The Hindu : International : 'Scramjet' makes historic hypersonic flight

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Thursday, Nov 18, 2004

International

International

'Scramjet' makes historic hypersonic flight

The "scramjet," attached to a modified Pegasus rocket under the wing of a B-52 aircraft, before its release off the southern California coast. — AP

LOS ANGELES, NOV. 17. A jet aircraft screamed into the record books high over the Pacific Ocean by reaching speeds of almost 11,300 kmph, brightening hopes that humans might one day be able to fly across a continent in minutes instead of hours.

The 3.6-metre-long X-43A supersonic combustion ramjet — or scramjet — flew on its own power for just 10 seconds after separating from a booster rocket, but it was enough to excite researchers.

"We've given industry and government a lot of confidence to go forward with hypersonic flight,'' said the X-43A project manager at the Dryden Flight Research Centre on Edwards Air Force Base. ``I think that technology definitely has a future."

Initial data indicated the aircraft flew at about Mach 9.6 — or nearly 10 times the speed of sound — said the scramjet propulsion team leader from the Langley Research Centre in Virginia. "We can really do this stuff," he said.

The way it went

The X-43A was mounted on a Pegasus rocket and carried aloft by a B-52 carrier aircraft of the National Aeronautics and Space Administration (NASA) to a range off the southern California coast. At 12,200 m, the Pegasus was released and ignited, soaring to high altitude and a speed of Mach 9.8 before the X-43A separated and flew on its own at an altitude of 33,800 m.

"It's 90 seconds of terror, but once it's over with you realise that you've really accomplished some great things," the project manager said. After 10 seconds of scramjet-powered flight, the X-43A became a glider and made a controlled glide to a splashdown in the ocean about 1,290 km offshore. It will not be recovered.

Much data

Although brief, the flight produced an enormous amount of data compared to the milliseconds of data that all Mach 10 ground tests have produced.

The flight was the last in a $230 million-plus programme to test a technology most likely to be initially used to power missiles or in military aircraft, such as bombers that could reach any target on the earth within two hours of takeoff. Scramjets may also provide an alternative to rockets for space launches. An informed source said the technology could eventually be used for commercial passenger flights.

Unlike conventional jet engines, which use rotating fan blades to compress air for combustion, the X-43A has no such rotating engine parts. Instead it uses the underside of the aircraft's forebody to compress air for mixing with hydrogen fuel. The airflow through the engine remains supersonic.

The X-43A launched on Tuesday was the last of three built for NASA's Hyper-X programme.

Earlier miss

The first X-43A flight failed in 2001 when the booster rocket veered off course and was destroyed. The second X-43A successfully flew in March, reaching Mach 6.83 — nearly 8,000 kmph — and setting a new world speed record for a plane powered by an air-breathing engine. That was more than double the top speed of the jet-powered SR-71 Blackbird spyplane, which at slightly more than Mach 3 is the fastest air-breathing, manned aircraft.

Not having to carry oxygen is one of the advantages scramjets hold over rockets. Rockets achieve the same kind of high speeds but the weight of oxygen tanks reduces the amount of payload they can carry.

— AP

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