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5 Answers

What does the “P” stand for in P-Factor?

Asked by: 10840 views Aerodynamics, General Aviation, Student Pilot

I know what P-Factor IS...but what does the "P" stand for?  Anyone know?  Perhaps for "propellor?"  Just curious...

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5 Answers



  1. Wesley Beard on Nov 20, 2010

    Bill Kershner defines P-Factor as “propeller disc asymmetric loading” in his book The Advanced Pilot’s Flight Manual 6th edition.  So I am fairly certain that P stands for propeller as P-factor cannot exist without a rotating disc of some kind.
     
    Perhaps helicopter pilots call it R-Factor for the rotor. 🙂

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  2. Pilot143 on Nov 21, 2010

    R-Factor…good one! I wonder if it’s true… 😉

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  3. Kent Shook on Nov 21, 2010

    Well, I don’t think they call it R-factor, but there are definitely some major gyroscopic forces at work in a helicopter! Their “propeller” is MUCH larger and heavier than ours. The physics behind helicopters are fascinating and occasionally mind-boggling! 😉

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  4. Skipp on Mar 11, 2011

    It is for plane (not the aircraft, rather in the geometric sense)

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  5. FlyinBrian on May 15, 2023

    It would seem the FAA, as of 2016, has decided the “P” stands for “Power”. See Advisory Circular 61-67C:

    “Insufficient or excessive control inputs to correct for Power Factor (PF), or asymmetric propeller loading, could aggravate the precipitation of a spin. At a high AOA the downward moving blade, which is normally on the right side of the propeller arc, has a higher AOA and therefore higher thrust than the upward moving blade on the left. This results in a tendency for the airplane to yaw around the vertical axis to the left.”

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