Michael Braukus Headquarters Washington September 4 2003 Phone 202/358-1979 Kathy Barnstorff Langley Research Center Hampton Va Phone 757/864-9886 Gray Creech Dryden Flight Research Center Edwards Calif Phone 661/276-2664 RELEASE 03-283 NASA OPENS NEW CHAPTER IN SUPERSONIC FLIGHT Flight tests completed by NASA with government and industry partners may have demonstrated a way to reduce the window-rattling impact of sonic booms In flights conducted Aug 27 on the same test range where Chuck Yeager first broke the sound barrier nearly 56 years ago the team showed modifying an aircraft shape can also change the shape of its sonic boom thereby reducing loudness This theory had never been demonstrated in actual flight The Defense Advanced Research Projects Agency Shaped Sonic Boom Demonstration SSBD program is a $7 million cooperative agreement supported by NASA Langley Research Center LaRC Hampton Va. NASA Dryden Flight Research Center Edwards Calif. and Northrop Grumman Corporation El Segundo Calif The program has also received support from other government and industry organizations This demonstration is the culmination of 40 years of work by visionary engineers said Richard Wlezien Program Manager for Vehicle Systems in NASA Office of Aerospace Technology Washington They foresaw a way to solve the sonic boom problem and to enable a generation of supersonic aircraft that do not disturb people on the ground It is but one of many frontiers in aeronautics that remain to be explored he said 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 merge to form shock waves which are heard as a sonic boom when they reach the ground The flight tests showed by designing the aircraft to a specific shape the pressure waves can be kept from merging When these weaker waves reach the ground the loudness of the sonic boom is greatly reduced The team was confident the SSBD design would work but field measurements of sonic booms are notoriously difficult said Peter Coen Supersonic Vehicles Technology manager at LaRC We were all blown away by the clarity of what we measured For the demonstration Northrop Grumman modified an F-5E fighter aircraft that was provided by the U.S Navy Naval Air Systems Command The company designed and installed a specially shaped nose glove and added aluminum substructure and a composite skin to the underside of the fuselage During the experiment the modified F-5E aircraft flew through a test range at Edwards Air Force Base Calif. at supersonic speeds NASA and industry sensors on the ground and in Dryden F-15B measured the shape and magnitude of the sonic boom Shortly thereafter an unmodified F-5E flew through the same airspace Comparison of the data confirmed the modified shape of the test aircraft altered the sonic boom as expected Repeated tests verified these results For information about NASA on the Internet visit