In a constant speed propeller, what happens to the RPM when the blade angle is increased?

When the blade angle of a constant speed propeller is increased, the pitch of the blades becomes steeper. This change in pitch causes the engine to work harder to maintain the same RPM. As the propeller blades encounter more aerodynamic drag due to the increased angle, the RPM actually decreases. The governor mechanism of a constant speed propeller detects this drop in RPM and automatically adjusts the propeller blade angle to maintain the desired speed. Therefore, it is essential to understand the relationship between blade angle and RPM in a constant speed propeller system.

In this scenario, the propeller's design allows for the optimization of performance at various flight phases, but an increase in blade angle — often used in climb or during initial thrust phases — can lead directly to a reduction in RPM if no adjustments are made by the governor. This principle is crucial for pilots to grasp in order to effectively manage propeller performance and engine power settings during flight operations.