According to a NASA press release published October 30, aircrafts flying at supersonic speeds generate a sonic boom, a sound similar to a thunderclap which is associated with the shock waves produced whenever an object moving through the air travels faster than the speed of sound. Most commercial supersonic flights are currently banned in the US by the Federal Aviation Administration.
However, this week, NASA pilots began flying an F/A-18 supersonic research aircraft, which reportedly only generates a quiet "thump" as opposed to a disruptive "boom." The purpose of the Quiet Supersonic Flights 2018 (QSF18) campaign, as NASA's experiment is called, is to determine how people and sensors on the ground react to the sound.
"QSF18 is a big step in NASA's efforts to understand what is required for acceptable supersonic overland flight," NASA's Commercial Supersonic Technology Project Manager Peter Coen said in the press release.
"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. We greatly appreciate Galveston's interest and support," he continued.
In order to generate just a quiet "thump," the F/A-18 starts out over water in Galveston before it is put into a supersonic dive maneuver at around 50,000 feet up. The dive still generates a typical sonic boom. However, by the time the sound reaches land, it is much more muffled than the typical sonic boom.
So far, 500 volunteers have been recruited from the Galveston area to provide feedback to NASA on the sound produced by the F/A-18. The data collected from QSF18 will be used to help NASA "understand successful data collection methods for future flights using an experimental aircraft called the X-59 Quiet Supersonic Technology," the press release states.
"Galveston is both honored and excited to be part of this project," Galveston Mayor James Yarbrough told NASA.
"This is the type of project that motivates engineers and innovators. In Galveston, we have a long and proud history of being involved in advances in science and technology, whether that's in medicine, rail or shipping. 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," he added.
Although the thumps generated by the F/A-18 present no risk of of physical damage to people or structures on the ground, NASA has found that factors like atmospheric turbulence and humidity can impact how different areas respond to sonic boom decibel levels.