Quote:
Originally Posted by fireship4
But as I understand it, a fine pitch causes more drag at high speed than a coarse one, therefore vmax may not be at max rpm?
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Only partially correct, because pitch doesn't equal RPM. The same pitch can give different RPM at different throttle settings and airspeeds.
You can easily test this in the Tiger Moth which has a fixed pitch propeller: if you accelerate or open the throttle the RPM goes up, if you decelerate or close the throttle the RPM goes down and all that happens with the pitch remaining rock steady.
Therefore, Vmax at max allowable manifold pressure and max allowable RPM doesn't mean full fine pitch.
It means the pitch that gives the max allowable RPM at the given airspeed range, which will be sufficiently coarse at that speed.
06-04-2011, 01:14 AM
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