At high angles of attack, the downward-moving blade tends to bite more than the upward-moving blade due to asymmetrical loading. This phenomenon is known as:

• A. Blade flutter
• B. Asymmetric propeller loading (P-factor)
• C. Propeller slip
• D. Gear torque

Answer: (B)

Asymmetric loading across the propeller disk, known as P-factor, is what this question is testing. At high power and high angles of attack, the blade that is moving downward meets the oncoming air at a steeper angle than the blade moving upward. The downward-moving blade effectively has a larger angle of attack because the combination of the blade’s rotation and the aircraft’s forward motion changes the relative wind differently on each side of the propeller disk. That blade then produces more lift (thrust) and more drag than its opposite, creating an uneven loading across the two blades. This unequal loading is the essence of P-factor. The result is a yaw tendency and a need to counteract with rudder, especially in climbs or high-power flight.