Assessing the future for supersonic and hypersonic flight
It is now more than two decades since Concorde, the last passenger aircraft to travel at supersonic speeds, was retired from service. Since that time, technology has moved forward significantly, and there are now serious discussions about a new generation of supersonic aircraft, potentially offering fast and potentially quiet (or at least quieter) travel.
This article will take a quick canter through the aviation industry’s history with supersonic travel and talk about what could be emerging, before briefly discussing the insurance implications.
Seventy years ago, in 1954, preliminary work began to create the world’s first supersonic passenger aircraft. It was the first major venture created by a European cooperative, with France and Great Britain signing a treaty for its development eight years later in 1962. The airframe design was a collaboration between British Aircraft Corporation (which eventually became part of British Aerospace) and Sud Aviation (which later became Aérospatiale), with the engines similarly jointly designed with Britain’s Rolls Royce and France’s SNECMA.
The result was the aptly named, visually stunning and technologically advanced Concorde.
After development started on Concorde, both the Soviet Union’s Tupolev and America’s Boeing started their own studies into the feasibility of supersonic transport. Boeing’s study, the B2707, never got past the design stage, but the TU144 actually made its maiden test flight two months prior to Concorde’s test debut. The Tupolev came into service in 1975 and went on to operate weekly between Moscow and Almaty in Kazakhstan. It suffered two fatal incidents, the second of which led to it being pulled from passenger service after three years, although it continued as a cargo service for the next five years, retiring in 1983. In total, it made just over 100 scheduled commercial flights.
Back in Western Europe, construction of the Concorde prototypes began in early 1965, with the first flight leaving runways in Toulouse in March 1969.
Initial predictions suggested a market of around 350 aircraft, but with the oil shocks of the 1970s, only around 100 orders were received, and only 20 aircraft were actually built. Despite this, the aircraft made its first commercial flight in 1976, and quickly became a much-loved icon. With a maximum cruise speed of slightly over Mach 2 (over twice the speed of sound), and at a cruise altitude of 60,000 feet (18.3km), traveling on Concorde meant flights’ times between Europe and New York were cut from around eight hours to about three.
This was a significant time-saving, if you could afford it. One notable passenger to take advantage of supersonic travel was popstar Phil Collins, who famously played the 1985 Live Aid concert in London, before taking his place at the drum stool for the Philadelphia sister gig a handful of hours later.
Iconic it may have been, but there were always question marks hanging over Concorde. Initial development costs are thought to have spiralled to more than 20 times the original estimates, a deficit from which aviation analysts suggest operations never really recovered. Sensitivity around the sonic boom also meant that it was prohibited from moving at supersonic speeds over land over most countries, which constrained it to operating exclusively between Paris and New York, and London and New York. Finally, the economic uncertainties of the 1970s gave way to increasing environmental awareness in the late 1980s and into the 1990s, each putting pressure on Concorde’s voracious fuel consumption.
Sadly, a catastrophic crash in July 2000, caused by debris on a runway from a preceding flight, virtually sealed the aircraft’s fate. Despite remedial work, it didn’t return to service with Air France. While it continued to fly for British Airways for another 18 months, the September 11 attacks led to a significant drop in demand for trans-Atlantic flights, and the final Concorde flight took place on November 7, 2001.
And that was the end of supersonic passenger travel. Or so it seemed.
Science doesn’t tend to stand still for very long, so while there may not have seemed to have been much commercial appetite for supersonic travel, it continued to be a topic of interest from both a space and a military perspective.
Two decades after Concorde’s retirement, NASA unveiled its X-59 Quesst (Quiet SuperSonic Technology) demonstrator jet. NASA’s concept, built in conjunction with Lockheed Martin, is an attempt to create a supersonic aircraft with a far quieter sonic boom,[1] which is still an important factor for people living near space ports and military bases.
One of the X-59’s key design changes is to have the engine mounted on top of the wing rather than below so the sound is not directed downwards. It also has a long, thin design which creates evenly spaced sound waves that are equal in strength. Without getting too far into the technical details, this leads to a gradual increase in air pressure that results in a sonic thump rather than the previous generation’s swift change in pressure which generated the sonic boom. Current targets are that the X-59 will create a level of noise of around 75 perceived decibels from the ground,[2] compared to Concorde’s 105 PLdB. For context, 75 PLdB is about the volume of a dishwasher, while 105 PLdB is about the same volume as a chainsaw at full power.[3]
As ever, aircraft development is complex and takes time, and the X-59’s maiden flight, initially scheduled for 2023, has slipped back to 2025 while the team behind the project works to get everything right.[4]
The renewed interest in supersonic travel also extends into the commercial space, with several companies vying to reintroduce supersonic travel for passengers. Boom Technology, Exosonic and Spike Aerospace in the US, Europe’s Destinus, and China’s Space Transportation, also known as Lingkong Tianxing Technology, are among the companies competing to deliver the next generation of super-fast passenger aircraft.
There is a wide ambition to make aviation more environmentally sensitive than it currently is and the new companies are vying to make supersonic travel quieter, more affordable and greener.
Some of companies behind the emerging generation of supersonic aircraft are making statements about using sustainable aviation fuel (SAF), but the challenge here is that the faster a plane travels, the more fuel it will burn, and SAF, made largely from food waste and animal fats, is currently not being produced in sufficient quantities for the existing aviation industry.
It is also more expensive than fossil fuels, which raises questions about whether supersonic travel can realistically be made economical. Compounding the issue, most of the new aircraft designs have seats for around 80 passengers, much less than the majority of aircraft currently use for transatlantic routes. Ultimately, there is a great deal of ambition, but there are significant challenges ahead, some of which go beyond simple engineering.
Some operators have even loftier ambitions and want to deliver hypersonic travel. But what is the difference between supersonic and hypersonic speeds? Supersonic is the term for something traveling faster than Mach 1, the speed of sound, whereas hypersonic travel is achieved at speeds beyond Mach 5, around five times the speed of sound, which is the stated ambition of both Hermeus with its Halcyon Jet[5] and Venus Aerospace with its Stargazer[6], either of which could reduce the journey time between London or Paris and New York to 90 minutes. Several of the companies developing supersonic aircraft also have their eyes set on a hypersonic future.
It is an exceptionally challenging feat of engineering though. Underscoring the difficulties, another company working on hypersonic engines recently went into administration after more than three decades.[7] Ambition is no guarantee of success.
Despite the hurdles, there is a clear desire for supersonic and even hypersonic travel. While these projects are exceptionally complex and demand a great deal of time and financial support, several major airlines have already placed orders for the next generation of aircraft, and it is reasonable to expect that some passengers could be enjoying supersonic travel before the end of the decade and could potentially be hypersonic travel ten years after that.
These the aircraft won’t be delivered for several years, but the airlines involved are already assessing how to integrate supersonic travel into their operations and vying to be the first to offer passengers the opportunity to fly at supersonic speeds. Hypersonic may be further down the agenda, but it is certainly being talked about.
Aviation projects like this show that the industry continues to push the envelope, but with millions and possibly billions of dollars at stake, risk management and insurance has an important role to play. The insurance sector has always flexed to embrace technological advances, from the new risk profile of supersonic transport and widebody aircraft of the 1960s, to the high costs associated with composite materials and high-bypass-ratio engines in more recent years. Aviation insurers have become adept at embracing the risks associated with novel technologies and enhanced materials that will be required by the rigors of super-fast air travel.
The reemergence of supersonic travel and the potential for hypersonic travel is a reminder of how far the aviation industry could be set to change in the near future, and it will be fascinating to see how much farther this develops over the next 70 years.
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