Used airplane propellers are the part of an airplane that spins and provides propulsion that have already been used to fly, and are therefore not new. Propellers convert rotational motion into propulsive force to push the plane forward while in the air, allowing the wings to create lift and keep the airplane from falling.
Propellers are found in many vehicles such as airplanes, boats and helicopters. Typically, smaller airplanes utilize one propeller on the nose of the plane, while other planes can use two or more propellers mounted on the wings. The propellers have angled blades that are able to push air in one direction when they rotate on an axle, which effectively allows the plane to move through the air. It is important to planes to make sure that the propellers are maintained and in good condition, as old, used propellers could break and cause the plane to malfunction.
Early airplane propellers were typically made of carved wood, but today they are most often made of metal. The blades of the propellers are precisely angled to allow the propeller to push the most amount of air with the least amount of drag possible. Large commercial planes make use of two contra-rotating propellers, which allows for an increased power output without adding length to the propellers' blades.