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Lesson 29 |
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The hovercraft |
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What is a hovercraft riding on when it is in motion? |
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Many strange new means of transport have been developed in our century, |
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the strangest of them being perhaps the hovercraft. |
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In 1953, a former electronics engineer in his fifties, Christopher Cockerell, |
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who had turned to boat-building on the Norfolk Broads, |
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suggested an idea on which he had been working for many years |
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to the British Government and industrial circles. |
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It was the idea of supporting a craft on a 'pad', or cushion, of low-pressure air, |
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ringed with a curtain of higher pressure air. |
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Ever since, people have had difficulty in deciding |
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whether the craft should be ranged among ships, planes, or land vehicles -- |
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for it is something in between a boat and an aircraft. |
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As a shipbuilder, |
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Cockerell was trying to find a solution to the problem of the wave resistance |
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which wastes a good deal of a surface ship's power and limits its speed. |
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His answer was to lift the vessel out of the water |
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by making it ride on a cushion of air, no more than one or two feet thick. |
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This is done by a great number of ringshaped air jets on the bottom of the craft. |
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It 'flies', therefore, but it cannot fly higher--its action depends on the surface, water or ground, over which it rides. |
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The first tests on the Solent in 1959 caused a sensation. |
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The hovercraft travelled first over the water, then mounted the beach, |
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climbed up the dunes, and sat down on a road. |
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Later it crossed the Channel, riding smoothly over the waves, |
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which presented no problem. |
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Since that time, |
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various types of hovercraft have appeared and taken up regular service. |
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The hovercraft is particularly useful in large areas with poor communications |
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such as Africa or Australia; |
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it can become a 'flying fruit-bowl', |
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carrying bananas from the plantations to the ports; |
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giant hovercraft liners could span the Atlantic; |
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and the railway of the future may well be the 'hovertrain', |
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riding on its air cushion over a single rail, which it never touches, |
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at speeds, up to 300 m.p.h.--the possibilities appear unlimited. |
