Space jet could leave rockets in the dust

A drawing of the X-43

By Richard Stenger
CNN

(CNN) -- A possible successor to the conventional rocket engine should soon make a series of test flights, roaring high into the atmosphere at speeds exceeding thousands of miles per hour.

The hypersonic combustion engine, an elusive technological dream for decades, could lead to faster, cheaper and more reliable flights into space, according to mission scientists.

NASA engineers in May will conduct three flights testing the experimental machinery, which relies on air-breathing scramjet engines instead of rocket power to gain incredible speeds.

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"This is the first time we're going to fly an aircraft more than seven times the speed of sound," said Vince Rausch, director of NASA's $185 million Hyper-X flight research program.

"This is the same level of paradigm shift of the piston engine over the steam engine," he told reporters Wednesday.

The fastest air-breathing plane in the world, the SR-71, cruised slightly above Mach 3, or three times the speed of sound.

The proposed X-43 hypersonic plane, by using atmospheric oxygen to combust its fuel, would be a marked improvement over rocket-powered crafts, which must carry their own supply of the element when their fly, considerably increasing their weight.

Hypersonic is defined as traveling at a speed equal to about fives times the speed of sound or greater.

A B-52 bomber will carry several so-called scramjet engines from NASA's Dryden Flight Research Center in Edwards, California, to successively higher elevations on three different runs over the Pacific Ocean.

The experimental vehicles, each about 12-feet long with a 5-foot wingspan, will drop from the aircraft and roar skyward, propelled by a Pegasus booster rocket.

When their altitude approaches 100,000 feet they will fly on their own power, racing at Mach 7 and later Mach 10 before splashing into the ocean.

"What the Wright brothers did for subsonics, the X-43 will do for supersonics," X-43 test flight manager Joel Sitz said.

The scramjet has a simple mechanical design with no moving parts. Rather than using a rotating compressor like a turbojet engine, the forward movement compresses air into the engine. Fuel, in this case hydrogen, is injected and the expanding hot gases from combustion accelerate the exhaust air and create thrust.

Scramjet technology could also allow more traditional aircraft to greatly reduce flight times and costs. Practical applications could be possible within decades, according to NASA.

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NASA
  • NASA Dryden Flight Research Center

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