Hopefully these photos will show how my retracts work. I epoxied a 2.5mm thick layer of hardwood on the two exposed sides of each mounting rail. The retract mechanism is narrower than the distance between the rails, so there is enough room for this. At the outer end of each rail I epoxied a patch of ply to cover the area around the end, hopefully to reduce the possibility for the ply wing rib to split under load.

At the bottom (that is the top of the wing) I have epoxied in a large piece of 1.5mm ply, all the way between two ribs. To support the servos I glued in two long 8mm x 16mm pieces of birch to the ply plate.

The opening in the wheel well had to be extended a little to get the servos into place.

Helge.