Is P-factor For Real?

Peter Garrison

Saturday, March 01, 2014 at 12:08 AM ET

Verified

Key Takeaways:

The article explores the reasons pilots need right rudder during a climb, attributing it primarily to P-factor, slipstream rotation, and torque, all of which tend to yaw the aircraft to the left.
An "inverted climb test" is introduced as a method to distinguish between the effects of P-factor and slipstream rotation, as their influence on rudder input changes predictably when flying upside down.
Experimental results indicate that P-factor is the predominant cause for the need of right rudder in a climb for most airplanes, whereas slipstream rotation and torque reaction are more significant during the takeoff roll.

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When climbing, you need some right rudder to keep the ball centered. If you perform a half roll and continue to climb upside-down, which rudder will you have to use to stay coordinated?

Why do we need right rudder in a climb, anyway? Is it because of slipstream rotation? The propeller drags some air around with it, and the airplane continually advances through this slipstream of deflected air. The fin, being behind the portion of the propeller disk where the blades are going left to right, feels a push to the right.