FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsHard
During the takeoff roll in a tailwheel-equipped light sport airplane, as the pilot raises the tail off the ground, the airplane yaws sharply to the left. This yaw is primarily caused by which effect?
- AGyroscopic precession
- BP-factor
- CSpiraling slipstream
- DTorque reaction
Show answer & explanationAnswer & explanation
Correct answer: A. Gyroscopic precession
Raising the tail applies a pitching force to the spinning propeller disc. Due to gyroscopic precession, this force is felt approximately 90° later in the direction of rotation, resulting in a yaw to the left for a clockwise-rotating (as viewed from the cockpit) propeller.
Why the other options are wrong
- B. P-factor is most significant at high angles of attack and low airspeed, not during tail-raising.
- C. Spiraling slipstream is a steady-state effect, not tied specifically to the tail-raising action.
- D. Torque reaction causes a rolling tendency, not the specific yaw from raising the tail.
Gyroscopic Precession
A property of rotating bodies (such as a propeller) in which an applied force is manifested 90° later in the direction of rotation.
- Most noticeable during tailwheel liftoff or attitude changes
- Force applied at one point appears 90° ahead in rotation
- One of the four left-turning tendencies in propeller aircraft
Memory trick: Push now, yaw ninety degrees later.