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.

FMI: www.northropgrumman.com; www.is.northropgrumman.com/index.html