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. The Waveforms and Sonic
boom Perception and Response, or WSPR, project gathered data from a select group
of more than 100 volunteer Edwards Air Force Base residents on their individual
attitudes toward sonic booms produced by aircraft in supersonic flight over
Edwards.
Image Credit: NASA/Jim Ross
The return of supersonic passenger travel may be coming closer to reality
thanks to NASA’s efforts to define a new standard for low sonic booms.
Several NASA aeronautics researchers will present their work in Atlanta this
week at Aviation 2014, an annual event of the American Institute of Aeronautics
and Astronautics. They will share with the global aviation community the
progress they are making in overcoming some of the biggest hurdles to supersonic
passenger travel.
The research generates data crucial for developing a low-boom standard for
the civil aviation industry. NASA works closely with the Federal Aviation
Administration and the international aerospace community, including the
International Civil Aviation Organization, to gather data and develop new
procedures and requirements that may help in a reconsideration of the current
ban on supersonic flight over land.
"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. "Other barriers include high altitude emissions, fuel efficiency
and community noise around airports."
Engineers at NASA centers in California, Ohio and Virginia that conduct
aviation research are tackling sonic booms from a number of angles, including
how to design a low-boom aircraft and characterize the noise. NASA researchers
have studied how to quantify the loudness and annoyance of the boom by asking
people to listen to the sounds in a specially designed noise test chamber.
A recent flight research campaign at NASA's Armstrong Flight Research Center
in Edwards, California, had residents explore ways to assess the public’s
response to sonic booms in a real-world setting. Researchers at Armstrong have
an advantage -- pilots are permitted to fly at supersonic speeds because the
facility is located on Edwards Air Force Base.
"People here are more familiar with sonic booms," said Armstrong aerospace
engineer Larry Cliatt. "Eventually, we want to take this to a broader level of
people who have never heard a sonic boom."
Similar work is conducted at NASA's Langley Research Center in Hampton,
Virginia, where volunteers from the local community rated sonic booms according
to how disruptive they determined the sound to be.
"They each listened to a total of 140 sounds, and based on their average
response, we can begin to estimate the general public's reactions," explained
Langley acoustics engineer Alexandra Loubeau.
She also conducted a study at Langley comparing results from tools used to
predict sonic boom noise at ground-level.
“Because of the interaction with the atmosphere, it is important to be as
consistent as possible in the implementation and usage of these tools. The
comparisons done so far have shown good agreement, but there are some
inconsistencies that need to be studied,” Loubeau said.
Other studies are focused on predicting the sonic boom and on design
approaches to reducing it. Participants from Japan, the United States and France
attended the first Sonic Boom Prediction Workshop, where they evaluated simple
configurations -- cylindrical bodies with and without wings -- and complex full
aircraft designs.
"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."
Wind tunnels are another tool used to help predict which airplane designs
might have quieter booms. The most recent tests were conducted at NASA's Ames
Research Center in Moffett Field, California, and Glenn Research Center in
Cleveland. Similar to designs of the past, current aircraft designs being
tested are characterized by a needle-like nose, a sleek fuselage and a delta
wing or highly-swept wings -- shapes that result in much lower booms.
NASA and industry engineers say they believe supersonic research has
progressed to the point where the design of a practical low-boom supersonic jet
is within reach.
For more information on NASA’s Aeronautics Research Mission Directorate, go
to:
To learn more about NASA’s supersonic flight research, go to:
For a schedule, and to watch NASA experts present their latest research
findings live at Aviation 2014, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
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