Sunday, January 7, 2007

PARACHUTE


A parachute is usually a soft fabric device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are generally used to slow the descent of a person or object to earth or another celestial body within an atmosphere. Drogue parachutes are also sometimes used to aid horizontal deceleration of a vehicle (a fixed-wing aircraft or space shuttle after touchdown, or a drag racer). The word parachute comes from the French words para, protect or shield, and chute, the fall. Therefore parachute actually means "fall protection". Many modern parachutes are classified as semi-rigid wings, are quite maneuverable, and can be flown as a glider.
Parachutes were once made from silk but now they are almost always constructed from more durable woven nylon fabric, sometimes coated with silicone to improve performance and consistency over time. Originally silk was used for parachute suspension lines, but was replaced by nylon during the Second World War. When square (aka ram-air) parachutes were introduced, manufacturers switched to low-stretch materials like Dacron or zero-stretch materials like Spectra, Kevlar, Vectran or high modulous aramids. Kevlar is rarely seen except on reserve canopies

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