pitch angle

Propellers on airplanes function like rotating airfoils. Their "pitch" refers to the angle of the blades.

• Fixed-pitch propellers have a set blade angle, optimized for a single flight condition, which can limit overall performance.
• Variable-pitch propellers allow pilots to adjust the blade angle for different phases of flight, such as a lower pitch for takeoff and a higher pitch for cruising. Modern aircraft often use automatic variable-pitch propellers for continuous efficiency.
• Feathering is a feature where blades are turned edgewise to reduce drag if an engine fails. Some propellers can also be reversed after landing to shorten the stopping distance.

The geometrical pitch is a theoretical distance an airplane propeller would advance in one revolution, while effective pitch is the actual distance it moves along its flight path per revolution.123