Thursday April 19 6:23 AM ET
NASA Unveils Futuristic Aircraft
By ANDREW BRIDGES, AP Science Writer
EDWARDS AIR FORCE BASE, Calif. (AP) - NASA (news - web sites) has unveiled a futuristic aircraft designed to accelerate through the atmosphere at speeds up to 7,200 mph, making it the world's fastest plane.
The National Aeronautics and Space Administration's first unpiloted X-43A will make its maiden flight in mid-May, flying under its own power for just 10 seconds and about 17 miles before crashing into the Pacific Ocean.
NASA said the plane, which it unveiled Wednesday, is designed to fly seven to 10 times faster than the speed of sound. Mach 1 is the speed of sound, which varies by altitude and is about 750 mph at sea level.
After the initial flight, two more of the 12-foot-long, surfboard-shaped planes will fly at six-month intervals. If successful, the planes will smash the speed record of Mach 6.7, set by an X-15 in October 1967.
``This is an aviation first,'' said Vince Rausch, manager of the X-43A program at NASA's Langley Research Center.
Unlike the rocket-powered X-15, the X-43A has an air-breathing engine. It carries hydrogen for fuel, but must scoop oxygen out of the atmosphere to combust it. Conventional rockets carry both fuel and an oxidant.
Currently, the fastest air-breathing aircraft is the SR-71 ``Blackbird,'' which cruises slightly faster than Mach 3. The X-43A should become the first air-breathing plane to go hypersonic, or faster than Mach 5.
The government has pursued the idea of routine hypersonic flight for four decades, including an abortive $2.4 billion effort begun under President Reagan to build a ``National Aero-Space Plane'' capable of zipping halfway around the globe in a few hours.
``The concept is pretty simple, it's just that no one can seem to make it work,'' said Howard McCurdy, a professor of public affairs at American University.
The $185 million X-43A project is purely experimental. Engineers will collect flight data needed to build future planes perhaps 200 feet in length. The first piloted prototypes may fly by 2025.
The X-43A, or Hyper-X, will probably never carry commercial passengers because of the high acceleration, heat generated by friction with the atmosphere and the difficulty of turning a plane at such high speeds.
Backers of the technology say air-breathing hypersonic propulsion could help space travel. Eliminating the need to carry oxygen could cut the weight of a space-faring version of such a plane in half.
The X-43A, however, requires a big boost to get going.
To make sure the air goes through the engine fast enough during test flights, a B-52 will haul the X-43A to about 24,000 feet and release it. A booster rocket will ignite to accelerate the X-43A to its test speed and altitude of about 100,000 feet. The X-43A will then separate from the booster and fly west over the ocean.
The X-43A needs the rocket boost in order for its specialized supersonic-combustion ramjet, or ``scramjet,'' engine to work. In normal jet engines, rotating blades do the compression work. A scramjet engine only works when air flows through it at supersonic speeds.
``The analogy is lighting a match and keeping it lit in a hurricane,'' said Joel Sitz, X-43A flight test project manager at NASA's Dryden Flight Research Center.