The Telegraph
Since 1st March, 1999
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Nasa screams into age of superfast flights

California, March 28: A 12-foot experimental plane equipped with a special jet engine streaked across the Pacific Ocean at more than seven times the speed of sound yesterday, shattering a technological barrier and brightening future prospects for superfast airline flights.

Flying faster than any aircraft ever built, Nasa’s X-43A Hyper X plane reached a top speed of about 5,000 mph, or about a mile-and-a-half per second, before the unmanned craft intentionally was ditched into the ocean.

The previous record holder for a jet aircraft was the SR-71 spy plane, which reached speeds of 2,100 mph. The X-43A also surpassed the Mach 6.7 speed record set by the X-15 rocket-powered plane in 1967.

The world’s fastest flight came after five decades of research that was fraught with frustration and setbacks. For a while, aerospace analysts asserted that developing a jet plane that can reach hypersonic speeds, or exceeding five times the speed of sound, was harder to accomplish than sending a man to the moon.

A successful flight, they said, would be akin to the breaking of the sound barrier more than 55 years ago.

“It worked wonderfully,” said Joel Sitz, the project manager for the National Aeronautics and Space Administration’s X-43A programme at Edwards’ Dryden Flight Research Centre. “Today was a grand slam in the 12th inning. Everything went as planned.”

The hypersonic flight lasted only about 11 seconds, but it demonstrated a technology that one day could lead to an airliner flying from Los Angeles to Tokyo in two hours or a bomber that would be too fast to shoot down.

The successful flight, two years after the first attempt failed, is also likely to bolster efforts to expand development of jet technology. Since President George W. Bush announced an initiative earlier this year to send a person back to the moon and then to Mars, many of Nasa’s aeronautical research efforts have been in jeopardy.

“A lot was riding on this flight,” said Vincent Rausch, programme manager for Nasa’s hypersonic research.

The hypersonic plane, resembling a boogie board with twin tail fins, was propelled by a supersonic combustion ramjet engine or “scramjet,” essentially a rectangular copper box mounted to the belly. But the simplistic design belies a science that has been one of the more difficult technological barriers to overcome.

The common turbojet on most commercial and military aircrafts uses turbines inside the engine to compress air, which ignites with kerosene to create combustion and then thrust. But air flows too slowly and overheats the engine at high speeds.

Engineers figured out how to resolve the heat problem by developing a ramjet, basically a hollow tube with no moving parts. Air flows into the front of the ramjet, is compressed and then mixed with fuel. The resulting combustion creates thrust.

But the ramjet cannot power an aircraft past Mach 5. That required the development of the scramjet, in which gases flow into the chamber at supersonic speeds.

Although it seems mechanically simple, it is vastly more complex aerodynamically than a jet engine. The aircraft had to be designed in a way so that the front end of the X-43A — its flat nose — helps compress the oxygen before it enters the copper alloy chamber, where it mixes with hydrogen and burn, creating pressure from the expanding gas to propel the plane forward.

Reminiscent of the notable X plane experiments during the heyday of aerospace test flights here, a modified B-52 bomber took off with the rocket — about the same size as a F-16 fighter jet — attached to its wings, flying to 40,000 feet about 50 miles southwest of Los Angeles. Two F-18B chase planes followed the B-52 and transmitted live video images to nervous Nasa officials watching from a flight operations room at Dryden Flight Research Centre based at Edwards. The flight could be seen live on Nasa TV showing mostly the large white rocket as it started to climb with the black craft on the tip of its nose.

As the B-52 neared San Nicolas Island, the booster detached from the wing and began a five-second free fall before the rocket engines ignited. The rocket surged ahead and began a rapid climb, reaching 95,000 feet where the hypersonic plane then separated from the booster and began its autonomous flight.

About 11 second later, the scramjet turned off automatically, letting the airplane glide for about six minutes before splashing into the ocean 400 miles from where it had separated from its B-52 mother plane.

The 11 seconds of powered flight covered about 15 miles. By comparison, the Wright Brothers plane flew for 12 seconds and covered about 120 feet when it made aviation history in 1903.

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