The test of the X-43A "scramjet" was the third and most ambitious test of a series. The second test reached 5,000 miles per hour, while the
NASA researchers declared the test, which was aimed both at testing the capacity of the supersonic engine and the performance of the vehicle at the extremely high speeds, a success.
The engine differs substantially from an ordinary jet engine, which typically uses internal rotors to help compress air. The scramjet works more like a simple duct, taking in air through a large opening and funneling it through a much narrower passage.
The rocket plane was carried to its initial altitude of 40,000 feet under the wing of a B-52 bomber, and then released. A rocket carried the plane to its full height of 110,000 feet, where it separated and let the jet operate on its own power.
The Mach 10 speed reached by the plane would be fast enough to travel from Washington, D.C., to Los Angeles in about half an hour.
NASA plans to use the information gathered from the test to help with hypersonic missile and aircraft projects.