Originally Posted by Don Stackhouse
I've experimented with it in some depth on swept wings, which for the most part should also apply to deltas. Tricky. Chord is important. When you droop a leading-edge control surface, you increase the camber of the airfoil, at the same time you reduce its incidence. Depending on the details, chord in particular, the result can go either way as far as whether lift is increased or reduced. Effects on adverse/proverse yaw can also be interesting, and it's very possible to get something that responds in one direction for small deflections, and the other direction for larger deflections.
thanks Don, never did say thanks.
thats interesting that different degree of deflections could cause the opposite reaction!