Which statement correctly describes P-factor?

• A. A tendency for an aircraft to yaw to the right due to the descending propeller blade on the left producing more thrust than the ascending blade on the right.
• B. A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left.
• C. It is only observed in aircraft with counter-rotating propellers.
• D. It has no effect on yaw.

Answer: (B)

P-factor is the asymmetric thrust that occurs when a propeller operates at high angle of attack. The blade in the descending half of rotation encounters a different effective airflow than the ascending blade, so it produces more thrust. In a typical single-engine airplane, the propeller rotates clockwise when viewed from the cockpit, so the descending blade is on the right. That right-hand blade’s greater thrust pushes the airplane’s nose to the left, causing a yaw to the left. If the propeller rotated the other way, the yaw would be to the right. This effect is most noticeable during high power and high angle of attack, such as during takeoff or a climb.