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Tuesday 1 June 2010

Experimental 'scramjet' sets hypersonic record as it flies at six times the speed of sound


Arcing through the hazy air above California, this is the incredible sight of a scramjet as it flies at six times the speed of sound. The experimental aircraft set a record for hypersonic flight, blazing through the air for more than three minutes at Mach 6, or more than 4,500 mph. The X-51A Waverider scramjet was released from a B-52 bomber last week before its engine took it to Mach 6 and it flew autonomously for 200 seconds. Scramjets work by using oxygen rushing in through the engine at supersonic speeds to ignite hydrogen fuel. In a conventional jet engine, spinning blades suck air into the engine and compress it for combustion. The next step up is the ramjet engine, powered by fuel burning after subsonic air is forced into the engine by the speed of the aircraft. But in scramjets, so-called because they are 'supersonic combustion ramjets', airflow throughout the engine remains supersonic - using the oxygen in the incoming air to ignite hydrogen fuel. The expanding hot gases from combustion accelerate the exhaust air to create tremendous thrust. The engines could slash satellite launch costs, because there is no need for liquid oxygen as fuel. The U.S. space shuttle has to carry more than a million pounds of liquid oxygen each time it lifts off. (Daily Mail)