By: JT, '09
A hovercraft is a machine that flies on a cushion of air above the ground. A man named John Thornycroft first thought of this idea. However he could not come up with a way to keep the cushion of air that the machine was flying on contained. Christopher Cockerell thought of a way to contain the air cushion in 1955. As these two inventor's ideas were changed and perfected the final product turned out to be an all terrain vehicle, the hovercraft (or ground effect machine). These machines could achieve speeds of up to 50 kts. on calm days at sea and 40 kts. on rough waters. This was much better than the British navy and coast guard soon drafted the current boats and hovercraft into use.
Hovercrafts are machines of pressure. A common thought is that they float many feet off the ground. This is impossible. They actually float only a fraction of an inch above the ground. You may wonder why, if they float only a small distance over the ground, water, etc. they are able to float over many different kinds of terrain. This is because as they travel over the object the cushion of air will adapt to the object and the hovercraft will move over it. Because of this the hovercraft are amphibious (they can travel over land and water).
The hovercraft floats on a cushion of air. This is made by air being pushed under the hovercraft by high power fans. As the hovercraft floats over itŐs surface it adapts to the surface. This idea has been adapted (shown here, bottom) in several ways including the wing in ground effect.
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