Boom or Bust: Can supersonic air travel take off once more?

Supersonic air travel projects have been generating media buzz worldwide, but how likely is flying faster than sound in the near future? Lauren Chester investigates

I recently flew from Europe to Australia – a 24-hour journey I’ve undertaken many times before that never seems to get easier. There is the claustrophobia-inducing lack of space, the air pressure akin to being on top of a 2.4 km-high mountain, the humidity lower than some of the world’s driest deserts, the paranoia of someone coughing near you and, if you’re unlucky, an unruly child kicking your seat for hours on end. You just want the journey to be over as quickly as possible.

But why aren’t commercial flights getting any faster? The main reason is fuel efficiency. The faster a plane flies, the more fuel it burns, and so for economic and environmental reasons, progress has stalled. In fact, overall, commercial planes have become slower. Meanwhile, we have the technology to travel faster than the speed of sound with supersonic flight, so why aren’t we using it?

Snails of the skies: What’s slowing air travel?

With American Airlines’ announcement to buy 20 ultrafast jets from the aviation startup Boom Supersonic, air travel beyond the sound barrier is back on the agenda. This comes more than 50 years after Concorde’s first flight –  the world’s first commercial supersonic jet developed by Britain and France that was eventually decommissioned in 2003. To assess the viability of supersonic air travel, it’s necessary to go back and understand what went wrong.

Concorde: feat or fiasco?

Despite being a feat of aerospace engineering that was set to revolutionise air travel, Concorde was plagued by problems. The first was economic. It guzzled fuel at a rate of 25 629 litres per hour while airborne. Yet it could only seat 100 passengers. The ticket price needed to justify the cost of fuel meant that passenger demand wasn’t exactly high. The next issue was noise. To fly at supersonic speed requires breaking through the sound barrier, creating a “sonic boom”. Due to the noise they generate, supersonic jets are banned from flying over land. This meant that Concorde’s engines at around 105 decibels could only fly above the speed of sound over water, limiting its possible routes.

The project ended in tragedy. In 2000, a Concorde flight from Paris to New York burst into flames and crashed into a hotel, killing 113 people. This disaster proved to be impossible to recover from, and the planes were decommissioned within a few years.

The supersonic renaissance

The dream of commercially viable supersonic flight may well become a reality, with aircraft manufacturers currently in a race to build jets that are not only cost-effective but also more environmentally friendly. With the combined challenges of recouping pandemic profit losses and curbing carbon emissions, the market is ripe for airlines to develop new revenue sources. But critics are sceptical that the financial, technological and environmental hurdles can be overcome.

So how does the new generation of supersonic jets compare? Boom Supersonic’s “Overture” jet is set to be rolled out in 2025 and carry its first passengers by 2029. The plane is being designed to carry 65 to 80 passengers at Mach 1.7 over water – about twice the speed of today’s fastest commercial aeroplanes – and could fly more than 600 routes around the world in half the time.

Timely promise: Boom Supersonic’s slick marketing centres on sustainability

The company is aiming to achieve net zero carbon dioxide by 2025 and net zero greenhouse gas emissions by 2040, saying they are “optimising the airplane to accommodate 100% sustainable aviation fuels”. With improvements in carbon fibre technology and software, the Overture is set to be lighter, quieter, more fuel-efficient and more aerodynamic than its predecessor.

Other competitors in the supersonic jet market include Lockheed Martin, which is working in collaboration with NASA on the X-59 QueSST (Quiet Supersonic Technology). The focus of the aircraft is to reduce sonic booms to a sound they describe as “as loud as a car door closing”. NASA will fly the X-59 over communities in the United States in 2025 to collect data that will inform the future of commercial supersonic flight over land.

Can supersonic ever be green?

Despite the enticing claims made by new generation supersonic jets like the Overture, some scientists and aerospace engineers are unconvinced, arguing that these innovations are difficult to execute.

According to the International Council on Clean Transportation, fuel costs will be a large barrier to supersonic air travel becoming viable. They found that supersonic aircraft will burn seven to nine times more fuel than normal “subsonic” craft, increasing fuel costs by about 25 times compared to aircraft using regular fuels. With the limited supply of sustainable aviation fuel and high cost, they predict zero profit for supersonics burning sustainable aviation fuels under most conditions.

Supersonic dreams: Concorde captured imagination across the globe, although few could ever hope to get on-board

While I still dream of halving the flight time to Australia, the reality is that if supersonic travel came back, it would be for the elite few. Flying this fast would be so resource-intensive that we could be just looking at the Concorde 2.0 with better branding. There’s no doubt that we are on the cusp of huge advances in aviation technology. The question is, at what cost?

An Australian national, Lauren Chester works at the International Transport Forum in Paris as an editor on cutting-edge mobility insights from the ITF’s Corporate Partnership Board to inform a global audience of industry leaders and policy makers.

ITF’s work on sustainable transport includes a particular focus on hard-to-decarbonise sectors, including aviation. Experts are working on pathways to scale up the use of Sustainable Aviation Fuels as a solution to meet increasing air travel demand sustainably. Find out more

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