Propeller is a kind of propeller which converts engine power into propulsion by rotating blades in air or water. It can have two or more blades connected with the hub, and the backward side of the blade is a helicoid or similar to a helicoid. There are many kinds of propellers, which are widely used, such as the propellers of airplanes and ships.
In 1836, the British Archimedes used a screw propeller, which is a long wooden screw like screw. At the beginning of the test, it sailed at a speed of 4 knots. Suddenly, the obstacles in the water broke the screw, leaving only a small section. Just as Smith, the shipbuilding engineer, was at a loss, the ship unexpectedly speeded up to 13 knots. This inspired the shipbuilding engineers. They changed the long screw into the short screw, and then the short screw into the blade shape, so the propeller was born.