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Nasa plane to try Mach 7 flight 27.03.04 (BBCNews 24) close X Nasa plane to try Mach 7 flight The US space agency will attempt to fly its experimental hypersonic research aircraft, the X-43A, this Saturday. The unpiloted 3.7m-long vehicle uses a scramjet to reach a design speed in excess of Mach 7, more than 8,000 km/h (5,000 mph). Scramjets burn hydrogen but take their oxygen from the air which is forced into the engine at very high speed. It is hoped this technology could one day dramatically reduce the length of long-haul passenger flights and make it much cheaper to launch space payloads. Nasa will just want its latest experiment to complete its goals without incident. The first attempt to fly an X-43A ended in the destruction of the vehicle when its launch system failed. The new flight will take place over a naval range in the Pacific Ocean, off the coast of southern California, at 2000 GMT. A scramjet operates by the supersonic combustion of fuel in a stream of air compressed by the high forward speed of the aircraft, as opposed to a normal jet engine, in which fan blades compress the air. But scramjets only start to work at about Mach 6, or six times the speed of sound. And this means they first have to be boosted to their operational velocity. In the case of the X-43A, this will be done by a modified Pegasus rocket, which will be released from under the wing of a B-52 bomber. If all goes well, the 1,300kg wedge-shaped research craft will separate from its booster and accelerate away with the power from its scramjet. The engine should operate for just 10 seconds. The X-43A will then glide through the atmosphere conducting a series of aerodynamic manoeuvres for up to six minutes on its way to splashdown. If successful, the test will mark the first time a non-rocket, air-breathing scramjet engine has powered a vehicle in flight at hypersonic speeds. Engineering challenge Scramjet technology was first proposed in the 1950s and 60s. Because they take their oxidant from the atmosphere, the weight of any aircraft is therefore substantially reduced. Those weight savings could be used to increase payload capacity, increase range or reduce vehicle size for the same payload. The scramjet attraction is obvious. If the many engineering challenges can be overcome, this propulsion technology could make it possible to fly, for example, from London to Sydney in just a couple of hours. More likely in the first instance, they will find applications in the space delivery business - launching small payloads, such as communications satellites, into orbit. The first ever free flight of a scramjet was conducted by the US Defense Advanced Research Projects Agency (Darpa) in 2001. Its engine was fired from a gun in an enclosed facility on the ground. A year later, University of Queensland researchers flew their HyShot scramjet on a missile.

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