Propeller – a type of fan which transmits power by converting rotational motion into thrust for propulsion of a vehicle such as an aircraft, ship, or submarine through a mass such as water or air, by rotating two or more twisted blades about a central shaft, in a manner analogous to rotating a screw through a solid. The blades of a propeller act as rotating wings (the blades of a propeller are in fact wings or airfoils), and produce force through application of both Bernoulli’s principle and Newton’s third law, generating a difference in pressure between the forward and rear surfaces of the airfoil-shaped blades and by accelerating a mass of air rearward.
- USS Churchill propeller (photo) – test of the ship’s system that reduces cavitations made by the screws while underway
Energy source, transfer
The origin of the actual screw propeller starts with Archimedes, who used a screw to lift water for irrigation and bailing boats, so famously that it became known as the Archimedes screw. It was probably an application of spiral movement in space (spirals were a special study of Archimedes) to a hollow segmented water-wheel used for irrigation by Egyptians for centuries. Leonardo da Vinci adopted the principle to drive his theoretical helicopter, sketches of which involved a large canvas screw overhead.
waterwheel – The waterwheel was the first major energy source beyond human muscle and animal labor, which freed people to perform more sophisticated tasks.
rotational motion – The engine or motor turns a shaft. To put this power to work propelling a ship or a boat, the power by converting rotational motion into thrust for propulsion
- propeller, airfoil, screw, rotational motion, thrust, cavitation, power, conversion