Commercial supersonic aircraft may soon return for the first time since Concorde was retired in 2003. Several companies are working on designs and NASA is investing millions in developing technology to eradicate the problematic sonic boom such planes generate. However, whether there will be a market for these kind of flights isn’t known, especially given their large carbon footprint.
Aircraft create shock waves once they pass the speed of sound, which is about 1224 kilometres per hour and known as Mach 1. This results in a sonic boom so loud that it can startle humans and other animals and even shatter windows and set off car alarms. When flying at 15,000 metres, Concorde would create a boom that hit a 100-kilometre-wide area below. Because of this, many countries have blanket bans on supersonic commercial aircraft.
However, NASA has developed a prototype aircraft that it calls the X-59 (pictured, below) as part of its Quiet Supersonic Technology (Quesst) project. The plane is being built by Lockheed Martin, and the aim is to investigate ways to minimise sonic booms. NASA plans to in 2025 at 1510 kilometres per hour and then survey residents about the experience. That data will be passed to the Federal Aviation Administration to inform future legislation.
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Efforts are also under way to design working airliners that could go almost twice the speed of sound. US-based startup Boom Supersonic is focused on a prototype it calls (pictured above). This first flew in March 2024 and has been ramping up test flights since, reaching Mach 0.69 so far, but the plan is for it to break the sound barrier in coming months.
Information from these flights will inform the design of the company’s , which it claims will cruise at Mach 1.7 and carry 80 passengers. The firm says the first one will , but won’t carry passengers until 2029.
Leading the way in terms of test flights is Dawn Aerospace, which r to an altitude of more than 25000 metres and a speed of Mach 1.1. The company claims that this is the first time a civilian aircraft has flown at supersonic speeds since Concorde. Dawn Aerospace expects the Aurora will eventually reach Mach 3.5 and go to the edge of space at altitudes of 100 kilometres.
at Swansea University, UK, can remember hearing Concorde’s sonic boom as a child once it had passed the Bristol Channel, a coastal inlet in south-west England, after which it was allowed to accelerate beyond the speed of sound. A similar problem will be faced by future supersonic craft, despite NASA’s efforts.
“If something flies faster than the speed of sound, it drags a shock system with it,” says Evans. “You can do your very, very best to make that shock system as weak as possible, but I’ve not seen any evidence that you can completely attenuate it.”
Excessive noise would mean that future supersonic aircraft have to exit the coastline of a country before passing the sound barrier, and would be excluded from routes that only pass over land. Evans believes there are other hurdles, too, such as cost and environmental damage.
He says the drag of an aircraft increases as you approach and push past the speed of sound and that this requires extra thrust to maintain speed. This burns more fuel, which would raise emissions – aviation already contributes 3 per cent of global carbon emissions from burning fossil fuels – and increase the cost of tickets.
“I’m unconvinced there’s a market for it,” says Evans. “People’s bigger concerns are going to be about how sustainable it is, how comfortable it is. Do we ever really now need, with the likes of Zoom, to fly across the Atlantic for a couple of hours to meet someone and then fly back? Those days are over.”
Evans believes that many of the companies developing supersonic and hypersonic aircraft ostensibly for commercial transport know that the most likely source of revenue is from military applications, where budgets and carbon footprints are considered less important than all-out performance.
