The glamorous age of supersonic passenger jet travel dawned with the arrival of Concorde in 1976 and the pencil-like aircraft with its revolutionary delta swpt-back wings and unique drop-nose feature soon became a favourite of the rich and famous.
At Mach 2,or 2,470kph - twice the speed of sound - the plane could propel those with the cash from London to New York in under three and a half hours, astonishingly fast given the standard duration of around eight or nine hours on a normal jet in the 1970s. But it was really only an option for the wealthy traveller; a return trip to the Big Apple from the UK capital came in at about £8,000 (Dh38,417) - at today's prices that equates to Dh129,657.
It was, though, extremely advanced technology for the time, even if airport infrastructure didn't quite match up; as the late US comedian Bob Hope once quipped: "Concorde is great. It gives you three extra hours to find your luggage."
But the tragic 2000 crash of Air France flight 4590 into a hotel in Gonesse, France, just 5 kilometres from where it took off and which killed 113 people, became a fiery epitaph for Concorde after TV news channels beamed film of the aircraft, flames blazing from its broken port-side engine, struggling vainly to stay in the air. The accident plus the high ticket price, escalating running costs and the arrival of cheaper standard airliners that were faster than predecessors ultimately led to its demise in 2003.
It seemed the days of faster-than-sound commerical flying were over for good.
Until now; currently there are several firms actively enaged in bringing super-fast passenger jets back to reality. One such is Aerion Supersonic, a US aircraft manufacturer based in Reno, Nevada, whose projects include the eight to 12-passenger AS2 supersonic business jet.
According Mike Mancini, chief financial officer and executive vice president, strategy, for Aerion, the future of supersonic passenger flights and even faster is on the near horizon. "Aerion has a 50-year technology roadmap that begins with supersonic aircraft," he tells The National.
"We are big believers that technology will revolutionise travel in amazing ways. Our first step toward this faster future is with the supersonic AS2."
Mr Mancini says the AS2 will begin flight testing in 2023 and enter service in 2025. That will mark a more broadly available supersonic future, he adds, enabling the company and other manufacturers to overcome economic, regulatory, environmental and technological challenges.
In February, the company signed a partnership agreement with Boeing, which will provide engineering, manufacturing, flight-test resources and other support.
After the AS2 enters service, Aerion’s next step would be into the airline market. "We want to do this thoughtfully and in an environmentally responsible way so that we avoid all of the problems that limited the potential of the Concorde many years ago," he says. "It would be reasonable to expect a first generation of supersonic airliners in the 2030s."
And the demand may well be there for a new age of supersonic flight. Aviation Week reported on an independent study in 2016 which concluded that as many as 1,300 supersonic aircraft worth $260 billion may be needed over a 10-year period to 2035.
Aerion is entirely funded from the private sector and Mr Mancini says it is dedicated to the civilian market. "Our goal is to revolutionise global mobility, giving travellers back precious time so that they can do great things with it."
Given the advances made in airport infrastructure, that probably won't mean spending the time saved trying to find luggage.
Mr Mancini says Aerion already has the necessary engine technology to power its AS2 aircraft.
"Of all the advances required, the key enabling technology has been a modern and efficient supersonic engine from GE Aviation," he says.
The engine will help the firm meet stringent new standards for take-off and landing noise, one of the major problems for Concorde which, due to the "sonic boom" the aircraft created when breaking the sound barrier, meant it was only allowed to hit supersonic speeds over the sea.
The sonic boom is not caused by the engine, Mr Mancini points out. "Engine noise is a different issue and we have taken pains to develop a quiet engine for the AS2." A sonic boom is caused by the compression of air around the aircraft as it approaches Mach 1, the speed of sound. At Mach 1 and above, aerodynamic shockwaves form and trail the aircraft like the wake of a boat. When the shockwave descends to the ground it is perceived as a loud crack or a boom. There are two ways to mitigate this, says Mr Mancini. The first is aerodynamic shaping to reduce the loud boom to something more like the rumble of distant thunder.
However, Aerion is proceeding with a no-boom design approach - in other words, not allowing a boom to reach the ground at all.
At speeds up to about Mach 1.2, Mr Mancini says, its plane will deflect the boom upwards off warmer layers of the atmosphere and therefore it will not be heard on the ground. Aerion is developing the cockpit technology to accurately measure atmospheric conditions ahead of the aircraft and maintain a supersonic speed over land that keeps the boom from touching down.
"We see this as the only practical boom mitigation technology for years to come, if not decades. We have trademarked this capability as Boomless Cruise," Mr Mancini says.
