NASA tries to set airspeed record

NASA on Monday postponed its attempt to set an airspeed record with its pilotless X-43A "scramjet," saying it will attempt the feat on Tuesday instead.

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The X-43A will attempt to reach 7,000 mph, or 10 times the speed of sound (Mach 10) over U.S. Naval airspace off the coast of Los Angeles. The launch will be the third and last of a series, coming eight months after the NASA aircraft reached nearly 5,000 mph in March. Its first launch in June 2001 was aborted when its rocket booster went out of control.

The space agency is testing a type of supersonic engine that uses forward motion for power. As the scramjet propels itself at an altitude of about 100,000 feet, air flows through its engine, where it is isolated and then used for combustion when it mixes with rocket fuel. Common engines on airlines or fighter jets use fan blades to compress air.

To get up to its launch atmosphere, a B-52 bomber will first carry the X-43A, attached to a rocket, in its belly. At 40,000 feet, the B-52 drops its payload and the rocket shoots itself to an altitude of 95,000 feet, where the X-43A turns on its scramjet engine for its attempt to reach Mach 10.

If it works, NASA hopes to use the scramjet concept to build hypersonic missiles and aircraft.

Isn't the Shuttle already faster?

I thought the Shuttle already had the airspeed record. I think on re-entry it comes in at about 18,000 mph. I'm not sure about that number but it sounds right. Maybe they mean powered airspeed record? Or maybe the Shuttle doesn't count because of it's altitude at that speed or something.