A Propeller “Lifts” an Airplane Forward
Think of a propeller as a spinning wing. Like a wing, it produces lift, but in a forward direction—a force we refer to as thrust. Its rotary motion through the air creates a difference in air pressure between the front and back surfaces of its blades. In order for a propeller blade to spin, it usually needs the help of an engine.
Test A propeller is a wing with a twist. In cross section, a propeller is shaped like a wing to produce higher air pressure on one surface and lower air pressure on the other. This is the Excalibur III, a North American P-51C Mustang, on display at the National Air and Space Museum’s Steven F. Udvar-Hazy Center.
A Propeller Is a Wing with a Twist
In cross section, a propeller is shaped like a wing to produce higher air pressure on one surface and lower air pressure on the other.
Propellers and Pitch
Angle of attack is the angle a wing makes with the oncoming airflow. Pitch angle is the angle a propeller blade makes with its plane of rotation. A wing has nearly the same angle of attack across its entire length. But a propeller blade has a twist, so its pitch angle varies along its length.
On a controllable-pitch propeller, the pitch of the entire blade can be altered during flight to give the best performance at different air speeds. This is similar to changing gears with a car or bicycle.
A ship’s propellers create thrust in water in much the same way an airplane’s propellers create thrust in air.
In order for a propeller blade to spin, it usually needs the help of an engine.
