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2m Foamboard EP Sailplane - Design and Build

Hi everyone,

My name is David Mason. I am an process controls enginner and I live in St. Louis Missouri. I build foam-board airplanes in my basement.
I have built a lot of the Flite Test designs. My latest ones were the Sea Duck and the Edge. I love the Sea Duck and I haven't even had it on water yet.

I have been building FT planes for about 2 and a half years now and I am ready to step into the design world for a new challenge. A few weeks ago I designed and built a twin boom pusher based strongly on Andrew Newton's Depron Spectre. The final product came out relatively nice and after balanced, it flew well and I have taken it out several times. This did nothing but boost my confidence of course. I am now in the process of designing a 2 meter EP Foamboard Sailplane. I have jotted a few ideas down on paper and started testing out some wing ideas.

I will use this thread to document my progress and I welcome all feedback you can provide to me.

Below are the first ideas I wrote down. I knew I wanted it to have a wide wingspan and be made mostly of foam board.
I would like to have the wing be at least two pieces. So I need to find a way to assemble it in the field.
I would like to have a horizontal stabilizer mounted on the top of the vertical.
Im considering adding flaps and spoilers.
My biggest concern at this point is how to reinforce the wings. I have had ideas to use dowels, aluminum, and carbon wing spars but I need to keep the thickness of the wing to a minimum.
The wing chord also needs to be a lot shorter than a standard airplane. So I need to find ways to reduce the chord and thickness while also having a rigid wing that is able to be disassembled.


Biplane Guy
Looks awesome! Love to see gliders built out of FB, we need more of them.

Also, I just can't resist this with your name...



Well-known member
I agree with @AkimboGlueGuns, it looks awesome.

Ed from Experimental Airlines uses a carbon arrow shaft to join his Armin wing. Further out on the wing, I’d use bamboo BQS, the idea is to make an I beam, BQS on top and bottom with foam webbings between. The dihedral is no problem.


Old and Bold RC PILOT
A wing jointing method I have used in the past on my rendition of the retro flying called "Bobbles" was to make a spar box out of FB and slide a CF spar into the support on each wing.

If you have a 5mm gap to play with between top and bottom wing skins you could make up two FB spars about 5mm apart so that when the wing is folded and glued you would have a 5mm square hole/tube/slot between the FB spars.

Measure the distance the CF spar would need to be inserted into the wing when the wings are mated to the fuselage. With this measurement fit an end plug or stopper between the small FB spars to stop the CF spar being inserted too far.

Round of the sharp edges on the CF tube/spar and with a little lube force the CF spar into the wing between the FB spars and the top and bottom wing skins. with a couple of reinforced holes through the fuselage for the CF spar the wings can be fitted. TO assist in wing incidence fixing a couple of BBQ Skewers could be fitted into the wing root so that they key into the fuselage and the wing is ready to go.

See the threads: https://forum.flitetest.com/index.php?threads/my-backpack-wing-v1.37110/
and https://forum.flitetest.com/index.php?threads/removable-cf-spar-wings-simple.37025/

Bubbles is still flying!

Have fun!