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 on: Today at 03:42:06 AM 
Started by ksn3n3 - Last post by Jack Plane
I agree very largely with F4FGuy.

I have only dim memories of flying CL Stunt, but its certainly all to do with wing-loading - and IMO a reasonably convincing 'scale speed'.

An example from RC of choosing suitable motor sizes:  For aerobatics I usually fly a 59" span low-winger weighing 6lbs with a 70 four-stroke giving a rated max thrust of 800 watts - which equates to 133 W/lb.  I'm now building a slightly larger 63" but much lighter 4lb low-winger also for sports aerobatics, and am fitting a 35 two-stroke with a thrust of 660 watts - equating to 165 W/lb.  Clearly the larger, lighter model will suffer more from drag, but the higher thrust/weight ratio should overcome this.  For scale, a weedy 30 four-stroke is all that's needed for a 40" 1930s biplane (albeit with a wing area greater than the two aerobatic types above) in order to achieve realistic flying speeds.

In FF rubber scale, overall size, configuration and environment are also factors.  For example a sleek, small (20") low-wing monoplane outdoors penetrates nicely with a wing-loading of 0.7g/sq in, whereas a larger (30") biplane in the same environment can get away with a heavier loading of 1g/sq in.

Indoors however, I'll be aiming for about 0.4g/sq in for a 20" high-wing cabin model (with less power needed and therefore a weaker, lighter rubber motor), maybe up to 0.5g/sq in for a 16" draggy biplane (with a bit more grunt from a thicker motor).

For indoor Peanut scale (13" span) rubber (where duration wins points, unlike the larger scale classes where flight realism is the key), the wing-loading to aim for would be about 0.25-0.3g/sq in!

This should all translate into CL with its not dissimilar variables.

 on: Today at 03:34:55 AM 
Started by Jack Plane - Last post by abl
I thought the glide without the extra noseweight was pretty good, actually. And I think you might be right about the slightly thicker rubber.

Looks very stable; looking forward to seeing it at Newbury.


 on: Today at 03:29:28 AM 
Started by Pete Fardell - Last post by Mefot
I think skyblue was quite widely used back in the day. I have come across references of it being used on Farman aircraft and I seem to remember reading it being used on Morane Saulnier aircraft too.
This reference is more use to me than Peter as it refers to the exact aircraft I am interested in. From a supplement of the Poverty Bay Herald which we all know is from New Zealand !!!
Meanwhile the search goes on for decent photographs !!!  Grin

 on: Today at 02:44:11 AM 
Started by Jack Plane - Last post by Jack Plane

That's looking promising indeed!!


The key change was to remove the excess right-thrust, everything else then followed.

 on: Today at 12:48:10 AM 
Started by dslusarc - Last post by Tapio Linkosalo
Hope this explains better how this specific meter is set up.

Thanks! Yeah, a picture is worth of a thousand words, indeed. I was thinking about the math in the way to wrote it down, but did not have the time to do it yet. Now I do not need to.

Yes, I stand corrected, I think your math is correct. And luckily this also explains why my meter readings are so low, I have always wondered how people han wind their motors to such huge torque readings, while my motors always break at much lower TQ. My meter is adjusted the wrong way, and as I am using gram*centimeter, my arm is much shorter, and hence the ratio L2/L1 is much larger, giving a considerably higher error.

 on: September 19, 2017, 11:38:17 PM 
Started by Aero58 - Last post by F4FGuy
Aero 58,
I know little about the Kit you reference but, I've known Eric Rule for about 20 yrs.  He's produced kits for our club's kids program many times and I've never had a quality problem with any of his products. Wood has always been right for the application, and cutting has been to the  highest standard.
If there is a problem, a simple phone will correct it. My profile .15 size Mustang, now part of Eric's line, has taught over 100 12 -14 yr old kids to build and fly UC. His kits, at least in my experience, are easy, i.e. everything fits, holes and slots end up where they should be, and wood selection is superb.

