An experimental aircraft commissioned by NASA will fly over major US cities at faster than the speed of sound. The purpose of the X-59 plane聽is to gather evidence that will determine if supersonic commercial aviation over land should be legalised.
Aircraft create a wake of shock waves once they pass the speed of sound. This 鈥渟onic boom鈥� is so loud it can startle humans and animals and even shatter windows and set off car alarms. When flying at an altitude of 15,000 metres, the now-retired Concorde would create a boom that hit a 100-kilometre-wide area below.
There are currently blanket restrictions on supersonic flight over land, but X-59 may be the start of that changing. NASA developed the X-59 as part of its Quiet Supersonic Technology (Quesst) project, which aims to investigate ways to minimise sonic booms. It plans to fly the aircraft over major US cities at 1510 kilometres per hour and then survey residents about the experience. That data will be passed to the Federal Aviation Administration (FAA) to inform future legislation.
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The aircraft will undergo ground testing before high-speed taxi tests and eventually a first flight, which NASA has not yet set a date for.聽, who manages the project at NASA, says there is only one X-59 aircraft and testing will therefore be thorough. 鈥淲hen it takes off, I鈥檒l be holding my breath until it lands,鈥� she says.
Bahm hopes the project will prove that regulations can be changed to allow overland supersonic flight, essentially by changing current rules from a speed limit to a sound limit.
鈥淐oncorde鈥檚 sound would have been like thunder right overhead or a balloon popping right next to you, whereas our sound will be more of a thump or a rumble, more consistent with distant thunder or your neighbour鈥檚 car door down the street being closed,鈥� says Bahm. 鈥淲e think that it鈥檒l more blend into the background of everyday life than the Concorde did.鈥�
Despite the X-59 being a small, experimental aircraft, Bahm is confident that if it proves successful it will be able to inform designers of large commercial aircraft to achieve the same thing at scale in future. NASA created analytical and design tools to make the X-59 that companies will be able to use to design future aircraft that also minimise sonic booms.
鈥淚 believe that there will be parts of the X-59, essentially the DNA of X-59, incorporated into those aircraft: the long nose, the engine over the wings, the smooth surface under the aircraft. I think those are all key for the lower noise signature,鈥� says Bahm.
If sonic booms can be minimised, the FAA could begin to allow some aircraft to break the sound barrier over US land in order to reduce journey times, despite聽. Reintroducing supersonic travel could also lead to聽, a NASA report found in 2021.
