FAA Flight Instructor Airplane (FIA)Aerodynamics and Principles of FlightMedium
During a full-power climb at a high angle of attack, a single-engine airplane with a clockwise-rotating propeller (viewed from the cockpit) tends to yaw left. This is primarily the result of:
- Atorque reaction rolling the airframe opposite propeller rotation
- Bthe descending propeller blade on the right producing more thrust than the ascending blade on the left
- Cspiraling slipstream striking the vertical stabilizer
- Dgyroscopic precession from the propeller
Show answer & explanationAnswer & explanation
Correct answer: B. the descending propeller blade on the right producing more thrust than the ascending blade on the left
P-factor occurs because at high angles of attack, the descending propeller blade (on the right side, for a clockwise-rotating prop) has a greater angle of attack and produces more thrust than the ascending blade on the left, creating asymmetric thrust that yaws the nose left.
Why the other options are wrong
- A. Torque reaction causes a rolling tendency, not the yaw described here.
- C. Spiraling slipstream contributes to left yaw but is a secondary, more constant effect rather than the AOA-dependent cause described.
- D. Gyroscopic precession causes yawing primarily during pitch changes of the tailwheel or nose during takeoff roll, not steady climb.
P-Factor (Asymmetric Thrust)
P-factor is the yawing tendency caused by the descending propeller blade producing more thrust than the ascending blade at high angles of attack.
- Most pronounced at high AOA/low airspeed, such as climb
- Descending blade (right side, clockwise prop) has higher AOA
- Causes left-yawing tendency in most U.S. singles
- Corrected with right rudder
Memory trick: 'P for Pushier blade' — the descending blade pushes harder