Why don’t we have supersonic aircraft any more? Although commercial supersonic air travel kicked off in the 1960s with the arrival of the Concorde, since that jet was retired in 2003, there are no supersonic jets in common civilian usage any more. Part of that is because the Concorde was expensive and difficult to maintain, and the increase in speed wasn’t worth the huge bump in money and effort it took to keep it flying. But another part of it is something that seems to be endemic to faster-than-sound travel: the sonic boom.
When an object accelerates to faster than the speed of sound, it creates shockwaves that cause a sonic boom. This is noisy enough to wake people sleeping beneath an aircraft’s flight path, and can even damage buildings or other structures on the ground. So, understandably, supersonic flights are forbidden across the U.S.
But NASA wants to show that faster-than-sound travel is possible without the annoyance of the boom, which is where its X-59 experimental aircraft comes in. The X-59, built by Lockheed Martin, is designed to create a “thump” rather than a boom when traveling past the sound barrier, with the aim to make it less annoying to those people beneath.
The aircraft recently fired up its engine for the first time, with tests checking that everything operates correctly when the engine is running at lower speeds before the engine is run up to its high speeds.
“The first phase of the engine tests was really a warm-up to make sure that everything looked good prior to running the engine,” said Jay Brandon, NASA’s X-59 chief engineer. “Then we moved to the actual first engine start. That took the engine out of the preservation mode that it had been in since installation on the aircraft. It was the first check to see that it was operating properly and that all the systems it impacted – hydraulics, electrical system, environmental control systems, etc. – seemed to be working.”
Though the X-59 is a research project, not an attempt to build a commercial aircraft, NASA’s aim is to create quiet supersonic technologies that could eventually be adopted by commercial companies. The Quesst mission involves not only building the X-59 aircraft,but also collecting data on how the noise is perceived by people on the ground, with the aim of getting the ban on supersonic flight lifted.
For now, the aircraft will remain on the ground as it goes through more testing before it takes to the air for its first flight test. “The success of these runs will be the start of the culmination of the last eight years of my career,” said Paul Dees, NASA’s deputy propulsion lead for the X-59. “This isn’t the end of the excitement, but a small steppingstone to the beginning. It’s like the first note of a symphony, where years of teamwork behind the scenes are now being put to the test to prove our efforts have been effective, and the notes will continue to play a harmonious song to flight.”
