reduce the weight slightly. However it may be best to leave it flat for strength.

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on September 08, 2019, 06:01:56 PM
Jetcats are still distracting me from other models (one of these days I've got to finish that Sopwith 1-1/2 Strutter).  Here's a pair of F-111B jetcats built for the carrier launch Jetcat event at next month's WestFAC meet in Phoenix AZ.  For this event we'll launch jetcats flat and level off a carrier deck (picnic table equipped with a standard 9" loop of 1/4" rubber on a 3' string as the catapult).  The unique thing with this event is the dead-flat launch, which means trimming a bit different than typical jetcats.

The models are adapted from the West Wings/Estes F-111 catapult glider kit.  The swept-wing bird (marked as the Phoenix missile test aircraft) is built from the kit, 12" span with the nose trimmed to F-111B shape, a 1/64" doubler inserted in the forward fuselage and a fin cut from lighter wood.  The approach-configured bird (marked as the carrier trials aircraft) is 14" span, built using kit parts as templates but cut from lighter wood and with the wing unswept with flaps and slats depicted as deployed to get a bit more wing area.  Both have airfoil and washout sanded into the wings and all surfaces thinned out and smoothed as much as seemed prudent.  The kit had panel lines printed on the wood, so I drew them back on after sanding and before painting the models.  Paint is airbrushed on thin enough for the panel lines to show when holding the model.  Markings were printed on a scrap of esaki, doped, then glue-sticked to the models.

The swept-wing bird is a brick at 23g (I think they got their balsa from Guillows' reject pile), however, it launches beautifully with a wide climbing right turn, gradually rolls level at the top, then glides straight and fast in whatever direction it rolled out at.  Best flights have been just over 20 seconds, but it covers a lot of ground - had to climb a fence for retrieval after it flew off the field.  Video at:  https://youtu.be/p0MGONvVbDc (https://youtu.be/p0MGONvVbDc)

The approach-configured bird is lighter at just under 17g.  I borrowed the flap bending approach Tony Ross used on his excellent F-16 jetcat to increase camber and washout on the wing.  Just finished it this morning so flights have been limited to test glides in the yard.  It floats along quite nicely, much slower than the swept-wing version.  Hope to get some launches on it in the coming week.

This'll be fun...


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on September 08, 2019, 08:09:31 PM
Looks like a fun project. Great flights are always welcome. Great choice for the deck launch event. Already flying great.


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on September 09, 2019, 02:54:33 AM
Carrier launched Catjets.Thats innovative Mike. do you have a herd of elves working for you by any chance? Fun incorporated.

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on September 09, 2019, 09:16:21 AM
Carrier launched Catjets.Thats innovative Mike. do you have a herd of elves working for you by any chance? Fun incorporated.

John

I didn't come up with it, I'm just a willing victim enthusiastic participant!  Tom Arnold and the WestFAC steering group chose the carrier aviation theme for this year's meet and (inspired by some interesting videos out of Japan) came up with several deck-launch events.  It promises to be entertaining...

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on September 12, 2019, 07:39:33 AM
Don't forget the crash helmets and the fire extinguishers :)

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on September 13, 2019, 05:30:19 PM
I think I should have gone for a bit more stiffness in the wings on the approach-configured F-111B - see sequence of frames grabbed from 120fps video...

Mike


Title: Re: CATAJETS: Design and Development
Post by: flyfac on September 13, 2019, 07:17:15 PM
Ornithopter CLG!

Best,

Scot Dobberfuhl
Forest Grove, OR


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on September 13, 2019, 07:52:15 PM
Mike we had fun while it lasted. The launches were just  very nice, We should have a lot of fun next Saturday,


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on September 14, 2019, 06:41:18 AM
A couple of strands of carbon on top and bottom will fix that. That is good balsa - lots of flex and it didn't break.

John


Title: Re: CATAJETS: Design and Development
Post by: MKelly on September 15, 2019, 09:29:42 PM
A couple of strands of carbon on top and bottom will fix that. That is good balsa - lots of flex and it didn't break.

