X-43A AIRCRAFT PROGRAM REACHES KEY MILESTONES.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - NASA's Hyper-X program, aimed at creating a high-speed aircraft powered by an unconventional type of jet engine, hit two milestones with the mating of the first X-43A aircraft to a Pegasus booster and the arrival at Edwards Air Force Base of the second aircraft.

The first of three X-43A aircraft has gone through electrical and mechanical checks and was attached to a Pegasus rocket booster. The Pegasus/X-43A tandem will go through ``captive-carry'' flight tests hung underneath the wing of a modified B-52 before its first flight this spring.

``The project team is excited about this milestone. Everyone is anxious to fly,'' said Joel Sitz, the National Aeronautics and Space Administration's Dryden Flight Research Center's X-43 project manager. ``We have worked extremely hard on improving the chances for Hyper-X mission success.''

The second X-43A arrived at Dryden in late January.

The ultimate goal of the Hyper-X program is to create a scramjet-powered aircraft, one that would use air from the atmosphere rather than carry oxygen like a rocket. The savings from not having to carry oxygen fuel tanks would allow an aircraft to carry more scientific or other equipment.

A scramjet is a high-altitude, very-high-speed version of a ramjet, an engine that lacks conventional jet engines' whirling fan blades for compressing air to oxidize fuel.

In a ramjet, the fuel is continuously compressed by being rammed into the inlet by the aircraft's high velocity. In a scramjet, the airflow through the whole engine remains supersonic.

Three X-43A aircraft will be used for test flights ranging from Mach 7, which is about 5,320 mph, to Mach 10, about 7,600 mph.

During each mission, an X-43A attached to a Pegasus booster rocket will be taken aloft from Edwards by a modified B-52. The X-43A will be dropped from the B-52 off the California coast near Vandenberg Air Force Base.

The Pegasus booster will hit Mach 7 and carry the X-43A to more than 100,000 feet in about 90 seconds. From there, the X-43A will separate from the booster, and the aircraft's scramjet will fire for five to seven seconds.

After the engine shuts off, the X-43A will perform a series of preplanned aerodynamic maneuvers before it slams into the Pacific Ocean.

The X-43A airframe is a scaled-down version of the X-30, the national aerospace plane. The X-30 was a NASA effort to try to develop a spacecraft that could fly into space on a single stage, taking off and landing on conventional runways. The program was canceled in the early 1990s.

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(color) NASA's X-43A aircraft program is aimed at creating a high-speed aircraft powered by an unconventional type of jet engine.