|As the name implies, a fixed pitch propeller has the blade
pitch (blade angle) built into the propeller. For that reason the pitch
angle cannot be changed by the pilot, as it can on controllable pitch propellers.
Generally, this type of propeller is constructed of wood or aluminum alloy
Fixed pitch propellers are designed for best efficiency at one rotational and forward speed. They are designed to fit a specific set of conditions involving both the engine rotational speed and the airplane's forward speed. Any change in these conditions reduces the efficiency of both the propeller and the engine.