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Outdoor Free Flight Forum => EDF, Jetex or Rapier Powered Free Flight Jets => Topic started by: tom arnold on May 15, 2014, 08:16:37 PM



Title: F-86D Sabre
Post by: tom arnold on May 15, 2014, 08:16:37 PM
Well, my computer is up again and here's the progress on the Sabre Dog. For a release agent from the blue foam form of the inlet duct I was at the height of laziness and sprayed it with "Pam" brand cooking non-stick spray. Amazingly enough, it worked great. The duct is made from wet bond paper and white glue as a mastic. Because of its compound curved shape, the paper was cut in a long strip and spiral wrapped around the form. Even that did not cover all the area and a second wrapping the opposite way was needed to complete it. It looks rough on the outside but that was not my concern-----the inside was what I wanted smooth.

When dry (overnight), I cut the shell off lenghwise. Examining the inside, it was rougher that I wanted but I think it will work. I think the next time I will put the mastic on the inside also to have a liquid "coat" of the paper duct. I think I will try to tear the paper in strips to encourage the individual strips to feather against each other too.


Title: Re: F-86D Sabre
Post by: tom arnold on May 15, 2014, 08:22:40 PM
The next step was to re-glue the shells together with an attached lip, which worked well. Then to imprision it forever in the fuselage.

The fan is attached to the back face of a former by trapping the lip at the front in a balsa-ply sandwich. It was just easy to do in this case. Now for planking the belly and nose with dead soft 1/8th sheet that is let stand a bit proud for sanding. 1/16th sheet is just too thin to accommodate the fuselage curvature.


Title: Re: F-86D Sabre
Post by: Copbait73 on May 15, 2014, 09:31:37 PM
Looks great, like the engineering.


Title: Re: F-86D Sabre
Post by: tom arnold on May 23, 2014, 06:29:23 PM
Here's some update photos. The fuselage is planked with soft balsa and stringered. The wing is being joined by thin bamboo skewers (found in the grocery store) and glued with Duco (in case I screw up and have to separate them and redo). The bamboo spars are joined to small sub spars in the first bay. There will be a sheet balsa floor between the wings to hold the electronics.


Title: Re: F-86D Sabre
Post by: Sky9pilot on May 23, 2014, 09:40:01 PM
Looks really good.  Thanks for sharing.

Tom


Title: Re: F-86D Sabre
Post by: tom arnold on May 28, 2014, 09:22:48 PM
A little progress update here. At this point the model is held above the head and you run through the house making airplane noises. The gray smears on the balsa fill around the nose is auto primer sanded down to find the low spots. There seems to be no substitute for sanding sealer and careful elbow grease.

The wing is removable and all the electronic guts are stacked on it and are conveniently located on the CG. Not a lot of room in there, I found, and I had the same challenge with the Cougar. The charging jack is on the bottom of the wing mounted on a hollow balsa shell. The wing is aligned in place by a short carbon fiber rod that sticks into a hole in the fuselage former and the rear is held in place by a couple of orthodontic bands linked up with a small hook and a dowel protruding from the fuselage. Sort of like the old classic competition models. The arrangement is not designed to pop off on a wing-low landing, however.

The last shot is looking into the fuselage after the wing is removed. The nose inlet is on the left and the exhaust is on the right. The exhaust duct is a rolled piece of tracing paper spot-glued at strategic spots.





Title: Re: F-86D Sabre
Post by: Sky9pilot on May 28, 2014, 11:58:12 PM
Looks great Tom...well done!
Tom
Sky9pilot


Title: Re: F-86D Sabre
Post by: PaulM on May 29, 2014, 03:12:54 AM
Excellent!!! its really nice to see a different slant  :)


Title: Re: F-86D Sabre
Post by: Copbait73 on May 29, 2014, 08:42:49 AM
Tom-
Looks great, I'm sure you have a winner with this one.


Title: Re: F-86D Sabre
Post by: tom arnold on May 29, 2014, 11:10:39 PM
Here's my paint scheme although I have been told by a couple of good authorities that it now becomes a F-86K. The "K" consisted of parts manufactured by North American and assembled by Fiat in Italy for the Germans. WWII had ended only 10 short years before!


Title: Re: F-86D Sabre
Post by: Copbait73 on May 30, 2014, 12:10:53 AM
Hey, that's the same camo as my F-84 Thunderstreak.
Any Soviet Bloc MiGs out here?


