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[ti:The Hovercraft]
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[00:01.55]Lesson 29
[00:03.46]The hovercraft
[00:11.25]What is a hovercraft riding on when it is in motion?
[00:17.57]Many strange new means of transport have been developed in our century,
[00:22.14]the strangest of them being perhaps the hovercraft.
[00:26.77]In 1953, a former electronics engineer in his fifties, Christopher Cockerell,
[00:34.08]who had turned to boat-building on the Norfolk Broads,
[00:37.87]suggested an idea on which he had been working for many years
[00:42.15]to the British Government and industrial circles.
[00:45.90]It was the idea of supporting a craft on a 'pad', or cushion, of low-pressure air,
[00:53.92]ringed with a curtain of higher pressure air.
[00:57.78]Ever since, people have had difficulty in deciding
[01:01.28]whether the craft should be ranged among ships, planes, or land vehicles --
[01:07.60]for it is something in between a boat and an aircraft.
[01:12.26]As a shipbuilder,
[01:13.66]Cockerell was trying to find a solution to the problem of the wave resistance
[01:18.68]which wastes a good deal of a surface ship's power and limits its speed.
[01:24.61]His answer was to lift the vessel out of the water
[01:28.09]by making it ride on a cushion of air, no more than one or two feet thick.
[01:34.95]This is done by a great number of ringshaped air jets on the bottom of the craft.