What is the difference between fixed-pitch and variable-pitch propellers?

Fixed-pitch propellers are designed with blades that are set at a constant angle relative to the plane of rotation. This means that the angle of attack for the blades does not change during operation, which can limit the performance and efficiency of the propeller across different flight conditions. As the aircraft's speed and engine power change, the fixed angle may not be optimal, leading to less efficient thrust generation.

In contrast, variable-pitch propellers have blades that can change their angle during flight, allowing for better control of the propeller's performance under varying conditions. This adjustability helps optimize thrust and efficiency, making variable-pitch propellers more versatile for different phases of flight, such as takeoff, cruising, and landing.

Understanding this distinction is crucial for technicians in the field, as it influences the choice of propeller based on the specific requirements of an aircraft's engine and intended use.