When Will Supersonic Air Travel Return?

“I feel the need: The need for speed.” If you recognize this quote, then you were likely weaned on a steady diet of 1980s Tom Cruise blockbusters. Or maybe you’re just a big fan of Scientology. Either way, you might be interested – or maybe traumatized – to learn that a sequel to Top Gun is in the works. It’s been more than 30 years since hotshot pilot Pete “Maverick” Mitchell zoomed across the skies at supersonic speeds in his F-14A Tomcat fighter. In the real world (unless Elon Musk is right and we live in a simulation), it’s been about 15 years since the last commercial supersonic jet took paying passengers on a journey faster than the speed of sound. A handful of big aerospace companies and small startups are developing their own sequels to the storied Concorde. So when will supersonic air travel return?

A Short History of Supersonic Flight

A supersonic aircraft is one able to fly faster than the speed of sound, referred to as Mach 1. The speed required to break the sound barrier and produce a thundering sonic boom varies based on temperature and atmospheric pressure. At sea level, it’s about 760 miles per hour, while at a cruising altitude of 35,000 it’s only 660 mph. For comparison, most commercial passenger jets cruise at about 550 to 575 mph.

While World War II might have been humanity’s lowest point (aside from the year parachute pants came out), it turns out that all of that death and destruction led to a number of technological breakthroughs, including rocket- and jet-powered aircraft. The first official flight to break the sound barrier following the war occurred on October 14, 1947, when Chuck Yeager piloted the experimental Bell X-1 research rocket plane. In fact, most supersonic and hypersonic (Mach 5 or about 3,800 mph at sea level, and above) jets usually belong to the military or are some sort of experimental aircraft that get mistaken for UFOs. For example, the fastest airplane ever was actually developed by NASA: The unmanned X-43A still holds the Guinness World Record for the fastest aircraft at Mach 9.6 (more than 7,000 mph), though true aviation geeks will note that the record is for an air-breathing engine, which means it uses atmospheric oxygen for combustion rather than on-board liquid oxygen.

The X-43A reached nearly Mach 10, a world record.
The X-43A reached nearly Mach 10, a world record. Credit: NASA

The fastest speed by a manned aircraft happened way back in October 1967 when the X-15A-2 hit Mach 6.7 (more than 5,000 mph). The Russians own the fastest supersonic fighter jet, as the MiG-25 has been clocked at Mach 3.2 (about 2,455 mph). Incidentally, the world’s fastest car is capable of reaching a speed just north of Mach 1. Meanwhile, the Concorde, which flew from between 1976 and 2003, had a top speed of Mach 2, or twice the speed of sound. It was operated jointly by Air France and British Airways, mainly on transatlantic flights, which commanded ticket prices of about $8,000 for a round-trip ticket from New York to London in 1997. It remains the only commercial supersonic transport (aside from the Soviet-era Tupolev Tu-144 that flew commercially in 1977-78).

Don’t Bring the Noise

Such luxury travel didn’t come cheap: It cost an estimated $3.6 to $5.1 billion in 1977 dollars (upwards of $20 billion or more today, depending on your online calculator) to develop and eventually manufacture 20 of the supersonic jets. We already know that supersonic technology exists, so the question is whether a new generation of supersonic jets can be economically viable, more fuel efficient, and more environmentally friendly. While no one would expect supersonic travel to be as eco-friendly as an electric airplane, supersonic passenger jets probably would need to match their subsonic counterparts in CO2 emissions standards. And they would have to somehow filter out that earth-shattering boom that accompanies the jump into Mach 1 and above. Currently, supersonic transport over land is prohibited because of noise pollution.

The Big Fish in the Supersonic Pond

So the company that is going to develop supersonic commercial transport needs money and know-how. It’s no surprise, then, that one of the leaders in developing supersonic jets is aerospace giant Lockheed Martin (LMT). In fact, Lockheed secured a $247.5 million contract last year from NASA to build a super-quiet supersonic jet that’s been dubbed the X-59 QueSST (for quiet supersonic technology). The X-59 is designed to cruise at 55,000 feet at a speed of about 940 mph (Mach 1.42) and create a sound about as loud as a car door closing (that’s about 75 on the Perceived Level decibel scale).

The next-generation of supersonic jets will need to bring down the noise.
The next-generation of supersonic jets will need to bring down the noise. Credit: Lockheed Martin

The BBC explained that the key to saying goodbye to the boom is redesigning the aircraft frame. The shockwaves coalesce as they expand away from the nose and tail, creating two distinct sonic booms. The experimental aircraft would be shaped in such a way as to maintain the distance between the shockwaves as they travel away from the aircraft. Lockheed is scheduled to complete the X-59 by 2021, with overland tests to commence in 2022.

