the prop is matched to the engine and it's power band not the airframe, the airframe only limits how small of a prop you can us and effectively generate thrust out of it. same engine turning equally loaded props the smaller diameter higher pitched will be faster then the larger less pitched at the same RPM. not only is the pitch of the prop pulling through more air the diameter of the prop is reduced and that reduces prop breaking drag. under propping an engine that is timed and ported for torque to get a much higher RPM is simply going to result in overheating and leaning out so you're dead sticking after a couple min of WOT, it's not all about the most RPM.


kc