Title: Re: F-86D Sabre
Post by: PaulM on May 30, 2014, 02:22:29 PM
Should be 2 Mig 17s ..one of them in Cuban colors :)


Title: Re: F-86D Sabre
Post by: Copbait73 on May 30, 2014, 02:24:45 PM
Now we have some combat!


Title: Re: F-86D Sabre
Post by: PaulM on May 30, 2014, 06:42:40 PM
As it should be :)


Title: Re: F-86D Sabre
Post by: tom arnold on May 30, 2014, 08:14:36 PM
I have a small problem here and I am hoping for a real forehead slapper solution. The horizontal stabs are raised a bit such that a carbon fiber rod of 1/16th diameter can serve as a pivot axis. The rod is very (very) carefully threaded into each sheet balsa stab and a shot of thin CA has welded one in place forever. The other at this point can be slid on and off so I can play with it. Right now the whole affair is very "tight" and holds angular settings nicely but not nicely enough to fly. My challenge is to find a way to hold whatever setting I twist it to as I trim-flight this charming pig. The carbon fiber rod twists so it is not really a solution----it more or less holds the individual sides level.


Title: Re: F-86D Sabre
Post by: Copbait73 on May 31, 2014, 12:40:45 AM
You could bond some very fine wire to inner leading edge. Bend it forward to match the fus. profile. Now you can make and hold your adjustments with Testors or tape. Just like I do on my thrust diverter tabs. When you get your setting secure the stab and remove the hardware or leave it for ongoing adjustment.
Stab adjustment is a touchy thing because of our wingloading and speeds.


Title: Re: F-86D Sabre
Post by: Sky9pilot on May 31, 2014, 01:33:31 AM
sounds like a great solution that I can use on my Fury...thanks a bunch!


Title: Re: F-86D Sabre
Post by: tom arnold on June 01, 2014, 02:44:27 PM
That is a great idea and that is what I will do, too.

Here is my attempt to replicate the rather exotic shapes of the tail of the F-86D which is unique, to say the least. I added some small sub formers to help hold the shape of the fillets and sanded them to blend in with the general contours of the tail. Then using bond paper I cut patterns to create the fillets between these sub formers and when happy with my cut-and-try templates transferred these to tracing paper. I like tracing paper as it is sort of water resistant (or at least more so than bond paper) and you can see through it for trimming up. Using a glue I found at Walmart called "Scotch Quick Dry Adhesive", the fillet pieces were attached to the frame. The glue is very handy as it is a PVA like Elmer's but a lot of the water is drawn out---much more so than Elmer's. As a result it doesn't soak into paper and gets sticky really fast. It is perfect for thin layers attaching the tracing paper to balsa. I use it often. The fillet pieces were laid on beginning from the back such that the edges will face towards the rear like shingles and will be trimmed against the stringers with a really sharp razor blade. (The tracing paper is the same weight as 5# 1/32nd balsa sheet for general info.)



Title: Re: F-86D Sabre
Post by: tom arnold on June 06, 2014, 02:46:12 PM
Well, the Dog is ready for test flights. I am still learning how to set the speed-time-decay potentiometers at the bench but the grass is high and I am anxious to see this thing in the air. You can see the little wire tangs at the leading edge of the stabilizers that was suggested by Marty as a trimming device. Those will be taped to the sheet balsa base at various angles of the stab and then glued in place. I have also got a removable hook on the belly to experiment with a bungee launch or a "sling" launch with a loop of string.

At this stage, weight is 100g, wing area is 113 in-sq, span is 20" and thrust is estimated around 50-60g.


Title: Re: F-86D Sabre
Post by: Copbait73 on June 06, 2014, 08:24:20 PM
Waiting for an update, did she go today?


Title: Re: F-86D Sabre
Post by: tom arnold on June 10, 2014, 09:40:16 PM
Success!! The Dog Sabre actually flies! Just like Marty said----how could I have been such a doubter? The weather gave me a break (finally) and I had a gorgeous day at my favorite knee-high alfalfa field. The plane balanced right on the CG and the little screaming fan pumped air all morning and flew and flew and flew. It flew through irrigation sprinklers, it flew through a barbed wire fence (no hits), it flew and chased some neighboring horses (Oooooo, bad), and it flew almost into a pond for an Air Force ditching. My only mechanical problem was my thrust tabs at the end of the duct needed some firming up with a couple of shots of CA and that was it. My launches were absolutely horrible and I continually would throw it like a wobbly football, yet it would still recover and climb out. I had installed a removable hook near the nose to use as kind of a sling launch with a loop of twine. It popped out on the first attempt so I never found out if that would help or not. The only negative besides my crappy launches was the plane wing-rocked the whole time as it circled around me. I don't know what would cause that unless it was continual tip stalling but it was so regular and smooth. The swept wings have a bit of dihedral but not much. Maybe more dihedral would cure it.....I don't know but it seemed stable enough with the existing amount even in the mild gusts that tumbled through.

