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Aug 08, 2020, 11:33 AM
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tspeer's Avatar
I just took a quick look at the Nestofdragons wing design tool, and it looks to me like it uses strip theory without taking into account the mutual interaction of the sections. I suppose it would be a starting point and a good way to do the interpolation of section shape and twist along the span. But I think you'd need a genuine aerodynamic calculation of the lift distribution.
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Aug 08, 2020, 01:36 PM
Inspired by the wings of an An
Andycap's Avatar


Hi Guys.

Its my video of the FVT3 Wing.
Let me first be honest with you all and admit the aerodynamic theory and maths involved is not my strong point, in fact far from it.

Im a life long modeller who knows how to design an airframe and make it fly...

I have worked with Marko Stamenovic on this project since May 2019, and have built 2 versions of the wing. The original really suffered with dutch roll, this was in part the design having excess Dihederal and also the fact it had a too far rearward CG and. So in good coastal lift it keep going up! Even with full down eleavtor, which reduced the twist, reduced the stability and met its maker on the first flight. I have video somewhere.

So after a break from the design, which both Marko and myself knew had potential Marko modified the design and reduced the dihederal. I redesigned the structure form a solid 3d cad model and built the new version.

The first test flight was very encouraging, although mild Dutch roll was still evident.
Cutting the flight short and capturing the video for Marko to look at.

It was then Idiscussed the idea of adding a Flight controller which whilst I know isnt the solution, ws really to see what would happen, and I had one.

So CG moved forwards but 2mm and the flight controller installed I tried again.

Launched with flight controller off, as I had no idea on gains the wing flew away beautifully with no trim and the elevons now in the neutral rather than 2mm down position.

What a transformation, we now had a model flying with almost no dutch roll at all except almost negligible in turbulence. So after five minutes of trying to upset the model it was time to try the flight controller, an Auro8

Switching to low gains the model just locked in beautifully, Whilst it didn't need the flight controller, it now fealt "Bigger", sme for the higher rate gains I had available too.

So still have limited stick time on the model but it really does fly nice, very easy to fly and Ive yet to upset it enough for it to get angry with me!

We feel we could move the CG further forwards still which is something I plan to try next time out.

The plan is to manufacture the model as a kit with a release date sometime towards the end of October if all goes to plan.

I will try to add details to my Build logs on the website when i get chance, and also hope to do a youtube video of the early attempts and basic details of the construction.

Im not technical with the aero work so cant really answer any questions there

The design is approx 1.15m span and weigh in at 330g, almost 1/3rd of the models flying weight is lead. For slope flying I don't think i would want it any lighter though.

As its elevons only the biggest issue is getting it down without building up loads of speed, Ive found that just maintaining a reasonably tight turn away from the main compression zone that it descends nicely and predictably. The landing on the video is not pretty but it caught the edge of a WWII bomb crater.

I cant add the links to the build pics as fbook seems to be banned.
Anyone who wants links can email me @ [email protected]
Aug 08, 2020, 01:53 PM
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landru's Avatar
Very cool, Andy.

I've made a note in my calendar to check your Website in October.

As we saw earlier in this thread, RCG has some shall we say, interesting, policies. Not allowing links to F a c e b o o k is another. I'm no fan of the F site but this is childishness.

If you replace 'koobecaf' in the following URL, you should see the build pics referred to above:

Oct 25, 2020, 05:25 AM
Registered User
Hello all its been ages since I've been on RCGroups!
I'm fascinated with the Prandtl D phenomenon!
I'm wondering how effective it'll be for low aspect ratio swept(55+degree) arrow deltas that I want to use for a WIG design.
The Mars project flying wing seemed to have a lower aspect ratio, about what was the LE sweep?
Oct 31, 2020, 04:49 PM
Inspired by the wings of an An
Andycap's Avatar

Kit Built

My FVT3 built from the first batch of kits that have been sent out
Oct 31, 2020, 05:43 PM
Alien_Tech's Avatar
Thread OP
Originally Posted by Andycap
My FVT3 built from the first batch of kits that have been sent out
Love it!!

