Revolutionary aircraft poised for test flight

A drawing of the X-43

By Richard Stenger
CNN

(CNN) -- NASA is preparing this week for the upcoming test flight of an experimental rocket engine that could revolutionize space and air travel.

The hypersonic combustion engine technology, an elusive engineering goal for decades, could someday allow craft to fly ten times faster than the speed of sound, a pace now reserved to conventional rockets.

So-called "scramjet" technology relies on air-breathing engines instead of rocket power to gain speeds exceeding thousands of miles per hour. Currently, the SR-71 holds the title as fastest air-breathing plane in the world. It has cruised slightly above Mach 3, or three times the speed of sound.

The first trial run of the experimental engine could take place as early as Saturday. But weather and technical conditions must be ideal at the flight center in Edwards, California, NASA said.

VIDEO Watch an animation of the X-43 in flight (Courtesy NASA) Play video (QuickTime)

A B-52 bomber will carry the engine from NASA's Dryden Flight Research Center. The experimental vehicle, about 12 feet long with a 5-foot wingspan, will drop from the aircraft and roar skyward, propelled by a Pegasus booster rocket.

When its altitude approaches 100,000 feet, the scramjet will fly on its own, reaching a speed up to Mach 7 before splashing into the ocean.

The second test of the $185 million Hyper-X flight research program should take place during the winter. A third is set for late next year, during which the scramjet is expected to reach Mach 10.

The proposed X-43 hypersonic plane would be a marked improvement over a conventional rocket-powered craft, NASA said. The former uses atmospheric oxygen to combust its fuel. But the latter must carry its own supply of the element, considerably increasing its weight.

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

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.