Thanks, guys. I was rather imprecise and sloppy in my question. I was not implying the same airframe with three different airfoils, but rather 1) a pattern plane with a symmetrical airfoil, 2) a sport plane with a semi-symmetrical and 3) an aileron trainer with a flat-bottom airfoil. I see that the dive test would work for all to determine the "neutral" CG point but the CG might be moved forward various amounts for stability. Is this correct?