This week we talk about Mach 1, the Bell X-1, and the Concorde.

We also discuss the X-59, the Tu-144, and Boom Supersonic.

Recommended Book: Red Team Blues by Cory Doctorow

Transcript

The term “supersonic,” when applied to speed, refers to something moving faster than the speed of sound—a speed that is shorthanded as Mach 1.

The precise Mach 1 speed of sound will be different depending on the nature of the medium through which an object is traveling. So if you’re moving at sea level versus up high in the air, in the stratosphere, the speed of sound will be different. Likewise if you’re moving through moist air versus dry air, or moving through water versus moving through syrup, different speed of sound, different Mach 1.

In general, though, to give a basic sense of how fast we’re talking here, if an object is moving at sea level through dry air at a temperature of 20 degrees celsius, which is 68 degrees fahrenheit, Mach 1 is about 768 miles per hour, which is about 1,126 feet per second, and 343.2 meters per second.

It’s fast! It’s very fast. Again, this is the speed at which sound moves. So if you surpass the speed of sound, if you go supersonic, you will arrive faster than the sound you make while moving.

Back in 1947, an experimental American plane called the Bell X-1 broke the sound barrier, surpassed Mach 1, reaching a speed of almost 1,000 miles per hour using a 6,000 pound thrust rocket propulsion system. A later version of the same rocket-powered plane, the Bell X-1A, which was basically the same vehicle, it just had more fuel capacity, allowing the rocket to burn longer, achieved 1,600 miles per hour in 1956.

Prior to that, in 1943, British began working on a secret experimental aircraft called the Miles M.52, intending to build a plane capable of traveling 1,000 mph. Interestingly, this project was apparently the result of the British wanting to keep up with a supposed already existing German aircraft capable of achieving that speed, though it’s now believed the intelligence that led the British to believe the Germans had a supersonic-capable plane was the result of a mistranslation—the Germans hit 1,000 km per hour, which is about 621 mph, and still subsonic.

Though apparently a success in terms of research and innovation, the Miles M.52 project was cancelled in 1946, due partly to budgetary concerns, and partly because the new government didn’t believe supersonic aircraft were practical, or maybe even feasible.

After the existence of this project was revealed to the public, however, criticism for the cancellation mounted, and the design was translated into new, unmanned scale-model experimental versions of the plane which achieved controlled Mach 1.38 supersonic speeds, and both the design and research from this program was shared with the American company, Bell, and all that knowledge informed the development of the aforementioned Bell X-1 supersonic plane.

Again, that successful Bell mission was flown in 1947, and in 1961, a Douglas jetliner, a commercial jet, broke the sound barrier during a controlled test dive, and that fed the development of an intended supersonic airliner in the US, though similar research being conducted elsewhere would bear more direct and immediate fruit.

In the Soviet Union, a supersonic jetliner called the Tupolev Tu-144 entered service in 1968, and a jetliner co-developed by the British and French, the Concorde, began construction in 1965, and tallied its first flight in March of 1969.

The Tu-144 was thus the world’s first commercial supersonic airliner, by a few months, and it also became the first commercial transport to exceed Mach 2, twice the speed of sound, in 1970.

The Tu-144 was plagued by reliability issues from the get-go, however, and while performing maneuvers at an air show in Paris in 1973, it disintegrated in midair, which—combined with its high operating costs reduced its long-term market viability, especially internationally. By the mid-1970s, it was primarily operating within the Soviet Union, and after a new variant of the jet crashed in 1978, the Tu-144 program was cancelled in 1983. Existing models continued to be use for niche purposes, like training space program pilots, and for a supersonic research program undertaken by NASA in the late-1990s, but the final Tu-144 flight was in mid-1999, and all surviving aircraft are now on display or in storage.

The Concorde has a similar history. Original forecasts for the supersonic airliner market were optimistic, and while the craft seemed to be generally more reliable and less issue-prone than the Tu-144, and it enjoyed a period of fanfare and promotion, as a sort of luxury experience for folks crossing the Atlantic in particular, cutting travel times in half, a major crash in mid-2000, which killed all 109 occupants and four people on the ground, led to the suspension of service until late-2001, and all remaining Concorde aircraft were retired in 2003—about 20 of them are on display throughout North American and Europe, as of the mid-2020s.

The costs associated with operating Concorde aircraft, as with the Tu-144, were also quite high, and those costs and other complications led to the cancellation of a would-be supersonic jetliner competitor from Boeing, the 2707, in 1971, before it built any prototypes.

What I’d like to talk about today is a renewed enthusiasm for supersonic passenger aircraft, and what’s changed that might make supersonic transport a viable market, today.

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In the United States, commercial aircraft are not allowed to fly at supersonic speeds. This is because the sonic booms generated by supersonic flight, which are shockwaves that work a bit like the crack of a bullwhip or the firing of a bullet, but much, much larger, can set off alarms, rattle or shatter windows, and generally create all sorts of chaos on the ground, even in areas not directly under the aircraft that’s breaking the sound barrier.

This was true even during the heyday of the Concorde: the craft was only allowed to travel at supersonic speeds over the ocean, because doing so over populated areas was such a pain, and in some cases, a danger.

