What is P-factor?

P-factor refers to the yawing motion that occurs due to the difference in thrust produced by the descending and ascending blades of a propeller in a non-zero angle of attack situation. As the aircraft is at a climb or descent angle, the propeller blades do not just travel through air equally.

As the propeller spins, the blade that is moving downward through the air (the descending blade) encounters a higher relative airflow and produces more thrust than the blade moving upward (the ascending blade). This discrepancy in thrust between the two blades causes a yawing moment that tends to turn the aircraft to the left or right, depending on the rotation direction of the propeller. This effect is particularly noticeable in high-power applications and is a critical consideration for pilots, especially during takeoff and climb.

Understanding P-factor is key for managing aircraft control since it can impact the stability and direction of an aircraft during various flight phases, particularly in climb, where the increased angle of attack exacerbates the effect. Recognizing how P-factor operates allows pilots to make necessary control inputs to counteract any unintended yawing motion during flight maneuvers.