Quiet supersonic jets may one day fly over land to offer faster commercial and passenger flights. Before that can happen, however, the FAA will need to establish new rules regarding these typically noisy flights. To help usher in that era, NASA plans to test Lockheed Martin’s X-59 QueSST, an experimental supersonic jet that produces a ‘thump’ instead of a ‘boom,’ something the space agency will verify using a microphone array that is 30 miles long.
Since the early 1970s, it has been against the law to conduct supersonic flights over U.S. soil due to the loud booming noises caused by breaking the sound barrier. NASA is paving the way to eventually change this legislation with its Low-Boom Flight Demonstrator program, which will involve testing and validating technology that produces quieter supersonic flights.
Unlike the loud booms associated with existing supersonic jets, the X-59 aircraft can break the sound barrier while only producing a quieter ‘thump’ sound. This noise is likely far less distracting to people on land, but NASA will need to prove that using a series of upcoming tests.
NASA plans to eventually conduct authorized supersonic flights using the X-59 over select communities in the United States in order to gather feedback and data on the noise produced and how it impacts the cities and neighbors nearby. Ahead of that, however, the space agency will conduct test flights over the Mojave Desert in California and monitor the noise levels produced using microphones spread over 30 miles.
These microphones have been ‘specially configured’ for these tests, according to NASA, which will verify the quiet ‘thumps’ produced by the X-59 using data from the array. The high-fidelity microphones can measure 50,000 samples per second; various microphone sites have different configurations, as well, to determine the best arrangement for gathering these noise measurements.