Little further - hopefully I'll have the center glassed by tomorrow - that wood putty has to dry over night probably before I can sand it. I used a chunk of the foam that the wings are cut from to make the form where the wing meets the fuse and just covered it lightly with wood putty to fill in the gaps. It isn't a load bearing section so I don't anticipate any need for real strength there. I'll be glassing that center section anyway but it was much easier than cutting a chunk of balsa - I was having trouble finding a scrap the right size and that foam is precut to just the right shape.