Originally Posted by
BASHER
im going a differant route with using expandable foam for the center section....may back the original spar with 4ply birch but i'm thinking consolidate all the air space and voids to act as 1 solid unit! not the entire center section just whats needed,i'll put tubes in for my wiring and block off where i dont want the foam to penetrate then put a few venting holes so excess has somewhere to go rather then blow the skins off the ribs and other structure, they sell high density 2 part foam for use in setting deck posts in the ground.
I did that on my 85” ESM Corsair and it worked great! Still flying today. Heavier yes...but not enough to hurt flight characteristics. I doubt you will notice any difference. Bonds to the frame really well! Go for it!!!