Volfy makes some very good points. However, while the four-star 60 fuse failures I've seen may have been caused by the lite-ply butt joints failing, the result was the fuse snapping in half right behind the wing trailing-edge former. This seems to be a result of the cut-outs being too large, not leaving enough wood for sufficient strength. That's what led me to just double-up on the narrow strips behind the wing.

But you guys are right. Lite-ply is fairly brittle. I think it's made from poplar in many cases - very brittle wood. I think that tri-stock would have been a better choice.

To those of you who replace the lite-ply pieces with balsa: You have my respect! No way would I have time to do that on a plane such as the four-star 60!