A propeller is a device designed to produce motion consisting of two or more blades mounted on a motor-driven shaft. A propeller turns engine power into forward thrust for the vehicle. The best-known types of propellers are those that drive ships or airplanes. The blades of a propeller produce a type of force known as aerodynamic lift that pushes or pulls an airplane through the air and pushes a ship through water. Aircraft propellers, the best-known types of propellers, are sometimes called propellers. Most of them are made of two or more blades or props. Pitch is the angle between the cross section of the blades or propellers and the plane through which they rotate. A propeller travels through the air at the same speed as pitch; so pitch is equivalent to the speed at which a propeller travels through the air. A propeller is also a wing and a mechanical device. It is called a helix because it travels through air or water just as a screw would travel through wood or a bolt would travel through an anchor with a set number of rotations. Pro...