Based on recent events, Boeing (BA) seems to have fewer concerns about planes going boom. Last summer, it introduced a hypersonic passenger jet concept at the Aviation and Aeronautics Forum hosted by the American Institute of Aeronautics and Astronautics. Such an aircraft would be able to make the Kessel Run in less than 12 parsecs cross the Pacific Ocean in about three hours. That’s fast, though still slower than a spacecraft re-entering Earth’s atmosphere at a scorching 17,500 mph (Mach 25).

Illustration of Boeing hypersonic aircraft.
Hypersonic aircraft concept for the new Space Ghost airliner. Credit: Boeing

Wired reported that the unnamed hypersonic passenger jet would use an engine system similar to Lockheed Martin’s 1960s SR-71 Blackbird reconnaissance airplane, which holds the world record as the fastest unmanned jet-powered airplane. In the case of the Boeing plane, two “jet engines would operate up to Mach 2 or 3 before the inlets seal off the jet engine and divert air into the ramjets, which can handle faster airflow,” according to Wired. And that’s when the supersonic jet could hit speeds of up to 3,800 mph – at some point in the very unspecified future.

Supersonic Startups

Click for company websiteSupersonic transportation is big on Boeing’s agenda, as it just made a “significant investment” earlier this year into Reno, Nevada-based Aerion Supersonic, which is developing a faster-than-sound business jet that can carry 12 passengers. (The announcement sent the company’s stock soaring to its all-time trading high, but then the second 737 MAX 8 crash in March eventually erased those early-year gains.) Founded in 2003, Aerion says the AS2 is designed to fly at speeds up to Mach 1.4, or approximately 1,000 mph, which means the business executives should still be well coked up by the time they make it to that meeting in Paris. The aircraft is slated for its first flight in 2023.

An illustration of the Aerion AS-2.
An illustration of the Aerion AS-2. Credit: Aerion Supersonic

For Aerion, the Boeing deal was its third attempt to partner with one of the big aerospace companies, having already approached both Airbus and Lockheed Martin. Other partners include GE’s (GE) Aviation business unit, which is developing the engine, and Honeywell (HON), which is designing the cockpit, Xconomy reported.

Click for company websiteFounded in 2014, Boom Supersonic out of the Denver area nabbed a $100 million Series B last December, bringing its total disclosed funding to $141 million. Boom is designing a supersonic 55-passenger jet it calls Overture that will be configured for business travelers who can’t afford their own supersonic business jet. Boom told Forbes that the business case is based on the projected 65 million passengers who would fly business class each year by the mid-2020s. The planes would cost about $200 million each, with the first one expected off the production line by 2023.

The specs on the Boom Overture.
The specs on the Boom Overture. Credit: Boom Supersonic

Max speed would be about Mach 2.2, or about 1,700 mph. The company is currently testing the concepts on a smaller scale version called XB-1, made out of a carbon composite material such that the tail weighs just 43 pounds but carries over 10,000 pounds at temperatures exceeding 300 degrees Fahrenheit.

Click for company websiteSounds like 2023 could be the make-or-break year for supersonic startups, as that’s also the date that Boston-based Spike Aerospace says it will launch the S-512, a quiet supersonic business jet that will carry between 12 and 18 people. The S-512 will be able to reach Mach 1.6 (1,100 mph), and it will feature the company’s patent-pending (i.e., still figuring it out) Quiet Supersonic Flight Technology that will largely keep the sonic boom mum. The luxury cabin will also boast another patent-pending technology Multiplex Digital – expansive, high-definition screens spanning each side of the aircraft that can display real-time surroundings or your favorite movie or Top Gun.

Illustration of Spike Aerospace supersonic airplane.
It’s nice if you can afford it. You probably can’t. Credit: Spike Aerospace

Click for company websiteSpeaking of the need for more speed, our last supersonic startup is Atlanta-based Hermeus, which was founded just last year with the goal of developing a Mach 5 aircraft. The company raised an undisclosed Seed round this month led by top VC firm Khosla Ventures. The funds will go toward further development and testing of the company’s propulsion system. So far, there’s more hype than hypersonic, though the team consists of veterans from SpaceX and Blue Origin and all four founders worked together at an outfit called Generation Orbit that designs and builds hardware for space flight.


In fact, the line between supersonic and spaceflight travel is blurring. Some of the companies developing space planes, for instance, are interested in terrestrial transportation as well. That’s especially the case for companies like Virgin Galactic that hope to launch a space tourism business. One could envision that spaceports could eventually serve both types of aircraft. Of course, it could all be part of an elaborate escape plan for the rich and famous who can afford to abandon the planet if we don’t start mining the Earth more responsibly or at least start mining the moon for more resources. Sounds like the views will be nice at least.

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