The left-turning tendencies
Torque, spiraling slipstream, P-factor, and gyroscopic precession.
14 min read · Advanced aerodynamics
After this lesson you can
- Name the four elements that make a propeller airplane pull left, and the flight condition in which each is strongest.
- Explain torque reaction and the corkscrewing slipstream, including their effect on the takeoff roll.
- Apply the 90-degree rule of gyroscopic precession to a tailwheel takeoff.
- Explain why P-factor exists only at higher angles of attack, and connect all four effects to a commercial maneuver such as the chandelle.
A propeller airplane whose engine turns the propeller clockwise, as seen from the pilot's seat - true of most US-built engines - pulls left. That single fact is learned at the private level; at the commercial level it needs to be taken apart, because the four causes behind it do not act under the same conditions or with the same strength.
This is not academic. Commercial maneuvers stack changes in pitch, power, and airspeed in configurations where these four effects combine or partly cancel. A pilot who knows which of the four is dominant at a given instant corrects for it ahead of time instead of chasing it with rudder after the fact.
These effects are also a steady source of error in slow flight at high power - precisely the regime of a chandelle, a short-field takeoff, or a go-around.
The rest of this lesson
- 1.Four elements, one name
- 2.Torque reaction
- 3.The corkscrewing slipstream
- 4.Gyroscopic precession
- 5.Asymmetric loading, or P-factor
- 6.What this means in a commercial maneuver
- 7.What to remember
These 7 sections, their figures, the checks along the way and the end-of-lesson quiz come with the CPL track. Paid once, yours for good.
Key terms
Try to recall each definition before turning the card.