Imagine a new breed of space transportation vehicle, able
to fly at seven times the speed of sound, using a next-
generation air-breathing jet engine. NASA takes a hypersonic
leap into the future of aerospace technology with the flight
of the scramjet-powered X43A.

It will be the first time a non-rocket propelled, air-
breathing engine has powered a vehicle in flight at hypersonic
speeds, or five times the speed of sound. An aircraft moving
at Mach 5 would travel about one mile per second, or about
3,600 mph at sea level, far faster than any air-breathing
aircraft has ever flown.

Unlike a rocket that carries its own oxygen for combustion,
the X-43A’s scramjet scoops air from the atmosphere, making
the aircraft lighter, which enables it to carry heavier
payloads. The hydrogen-fueled aircraft has a wingspan of
approximately 5 feet, measures 12 feet long and weighs about
2,800 pounds.

The first unpiloted X-43A and its Pegasus booster rocket will
be air-launched from a B-52 from NASA’s Dryden Flight Research
Center, Edwards, CA. The booster will accelerate the
X-43A to Mach 7 at approximately 95,000 feet. At booster
burnout, the X-43 will separate and fly under its own power on
a preprogrammed flight path.

The NASA Hyper-X Program’s development and flight testing of
the X-43 vehicle is conducted jointly by Dryden and NASA’s
Langley Research Center, Hampton, VA. “The Hyper-X Program and
the X-43A Flight Project have forged a very fruitful
partnership and national asset,” said Joel Sitz, Dryden’s X-43
project manager. “What the country is witnessing is the re-
birth of hypersonics.”

Sitz added, “After a successful X-43A mission, the ‘brain
trust’ will exist to move forward with future propulsion-
research vehicles that will ultimately result in more
efficient space access vehicles.”

“The Hyper-X program takes what we’ve been doing for the last
40 years in wind tunnel research to flight. Flight is
reality,” said Vince Rausch, Hyper-X program manager at
Langley. “The program is structured around the scramjet engine
and should be a major leap forward in the national capability
for access to space. The country is looking for safer, more
flexible, less expensive ways to get to space, and that’s what
the scramjet engine would bring us.”

Scramjet technology could also allow more traditional
aircraft-like operations of launch vehicles, with horizontal
take-off, landing and servicing, which could greatly reduce
operational cost and time between flights.

Three X-43A flights are planned; the first two will fly at
Mach 7 and the third at Mach 10. Valuable performance data
will be relayed electronically to Dryden and Langley. Each
experimental aircraft will fly once in the Naval Air Warfare
Center Weapons Division Sea Range off the southern coast of
California and impact into the Pacific Ocean.

Like the comparatively slower ramjet counterpart, the scramjet
has a simple mechanical design with no moving parts. However,
scramjet combustion occurs at supersonic air speeds in the
engine. Rather than using a rotating compressor like a
turbojet engine, the forward velocity and vehicle aerodynamic
design compress air into the engine. There, fuel, usually
hydrogen, is injected and the expanding hot gases from
combustion accelerate the exhaust air and create thrust. In
the case of X-43, the thrust will propel the vehicle at
hypersonic speeds up to Mach 10.

The first free-flight test will be approximately three weeks
after an upcoming captive-carry flight, where the B-52 flies
with the X-43A “stack” to the test range for a series of
flight systems tests.

Following the first series of X-43A hypersonic flights, the
next step is an expanded hypersonics research ground and
flight program currently in place as part of the Advanced
Space Transportation Program, which is led by NASA’s Marshall
Space Flight Center, Huntsville, AL.

The vehicle contractor team, led by MicroCraft in Tullahoma,
TN, includes The Boeing Co., Seal Beach, CA, and GASL, Inc.,
Ronkonkoma, NY. The booster is a modified Pegasus rocket from
Orbital Sciences Corp., Chandler, AZ

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