Sonic booms aren’t the only reason supersonic aircraft like the Concorde failed to establish a long-term presence in the airline industry, but they’re a big part of it. It’s just really difficult to work around that kind of persistent issue.

This is why a new experimental project by NASA, the X-59 Quesst, with two-s’s, Quesst standing for Quiet SuperSonic Technology, is garnering so much attention. Built by Lockheed Martin, the X-59 is said to dramatically reduce the scale of sonic booms, instead producing what’s been described as a sonic thump, its long, slender nose breaking up the pressure waves that otherwise build up and create that much larger, more impactful shock wave boom, and its engine is on top of the plane rather than underneath it, a design choice that sends the majority of remaining shock wave impacts upward toward the sky, rather than down toward the ground.

The X-59 is still just an experimental jet. It’s a single-seater, it’s about twice as long as an F-16 fighter jet, and it can cruise at around 925 miles per hours, which is Mach 1.4.

It’s hoped that this new design will allow for the creation of future supersonic jetliners, though, as being able to traverse oceans twice as fast would bring massive economic benefits, in terms of shipping people, but also all kinds of goods. Being able to use these aircraft fully, at their full speed, over land and to and from any airport, would likewise make them more versatile and introduce new benefits and, hopefully, favorable economics.

Worth noting here is that this jet is a descendent of that first Bell X-1 plane that broke the sound barrier in 1947; NASA’s X-planes are innovative models meant to push the boundaries of what’s currently possible, and the X-59 is just a more modern version of that initial X-1 conception in many ways.

That said, the X-59 has only been successfully flown at low speeds and altitudes at this point. It got a lot of press at the end of October 2025 for successfully completing its first flight, which shows it can fly and land, which is good. But its inaugural flight stuck with a low altitude and just 240 miles per hour; really slow for a jet, and too low for a commercial airliner.

The folks behind this project have also said that while they have every reason to believe this design will both work and create a far less impactful sonic boom, they don’t yet know if that boom will actually be tolerable for people on the ground. Simulating such things is different from the experience of them, and they won’t know until they power the thing all the way up and have it break the sound barrier whether the sonic thump will be barely noticeable and tolerable for folks near airports and flight paths, or if it will be better, but still not good enough to make this a viable alternative to existing jets.

There are other entities working on similar things right now, including a company called Boom Supersonic that has already flown a piloted demonstration aircraft, the XB-1, at supersonic speeds—Mac 1.122, which is about 750 mph—at an altitude of over 35,000 feet; the first time a non-government-affiliated aircraft has done so.

That was back in March of 2024, and the company plans to build a commercial supersonic aircraft that will carry between 64 and 80 passengers at Mach 1.7, on hundreds of global routes; they say they already have a large number of orders for this passenger aircraft they intend to build, and they say to begin with, they’ll be able to produce 66 of them per year from their factory in North Carolina. They say that they’ll have the first full-scale prototype of that passenger aircraft, called the Overture, in 2027, and they’re aiming to put that craft into service beginning in 2029 or 2030.

They’re not the only private company aiming to produce supersonic aircraft for various purposes, either. The promise of moving people and things around the world, faster than most of today’s options can manage, and in many cases far faster, is still tantalizing for many industries, so long as regulatory, safety, and technological hurdles can be traversed. For most of these private companies, their innovation seems to be mostly in price and scale, not reducing the boom, but some have also claimed that their sonic booms are more moderated; there’s also a good chance findings from the NASA X project will translate over to the commercial world in due time, if these companies survive, blending those innovations.

It’s an interesting moment in this space, then, in part because it seems like supersonic flight is appealing again, to some, at least, after a long period of dashed hopes—that dashing partly the consequence of flaws in earlier models, and headline-grabbing crashes that ruined a lot of appetites for the option.

But also because we could see modern technologies, from sensors to propulsion systems to manufacturing capacities applied to this vehicle type, which could ease a lot of the issues that made the Concordes and Tu-144s non-workable the first time around, and could make this type of transport and travel cheaper, too, though probably not until mid-century at the earliest, according to current timelines.

Show Notes

https://arstechnica.com/space/2025/10/nasa-test-flight-seeks-to-help-bring-commercial-supersonic-travel-back/

https://en.wikipedia.org/wiki/Sonic_boom

https://www.wired.com/story/nasas-quiet-supersonic-jet-takes-flight/

https://www.sofeminine.co.uk/back-in-4-years-your-london-new-york-time-slashed-by-3-hours-as-60-80-seat-supersonic-jet-nears/

https://abcnews.go.com/US/wireStory/nasa-takes-step-closer-launching-quiet-supersonic-jets-127036299

https://boomsupersonic.com/

https://www.grc.nasa.gov/www/k-12/airplane/lowsup.html

https://www.nasa.gov/aeronautics/supersonic-flight/

https://www.spikeaerospace.com/

https://en.wikipedia.org/wiki/Miles_M.52

https://en.wikipedia.org/wiki/Bell_X-1

https://en.wikipedia.org/wiki/Supersonic_aircraft

https://en.wikipedia.org/wiki/Tupolev_Tu-144

https://en.wikipedia.org/wiki/Concorde

https://en.wikipedia.org/wiki/Supersonic_transport

https://en.wikipedia.org/wiki/Supersonic_speed

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