Propeller

<p>A  propeller (often called a screw if on a <a href="/facts/Ship/418ptx1L">ship</a> or an airscrew if on an <a href="/facts/Aircraft/EhC4mBep">aircraft</a>) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear <a href="/facts/Thrust/EM04CqV7">thrust</a> upon a working fluid such as water or air.  Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a <a href="/facts/Boat/dz9LnNN6">boat</a> through water or an <a href="/facts/Aircraft/EhC4mBep">aircraft</a> through air.  The blades are shaped so that their <a href="/facts/Rotational/yChkz49x">rotational</a> motion through the fluid causes a pressure difference between the two surfaces of the blade by <a href="/facts/Bernoulli%2527s_principle/Y7urHvPr">Bernoulli's principle</a> which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a <a href="/facts/Propeller_shaft_(ship)/lHnhqzzT">propeller shaft</a> with an approximately horizontal axis.
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Propeller open-in-new

Propeller