A tiny unmanned NASA "scramjet" soared over the Pacific
Ocean Tuesday to demonstrate a radical new engine
technology by attempting to fly at a record speed of
about 7,000 mph, almost 10 times the speed of sound.
The 12-foot-long X-43A supersonic combustion ramjet was
to fly under its own power at Mach 10 for about 10
seconds after separating from a booster rocket at
110,000 feet, then glide to a splash landing.
The flight was an apparent success, and confirmation of
the speed achieved was expected to be announced later by
officials at NASA's Dryden Flight Research Center at
Edwards Air Force Base.
"The research vehicle was absolutely rock-solid stable,"
said Griff Corpening, chief engineer on two previous
X-43A flights. "All indications (are) we had a
The X-43A, mounted on a Pegasus rocket used to boost it
to flight speed, was carried under the wing of a B-52
aircraft and released at an altitude of 40,000 feet over
a test range off the Southern California coast. The
rocket motor then fired for a 90-second ascent.
Like its predecessors, the X-43A will not be recovered
from the ocean.
The flight was the last in a $230 million-plus effort to
test technology most likely to be initially used in
military aircraft, such as a bomber that could reach any
target on Earth within two hours of takeoff from the
United States, or to power missiles.
Scramjets may also provide an alternative to rockets for
Unlike conventional jet engines which use rotating fan
blades to compress air for combustion, the X-43A has no
rotating engine parts. Instead it uses the underside of
the aircraft's forebody to "scoop" up and compress air
for mixing with hydrogen fuel.
The X-43A launched Tuesday was the last of three built
for NASA's Hyper-X program.
The first X-43A flight failed in 2001 when the booster
rocket veered off course and was destroyed.
The second X-43A successfully flew in March, reaching
Mach 6.83 - nearly 5,000 mph - and setting a world speed
record for a plane powered by an air-breathing engine.
That was more than double the top speed of the
jet-powered SR-71 Blackbird spyplane, which at slightly
more than Mach 3 is the fastest air-breathing, manned
The old X-15 was the fastest rocket-powered manned
airplane, hitting Mach 6.7. Rockets do not "breathe"
air, but instead carry oxidizers that are combined with
fuel to allow combustion.
Not having to carry oxygen is one of the advantages
scramjets hold over rockets. Rockets can also achieve
high speeds, but the weight of oxygen tanks or other
oxidizers reduces the amount of payload they can carry.
Tuesday's launch was expected to be the last research
flight for NASA's B-52, which is being retired after
some 40 years of service.