New Era of Supersonic Travel Possible Soon?
If it weren't for the noise of the sonic boom, there would be a
whole lot more supersonic travel. As it is, though, where high
speeds are so desireable to those in a hurry, one result -- the
really loud "boom" -- is unacceptable to those who aren't
getting that speed's benefits. Hence, supersonic travel is reserved
for government employees (and the last few rich souls who will take
the Concorde, where the boom is made over the ocean).
That may change.
Next week, officials from DARPA, Northrop Grumman and NASA will
discuss the results of Wednesday's sonic boom demonstration.
Northrop Grumman Corporation's Integrated Systems sector, in
cooperation with the Defense Advanced Research Projects Agency
(DARPA) and NASA, has made aviation history by demonstrating a
method to reduce the bone-jarring impact of sonic booms, a
technology that could usher in a new era of supersonic flight.
In flights conducted
August 27 on the same supersonic test range where Chuck Yeager
first broke the sound barrier nearly 56 years ago, the
government/industry team showed that modifying an aircraft's shape
can reduce the intensity of its sonic boom. This theory had never
been demonstrated in actual flight, until then.
The technology, being developed as part of DARPA's Quiet
Supersonic Platform (QSP) program, could eventually lead
to unrestricted supersonic flight over
land.
"During this centennial year of manned flight, Northrop Grumman
has demonstrated once again that it remains on the cutting edge of
technical innovation," said Charles Boccadoro, Northrop Grumman's
QSP program manager. "This theory had been demonstrated only in
laboratories and wind tunnels. It took a cooperative effort to
achieve this breakthrough."
An aircraft traveling through the atmosphere continuously
produces air-pressure waves similar to waves created by the bow of
a ship. When the aircraft exceeds the speed of sound (approximately
750 mph at sea level), the pressure waves combine to form shock
waves, which are heard as a sonic boom when they reach the
ground.
The flights were conducted at the NASA Dryden Flight Research
Center at Edwards Air Force Base (CA). An F-5E aircraft with a
specially-modified nose section flew supersonically through the
test
range, and sensors on the ground and in other aircraft measured the
sonic boom overpressure.
Shortly thereafter, an unmodified F-5E flew supersonically
through the same airspace. The data comparison of the two aircraft
signatures clearly showed a reduction in intensity of the sonic
boom produced by the F-5E with a modified fuselage. An identical
test later in the day confirmed these results.
"The demonstration has proven the theory that you can reduce
sonic boom intensity by changing aircraft shape, and engineers will
be able to study the data to learn more about the effects of
aircraft shaping on sonic overpressure," said Boccadoro. "Based on
those studies, an experimental aircraft could eventually be built
that will produce a noticeably quieter sonic boom."
The F-5E's modifications, which were designed and installed by
Northrop Grumman, include a specially shaped "nose glove" and the
addition of aluminum substructure and a composite skin to the
underside of the fuselage. The U.S. Navy's Naval Air Systems
Command provided the F-5E aircraft.
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