My next step is to remake the removable hook and to "up" the speed a bit to get a smidge higher. Actually, if I can just get consistent launches I may be able to keep the speed at 50 percent as once, with a good launch, it climbed smoothly up to about the height of a telephone pole at a good 40 degree angle and motored around. I found that you can fly in a higher wind---in fact, it helps the launches--than a rubber model can take.


Title: Re: F-86D Sabre
Post by: Copbait73 on June 10, 2014, 11:48:19 PM
Great report, congratulations! The wing rocking is typical in less than ideal wind conditions. Much preferred to rolling off and going in at high speed.
 How is the torque turn?  If it is controlled all you need to do is crank in some additional thrust. You have enough on tap to make it a tiny dot overhead, assuming it doesn't torque into the ground at launch. Not unlike a rubber model, just that your jet is doing it quicker.


Title: Re: F-86D Sabre
Post by: tom arnold on June 14, 2014, 01:18:03 PM
Continued testing has revealed more gremlins that are getting shot off one by one. One test session was cut short as the motor would stutter, catch, and then stop. The culprit was a loose connection and once found and resoldered we were back in business. It was a good demonstration of why you should make everything accessible and removable.  Next time out, I was not flying at 50% thrust as I had thought---I was more like at 90% and it was looking really gutless at 100% with only a wide circle with a good launch and a powered glide with a bad one. It was very underpowered which meant that it had to be a lack of air as I knew the motor was putting out fine. The few good flights I had in the past was a combo of a good launch into the wind which gave me a nice climb but they just were not consistent. My launches were horrible as my hand would twist as I followed through like a baseball throw and snap roll the plane right into the alfalfa about 10' in front of me. I finally developed an "overhead" launch, like a soccer throw, that gave me more height and stopped the roll.

Back in the shop, I installed a cheater hole. It consisted of a stiff paper box slipped in a square hole cut underneath the duct and glued to the bottom of the duct. Then I took a very sharp X-acto, reached in and sliced out the duct piece. BIG difference at the field. The next test session was very inconclusive due to a lot of wind and wet grass but a good 20-40% thrust increase was noted even in spite of being thrown around due to the gusts.

The other shot is my approach to trim tabs in the exhaust. They are clear tabs CA'ed to piece of soft wire bent with "U" in the middle and the wires are CA'ed into the outside edges of the exhaust outlet. It is important to glue the the clear tabs to, not only the "U", but also to the "shaft' of the wire. They work pretty good and even using soft florists wire they are pretty stiff.


Title: Re: F-86D Sabre
Post by: tom arnold on June 15, 2014, 11:35:10 PM
An update on the flying: The F-86D flies like a champ! I took it out to the dead calm flying field and had 6-7 perfect flights in a row. I only quit because I was afraid I'd lose it with night coming on---what a blast it was. My launch is an over-head soccer throw and it settles a little about 20' in front of me and then climbs up to about 15-20' and motors around in a big circle. As it flies I can see it pick up speed and a slight climb is detected which is just fine before my timer shuts things off. The flights ended in a straight, fast, and flat glide skimming right over the top of the alfalfa. What an evening.


Title: Re: F-86D Sabre
Post by: Sky9pilot on June 18, 2014, 08:53:52 PM
Congratulations Tom...well done.  Look forward to flying pics.
Tom


Title: Re: F-86D Sabre
Post by: tom arnold on July 08, 2014, 05:38:31 PM
Well, it is done......or maybe I'm done. In time for Geneseo, too. A friend of mine once said that his building skills took a tremendous improvement when he stopped bringing attention to his screwups when people would look at his airplanes. I think that is a great philosophy that I am going to implement immediately as this is the best it will ever look. It is all downhill from here but I expect a lot of flying in the meantime. However, I will say that the insignia and graphics were done by Callie Graphics (you can find her on the internet) in record time. She needs some clear photos, 3 views, that are as 90 degree to the surface as possible, some type of scale basis, and then she uses a graphics program and a library of insignia, fonts, etc. to produce very thin (like Saran wrap almost) vynl stick-ons. They are far better than decals and a lot more rugged to boot. What you see on model cost $21----I can't take my wife out to lunch for that. And in case of a crash or recovering, Callie will have the files to reproduce everything.

