P-factor
P-factor is an aerodynamic phenomenon experienced by a moving propeller with a high angle of attack that produces an asymmetrical center of thrust[1]
Causes
The p-factor is caused by the difference in angle of attack between the ascending and descending blades of a rotating propeller blade. Specifically, the descending blade has a higher angle of attack, relative to the ascending blade. In accordance with the Bernoulli Principle, the propeller blade with the higher angle of attack will provide more force, in this case, measured as thrust[2]. With the descending blade providing more thrust than the ascending blade, the center of thrust is moved away from the center and out towards a parallel point somewhere along the descending blade.
Effects
The effects of the p-factor, on a single engine right-hand propeller aircraft, are observed through the aircraft tendency to have left yaw. These effects are most noticeable during take off[3] or in flights with high power and high angle of attack[4]. In multi engine propeller-driven aircraft the P-factor is considered for determining the critical engine, unless handed engines are used which is now uncommon.
Sources
- Willits, Pat, ed. (2004). Guided Flight Discovery - Private Pilot. Abbot, Mike Kailey, Liz. Jeppesen Sanderson, Inc. ISBN 0-88487-333-1.
{{cite book}}: Unknown parameter|origdate=ignored (|orig-date=suggested) (help) - Ramskill, Clay. "Prop Effects". Retrieved 2006-12-5.
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