Foam Wing Joining

Guys,

I'm looking for a consensus regarding wheather or not it would be feasible to join Foam Wings together before sheeting the center section and then sheeting the center section with continuous sheeting. Doing this would eliminate the seam in the middle and possibly help strengthen the joint, but I think that some fiberglassing of the center should still be done. How about it, what do y'all think on the subject?

This is for wings done in the Time Machine fashion!

Unless you can find 60+ inch wood you will need a joint someplace. I would think it would be best in the center where you can hide the reinforcement.

My 2 cents worth..

Heres a way to do it.
Take some 1/64th ply, Cut it with jagged edges, like
with pinking shears only larger points. Sand the core
a bit to get the ply flushish with the core. join the cores
using your favorite epoxy. Sheet the cores. The bond line
of the 1/64th to the sheeting elimintes the stress riser
at the wing center. This is a lot of work, but if you just HAVE to do it, it will work fine. It isn't any lighter than an external reinforced joint, but what the heck.......

Personally I'd just bag the wings and use a monolithic layup
using e-glass and carbon. Lighter, stronger and easier to repair later....

Jim,
I don't think you'd want to use a continous piece for center section sheeting. My guess that the root is thicker than the tip. You'll end up having the sheeting making a compound bend over the center seam....doesn't sound like a good thing to do. Think about it, the sheeting will have to curve for the airfoil, then make a bend "down" to follow the thickness taper toward the tip. I believe you're going to sheet the foam wing like it was a built up wing...ala the "quick" build method that Tom had in SN a few issues back..right? I'd sheet each wing individually, (which is easier to do), then join them.

I've done a BUNCH of foam wings... Don't even try to join the halves before sheeting!

Beleive me, by joining the cores first, you'll just give yourself a headache, and compromise your project.

If you follow any of the traditional methods for sheeting and joining the cores you'll do fine.

On the comment of the Dixon method of "saving weight" by sheeting it like a built up wing, if you sheet the entire wing with 1/20 balsa instead of using 1/16 the Dixon way, you will have the same weight and save a lot of work.

Use fiberglass to strengthen the center section. One method that I like is to use one half ounce layer out six to eight inches, a second out four to five, a third out three to four. Round the endges so there are no sharp shear points and make sure all fiberglass is out beyond the fuselage joint. This spreads the load at the center and keeps it from breaking inside the fuselage and taking the fuselage with it.

Leonard Neumann

Thanks all,

I believe the consensus is just do the sheeting with 1/20th and save a couple ounces that way and strengthen the center section with layered fiberglass. Done deal! I will do it that way!