I've used two methods on my pattern planes. One, as above, uses hooks in the root rib that fit into the fuse sides. I use O-rings between the hooks. On the other plane, I screwed 1/4x20 nylon bolts through the root ribs from the inside. The bolts then go through the fuse sides when the wings are mounted. Nylon wing nuts are then put on the bolts from the inside of the fuse. Actually, for insurance, I put regular nylon nuts on first, then wing nuts over those. I like the nut and bolt method better.