Originally posted by Sport_Pilot
One thing I see people do that is wrong is assume that RPM * pitch = plane speed. That is wrong. For one the prop pitch is not constant, it is the average pitch along the prop. The inside of the prop is at a much higher pitch.
This isn't strictly correct. The ANGLE of the blade relative to the hub axis varies continuously from close to the hub out to the tip but the actual PITCH remains constant. It's a matter of geometry for differing radius.