Without starting a dogfight, semi-sym (or sym) airfoils don't penetrate any better than flat bottomed airfoils, nor are they faster. Penetration is a function of drag vs available power. The Avistar is relatively small compared to the majority of 40-size trainers & is also a bit cleaner due to its lower cabin height -- its better penetration stems from that.

I never said the Avistar was faster or penetrated better due to the airfoil alone. I simply stated it is a faster plane.

A flat bottom airfoil balloons more easily. When this happens, the AOA tends to increase, thereby increasing drag, which lessens penetrating ability; as you state.

Also, which wing typically has more drag? Flat bottomed or semi-symmetyrical?

Dr.1