What happens to a propeller that is windmilling?

When a propeller is windmilling, it means that the blades are rotating due to the airflow created by the forward motion of the aircraft, rather than being driven by the engine. This windmilling effect occurs when the engine is not producing power, such as during an engine failure or when the power is reduced significantly.

In the context of this question, the windmilling propeller indeed rotates in the normal direction of the engine. As it spins, it generates drag due to the resistance of the propeller blades against the incoming airflow. This drag can have significant implications for aircraft performance, particularly in situations where engine power is lost or significantly reduced, as it can lead to increased descent rates and affect maneuverability.

Understanding the dynamics of windmilling is critical for pilots, as they must be aware of how it impacts their aircraft's performance and what actions are needed to manage it effectively during flight.