The yawing moment coefficient () resulting from rudder deflection signifies how the angle of the rudder influences the aircraft’s tendency to rotate about its vertical axis. The yawing moment coefficient provides insight into how an aircraft responds to yawing motion. A positive  indicates a stabilizing effect, meaning the aircraft tends to return to its original heading when disturbed. A negative implies a destabilizing effect, potentially leading to uncontrolled yawing motion. The yawing moment coefficient changes proportionally with rudder deflection in an aircraft. As the rudder angle increases or decreases, the corresponding yawing moment adjusts, influencing the aircraft’s yawing motion and directional stability. The formula to calculate Yawing moment Coefficient as follows:
Where:
- N is the Yawing Moment (-ve).
- Qw is the Dynamic pressure of wing in Pa.
- S is the wing area in m2.
- b is the wingspan in m.