ORIGINAL: 91zulu

How thick are the wings and how big ? Reason I ask is if the wing is about 1 inch or thinner and it would be on a fast plane , it would help to cut in a spar across the center or what we use to do on quickie wings, cut in 1/4 inch dowel channels top and bottom along the high point of the wing each side from tip to tip. Slide in the dowels into the channels then sheet the wing. Epoxy the wings together using 30 min . When dry glue on the fiberglass cloth in the center. We used 6 inch wide because of the high stress.
Note we used regular hard wood dowels my flying buddy and I. Some people used Dave Brown carbon rods instead of dowels or even carbon fiber thread or tape also from Dave brown . The thread was glued onto the foam high point ,top and bottom. Good thing about using the thread you don`t have to make channels in the foam. How its done is you coat the wing with 30 min epoxy if you are experience in doing this method , lay the thread along the high point , brush it down then lay your balsa sheets over it. You do both sides lay the wing back in its cradle and put weights on top . Each wing half is done then glue halves together and glass center . Pros of this method , wing is very strong . Depends how big the wing is determine how wide the carbon thread you use, example our wingspan would be about 52 to 54 inch 9inch cord.and used 1/2 in wide thread or carbon tape. No channel to make. Cons...you use a lot of epoxy.
Yep those were the days nothing but hot Fox , MDS , Thunder Tiger 40s boring holes in the sky.
Note though if for regular sport flying, no need for spars . just sheet wing halves glue together with epoxy and glass the middle. You must glass the middle or it will break in flight. Don`t think it will next time you go driving stick your hand out the window at 50 miles an hour. Feel that pressure on your hand ? That will break the wing.