The rear fins don't need bracing....they are solid wood, and fit down deep
into the wing. When they are solidly epoxyed into place they are very strong.
The air-brakes are kinda just for show, I think....and if I used a 90 degree
deflection in the rudder, it left too big of a gap in the hinge line. The rudders
are too small to any serious braking on that big a plane.

Dave.