John

Actually, while the wing panels stayed intact through the flutter the top sheet on the fuselage didn't  - see first deck launch in the video here:

https://www.youtube.com/watch?v=JQcNM345AwM (https://www.youtube.com/watch?v=JQcNM345AwM)

As shown in the video, a strip of carbon fiber epoxied to the underside of the (reassembled) wings cured it all.

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: Walt on September 15, 2019, 11:30:56 PM
Neat stuff there Mike, I enjoyed the video.
Wally


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on September 16, 2019, 05:15:36 AM
You must have been using the afterburner Mike. :) Thanks for the video.

John


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on September 17, 2019, 11:44:04 PM
Mike I can't get the F-111 out of my head. Just gotta do the thing.


Title: Re: CATAJETS: Design and Development
Post by: tross on September 29, 2019, 10:52:42 PM
Those are some cool jets Mike. :)
I like the hook on your design.
The paint finish coupled with printed tissue has a nice look.
The tissue is printed gray to blend in correct? (except for the white areas)

a couple of pictures of the latest (hopefully final) 12" WS F16.
AUW is 14.75 grams and the initial trim glides look descent.
Since the weather here has turned anti-glider (windy) we're stuck with at or near dark trimming. :P
Hopefully we can squeeze in a couple more days before the season is over to get it dialed in.

https://youtu.be/o4KvTUfbC08

Tony

Ratz Edit: one attachment removed due to being corrupted.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on September 30, 2019, 11:12:34 PM
That's giving you some nice glides Tony!   Yep, I borrowed your hook configuration for the F-111s - as a matter of fact the wire is the remaining stock from the F-16...

Surprised at how much camber you've put in the LE of the bigger F-16.  Certainly seems to be working.  Maybe I should camber the LE slats of the unswept F-111B.

Mike


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on October 01, 2019, 04:48:46 AM
As usual - very nice glide Tony.

John


Title: Re: CATAJETS: Design and Development
Post by: Crabby on October 01, 2019, 09:14:41 AM
Great stuff Mike. Nice spin too. That was the highlight of the video for me! My Migs do that from time to time and I get a real laff out of it! ;D ;D ::)


Title: Re: CATAJETS: Design and Development
Post by: MKelly on October 01, 2019, 09:54:04 AM

The tissue is printed gray to blend in correct? (except for the white areas)


Tony, I printed the markings on scrap white Esaki with a faint gray background - once you dope the Esaki it turns almost clear so the background printing didn't really make much difference.  As usual I colored the back of the white areas with a white Prismacolor pencil.

Crabby, the spins make me chuckle every time (even when its an official flight).  That's been the weakness of the F-111s - if you slow them down too much at the top of the launch they'll spin just about every time, makes it tough to come off the launch right into the glide.  I usually lose around 1/4 to 1/3 of the launch height before the model settles into the glide.

Mike


Title: Re: CATAJETS: Design and Development
Post by: tom arnold on October 01, 2019, 03:04:35 PM
I might add to the discussion that if you fly a jet cat in FAC competition, the curved sheet wing will probably be a disqualification. Dropped leading edge slats and  dropped flaps would be acceptable but a cambered wing (unless the original plane had it) would be a killer in front of the judges. For fun flying, of course, it is a non-issue and the F-16 certainly shows the efficiency of that cambered wing.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on October 01, 2019, 03:48:03 PM
I might add to the discussion that if you fly a jet cat in FAC competition, the curved sheet wing will probably be a disqualification. Dropped leading edge slats and  dropped flaps would be acceptable but a cambered wing (unless the original plane had it) would be a killer in front of the judges.

Tom, you made me go back and read the rulebook (yes, Air Force types mostly can read).  The prohibition on undercambered airfoils appears in section III for FAC Scale.  I didn't see anything about it in section II (primary rules) or section VIII.4 (jetcat).  Seems like I've seen jetcat plans with arched wing slots - are you sure the undercamber prohibition applies for jetcat?

Look forward to seeing you in two weeks!

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: tom arnold on October 02, 2019, 12:01:40 AM
Mike, you make a good point and I will pursue this with the FAC honchos and get back to you on this forum in case there are any more WESTFAC attendees with that question.


