What is the aerodynamic issue that arises from excessive rudder input without sufficient bank?

Excessive rudder input without sufficient bank primarily leads to a condition known as skid. This aerodynamic issue occurs when the aircraft is utilizing too much rudder to turn but not banking sufficiently to create the necessary lift on the wings. In this situation, the aircraft’s nose is pointed more into the turn than the actual flight path, causing it to slide sideways or "skid" in the direction opposite to the turn.

In a well-coordinated turn, the bank angle helps balance the horizontal component of lift with the required horizontal force to change direction, effectively keeping the aircraft on a desired flight path without adverse aerodynamic effects. When just rudder is applied excessively, without an adequate corresponding bank angle, it can lead to an unstable flight condition, where the aircraft may lose altitude or experience excessive drag due to the misalignment of the flight path.

Understanding this concept is essential for effective flight control and maintaining a safe and efficient flight profile. Skid conditions can be detrimental, particularly in terms of energy management and maintaining control during maneuvers, making proper coordination between rudder input and aileron (bank) input crucial for safe flight operations.