John,

I typically build my 60-64" combat wings from "blue" foam and also run 1/8" FG spars along the length at the high points glued in with PU glue ( Gorilla ). I have found it is not until you apply the Bi-Di FG tape that they really become stiff. The spars by themselves ads some rigidity, but it is the tape that really binds it all together. I also use 3M Super 77 spray glue to lay down my tape with and set it with a low temp covering iron. The resulting wings have always been extremely strong and rigid. Hope that helps.

BNC