feihu,

I am designing the mech now, which is the problem. You're pic is exactly what I have been struggling with, namely, "How long are arms and 90 deg control horns?" I can handle the math part (AutoCAD 2004 rules!), but I need to know how to apply it for my needs. I figured out a curve that would seem to be correct based on the chord as it would rotate when the flap is extended. Without building a small test setup, I can't tell if it would work. Let's say that I plan on buying some plywood and making some test ribs this weekend...