新概念英语听力mp3下载第四册lesson 29 The hovercraft

 
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Many strange new means of transport have been developed in our century, the
strangest of them being perhaps the hovercraft. In 1953, a f.mp3er electronics
engineer in his fifties, Christopher Cockerell, who had turned to boat-building
on the Norfolk Broads, suggested an idea on which he had been working for
many years to the British Government and industrial circles. It was the idea of
supporting a craft on a' pad ', or cushion, of low-pressure air, ringed with a curtain
of higher pressure air. Ever since, people have had difficulty in deciding
whether the craft should be ranged among ships, planes, or land vehicles--for it
is something in between a boat and an aircraft. As a shipbuilder, Cockerell was
trying to find a solution to the problem of the wave resistance which wastes a good
deal of a surface ship's power and limits its speed. His answer was to lift the
vessel out of the water by making it ride on a cushion of air, no more than one or
two feet thick. This is done by a great number of ring-shaped air jets on the
bottom of the craft. It 'flies', therefore, but it cannot fly higher--its action depends
on the surface, water or ground, over which it rides.
The first tests on the Solent in 1959 caused a sensation. The hovercraft
travelled first over the water, then mounted the beach, climbed up the dunes,
and sat down on a road. Later it crossed the Channel, riding smoothly over the
waves, which presented no problem.
Since that time, various types of hovercraft have appeared and taken up regular
service--cruises on the Thames in London, for instance, have become an annual
attraction. But we are only at the beginning of a development that may transport netsea
and land transport. Christopher Cockerell's craft can establish transport
works in large areas with poor communications such as Africa or Australia; it
can become a 'flying fruit-bowl', carrying bananas from the plantations to the
ports, giant hovercraft liners could span the Atlantic; and the railway of the
future may well be the 'hovertrain', riding on its air cushion over a single rail,
which it never touches, at speeds up to 300 m.p.h.--the possibilities appear
unlimited.