29 The Hovercraft

名称：29 The Hovercraft
内容简介：
新概念英语第四册（英音）
[al:新概念英语（四）]
[ar:MP3 同步字幕版（英音）]
[ti:The Hovercraft]

[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.
[01:41.73]It 'flies', therefore, but it cannot fly higher--its action depends on the surface, water or ground, over which it rides.
[01:53.81]The first tests on the Solent in 1959 caused a sensation.
[01:59.78]The hovercraft travelled first over the water, then mounted the beach,
[02:04.58]climbed up the dunes, and sat down on a road.
[02:08.98]Later it crossed the Channel, riding smoothly over the waves,
[02:13.43]which presented no problem.
[02:16.47]Since that time,
[02:17.95]various types of hovercraft have appeared and taken up regular service.
[02:23.27]The hovercraft is particularly useful in large areas with poor communications
[02:29.10]such as Africa or Australia;
[02:32.28]it can become a 'flying fruit-bowl',
[02:35.28]carrying bananas from the plantations to the ports;
[02:38.98]giant hovercraft liners could span the Atlantic;
[02:43.10]and the railway of the future may well be the 'hovertrain',
[02:48.02]riding on its air cushion over a single rail, which it never touches,
[02:53.47]at speeds, up to 300 m.p.h.--the possibilities appear unlimited.