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X-43A Destroyed In Flight After Booster Goes Awry
By Paul Hoversten

02-Jun-2001 8:16 PM U.S. EDT

The maiden flight of the unmanned X-43A "Hyper X" research aircraft ended in failure Saturday when NASA managers were forced to blow it up over the Pacific Ocean after its attached Pegasus booster rocket veered out of control.

The 12-foot-long, surfboard-shaped X-43A (depicted in image) was destroyed just minutes before its revolutionary supersonic combustion ramjet engine -- called "scramjet" -- was to fire and push it to a hoped-for record speed of Mach 7 or about 5,000 mph.

Instead, managers triggered on-board explosives to destroy it in mid-air after cameras aboard two F-18 chase planes showed the Orbital Sciences-built Pegasus rocket careening off course and falling out of control.

"We're disappointed but we'll fix it and fly again successfully," said Vincent Rausch, program manager at the Langley Research Center.

The X-43A, built by MicroCraft of Tullahoma, Tenn., and the Pegasus were carried to 24,000 feet under the wing of a NASA B-52 bomber from Edwards Air Force Base, Calif.

After release from the B-52, the Pegasus was to carry the X-43A to speeds of Mach 7 at 95,000 feet before the X-43A was to separate and fly on its own for a few seconds -- and set a speed record.

The 41,400-pound combine booster/X-43A "stack" appeared to be flying smoothly after the B-52 dropped it.

But five seconds later, the booster suddenly flew out of control, prompting the detonation.

Pieces of the booster and the X-43A fell harmlessly into the ocean.

There was no damage to property on the ground and no injuries, NASA said.

The U.S. space agency has formed a review board to investigate the reasons behind the failure.

"We're disappointed but we'll fix it and fly again successfully," said Vincent Rausch, program manager at the Langley Research Center.

It was the first of three flights for the X-43A in a five-year, $185 million program to demonstrate future hypersonic propulsion and airframe technologies.

The other flights are scheduled for late 2001 and 2002.

NASA has said the program represents the future of aviation and could lead to cross-country commercial flights lasting just 30 minutes.

The hypersonic or "scramjet" engine -- in development for four decades -- has only been tested in ground facilities such as wind tunnels.

A ramjet operates by subsonic combustion of fuel in a stream of air compressed by the forward speed of the aircraft itself, as opposed to a jet engine where a compressor section compresses the air.

The scramjet is a ramjet engine in which the airflow through the whole engine remains supersonic. The fuel for the X-43A is hydrogen.

Unlike a rocket that must carry its own oxygen for combustion, an air-breathing engine scoops oxygen from the atmosphere. Without the need to carry oxygen, an air-breathing engine powered vehicle can carry more payload than a rocket-powered propulsion vehicle.

The X-43 uses the body of the aircraft to form critical elements of the engine with the forward section acting as the intake for the airflow and the aft section acting the nozzle.

The world's fastest air-breathing aircraft is the SR-71, which cruises slightly above Mach 3. NASA's X-15 rocket plane reached a top speed of Mach 6.7 in 1967.