I've always subscribed to the school of thought that running the lowest pitch and largest diameter prop that your engine can handle is the best for 3D flight. I have a 65" OMP Yak, YS 91AC, and APC 16x4W. Weighs 7lbs. 4oz. dry. I couldn't be happier with the performance. It has unlimited vertical, hovers at less than 1/2 throttle, and has enough thrust to save it from any attitude. However, some of the better 3ders at my field are telling me to try a wood 15x8 for 3d. Their reasoning is that the higher pitch will pull it out of a hover faster, and the spool-up will be quicker, since the prop is half the weight, and smaller in diameter. I used a Zinger 15x8 on the same engine in an Ultra Stick 60, and though the plane was heavier, it also had unlimited vertical. With my current setup, the engine turns at approx. 9000-9100 rpm. With a smaller diameter and steeper pitch, will it present the same load to the engine? Since the YS will turn 16" APC in it's ideal rpm range, should I try a Zinger 16x6? 16x8? I realize that I will have to be more aware of airspeed with a faster prop. By the way, the guys that are telling me this are running gassers on 80" Aeroworks Profiles. Is their theory limited to gassers, and completely false on glow engines? Just want to get a larger sampling of theories. Thanks.