/diy/ - Do It Yourself

>>1123944
Opposite direction That's just one of four propeller-related (generally left-) turning tendencies.
Propeller torque effects
>Are the equal, opposite reaction to the torque of the engine acting on the propeller
>Act to roll the airplane about the thrustline axis, regardless of orientation
>Are proportional to power setting
P-factor
>Is the result of dissymmetry of thrust in different sectors of the propeller arc (usually upward-moving and downward-moving sectors)
>Manifests when the oncoming airflow is oblique to the propeller axis (i.e. at large AOA, or less frequently sideslip), and is zero when thrustline is aligned with airflow
Spiral stream effects
>Are the result of swirl in the propwash impinging asymmetrically on the tail surfaces and/or fuselage
>Are most pronounced when the tail features a large, high-mounted dorsal fin and no ventral whatsoever
>Are minimal on airplanes which have nearly equal dorsal and ventral surfaces; i.e. modern F3A and F3P airplanes
And lastly, gyroscopic precession
>Is the gyroscopic response of the propeller (which has nonzero angular momentum) to pitch and yaw rates
>Is zero whenever the aircraft is not changing orientation
>For a standard-rotation propeller, will tend to yaw left in response to pitching up and will yaw right in response to downward pitch

All of these can, of course, be mitigated through counterrotation, as many F3P planes are now doing.