Title: Re: CATAJETS: Design and Development
Post by: Indoorflyer on October 02, 2019, 09:03:52 AM
Asking on the FAC FB group would be the quickest way to get the "official" answer/clarification. A few "honchos" hang out there. There have been similar cases where the rulebook didn't address an issue/question specifically, but "everyone" seemed to say the answer was "understood."


Title: Re: CATAJETS: Design and Development
Post by: mescal1 on October 02, 2019, 12:52:40 PM
I'd have to agree with Mike.  I'm pretty sure that rubber powered scale doesn't include catjets.  I'd still make sure with Dave M. just to be safe but
I don't see much of an advantage with undercamber in a catapult glider.  Would make it much harder to trim!
Mike


Title: Re: CATAJETS: Design and Development
Post by: tom arnold on October 02, 2019, 03:55:37 PM
Hello Gents,
I have received word straight from the CINC of the Flying Aces that there is no, repeat no, prohibition on cambered wings for the Jet Cat event. Welcome news and it will be fun to see the battle between the two types of airfoils as they both have their strong and weak points. See you all at WESTFAC!
Tom


Title: Re: CATAJETS: Design and Development
Post by: Indoorflyer on October 02, 2019, 06:10:41 PM
The FAC needs an English major with a law degree to rewrite the rulebook!  ;D


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on October 05, 2019, 07:08:39 PM
Hello Gents,
I have received word straight from the CINC of the Flying Aces that there is no, repeat no, prohibition on cambered wings for the Jet Cat event. Welcome news and it will be fun to see the battle between the two types of airfoils as they both have their strong and weak points. See you all at WESTFAC!
Tom
Thanks Tom for the ruling. Sure glad that happened.


Title: Re: CATAJETS: Design and Development
Post by: Bredehoft on October 12, 2019, 08:15:29 AM
My latest - a smaller - 8.5" span - F-4.  No room to give it full power around here.  But I'll get it tested in a couple weeks, I think.

(https://volareproducts.com/wordpress/wp-content/uploads/F470percent06.jpg)

You can see a few more photos on my Blog: https://volareproducts.com/blog/?p=3910/ (https://volareproducts.com/blog/?p=3910/)

--george


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on October 14, 2019, 12:48:05 AM
Interesting - it should have a good chance of flying well with the poly on the wings. looks neat.

John


Title: Re: CATAJETS: Design and Development
Post by: tross on January 25, 2020, 10:25:51 AM
I like that one George.
Looks like a great little flier.

The wind hasn't let up much here.
Searching around last fall for a new subject I was inspired by this video.
https://www.youtube.com/watch?v=aAHOM_MZZBw.
Here are a few of the initial test flights.
https://youtu.be/4eaE96Af8yI
Tony


Title: Re: CATAJETS: Design and Development
Post by: tross on February 15, 2020, 07:40:21 PM
The designed AUW for the De Havilland Vampire Cat-jet was 13.5 grams with paint and or covering.
It's been flying naked for a couple weeks at 10.5 grams to flush out any issues with fly-ability or structure.
Proving it can survive a full power launch, bounce off the driveway nose first, and get hung up in a tree, etc.
Once there was some assurance it wasn't going to burst into jet confetti all over the yard it was sent to the paint shop. :D

2 coats of sealer and a little thick on the paint resulted in 14.4 grams balanced for flight.
This is a work in progress. ::)

The flight report.
Friday was a chilly day, 17°F/-8°C with a slight wind chill of 5-8 mph.
The sun finally made an appearance which is always welcome, and the air was pretty good.

A few light powered trim flights in the yard and then out into the muddy field to have a look.
The average decent flights were in the 35-45 second range.
It's obvious from the video more practice is needed to see if we can smooth out the transition.

The last transition in this video hit home and one could only hope the camera was on and rolling. ;D
Enjoy.

https://youtu.be/2vN507VfygA

Tony


Title: Re: CATAJETS: Design and Development
Post by: MKelly on February 15, 2020, 08:56:44 PM
That Vampire really goes Tony - the glide is just about unbelievable.  Allen and I had the F-16s out flying today, still doing well.

