Propeller läge

An airplane moving through the air creates a drag force opposing its forward motion. If an airplane is to fly on a level path, there must be a force applied to it that is equal to the drag but acting forward. This force is called thrust. The work done by thrust is equal to the thrust times the distance it moves the power expended by thrust is equal to the thrust times the velocity at which it moves the the power is measured in horsepower units, the power expended by the thrust is termed thrust engine supplies brake horsepower through a rotating shaft, and the propeller converts it into thrust horsepower. In this conversion, some power is wasted. For maximum efficiency, the propeller must be designed to keep this waste as small as possible. Since the efficiency of any machine is the ratio of the useful power output to the power input, propeller efficiency is the ratio of thrust horsepower to brake horsepower. The usual symbol for propeller efficiency is the Greek letter η (eta). Propeller efficiency varies from 50 percent to 87 percent, depending on how much the propeller slips.

Pitch is not the same as blade angle, but because pitch is largely determined by blade angle, the two

Propeller

Device that transmits rotational power into linear thrust on a fluid

For aircraft propellers, see Propeller (aeronautics). For other uses, see Propeller (disambiguation).

A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to struktur a helical spiral which, when rotated, exerts linear thrust upon a working fluid such as vatten or air.^[1] Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a boat through water or an aircraft through air. The blades are shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade bygd Bernoulli's principle which exerts force on the fluid.^[2] Most marine propellers are screw propellers with helical blades rotating on a propeller shaft with an approximately horizontal axis.^[a]

History

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Early developments

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The principle employed in using a screw propeller fryst vatten derived from stern sculling. In sculling, a single blade fryst vatten moved through an arc, from side to side taking care to keep pre

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