乘浪者喷气机进行6马赫试飞
[font=Simsun][font=宋体, Verdana, Arial, Helvetica, sans-serif][size=14px][font=Verdana, Arial, Tahoma][size=12px][font=宋体, Verdana, Arial, Helvetica, sans-serif][b]The US military has conducted a test flight of its hypersonic jet Waverider, aiming to reach Mach 6 (6,900km/h). [/b][/font][font=宋体, Verdana, Arial, Helvetica, sans-serif][b]美国军方对其极超音速喷气式飞机乘浪者进行了一次试飞，意图使其速度达到6马赫（6900公里每小时）。[/b][/font]
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[color=#0000FF]The 8m-long craft was expected to break into pieces at the end of its brief flight[/color]
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[font=宋体, Verdana, Arial, Helvetica, sans-serif]At that speed it could travel from London to New York in about an hour. Results from the test flight are expected later on Wednesday. [/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The Pentagon and Nasa hope to use the project to develop faster missiles.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]During a test in June 2011, Waverider travelled at Mach 5, but failed to reach the target speed.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]It is one of several projects currently under way to create a hypersonic aircraft.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The research could also be used to build a commercial plane, able to reach much higher speeds than today's jets, after Concorde was [b]decommissioned（退役的）[/b] in 2003.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif][b]Five-minute flight[/b][/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The [url=http://www.enread.com/news/sciandtech/89799.html]military[/url] used a B-52 bomber to lift the wingless unmanned jet from US Edwards Air Force Base in California to 50,000 ft (15,250m) between 1700 and 1800GMT.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]After being dropped from the B-52, the engine of the X-51A Waverider was supposed to [b]ignite（点燃）[/b]after a free fall of about four seconds.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The 8m long craft was then expected to climb to 70,000ft (21,300m) and eventually reach Mach 6. [/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The results of the test flight would be available later on Wednesday, a military spokesman said in a statement.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The Mach number is the ratio of the speed of an object to the speed of sound. Mach 1 is the speed of sound - approximately 768mph, depending on various factors including temperature and altitude. [/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]So [url=http://www.enread.com/news/sciandtech/89799.html]Mach[/url] 6 is six times the speed of sound. Concorde's cruising speed was Mach 2 - it flew from London to New York in just over three hours.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The Waverider test flight was expected to last for about five minutes before the craft fell into the Pacific.[/font]
[font=宋体, Verdana, Arial, Helvetica, sans-serif]The test is essentially a repeat of last summer's attempt, when the hypersonic aircraft reached Mach 5, but the engine failed to attain full power.[/font]
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更多[/font][/font][font=simsun][font=simsun][font=simsun][font=simsun][url=http://www.enread.com/news/index.html][font=宋体, Verdana, Arial, Helvetica, sans-serif][size=24px][color=#ED1C24][size=24px][b]英语新[/b][/size][/color][/size][/font][/url][/font][/font][/font][/font][font=simsun][font=simsun][font=simsun][font=simsun][url=http://www.enread.com/news/index.html][color=#ED1C24][size=24px][b]闻[/b][/size][/color][/url][/font][/font][/font][/font][/size][/font][/font] I want to have a try！ VERY GOOD
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