Mike


Title: Re: CATAJETS: Design and Development
Post by: DHnut on February 16, 2020, 03:31:36 AM
Tony,
       That was most impressive. I have a vampirenezzer and it shows the same sort of glide behaviour and has a very good stall recovery when it is flown with too much power. A Banks Mills .4 cc  engine is used. I am very tempted to build one. Is there anything I should be aware of.
Ricky


Title: Re: CATAJETS: Design and Development
Post by: tross on February 17, 2020, 11:27:58 AM
Thanks for that Mike.
Unfortunately this one really goes. :P
I'm glad the little beast is still flying. ;D

Out again for some test flights this time on Sunday.
We had multiple flights over 60 seconds and it's obvious now the field is too small.

The transition is looking better as a whole.
https://youtu.be/vBMfKWB7nsU

Sometimes it would just be nice if it would stall and come down.
https://youtu.be/xLm6j65ZNb8

In the evening with the sun low it's a 30 second glider.
The repairs are done, paint touched up, and it's back on the shelf waiting for summer, moving on.

Thanks Ricky, your model sounds awesome. I'm sure it's a hoot. :)
You mentioned an interest in building a catapult jet.
I can't think of anything that wouldn't be obvious I guess.
Build light, 1st generation jets fly better, um, build light... ;D :) ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on February 17, 2020, 02:05:37 PM
 You sure have the right touch when it comes to design, build, and FLY. Wow that Vampire is really great.


Title: Re: CATAJETS: Design and Development
Post by: tross on February 18, 2020, 06:49:48 PM
Thanks Flyace.
I really appreciate the encouragement. :)
I caught a glimpse of your jet (Skyray was it?) in one of Mike's vids.
That thing is a beast. ;D

Tony


Title: Re: CATAJETS: Design and Development
Post by: DHnut on February 19, 2020, 05:31:15 AM
Thanks Tony the posts have given me a ball park size to aim at. Many years ago I built a Viggen from a Flying Models plan that was a great performer from a mild bungee launch. I am not sure what a full blooded catapult would do.
Ricky


Title: Re: CATAJETS: Design and Development
Post by: tross on February 19, 2020, 07:27:17 AM
Hi Ricky,
Oh right. Size. Sorry.
There are kits on line you could browse to check out.
The wingspan range for those is from around 12" to 18" mostly.
Some of the tissue covered kits that have a built-up wing are something like 15"-17".
I think last year's champ was a Miles M.100 14" (correction?) solid wing construction.
Wing (model) stiffness during a full on power launch is a limiting factor and I think we are pushing that boundary.
Carbon fiber can help tame flutter in places if it shows up.
John (OZPAF) and Mike (MKelly) were dealing with that on one of Mike's gliders.

Tony


Title: Re: CATAJETS: Design and Development
Post by: DHnut on February 19, 2020, 02:57:15 PM
Tony,
        That was most helpful especially the comment about stiffness. Flutter is a quick exit for any model. I intend to make a prefab design that can be assembled easiiy after transport as I have a grand daughter in Sweden who is keen on anything that flies and a catapult is within her capability.
Ricky 



Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on February 20, 2020, 04:48:26 PM
Thanks Flyace.
I really appreciate the encouragement. :)
I caught a glimpse of your jet (Skyray was it?) in one of Mike's vids.
That thing is a beast. ;D

Tony
Tony that is the big Skyray all right. Sometimes I get lucky on the launch. That was probably the best launch of the big Skyray ever caught on film.


Title: Re: CATAJETS: Design and Development
Post by: tross on March 08, 2020, 09:31:34 PM
I like the idea of a knocked down finished model ready for assembly Ricky.
I think others probably do that but thought I'd give it a try.
It really helped with the masking.
Thanks for that. :)

You should ask a friend to get it on film before it flies away Allen. :o
She's a beauty. :D
Tony


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on March 09, 2020, 06:00:22 PM
Well tross  Mike does try and we keep getting out to fly some. He gets to fly more frequently than I do but we may be having to look for a new location soon as it looks like construction is about to chase us off.


Title: Re: CATAJETS: Design and Development
Post by: tross on April 08, 2020, 11:50:33 AM
The P59 glider is now complete.
Trimming it to circle in lift required a little more control input than the Vampire, and that had some effect on the launch.
Other than that the set up is similar.

