FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsEasy
When a pilot uses only the ailerons to enter a turn without applying rudder pressure, the airplane's nose tends to initially yaw opposite the direction of the turn. This tendency is known as
- AP-factor
- Btorque effect
- Cadverse yaw
- Dgyroscopic precession
Show answer & explanationAnswer & explanation
Correct answer: C. adverse yaw
Adverse yaw occurs because the aileron deflected downward on the rising wing produces more lift and, consequently, more induced drag than the aileron deflected upward on the descending wing. This extra drag pulls the nose toward the raised wing, opposite the intended turn direction, requiring coordinated rudder input to correct.
Why the other options are wrong
- A. P-factor is caused by asymmetric propeller blade thrust at high angle of attack, unrelated to aileron use.
- B. Torque effect is the reaction to engine/propeller rotation, not aileron-induced drag.
- D. Gyroscopic precession is a propeller effect from applied force 90° ahead in rotation.
Adverse Yaw
The tendency of an airplane's nose to yaw toward the outside of a turn when ailerons alone are used, due to unequal induced drag between the two wings.
- Caused by greater induced drag on the wing with the down-deflected aileron
- Corrected by applying coordinated rudder in the direction of the turn
- More pronounced at low airspeeds and high angles of attack
- Differential and Frise ailerons help reduce adverse yaw
Memory trick: Adverse yaw: the raised wing drags its feet