Dudley,

In my RB I did as Vampire suggested, I bought some hard balsa, 1/2" x 2" x whatever length my local hobby shop had in stock. I measured the distance between the ribs supporting the retract mounts and cut the balsa to fit. I then epoxied the pieces into position. Toward the front of the wing I used a single reinforcement, on the rearward section of the retract mount I installed two of these reinforcements, one after the other, laminating then together with a liberal coating of 30 minute epoxy. Rather than using simple wood screws to hold in the retracts I will install threaded brass inserts with a 6-32 internal thread and then use plastic/nylon screws to hold in the retract. The 6-32 screws are more than strong enough to handle normal takeoffs and landings. In the event you hit hard during a landing the plastic screws will shear off and hopefully prevent the retract mount from ripping out of the wing.

During new build up and when modifying during repairs is when I install flex plates. I've used flex plates designed for various BVM kits and I've also used the various carbon fiber products that BVM sells to fabricate flex plates.

Rich