Brian
the greater the distance between the elevators and cg, the less energy it takes to change pitch, advantage empennage. The shorter the distance, the more energy it takes to change pitch. However, with aft cg, it isn't changing altitude (climbing), instead it is loading the airframe, mushing. The difference is in the available "weight" of the a/c closer to the tail, which "aids" the pitch up. Specifically, loading the tail, depriving the a/c of lateral stability. A more correct cg loads the wings. Instead of "trimming the airframe", the tail carries load as the center of lift is moved aft, producing the instability. I'm sticking with that. (As cg inches aft, "balancing" pitch forces is more difficult. The a/c is easy to pitch up, more difficult to lower the nose, etc.) AF
Last edited by airfoilmod; 17th Jan 2009 at 07:28.