NASA’s experimental supersonic plane recently completed its 25th flight, racking up significant miles in the air before its noise levels are put to the test. The X-59 took off from NASA’s Armstrong Flight Research Center in Edwards, California, on August 21 for the latest in a series of successful tests. The plane flew for a total of 72 minutes, reaching a speed of Mach 1.2 and an altitude of about 49,000 feet (14 kilometers), according to NASA. Like all its previous test flights, the plane was accompanied by a NASA F-15 chase plane for follow-up. The sonic booms from the chase plane drowned out any noise produced by the X-59, but that won’t be the case for much longer. NASA is finally preparing to evaluate the experimental plane’s much quieter noises later this year, putting its innovative technology to the test. Supersonic Speeds The X-59 is designed to break the sound barrier without producing the loud, explosive sound known as a sonic boom. After years of development, the plane broke the sound barrier for the first time on June 5, reaching a top speed of approximately Mach 1.1, or 713 miles per hour (1,147 kilometers per hour). Since then, NASA has continued to test the performance of its plane before moving to the next phase. “Through our ongoing flight tests with the “Each test point has validated our models and predictions, and strengthened our confidence in the aircraft’s performance. Each flight brings us closer to transitioning to the next phase, where we will demonstrate the silent supersonic flight capabilities of the X-59.” During its acoustic validation phase, researchers will carefully measure the aircraft’s supersonic acoustic signature to confirm that the X-59 is performing as intended and producing a sonic thump instead of a boom. According to NASA, instead of a sonic boom, the X-59 aircraft is intended to mitigate noise and release a sonic boom. In this way, the experimental aircraft could pave the way for commercial supersonic flights over land. Make some noise The plane has performed well during its test flights and has not suffered any unexpected phenomena, such as instability or excessive vibration, in response to aerodynamic forces, according to NASA. Between each flight, pilots, engineers and maintenance personnel review flight test and aircraft data to make any necessary adjustments. So far, the team has only had to make some minor adjustments to the aircraft’s control software to resolve an issue in which its systems were interpreting nuisance alerts as caution warnings. NASA describes the next phase of testing as the “biggest benchmark for the X-59,” which involves measuring what it will sound like at supersonic cruising speeds. “This is the phase we have been working on,” Larry Cliatt, acoustic validation technical lead for NASA’s Questst mission, said in a statement. “Building and flying a new aircraft is an extraordinary achievement, but the next phase is where the real research begins.” During the acoustic validation phase, the team will use a variety of ground and airborne tools to measure and characterize the X-59’s sonic knocks. The aircraft’s sleek design is intended to reduce the pressure change flowing over the ground, while the engine is mounted on top to reduce the amount of aircraft noise reaching the ground. “The acoustic validation will test the tools and methods used to design the X-59, tools that could ultimately become part of the DNA of every future commercial supersonic aircraft,” Cliatt said. “It will be a complex and demanding flight campaign focused on demonstrating that the X-59 can produce the quiet sonic noise it was designed to produce.”