Ron Burn  (F4FGuy)

 on: September 19, 2017, 10:55:57 PM 
Started by Pete Fardell - Last post by ZK-AUD
Amazing colour reference.  I struggled to to get any kind of confirmation of the assertion that the Borel Hydravion was blue and if so what blue.  In the end I went with the slightly controversial sky blue colour because it was known that the French military blue was standarised around that time and because the contemporary photos don't look like a dark colour.  Now here is another French aircraft of the exact same vintage and with a contemporary reference to a sky blue.  

I'll hang my hat on that thank you very much indeed!

 on: September 19, 2017, 10:22:32 PM 
Started by Skymon - Last post by dslusarc
One thing I did to help with tip whippiness was to buy a pole a little longer,  then take out the tip section. I have a 13m pole I bought from Aliexpress a few years back for about $100 USD shipped and it is nice but I don't use the last section. When looking look at the pole specs look at the base diameter and tip diameter. The 13m I have is around 44mm at the base and original tip I do not recall but wiht that tip section taken out it close to 4mm. This pole is about 1 m long collapsed so the 13m is really around 12m with the tip section removed. So basically buy 1m longer than you need. I recently just bought this 16m pole for use at Rantoul which is just a little higher than I can comfortable reach with my current pole.


It has a 44mm base and the tip is 1mm but I removed that section so the tip is now around 4mm so now it is around 15m long. This pole was pricier, about $170 USD and have not tried it yet with a model, but will try in a few weeks when I go to Rantoul.


 on: September 19, 2017, 10:03:30 PM 
Started by dslusarc - Last post by dslusarc

Hopefully this thread will help people out. I am glad you did the 3D stuff. I am not strong in 3D CAD as we design in 2D 99.9% of the time due to the nature of what we make. I have no issue visualizing, its knowing the ACAD command to do it :-)

I like the sliding top cover idea. I think the only thing I would want different based on my build would be for the c-bore that the forward sleeve bearing goes into to be about 1mm shallower so I would not have needed to add that additional spacer between the stop collar and the Rulon J sleeve to make sure the washer cleared the front of the case. 


 on: September 19, 2017, 09:56:02 PM 
Started by FLYACE1946 - Last post by RandyW
According to my Complete Model Aircraft Manual Revised edition 1938, a twin pushers left prop should rotate counter clockwise and the right prop should rotate clockwise when viewed from the rear. I built the Mile a Minute twin pusher and discovered I had the props rotating the wrong direction.  Turned the a-frame upside down and solved the problem! Truth be told I don't have a clue why rotation would be an issue as long as the props counter rotated.

 on: September 19, 2017, 08:37:25 PM 
Started by C VEICH - Last post by Hepcat
An addendum to #21.

In #19 Yak mentioned 1that the pitching moment of a cambered wing section had an effect on the balance of forces about the cg. and you may not always have the pitching moment coefficients at your finger tips. I have just remembered that the spreadsheet I offered in #21also calculates a figure for Cm.  You will see this as the last item in the left hand column of the screen shot.

 on: September 19, 2017, 08:35:16 PM 
Started by Glenn (gravitywell) Reach - Last post by Glenn (gravitywell) Reach
Hi Don.  Thanks again for posting those pics.  I am going to post build photos, but please, snicker at my work in private only! LOL

Crabby.  I can't thank you enough for posting all your builds thru the years.  They have always inspired thru achievement, inovation and humour.

 on: September 19, 2017, 07:08:08 PM 
Started by Glenn (gravitywell) Reach - Last post by Crabby
Glenn you will notice Don's fair maiden as opposed to my Battle Axe! Maybe mine was overfed and pampered. Don is more elegant.

 on: September 19, 2017, 07:02:17 PM 
Started by Glenn (gravitywell) Reach - Last post by Don McLellan
Hi Glenn,

Glad the pic worked for you.  Post some pics of your progress.


 on: September 19, 2017, 06:53:00 PM 
Started by Jack Plane - Last post by danmellor
That's looking promising indeed!!



