FAA Private Pilot Airplane (PAR)Aerodynamics and Aircraft SystemsMedium
A pilot applies right aileron to begin a coordinated turn to the right. Immediately after aileron input, but before rudder is applied, the airplane's nose initially yaws slightly to the left. What causes this adverse yaw?
- AThe rudder is out of trim and needs adjustment before flight
- BThe down-going left aileron produces more lift and more induced drag than the up-going right aileron
- CGyroscopic precession from the propeller reacts 90 degrees later in the direction of rotation
- DP-factor causes the descending propeller blade to yaw the nose opposite the turn
Show answer & explanationAnswer & explanation
Correct answer: B. The down-going left aileron produces more lift and more induced drag than the up-going right aileron
Adverse yaw occurs because the aileron that deflects downward (on the rising wing) produces more lift and, as a byproduct, more induced drag than the aileron deflecting upward on the opposite wing. This extra drag on the rising wing side yaws the nose away from the direction of the turn. Pilots counteract this by applying coordinated rudder in the direction of the turn.
Why the other options are wrong
- A. Rudder trim is unrelated; adverse yaw is an aerodynamic characteristic of aileron deflection, not a rigging issue.
- C. Gyroscopic precession relates to propeller pitch/yaw forces, not aileron-induced drag differences.
- D. P-factor is related to angle of attack and thrust asymmetry, not aileron deflection during a turn entry.
Adverse Yaw
A yawing tendency toward the outside of a turn caused by increased induced drag on the up-going wing (down aileron) compared to the down-going wing (up aileron) during roll input.
- Caused by unequal induced drag between the two ailerons during roll input
- Corrected by applying coordinated rudder in the direction of the turn
- More pronounced with slower airspeeds and larger aileron deflections
Memory trick: Down aileron drags the nose the wrong way.