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CFD Used In Sonic Boom Test Program
Posted Tue September 23, 2003 @08:13AM
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Application Engineers at Wyle Laboratories have played a significant role in the Northrop Grumman sonic boom test program. Wyle was under contract to Northrop Grumman for the DARPA sponsored Quiet Supersonic Platform (QSP) and the Shaped Sonic Boom Demonstration (SSBD) project.

The objective of the Quiet Supersonic Platform was to develop advanced technology for low-boom supersonic aircraft while the objective of the Shaped Sonic Boom Demonstration project was flight verification that the shape of a sonic boom could be controlled by proper configuration of the aircraft.


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"The theory for 'shaped minimized' sonic booms was developed in the 1960s, but had never before been proven in flight," said Dr. Ben Sharp, head of Wyle's Acoustic Research unit. "The successful flight test showed that the annoying 'bang' of sonic booms can be substantially reduced, and thus opens the door to commercial supersonic flight."

Wyle participants included Dr. Kenneth Plotkin and Juliet Page, both experts in sonic boom.

In the Shaped Sonic Boom Demonstration project, Wyle provided engineering expertise in reduced sonic boom configuration analysis, and assisted Northrop Grumman in developing the shape of the modified Shaped Sonic Boom Demonstration platform. Propagation of sonic boom to the ground was calculated using PCBoom4, a program developed by Wyle.

"A critical point was reached in early 2002, when independent computational fluid dynamics calculations of the final configuration were performed by Northrop Grumman, Boeing and Lockheed," said Dr. Plotkin. "Apparent inconsistencies were seen among the three sets of calculations.

"Page's computational fluid dynamics expertise was called into action for a thorough critical review of the analyses. That review confirmed Northrop's Shaped Sonic Boom Demonstration platform design, a conclusion subsequently validated by wind tunnel tests and the historic flight test."

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, Calif. 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.

Wyle was also contracted by NASA to evaluate the effect of atmospheric conditions on the predicted sonic boom. Dr. Plotkin, an expert in atmospheric propagation, performed the analysis.

The study included definition of go/no-go criteria for the flight test. On the Aug. 27 morning of the historic flight, Dr. Plotkin was at Northrop's Palmdale control center and personally gave the go-ahead for launch. The next morning, he was at the measurement site in the Mojave Desert, operating a monitoring station and giving launch approval by radio after seeing the latest atmospheric sounding.

DARPA's Quiet Supersonic Platform program is an effort to identify and mature technologies that could allow military and business aircraft to operate with reduced sonic boom. Northrop Grumman has been working under contract with the QSP program since 2000 at its Advanced Systems Development Center in El Segundo. As part of that work, Northrop Grumman has designed a long-range supersonic military aircraft and validated key integration technologies associated with that design.

Wyle, with more than 1,500 employees at 13 major facilities across the nation, is a diversified high tech engineering company. The company provides life sciences services, technical support services, and aerospace and commercial test services.

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Related Links
  • DARPA
  • NASA
  • Northrop Grumman
  • Quiet Supersonic Platform
  • Shaped Sonic Boom Demonstration
  • Wyle Laboratories
  • More on Application
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