The second of three unpiloted X-43A vehicles in NASA’s
Hyper-X program is being prepared for a no earlier than Jan 24,
2004, captive carry flight, which is the dress rehearsal for
its free flight currently scheduled for Feb. 21, 2004.

Pending thorough evaluation of all flight data, the captive-
carry test could lead to the December flight of the X-43A
stack. The stack, consisting of the X-43A and its modified
Pegasus booster will be air-launched by NASA’s B-52 carrier
aircraft at 40,000 feet altitude. The booster will accelerate
the experimental vehicle to Mach 7 at approximately 95,000 feet
altitude. At booster burnout, the X-43 will separate and fly
under its own power on a preprogrammed path.

Distinctive to the X-43A is the blending of its integrated
airframe with a scramjet or supersonic combustion ramjet
engine, intended to make the X-43A the first air-breathing
hypersonic vehicle in free flight. The hydrogen-fueled aircraft
has a wingspan of approximately 5 feet, measures 12 feet long
and weighs about 2,800 pounds.

The flight of vehicle two is programmed for Mach 7 – seven
times the speed of sound. The third vehicle of the series is
planned to reach Mach 10. Using an air-breathing scramjet
engine instead of conventional rocket power, the X-43A could be
the forerunner in providing faster, more reliable and less
expensive access to space. A scramjet uses oxygen from the
atmosphere, unlike rockets that must carry oxidizer onboard.
This could enable scramjet vehicles to carry bigger payloads,
travel farther, or be smaller than comparable rocket vehicles.

On June 2, 2001, the first X-43A vehicle was lost moments after
the stack was released from the wing of the B-52. Following
booster ignition, the combined booster and X-43A vehicle
deviated from its flight path and was deliberately terminated.

Investigation into the mishap showed that there was no single
contributing factor but the root cause of the booster going off
its trajectory was resolved through development of better
analytical models and modification of the control system in the
booster. Now, the booster will carry less propellant and will
be released from 40,000 feet instead of 20,000 feet as was done
in the first flight.

Due to risky nature of the flight, the experimental aircraft
will fly in the Naval Air Warfare Center Weapons Division Sea
Range over the Pacific Ocean off the coast of southern
California, where after powered flight, it will glide to a safe
impact and sink. NASA’s Langley Research Center, Hampton, Va.,
and Dryden Flight Research Center, Edwards, Calif., conduct the
Hyper-X program jointly.

Allied Aerospace Industries in Tullahoma, Tenn., built both the
vehicle and the engine, and Boeing North American in Huntington
Beach, Calif., designed the thermal protection and propulsion
control systems. The booster is a modified Pegasus rocket from
Orbital Sciences Corp. Chandler, Ariz.

Media who plan to go to the runway to observe and photograph
the B-52/X-43A stack takeoff must contact the NASA Dryden
Public Affairs Office at: 661/276-3449. The west gate off
highway 14 at Rosamond, Calif., will be the only entrance for

Still photos and video footage will be available from the
Dryden Public Affairs Office to support this release four hours
after the return of the B-52.