Chinese name: propeller mbth: propeller principle: the ancestor of generating reverse thrust after rotation: Archimedes screw pump, bamboo dragonfly's historical origin, geometric parameters, diameter (D), number of blades (B), solidity (σ), blade angle (β), geometric pitch (H), actual pitch (Hg) and theoretical torque (HT) marine propeller. Working principle, air propeller, overview, principle, structural characteristics, rotation, classification, tension change, tension curve, effective power, comprehensive situation, propeller plane, historical origin 1, ancient wheel, so-called "paddle wheel" in Europe, with modern steam engine, a row of straight blades of the original paddle wheel are obliquely mounted on a hub, and the prototype of the propeller is formed. In ancient times, windmills could output torque when they turned with the wind. On the contrary, in water, when the windmill rotates with the input torque, the windmill in water may push the ship to move. 3. The Archimedes screw pump in ancient Greece, which was used for more than ten centuries at that time, can lift water horizontally or vertically, and the fact that the screw structure can pump water is an important revelation as a propeller. The great British scientist Hooke successfully adopted the principle of anemometer to measure the flow of water in 1683. At the same time, he put forward a new propeller-propulsion ship, which made great contributions to the ship propeller. Geometric parameter diameter (D) is one of the important parameters that affect propeller performance. Generally speaking, with the increase of diameter, the tension increases and the efficiency improves. Therefore, if the structure allows, try to choose a propeller with a larger diameter. In addition, it should also be considered that the airflow speed at the tip of the propeller should not be too large (