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Thursday, June 19, 2014

NASA Researching Supersonic Passenger Jet Design

Woodrow Bellamy III 

[Aviation Today June 19, 2014] Researchers at NASA's Ames Research Center are working on establishing a new standard for lowing the noise impact from sonic booms, as the agency attempts to reintroduce the concept of supersonic commercial passenger jets. 

NASA F/A-18 mission support aircraft were used to create low-intensity sonic booms during a resaerch project at the agency's Armstrong Flight Research Center in Edwards, California. Photo: NASA/Jim Ross.

FAA regulations prohibit supersonic flights over land due to the sound emitted from sonic booms. However, several NASA aeronautics researchers are currently using an F/A-18 mission support aircraft to create low-intensity sonic booms over the Armstrong Flight Research Center in Edwards, Calif., as part of the Waveforms and Sonic Boom Perception and Response project. Using data gathered from a group of more than 100 volunteer Edwards Air Force Base residents, the researchers will make conclusions about their individual attitudes toward low intensity sonic booms produced by aircraft engaged in supersonic flight. The researchers presented progress on their work at Aviation 2014, an annual event organized by the American Institute of Aeronautics and Astronautics. 
"Lessening sonic booms — shock waves caused by an aircraft flying faster than the speed of sound — is the most significant hurdle to reintroducing commercial supersonic flight," said Peter Coen, head of the High Speed Project in NASA's Aeronautics Research Mission Directorate at the agency's Headquarters in Washington, D.C. 
Aerospatiale-BAC Concorde performed the last commercial supersonic flight in 2003 on a flight from New York's JFK airport to Heathrow Airport in London. While sound is a major factor, other barriers such as high altitude emissions, fuel efficiency and community noise around airports prevent supersonic commercial flights from becoming widespread, according to Coen. 
NASA facilities in California, Ohio and Virginia are conducting research on sonic booms as well, including how to design aircraft that produce low intensity booms and also how to characterize the noise. During a recent study in Hampton, Va., NASA researchers asked volunteers from local communities to rate sonic booms on how disruptive they believe the sound to be. According to Alexandra Loubeau, an acoustics engineer at NASA's Langley center, based on average response the agency can "begin to estimate the general public's reactions."
While the agency did not propose a timeline or estimate when supersonic commercial flights could make its return to the National Airspace System, the agency is conducting a wide range of studies focusing on predicting the impact of aircraft-produced sonic booms and methods of reducing it. 
"We are working to understand the worldwide state of the art in predicting sonic booms from an aircraft point of view," said Mike Park, a fluid mechanics engineer at Langley. "We found for simple configurations we can analyze and predict sonic booms extremely well. For complex configurations we still have some work to do."

NASA's engineers believe that their research on the topic has progressed to the point where "the design of a practical low-boom supersonic jet is within reach." 

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