I installed bolt-on connection for my Hobbistar. There is a series of articles on MASportaviator called something like "not your stock Hobbistar" that illustrate the process. It called for adding a balsa doubler to the inner ribs to facilitate the bolt hole. In actuality I don't thinks its absolutely necessary since you sleeve the bolt with graphite arrow shafts (Dave Brown pushrods) and epoxy them in. Once epoxied in you restore the structural integrity.

One bolt in front and two in back. Just install the blocks as illustrated, rubber band your wing on firmly and drill so that you pass thru the center of the block. (you really do need to have a clear image in your mind when you do this since you're drilling blind) When you drill the front hole at just a slight angle so that you stay in wood you're drilling thru the epoxy layer that sandwiches the wings together. The bit will want wander off to the side since the epoxy is so much harder than the surrounding wood. It did on mine a little and seems to have done no harm. (The article shows cutting a path in each panel before epoxying them together but fails to mention the reason. Now you know! )

I used 2 1/2" 1/4 x 20 for the two rear bolts and a 3" in the front. Picked up the nylon hex head bolts at Home Depot and one of the sockets on my Dubro 4-way wrench fits them perfectly so you're not messing around with a slick flathead bolt.

At any rate, it really wasn't hard to do. Once drilled you tap the blocks, run the bolts in and out a few times, and harden the threads with CA.

Works great,

Clay