NASA to Test Quiet Thump Supersonic Propulsion Technique, Measure Sound Levels and Community Response

Lessons learned in NASA’s Quiet Supersonic Flights 2018 (QSF18) campaign will be applied to the X-59 Quiet Supersonic Technology (QueSST) experimental aircraft program.

November 5, 2018

Courtney E. Howard

NASA’s F/A-18 research aircraft will perform a special dive maneuver that will create a sonic boom out over the Gulf of Mexico in such a way that residents in Galveston would perceive it as a quiet thump – that is, if they are able to hear it at all. (Image courtesy NASA/Lauren Hughes)

NASA officials and engineers are prepping to fly the agency’s F/A-18 research aircraft over Galveston, Texas, using a “quiet thump” technique designed to reduce loud sonic booms typically associated with supersonic flight . This week’s test flight sets off a series of quiet supersonic research flights off the coast of Texas to test ways to measure supersonic aircraft sound levels and the community’s response to the supersonic acoustic experience.

With the goal of “going quiet over Galveston,” these supersonic research flights are part of NASA’s Quiet Supersonic Flights 2018 (QSF18) campaign, a cooperative aeronautics research effort involving NASA’s Armstrong Flight Research Center in Edwards, California; Johnson Space Center in Houston; and Langley Research Center in Hampton, Virginia.

Commercial supersonic flight is currently prohibited over land given that an aircraft flying at supersonic speeds – i.e., faster than Mach 1, the speed of sound – produces a loud sonic boom . Noise mitigation is currently a challenge and major aerospace engineering thrust.

During the test flight on Nov. 9, NASA test pilots will fly an F/A-18 supersonic research aircraft in a unique maneuver intended to produce a quieter “thump.” Test pilots will take the F/A-18 aircraft from Ellington Field, just north of NASA's Johnson Space Center in Houston, to Galveston, where QSF18 field team members operating microphone stations will measure sound levels.

A NASA F/A-18 demonstrates the quiet supersonic dive maneuver over NASA’s Armstrong Flight Research Center in California, creating a quiet thump in a necessary area instead of a louder sonic boom. NASA has used microphones to measure the levels of these sounds, and has studied the thumps to confirm they pose no danger to people, animals or structures. (Image courtesy NASA/Lauren Hughes)

“QSF18 is a big step in NASA’s efforts to understand what is required for acceptable supersonic overland flight,” affirms NASA’s Commercial Supersonic Technology Project Manager Peter Coen. “This is the first time in decades that we have reached out to a large community as part of our supersonic research.

“NASA has performed similar tests at our Armstrong Flight Research Center, using similar sounds created by the same F/A-18 . We’ve measured the noise levels and the impact on structures, as well as surveyed people for annoyance, to make certain that these tests are safe and well-planned,” Coen adds. “We greatly appreciate Galveston’s interest and support.”

NASA will fly an F/A-18 research aircraft in Galveston to perform an offshore supersonic dive maneuver. The maneuver will produce a quiet “thump” sound similar to the predicted sound signature of the recently-announced Low Boom Flight Demonstration (LBFD) aircraft. (Image courtesy NASA/Bill White)

The F/A-18, considered a typical supersonic aircraft, will be put into a quiet supersonic dive maneuver to quiet the boom, explains Matt Kamlet of NASA Armstrong Flight Research Center. Starting out over the water at around 50,000 feet the aircraft will be put into a special dive that still creates a regular sonic boom; yet, when the sound reaches land it should be heard as a quieter “thump.”

“NASA’s role as a leader into new frontiers paves the way forward toward new technologies, opportunities, and milestones across multiple endeavors, as we have always done throughout our history,” says Mark Geyer, director of NASA’s Johnson Space Center. “As our efforts also continue to expand our boundaries and capabilities in space, Johnson Space Center is proud to be working with our colleagues at NASA’s research centers at Langley and Armstrong, and to take part in the agency’s aeronautics research efforts to lead aviation into a new era as ‘One NASA.’”

“This is the type of project that motivates engineers and innovators,” says Galveston Mayor James Yarbrough. “In Galveston, we have a long and proud history of being involved in advances in science and technology. In this case, our residents will have an opportunity to participate in a study to advance aviation and the design of commercial planes that can break the sound barrier quietly. We’re excited to be a small part of it, and we’ll do what we can to support NASA and help ensure the success of this study. Thanks to NASA for choosing Galveston as the location for testing this idea.”

While the “quiet thumps” produced by the F/A-18 present no risk of causing physical damage to people or structures, NASA has learned that elements such as atmospheric turbulence and humidity can influence how certain areas may perceive the sound, which may be heard differently from other areas. NASA will operate a number of microphone stations in the area to match up the community’s response with the decibel level of each sonic thump.

In Galveston, NASA will survey 500 recruited volunteer residents to determine whether they heard the thumps and define the level at which they were able to perceive the sound. Doing so will help NASA better understand successful data collection methods for future flights using the X-59 Quiet Supersonic Technology (QueSST) experimental aircraft.

Starting in 2022, the X-59 will directly fly over communities to collect data using lessons learned from QSF18.

In several years, the X-59 Quiet SuperSonic Technology (QueSST) X-plane will test its quiet supersonic technologies by flying over communities in the United States. Meanwhile, NASA’s QSF18 features an F/A-18 flying off the coast of Galveston, helping NASA to confirm techniques for X-59’s future community response flights. (Image courtesy NASA)

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Courtney E. Howard is editorial director and content strategist at SAE International, Aerospace Products Group. Contact her by e-mail at This email address is being protected from spambots. You need JavaScript enabled to view it..