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Old October 10th 04, 04:41 AM
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On 7-Oct-2004, (PaulH) wrote:

At any altitude that permits you to develop 75% power with your
current prop, a constant speed prop won't gain you an inch unless you
want to fly at a higher power setting.

What the CS prop primarily gives is better climb and increased drag in
descent if you need get down in a hurry.



Because speed sells airplanes, most fixed pitch props are selected for
optimal cruise performance (i.e. "cruise props"). Airplanes equipped with
cruise props suffer in climb because under the load of the climb the engine
cannot generate maximum RPM. Remember, max rated power (for a normally
aspirated engine) will be delivered at full throttle, sea level pressure,
and redline RPM. With a fixed pitch prop in climb, with RPM well below
redline, actual delivered engine power will be below max rated. With a CS
prop at max RPM and full throttle, max power will be available in climb, so
climb performance will be significantly better. In some cases, this allows
CS-equipped airplanes to manage a higher max gross weight.

-Elliott Drucker

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-Elliott Drucker