Spinning propeller cause a plan to yaw while it is taxiing?

[RandomGuy88]

Hi Everyone,

There is something I am having trouble I am understanding. Why does a spinning propeller cause a plan to yaw while it is taxiing?

Also, how does the flow behind a propeller effect the performance of the control surfaces on the tail? Does it have any effect? Because the flow from a propeller is not straight so I would imagine it effects the aircraft somehow.

 

[FredGarvin]

At low forward speeds and high torque, it is simply Newton's third law. Because of the low forward speed you do not get any of the affects from the aerodynamic surfaces to help counteract the main engine torque.

http://wiki.flightgear.org/index.php?title=Understanding_Propeller_Torque_and_P-Factor

 

[mugaliens]

Good link, Fred.

The primary cause while taxiing involves propellor wash.

P-factor isn't a concern for tri-gear, and only a concern for taildraggers when the power's in and the forward velocity is fast enough to matter, a situation rarely encountered during taxi operations. Torque is a non-factor as the main gear simply torques back.