Originally posted by JetSD
Geist,
I had a feeling that that is how you came up with that number. However, I understand that the pitch spec on a prop is a theroetical number expressing how far forward the prop would move if traveling through a solid. Since air can be compressed, and drag holds us back, the props on our airplanes become less than perfectly efficient. There has to be a correction factor that takes in to account the efficeincy of the prop shape, air pressure, humidity, air temperature, altitude, overall drag of the airplane etc.
Jet
Quite true, you will never 100% efficient and it will get worse as the prop approaches sonic velocity at the tips. Get a radar gun it will be more accurate