Looking forward to seeing the other jet jocks there and the jet mass launch mission!


Title: Re: F-86D Sabre
Post by: gossie on July 08, 2014, 05:57:43 PM
Very very nice.  Well done.


Title: Re: F-86D Sabre
Post by: Copbait73 on July 08, 2014, 07:53:38 PM
Tom, that looks fantastic!
I'm sure there are no imperfections - this is your very first perfect model!



Title: Re: F-86D Sabre
Post by: Sky9pilot on July 08, 2014, 11:58:27 PM
Fabulous F-86K  Tom!  Well Done!

Tom


Title: Re: F-86D Sabre
Post by: PaulM on July 09, 2014, 03:41:47 AM
My word ..what a handsome beast :)


Title: Re: F-86D Sabre
Post by: Pat D on July 09, 2014, 04:07:50 AM
Looks fantastic, congratulations, well done...

Pat


Title: Re: F-86D Sabre
Post by: GeoffinIN on July 09, 2014, 08:56:27 AM
Whatever imperfections there may be are overwhelmed by its impressive gestalt.  Striking!

Geoff


Title: Re: F-86D Sabre
Post by: tom arnold on July 23, 2014, 07:35:13 PM
Geneseo was great with some fabulous aircraft and some matching weather. What little wind we had was to be expected and aircraft were flying everyday-all day. The Sabre Dog performed better than I had hoped for a first DF model. It took 2nd place in Power Scale, beaten only by Don Srull's amazing push-pull flying wing, the Perodactyl. After a short trimming flight ended in the grass due to a tightening turn, I added a clay weight to the wing tip and launched again. There was a slight breeze moving and for some reason it always takes off better under those conditions and climbed out from my overhanded and overhead launch technique. Moving in a wide 100yd circle, it passed over my head with a good head of steam up from its initial mushy launch speed. It was also about 5' above my head and climbed with each subsequent pass until it was WAY too high and gave no indication it was ever coming down. It was also starting to move over the crops at the far end of the field and I took off running as the crops are like a black hole that airplanes never come out of. Just before the Dog became the famous dot in the sky, the motor quit and the glide phase, which is fast and flat, continued to bring it around in large sweeping circles after circle---half out over the crops and half over the field. The motor run was 2 minutes and the glide was another 2 minutes. It finally came streaking over the tops of the beans and promptly disappeared in the vegetation. I had a line on it and Marci Olm (of Gizmo Geezer fame) had another line and we experts were convinced we could get it. The only problem was the greenery was so thick and high that I would find it by stepping on it! While we were carefully examining our area, the 8 year-old son of one of the French-Canadian contingent kept yelling "Its over there, it's over there" and naturally was pointing to someplace else. Finally, disgusted that we were not taking him seriously, he marched through the jungle, picked it up and announced "Here it is". I was so happy that I could have cried and let him carry the plane back to the flightline to cheers and applause. We had a photo op with him (Ben) and Marci and me that I will post when I can get a copy.

Needless to say my 2 subsequent flights were a LOT further upwind. In fact, so much so that the F-86 treated the flightline and all the peanut gallery to regular fly-bys as it did its climbing circles. Now I was worried that a car was going to get hit but both flights moved away from the tents and the glide and landings were right in front of the stands. Both times the final high height was a little unnerving. I could not have asked for better flights. I noticed that the jet had a very, very slight wing rock and I attributed that to the fact I had it trimmed for a flat circle which would cause the "outside" swept wing to rise a bit until a coordinated turn was established for an instant and then it would start a slide down and the low swept wing would then pick it up and the process would start all over. It was very subtle but if you looked for it, you could see it. I had the turn initiated by a bit of right rudder and I am glad I did as that kept the circle going from that high, high glide. I was unwilling to turn the speed down to keep the altitude lower as I needed every bit of oomph possible during that crucial launch.

