Flying Faster Than the Speed of Sound

The future of flight is here.



(Denis Belitsky /

Mankind has achieved amazing technological developments in the last century. We can reach the very limits of the Earth’s atmosphere and enter orbit in under 10 minutes. We can reach someone on the other side of the planet via telephone, and share data with them in under one second.

According to NASA, space shuttles enter orbit by traveling upwards at the astounding speed of 17,500 miles per hour. By contrast, the average passenger jet flies at around 500 miles per hour, reported NBC News. Supersonic airplanes (those that travel faster than the speed of sound) do exist, but they are currently too expensive to be practical for the average traveler. However, a number of companies are trying to change this, experimenting with new supersonic technology that would make super-speed travel as cheap as a business class ticket costs today, and much more environmentally-friendly. 

Here are some companies that are looking to reach the final frontier — flights from New York to London in under three hours. 

The retired Concorde
Supersonic passenger airplanes aren’t a new idea. Yahoo shares the story of the Concorde passenger jet, a supersonic airplane that hit the market in the 1970’s. The Concorde flew at roughly the speed of Mach 2.0, around 1,500 miles per hour.  It was also considered one of the safest airplanes, racking up only one crash in its nearly three decades of operation, with that crash caused by debris on the runway, and not due to any flaw in the aircraft’s design.

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Although the Concorde could carry up to 100 passengers and could fly from London to New York in three hours, it never really became profitable. Designing the Concorde turned out to be extremely expensive. Additionally, the supersonic jet proved to be incredibly fuel inefficient. It took the Concorde 45,195 pounds of jet fuel per hour to fly its 100 passengers around. By contrast, the Airbus A380, a subsonic passenger jet, can ferry 615 passengers through the skies, while requiring only 26,455 pounds of fuel per hour.

Both the high cost of development and the cost of fueling the jet, meant that riding the Concorde was expensive. At its peak, AirFrance sold Concorde tickets for $12,000 a seat! A few years after the deadly crash caused by runway debris, in 2003, the Concorde was discontinued and the age of supersonic passenger travel halted. 

A dual engine
Two decades after the Concorde’s grounding, the dream of supersonic passenger flight has yet to die. There are a number of companies jockeying to be the first to be approved to whisk passengers across the globe at thousands of miles per hour.

Hermeus is one company working to make not just supersonic passenger flights a practical reality, but actually hypersonic travel, Freethink reports. Hypersonic aircrafts travel at Mach 5, five times the speed of sound, or nearly 4,000 miles per hour! 

In order to make affordable hypersonic travel a reality, Hermeus is leaning on a new type of engine. The traditional airplane engine, CNN Travel reports, is called a turbojet and it works by compressing the air to release its energy potential, and then igniting it. The superheated air flows out of the back of the engine, pushing the airplane forward in accordance with Newton’s third law.

By contrast, supersonic airplanes usually use a ramjet engine, which is exactly what it sounds like. Because the airplane is traveling so fast, the air naturally compresses upon entering the engine, therefore, the ramjet merely rams the air, and doesn’t contain a compressor.

According to Freethink, ramjets don’t work efficiently below supersonic speeds. For maximum efficiency, an airplane would need to be optimized to fly at both subsonic and supersonic speeds. To this end, Hermeus is working on a TBCC or “turbine-based combined cycle” engine. The TBCC includes both components, the ramjet and the turbo jet. The turbo jet kicks in during takeoff and landing, and the ramjet does the heavy lift at cruising altitude. 

“The turbojet portion and the ramjet portion by themselves are mature technologies that we’ve been using for 50 years,” CEO AJ Piplica told Freethink, “The trick is to put them together, so we designed our own architecture around an off-the-shelf turbojet engine and then built out from there.”

Net carbon zero
Hermeus isn’t the only company racing to create a supersonic passenger jet, Vox reports. Boom Supersonic, is a startup that promises speeds that are twice as fast as conventional airplanes travel at. Not only that, but Boom promises to rely only on sustainable jet fuel, sourced from organic or waste sources. The company pledges that they will have airplanes with net-zero carbon emission levels.

Boom has some fans in the aircraft industry. American Airlines has already said they are interested in buying at least 20 of Boom’s planes, and United Airlines has announced they will buy 15 others. Boom hopes to have their first airplanes flying in the next few years.

Taking to the skies by 2023
Investors are also interested in the supersonic race, CNBC reports. Several prominent investors, including Sam Altman and Peter Thiel, have bought into Hermeus’s vision. 

Hermeus’s plan is to get their first, small scale prototype, Quarterhorse, flying by 2023. But, there are a few issues other than design that they, and other supersonic vendors, will need to address. CNN reports that currently the FAA doesn’t allow overland supersonic flight, because of the loud sonic boom that could be disruptive to people living below. However, there may be exceptions, allowing traveling across the ocean. Other supersonic startups are working on quieter supersonic models.

Some of Hermeus’s competitors, like Boom, who are also working on supersonic passenger jets, have pledged to become FAA certified in the next few years, and in the airports by 2029. It’s not clear if this is a realistic deadline, since it takes conventional airplane models upwards of five years to gain certification. 

What is definitely clear, however, is that there is a lot of interest in superspeed travel, and a number of innovators working on efficient and customer-friendly supersonic travel solutions. Nicole Viola, the project coordinator of the Stratofly consortium, another player in the hypersonic travel race, tells NBC News, “We want to go to Mars but still we have huge distances [separating us] here on Earth.” Maybe within the next few decades, we will be able to bridge those distances, and make our way around the planet faster than the speed of sound.

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