What is the primary purpose of the controllable pitch propeller?

The primary purpose of the controllable pitch propeller is to adjust the blade angle for optimal performance. This adjustability allows the pilot to modify the propeller's pitch depending on the flight phase and operating conditions. During takeoff, for example, a low pitch setting maximizes thrust, while in cruise, a higher pitch setting improves efficiency and fuel consumption.

This capability to change the blade angle enhances performance by allowing the aircraft to adapt to various situations, such as different speeds and power settings. By optimizing the angle of attack of the propeller blades, the controllable pitch propeller helps to ensure that the engine operates within its most efficient power range, leading to better overall flight performance, including climb rates, fuel economy, and speed management.