New York in an hour? The truth about hypersonic travel

Could British holidaymakers soon be jetting to New York in less than an hour? That’s the claim that’s been circulating in the press this month after a US aerospace company unveiled a new jet engine which it says will reach speeds of around 4,600 miles per hour.

The company behind the story, Venus Aerospace, might not have actually developed a plane to go with it yet, but already there’s been a flutter of excitement for what those kinds of speeds might mean for transatlantic ventures (which are typically between 3,500 and 5,500 miles, depending on which coast you’re jetting off to).

Exciting news, you might think. But then perhaps some scepticism would be justified, given it’s hardly the first time that we’ve seen headlines about supersonic (or, in this case, hypersonic) technologies said to be just years away from revolutionising commercial air travel.

Have any of these great strides come to pass? There was Concorde, of course, which reduced the flight time between London and New York to about three-and-half hours before being retired in 2003. These days, though, the great White Bird has become a museum piece, and flights to the Big Apple have reverted back to an eight-hour slog.

It isn’t that technology hasn’t moved forward. In 2010, an experimental aircraft developed by Nasa, known as the X-43A, reached a speed of Mach 9.6 in an experimental test flight. For reference, that’s almost ten times the speed of sound and almost exactly the same speed as the new jet that Tom Cruise’s character flew in Top Gun: Maverick.

Yes, the X-43A is an unmanned aircraft, but that certainly isn’t the case for Lockheed Martin’s legendary SR-71, which holds the record for the fastest journey between New York and London in just under two hours. When did the SR-71 Blackbird chalk up this fearsome feat? Way back in 1974.

Why haven’t we seen the same progress with commercial flights? As you might imagine, one of the biggest hurdles has been applying the hyper-speedy capabilities utilised by combat jets to passenger planes, which tend to come with much heavier loads and stringent regulatory requirements.

“If you look at a supersonic plane like the SR-71, the on-board experience could not be more different from a passenger aircraft,” says Dave Alexander, a former RAF pilot and now trainer with Leading Edge Aviation. And not just because the plane only carried two people.

To reach supersonic speeds, planes have to fly at much higher altitudes – around three times as much as a passenger jet – potentially placing strenuous demand on the bodies of anyone on board. “The crew of the SR-71 would have been wearing pressure suits similar to those worn by astronauts,” he adds.

Later military jets have departed even further from the traditional model of the civilian plane. Look at Nasa’s latest supersonic project, the X-59, which required the cockpit to be positioned halfway down the plane with the pilot guided by a live video feed, rather than looking out of the windshield.

Still, even these military-purpose jets can sometimes bring breakthroughs which might benefit civilian aircraft. Take the X-59, for example, which is defined by its ultra-long nose, designed to enable the plane to fly at supersonic speeds without causing ear-splitting sonic booms.

This is quite the development, given that loud sonic booms are the reason why commercial planes are banned from breaking the sound barrier when flying over land (hence Concorde being limited to supersonic speeds when flying over the ocean). The learnings from the X-59 may encourage authorities to revise their rules.

For that to happen, though, someone would have to develop such a supersonic passenger plane in the first place. While there have been various pronouncements on the topic over the years, there does appear to be one US-based venture which is working on a prototype to do just that – with funding from AI-supremo Sam Altman.

The plucky aerospace company, Boom Supersonic, is based in Colorado, where it just conducted a successful test on a smaller demonstrator jet (the XB-1) which it hopes will be the precursor to a full-scale passenger jet, known as the Overture – or, as it’s been dubbed by some, “the son of Concorde”.

Boom has set out some specifics for the project, saying that the Overture will carry around 80 passengers, as well as some rendered images of what it might look like. They’ve also received preliminary orders from passenger airlines, notably United and American, which might look like a positive sign.

For all the hype, though, analysts expect that bringing the project to fruition could require tens of billions in research dollars. They also question whether the commercial manufacturers would see that as a priority right now.

“The big concern for the aviation industry at the moment is how to make flying more sustainable,” says aviation analyst John Strickland. Many are more interested in how to make greener jet fuel, rather than investing in engines which will triple or quadruple their fuel consumption in the first place.

“Ultimately, manufacturers are responding to demand from airlines, and this isn’t something they’re asking for,” says Dave Alexander. Sometimes airlines want manufacturers to solve a specific challenge, like Qantas looking to fly direct from London to Sydney, but usually they just want the most efficient planes possible.

Ultra-fast planes smashing through the speed of sound may bring challenges for infrastructure too. “If operators wanted to use a conventional airport, they may need new infrastructure,” says Jack Richardson from the Royal Aeronautical Society. “For example, the planes may run on special fuel that needs to be handled away from other operators, or they may require extra space to cool down after landing.”

In the age of tech billionaires with moonshot dreams, could supersonic flights become viable as an ultra-luxury option for high-net-worth travellers? Given the feats involved, it’s not hard to imagine the appeal – but experts say it may actually prove to be slower than other methods.

That’s largely down to the boom in private aviation, which has changed the way that much of the jet-set elite travel. “Private flyers are already saving hours on their journey as they’re using special airports which massively reduce time spent on security and immigration,” he adds.

Of course, such headwinds are not an issue for the defence industry, which continues to invest billions in hypersonic capabilities. Just last month, one Florida based aerospace contractor, Hermeus, opened a new test facility for its hypersonic engine. Meanwhile, Nasa’s X-59 is expected to take its test flight before long.

Closer to home, Oxfordshire-based Reaction Engines, led by a former Rolls-Royce executive, has been working on the SABRE, an air-breathing rocket engine aimed at reaching hypersonic speeds. Crucially, it is also looking to use thermal technologies to reduce the fuel intensity of hypersonic engines.

It won’t be long, then, before you’re reading another overexcited report about faster flights over the Atlantic, triggered by another scientific breakthrough by aviation boffins. By all means, marvel at the technologies involved – but don’t expect to be buying a ticket any time soon.