Secondary Propeller Effects

081-07-04Pablo Asensio Martínez2026-04-011 min

1. Torque Reaction

Based on Newton's 3rd Law.

  • Effect: The engine turns the prop Right -> The aircraft tends to Roll Left (in the air) or Yaw Left (on the ground due to tire friction difference).

2. Slipstream Effect (Corkscrew)

The slipstream spirals around the fuselage.

  • Effect: Hits the Left side of the vertical fin.
  • Result: Pushes tail Right -> Nose Yaws Left.
  • Correction: Right Rudder (mostly at high power/low speed).

3. Gyroscopic Precession

A force applied to a rotating disc is felt 90° later in the direction of rotation.

  • Tail Up (Takeoff): Force applied to TOP of prop arc -> Felt at RIGHT side -> Yaws Left.

4. Asymmetric Blade Effect (P-Factor)

Occurs at high Angles of Attack (Climb/Takeoff).

  • Descending Blade (Right side): Has higher effective AoA and speed -> Produces MORE Thrust.
  • Ascending Blade (Left side): Has lower AoA -> Produces LESS Thrust.
  • Result: Center of Thrust moves to the Right -> Yaws Left.

Note: All examples assume a standard clockwise-rotating propeller (viewed from behind).

Written and reviewed by

Pablo Asensio · 2026-04-01

Aeronautical engineer. Passed the thirteen EASA ATPL(A) theoretical knowledge exams studying from these very notes. Writes and reviews each topic against the Part-FCL Learning Objectives.

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