Nov 14, 2020, 02:24 PM
Hals und Beinbruch !!!!
lw_hughes's Avatar
Just got a copy of “Ho229 spirit of Thuringia” excellent reading thus far. Some prandtl information.
Dec 31, 2020, 08:09 AM
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jaen's Avatar
It's for hanging on the wall and not for flying,
no just kidding great looking wing
Originally Posted by Andycap
My FVT3 built from the first batch of kits that have been sent out
Last edited by jaen; Dec 31, 2020 at 08:20 AM.
Jan 04, 2021, 01:55 PM
Hals und Beinbruch !!!!
lw_hughes's Avatar

plans and rib sections

Here is something that may help those wanting to make a conventional built up model. One could print off and trace out the ribs. They are oriented to each other as per the twist. Might have to draw a ref line before cutting them out. Thanks to Marko Stamenovic for providing this. Lw
Apr 17, 2021, 06:54 PM
Registered User
Hi guys, I have a gap in my knowledge of wing twist and I’m wondering if someone could help ...

I’ve been looking at building the NASA Prandtl design and read through the Al Bowers et al paper. I managed to find a set of interpolated airfoils from a cad program that someone exported as .dat files.

I’ve plotted the dat files out, with each airfoil scaled linearly from root to tip, and each airfoil has the correct twist angle as per the NASA paper.

When I go to set all of these airfoils in their proper location to create the loft for the wing (as in the image above), I realize that I don’t know where on the chord line I’m supposed to use as a rotation point!

If I use the leading edge as the chord rotation location for wing twist, then I have a straight leading edge and curved trailing edge. If I use the trailing edge then it’s a curved leading edge, or using the 1/4 chord I’d get curved leading and trailing edges.

Is there a ‘correct’ location on the chord and I’m such a newbie that everyone knows this and doesn’t mention it (I’ve looked far and wide), or is this just aesthetics ?

Thanks for your help and looking forward to making progress with this wing!
- Joe
Apr 17, 2021, 07:17 PM
internet gadfly
nmasters's Avatar
There's no aerodynamic reason to pick that axis. Use the hinge line for the axis of rotation so the elevons don't bind.
May 13, 2021, 07:15 AM
Registered User
Hello Red,

Any updates regarding the release of the 32" and 13" Prandl-M OML CAD ?

Thanks in advance for your response.
May 13, 2021, 08:45 AM
Alien_Tech's Avatar
Thread OP
Originally Posted by aerialthings
Hello Red,

Any updates regarding the release of the 32" and 13" Prandl-M OML CAD ?

Thanks in advance for your response.
Yes! I have the Ver 5.2 32" OML dubbed the Fat Falcon I can send you, it flies really well. The 13" one doesn't fly well enough to be released. Shoot me a PM with your email.

May 13, 2021, 09:44 AM
Registered User
Great! You should have a message with my email address. Thanks again.
May 27, 2021, 05:57 AM
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sp250's Avatar
Well that thread was one of the most interesting I have read in the last couple of years.
If I wanted to build a wing to compete in Light class of GPS triangle racing - and I do, would I stick with all of the above but a 4m span model?
Is the wing section best at slow thermal hunting, distance covering at best L/D or speed to get round the triangle?
All of which are needed to compete in GPS.

Or would I be better building my 4m competition wing based upon HJ Unverferth's philosophies over on Zanonia flyers?
Parallel chord, DSA tube tips and winglets from 50% chord to the rear of the wing, 30* sweep, a de-swept spar and constant chord trailing edge control surfaces, 2 or 3 per side and no rudders? Also has varying twist over the semi span.

Any help and guidance much appreciated. I also may put in a 3 axis gyro so I could run a rearward CG and then over control and instability would not be a problem (after trimming out and moving the CG back in increments). Gyro would have to be out for competition though. Maybe a movable CG - forward for speed and rearward for thermal.

I really think that a competitive model could be made as there is no landing task/spot and gentle electic power to launch means no winch stability or height deficit on launching and lighter construction.
What do the "interested in wings" and knowledgeable brains trust think?
TIA John M

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