There was some good air Sunday afternoon, and we captured around 40 flight clips to sift through.
The average decent flights were in the 30-40 second range, and I tried to include some of those.
As the afternoon went on the thermals started to rage a little, and we had to call it a day. :'(
The longer thermal flight clips are at the end of the video.

The last flight starts in the middle of the field, heads North,  buzzes over the trees in the side yard, circles back over the house, hits a tree in
the back yard and falls into a bush.   :o :o
Sometimes it's better to be lucky than good. ;D

I hope everyone is well. :)

Tony

https://youtu.be/d6Y_qqttY3o


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on April 08, 2020, 12:37:38 PM
TROSS you are just too good. Those are incredible flights. Sure hope to see you at the Outdoor Champs in Muncie.


Title: Re: CATAJETS: Design and Development
Post by: MKelly on April 08, 2020, 12:44:08 PM
Wonderful Tony!  You're going to lose that one soon.  What is the software you're using for design?

BTW, some of that nice balsa from the F-16 parts sheets has made its way into my Keleher Lark peanut build...

Cheers,

Mike


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 09, 2020, 09:44:27 PM
What a magnificent little flying beast Tony. Great choice of subject as well - particularly with that small fin. It transitions well - you are launching with the left hand? I agree with Mike - you were lucky to keep it out of Hung's hands.

I managed a CLG session just before lock down at a local park and lost it in a weak thermal.

Take care.

Cheers

John


Title: Re: CATAJETS: Design and Development
Post by: tross on April 10, 2020, 10:12:16 AM
Thanks guys I appreciate it.
It was a fun project.

Hi John I hope you are well.
I'm glad you had some time to fly before the lock down. :)
Too bad you lost that one.  >:(
Yes you're right of course, I'm launching left handed then circling right.

Thanks Mike, it's Auto Cad and xfoil.
I don't remember any good wood sent but am glad it's going to good use! ;D
I'll probably lose it in the trees. Should probably paint it orange. ::)

We'll have to see if we can get up to the outdoor event FLYACE.
What could be more enjoyable than watching models flying around! ;D
If nothing else that cup of Joe.

As far as design and development, I failed to mention in the last post the basswood strip along the wing leading edge.
Even though I think this is a common practice it's worth mention here for others that might come after.
The current model has seen it's share of hard hits with no damage.

I've put up a couple of clips of this tank in light thermals John and there's no chance of loosing it to Hung. ;D :) :D ;D

Please be safe.
Tony

https://youtu.be/3tlG-TTwQyc


Title: Re: CATAJETS: Design and Development
Post by: OZPAF on April 10, 2020, 08:32:59 PM
Thanks Tony. They must have been light thermals as your "tank" has a lovely floating glide. I think Hung must have been otherwise occupied :)

Take care

John


Title: Re: CATAJETS: Design and Development
Post by: FLYACE1946 on August 26, 2020, 12:56:45 PM
Tony will you be showing the pictures of the new and improved F-16 that went to the corn field to get lost? Maybe start a new thread for the revised layout ?


Title: Re: CATAJETS: Design and Development
Post by: Indoorflyer on August 26, 2020, 01:12:28 PM
Also, Tony---do you sell plans for your designs?


Title: Re: CATAJETS: Design and Development
Post by: graham_mca on September 26, 2020, 11:10:05 PM
Hi all, I stumbled across this thread a week ago, while looking for something in a profile model to cut to test a new laser cutter. I've been reading it ever since! Drew up a model, built it, and did back yard test glides today. Many people here have talked about being distracted by these CatJets. I'm now one of them  :)

I chose a Jet Provost T.Mk.2 as a likely subject and scaled it to 13-1/4" span (1/32 scale I believe). I was attracted by the short nose, lack of wing sweep and ample scale dihedral. The structure is; firm 1/8" fuselage, light 1/8" wings, 1/8" engine intakes, and a 1/16" tailplane and fin. Scale outlines throughout to see how that would work as the areas are pretty generous. It's a little heavy perhaps, 14g in bare wood, now 19g with one coat of shellac and the nose weight.

Hand glides in very light wind today looked good. The dihedral looks like enough at this stage of trimming, showing decent recovery from wind disturbance and over-hard throws. So far so good, but I gather that can all change in a flash when the catapult is released!

Graham