Later that afternoon we had a jet mass launch in which we had a time target to hit. It went off pretty cool as Marty Ritchie called out "Start your engines", we all switched on our motors, all waited for the 10 seconds for the motors to light off and as they did gave Marty a thumbs up and when he saw all thumbs up, it was 3-2-1 Launch! I had dialed in what I thought was 30 seconds but I forgot about the climb and long glide but even so, the Sabre Dog got the closest time so I guess it turned out well. 

Because I was flying, I have got no photos or videos to post of the flights and I am hoping some kind soul will do that because it really did look cool zorching up and down the field. Driving home to Wyoming from New York I kept building all sorts of jets in my head as I played truck-tag on the freeway. I am hooked!


Title: Re: F-86D Sabre
Post by: Sky9pilot on July 23, 2014, 10:31:34 PM
Tom...outstand account of the activities.  Thanks a bunch for sharing this with us!  I hope someone got some pics and video so we can see them as well.  Once again WELL DONE!!!! Wish I'd been there!
Tom
Sky9pilot


Title: Re: F-86D Sabre
Post by: PaulM on July 24, 2014, 03:30:46 AM
The mass launch was a hoot :) and it was also deafening, well done on the win Tom .if I hadn't lost my Mig17 in the corn during the week im sure id have given you a run for your money .Cant wait to do it again
  All the Best   Paul


Title: Re: F-86D Sabre
Post by: GeoffinIN on July 24, 2014, 07:13:13 AM
Good going!  And three cheers for that eagle-eyed kid!

Geoff


Title: Re: F-86D Sabre
Post by: tom arnold on August 06, 2014, 10:52:24 PM
And here is my retrieval team: Marci Olm and young, eagle-eyed Benedict Dion from Montreal. He carried my plane back for this photo-op and after this, everytime he would pass my tent I would yell "There goes my hero!".  He would grin and swagger on.


Title: Re: F-86D Sabre
Post by: Bredehoft on August 07, 2014, 07:54:40 PM
Well, Tom, I thought I had yours in flight - but - I guess not.  Maybe this is Marty's?

--george

(http://www.volareproducts.com/wp-content/gallery/2014-07-geneseo-ny-fac-nats/2014Nats030.jpg)


Title: Re: F-86D Sabre
Post by: Bredehoft on August 07, 2014, 08:02:12 PM
Well, Tom, I thought I had yours in flight - but - I guess not.  

oops - surprise!  This was during the mass launch.


(http://www.volareproducts.com/wp-content/gallery/2014-07-geneseo-ny-fac-nats/2014Nats032.jpg)

--george


Title: Re: F-86D Sabre
Post by: Copbait73 on August 07, 2014, 10:00:03 PM
Nice shots George, the top is my F-84F Thunderstreak and the bottom Tom's fine F-86 Sabre.  Both in German camo.


Title: Re: F-86D Sabre
Post by: Sky9pilot on August 07, 2014, 10:31:50 PM
Great pictures George...thanks for sharing them.  Thanks guys for putting such treasures into the air!!!
Tom


Title: Re: F-86D Sabre
Post by: sparkle on August 08, 2014, 06:05:56 PM
 ;D  I can't believe i've only just found this thread! Well done Tom, thinking outside the square should always be rewarded handsomely! Makes me tempted to look at the whole Jet thing. Thanks!  8) 8) 8)


Title: Re: F-86D Sabre
Post by: tom arnold on August 08, 2014, 08:18:25 PM
Thanks to Mike Stuart, our UK stalwart, here is a video of the Jet Mass Launch. Thanks, Mike. Note: this is graphic and not for young eyes what with the explosions, crashes, and midairs at launch.

https://www.youtube.com/watch?v=WeNGGU7kIkA


Title: Re: F-86D Sabre
Post by: Sky9pilot on August 09, 2014, 12:14:01 AM
Outstanding flight Tom...looks as if some of the others had some struggles with launch.  Congratulations again!
Tom


Title: Re: F-86D Sabre
Post by: tom arnold on August 08, 2018, 03:43:00 PM
As a very late addition to this thread, here is a video of the Geneseo flight:   https://www.youtube.com/watch?v=WeNGGU7kIkA


Title: Re: F-86D Sabre
Post by: fred on August 08, 2018, 10:35:22 PM
Very nicely done. In truth though It did look more like a demolition derby with all the rest of the entrants ;D


Title: Re: F-86D Sabre
Post by: playtime222 on September 07, 2018, 12:42:41 PM
Love the intake duct!