Water Resistant Foam Board Speed Build kit or regular???

[jack10525]

I've only bought I think 5-6 speed build kits but have built at least 10 planes from scratch using the free build plans. I have to admit the speed build kits are great. They give you all the little things you need along with perfectly cut foam pieces. Printing, cutting, taping plans over foam board is very time consuming. I am looking at buying the simple storch speed build. I'm just wondering if I need water resistant foam board or if I should just get the plain white. I do live in a moist environment (South FLA) and have had adams foam board warp slightly after a water landing. :black_eyed: I also think some of the speed build kits can be rather pricey. That is why I built so many from scratch. What are you opinions on water resistant foam board?

 

[Hai-Lee]

If you have waterproof FB then use it, I personally use a heavier paper covered FB which is not waterproof at all, (located in Australia).

To waterproof the paper FB I use a few methods. Simplest is to paint the FB, (Water based paint), second option and my preferred option is to wrap the FB outer surface in Packing Tape. Finally I use glue to coat all exposed surfaces, (White glue does well but only the thinnest of coats). In order to seal FB wings against water ingress I have but only rarely used an expansion foam but again do so frugally.

After the white glue dries I then use a solvent based paint for that special finish. Be frugal with the glue because of adding weight as well as making the paper very strong but rigid. Additionally too much glue can cause the paper to shrink in a similar manner to the use of Dope on Tissue paper in the old days. Mind you the practiced use of this property can remove warps from sheet FB or FB pieces which curl after being cut out. The FB can become so rigid that spars can be dispensed with on sheet FB wings.

If your FB de-laminates try using a very warm iron to re-activate the bond between the paper and the foam. Practice on a few scraps first because too much heat can be destructive to the foam. The ironing will work over paint and the tape if you use a layer of baking paper between the iron and the surface being re-laminated.