Its the yellowaircraft edge. I test flew mine today. Flies "biggish". Has the landing characteristics of a trainer. The elev. rates need to be high to do serious 3D. High alpha knife edges are superb. I had my CG set at 4 inches on the root chord and it was flying nose heavy, so it wouldnt do any harriers. besides, elev. deflection was only 20degs or so. Inverted Flat spins were very flat. wouldnt do tumbles due to the CG.