 on: September 19, 2017, 06:37:33 PM 
Started by p40qmilj - Last post by p40qmilj
 Grin  www.theloop.ca
jim Grin

 on: September 19, 2017, 06:30:05 PM 
Started by logair358430 - Last post by logair358430
cast off vortex, Thanks for the tip on the tip. Richard

 on: September 19, 2017, 06:28:01 PM 
Started by logair358430 - Last post by logair358430
scigs30, Nice airplane!! I will check out your build thread. Thanks Richard

 on: September 19, 2017, 06:15:36 PM 
Started by C VEICH - Last post by Hepcat
I am not wanting to argue with any of the other recent excellent contributions, just tidying up a bit on zero lift angle.
I hope I have my brain box connected a bit better today. Yesterday I blathered on about the importance of the zero lift line and never thought to mention how to draw it. In 1941 I bought a book: ‘Simple Aerodynamics for Aeromodellers’ by A.H. Smith for the amazing cost of three shillings (that is £0.15). Albert Smith was the ‘Aeromodeller’ draughtsman at the time and I am not sure anyone has written anything much better since.  He was the one who told me to draw the zero lift line from the trailing edge through a point on the camber line 40% back on the chord.  I have seen this recommended in much more impressive tomes since then.
I almost always use this simple method.  If you want to go further then Abbott & von Doenhoff’s ‘Theory of Wing Sections’ will keep you entertained. As well as explaining the ins and outs of a meg’s behind they also give two ‘simple’ approximations originated by Munk and  Pankhurst.  If you are interested I have a spreadsheet which takes a parabolic camber line with height and position of the maximum camber and calculates the zero lift angle ‘My’ way and by the Munk and Pankhurst methods so the three can be compared.  There is usually very little difference.  A screen shot of that part of the spreadsheet is attached.  If anyone wants a working copy just send me an email address.

 on: September 19, 2017, 05:24:08 PM 
Started by p40qmilj - Last post by Glenn (gravitywell) Reach
Buggers stole that too!

 on: September 19, 2017, 05:23:18 PM 
Started by Glenn (gravitywell) Reach - Last post by Glenn (gravitywell) Reach
Oh my goodness!  There it is....the shot I needed.  Thank you Don!  I needed that shot of the underside of the wing root, it shows exactly what I needed to know.  Thank you so much, now I can repair the idiotic thing I did and move the build along.

Crabby.....I thank you very much for your advice and encouragement.  Both are appreciated and needed.

 on: September 19, 2017, 05:11:41 PM 
Started by bgrove - Last post by bgrove
I found some great old photos last night of me with some U-Control planes back in the early 1970's.  I love the shot of my Nobler after I put it straight into the ground !!!

 on: September 19, 2017, 05:09:54 PM 
Started by scigs30 - Last post by scigs30
I have an old Scientific Super Flyers P-40 rubber powered kit that is missing the plans.  Any help would be appreciated. Thank you.

 on: September 19, 2017, 05:08:32 PM 
Started by bgrove - Last post by bgrove
I came across some old photos from the early 1970's and had to share them.

Here I am with a Sinbad at my workbench.  And a shot of my Dad and I flying the Sinbad in the California Bay Area foothills in back of the HP Labs (Palo Alto).  Great memories!!

 on: September 19, 2017, 04:46:35 PM 
Started by gossie - Last post by isismk2
These lightweight are addictive!!!!...this year I've been flying :
Elite Skyrocket
...on the board right now is my second Rara Avis IV and it's pretty light...I just finished the prop and am pleased with the effort so far and the last thing to build is the wing which I will add a 3/32" square spar on the bottom to have something to adhere the tissue to. I lost the Skyrocket just recently and will build another before the King Orange meet and retrofit all my models with a tracker because I'm finally getting good enough. Building is no problem for me as I love it but losing models that you can take out of the box and throw it knowing it will put in good times is frustrating...will look at the Thermal bug soon...

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