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

• RandomGuy88
In summary, the spinning propeller causes a plane to yaw while taxiing due to Newton's third law and propeller wash. P-factor may only be a concern for taildraggers during fast forward speeds but is not usually relevant during taxi operations. The main gear also counters torque.
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.

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

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.

## 1. How does a spinning propeller cause a plane to yaw during taxiing?

As the propeller spins, it creates a force known as torque. This torque causes the plane to rotate in the opposite direction, known as yaw. This yawing force is most noticeable during taxiing when the plane is moving slowly and the effects of the torque are more pronounced.

## 2. Can the yawing force from a spinning propeller be controlled?

Yes, the yawing force can be controlled by using the rudder. The rudder is a control surface located on the tail of the plane that can be adjusted to counteract the yawing force from the spinning propeller. Pilots use the rudder pedals to control the direction of the rudder and counteract the yawing force during taxiing.

## 3. Does the direction of the spinning propeller affect the yawing force?

Yes, the direction of the spinning propeller can affect the yawing force. The direction of the yawing force is determined by the direction of rotation of the propeller. If the propeller is rotating clockwise, the yawing force will be to the left, and if the propeller is rotating counterclockwise, the yawing force will be to the right.

## 4. Are there any safety concerns with the yawing force from a spinning propeller?

Yes, there can be safety concerns with the yawing force from a spinning propeller. If the yawing force is not properly controlled, it can cause the plane to veer off course and potentially collide with other objects on the ground. This is why it is important for pilots to be trained in controlling the yawing force during taxiing.

## 5. Does the size or type of propeller affect the yawing force?

Yes, the size and type of propeller can affect the yawing force. Larger and more powerful propellers will produce a greater yawing force, while smaller and less powerful propellers will produce a lesser yawing force. The type of propeller, such as a two-blade or three-blade propeller, can also affect the yawing force due to differences in the torque produced.

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