WASHINGTON, May 3 (Xinhua)
-- The U.S. Air Force announced
Friday its X-51A Waverider aircraft
has achieved the longest hypersonic
flight in history, flying for three
and a half minutes on scramjet
power at more than five times
the speed of sound.
The
final flight of the unmanned aircraft
built by Boeing reached Mach 5.1 over
the Pacific Ocean on May 1. It
traveled over 230 nautical miles in
just over six minutes.
"It
was a full mission success," said
Charlie Brink, X-51A program manager
for the Air Force Research Laboratory
Aerospace Systems Directorate. "I believe
all we have learned from the
X-51A Waverider will serve as the
bedrock for future hypersonics research
and ultimately the practical application
of hypersonic flight."
With the
test, the U.S. Air Force has
successfully completed a 300-million-dollar,
nearly decade-long hypersonic test program
that reportedly can be used to
deliver strikes around the globe
within minutes.
The X-51A took
off from the Air Force Test
Center at Edwards Air Force Base
in California, under the wing of
a B-52H Stratofortress. It was
released at approximately 15,000 meters and
accelerated to Mach 4.8 in about 26
seconds powered by a solid rocket
booster.
After separating from
the booster, the cruiser's scramjet
engine then lit and accelerated to
Mach 5.1 at 18,000 meters.
After
exhausting its 240-second fuel supply,
the vehicle continued to send back
telemetry data until it splashed down
into the ocean and was destroyed
as designed.
"This demonstration
of a practical hypersonic scramjet
engine is a historic achievement that
has been years in the making,"
said Darryl Davis, president of Boeing
Phantom Works, in a
statement.
"This test proves
the technology has matured to the
point that it opens the door to
practical applications, such as advanced
defense systems and more cost-effective
access to space," said
Davis.
This was the last
of four test flights for X-51A.
The first occurred in May 2010. It
was hailed as a success, as the
vehicle flew for nearly 200 seconds
and reached approximately Mach 5. The
next two flights, in June 2011 and
August 2012, both failed.
The
Air Force said that X-51A is a
technology demonstration program and was
not designed to be a prototype
for weapon system. It was designed
to pave the way to future
hypersonic weapons, hypersonic intelligence,
surveillance and reconnaissance, and future
access to space.
Since
scramjets are able to burn atmospheric
oxygen, they don't need to
carry large fuel tanks containing
oxidizer like conventional rockets, and
are being explored as a way to
more efficiently launch payloads into
orbit.
（Editor：HuangBeibei、Yao
Chun）