Assuming all goes to plan, he says, Aerion aims to serve a market for 300 AS2 supersonic business jets over the first 10 years of production and Mr Mancini expects his company's aircraft to be first to market.
"We are partnered with Boeing, GE and Honeywell Aerospace to make this happen," he says.
"We have a good understanding of the economics and the business case for the AS2 supersonic business jet, and that is why it will be our first aircraft. "Meanwhile, we are studying the airline segment so that we balance performance, capability and cost - so airlines can operate such aircraft profitably on a multitude of routes, and so that there is a large enough market to justify the investment to develop a supersonic airliner."
Rival supersonic business jet developer Spike Aerospace, meanwhile, believes the market for Mach-plus travel could exceed 13 million passengers annually. “While supersonic aircraft might be ushered in by the wealthy, they will ultimately benefit anyone who wants and needs to get to their destinations faster,” says Spike president and chief executive Vik Kachoria.
Spike is developing a Mach 1.6, 18-passenger aircraft called the S-512, and the firm says initial plans are underway for a 40 to 50-seat variant.
“This aircraft will actually create demand. It’s not just going to address existing demand,” says Tom Captain, an executive adviser for Spike who previously was vice chairman of Deloitte, leading the company’s aerospace division.
Spike based its projections on travel patterns of 4 billion passengers who flew globally in 2017, including a review of origin-destinations, distances travelled, types of passenger, cabin class and airlines. The analysis in particular looked at flights where supersonic speeds would provide the most value.
Boom Supersonic, based in Colorado, is also in the Mach-plus sector. The company says it has already secured a pre-order for 30 its Overture aircraft, 20 from Japan Airlines, which made a $10m investment in 2017, and 10 from Sir Richard Branson's Virgin Group. Boom began final stage testing of the XB-1 its Mach-2.2 supersonic aircraft concept in 2017.
The company is currently in final assembly of the full-size XB-1 aircraft to prove key technologies in-flight for safe, efficient supersonic travel. The data collected from XB-1 test flights will help refine the design of Overture - its 55-seat Mach-2.2 supersonic commercial airliner aimed at serving hundreds of transoceanic routes.
“As XB-1 continues to advance through the build stage, we’re excited to turn our attention to the development of Overture,” says Bill James, Boom’s senior vice president of operations.
In February, Boom selected Hoar Program Management (HPM) to lead its programme to locate, plan, design and build its first US manufacturing facility to produce the Overture, "which will begin passenger service in the mid-2020s", according to the aircraft maker.
“Finding a partner that could lead us through this process was an important step, and HPM’s experience in the aerospace industry made them the top choice. We couldn’t be happier to partner with HPM to lead our site selection process,” says Mr James.
In 2017, Boom anounced it had secured $33m in Series A funding. The investors included 8VC, Caffeinated Capital, Palm Drive Ventures, RRE Ventures, and Y Combinator’s Continuity Fund, as well as several angel investors. That brought the then-total funding to $41m - "enough capital for us to finish building the XB-1 supersonic demonstrator", Boom said at the time.
In December last year the company closed its $100m B investment round.
XB-1 is powered by three General Electric J85-15 engines, adapted by Boom for Mach-2.2 operation. Already tested with sustainable alternative fuels, XB-1 and Overture can operate with environmentally-friendly low-carbon jet fuel, according to the firm.
Boom points out that Concorde only had 100 seats and often flew with just 25 per cent filled. It operated profitably on just a single route and only 14 entered service. "Since we’re able to match the pricing of subsonic business class, we’ve put 55 seats on the Overture airplane, about the size of the premium cabin in subsonic widebody aircraft," Boom chief executive Blake Scholl says.
"This matters because while business class is just 10 per cent of seats, it represents nearly half of international airline revenue and the majority of profits," he says. indeed, as Mr Scholl points out: "Concorde died because it was too expensive to operate."
Of course, for business travellers, time is of the essence; Boom says using its plane the flight time from Sydney to Los Angeles would be under seven hours, rather than the current almost 14, and Tokyo to San Fransico would be around five and a half hours, rather than more than nine currently.
The company says the aircraft itself will come in at a relatively competitive price, given the travel time saved; while an Airbus A220-100 costs less than half price - around $80m at list prices - its 110 or so passengers flying from London to New York will spend at least eight hours in the aircraft. Overture, on the other hand, will whisk them there in just over three.
"The actual sale price of the aircraft is $200m, plus options and interior," the firms says. "On an available premium-seat-mile basis, Overture is meaningfully less costly to operate than subsonic widebody aircraft."
Regarding how much passengers might expect to pay, Boom says ultimately ticket prices will be determined by the airlines. "But we’re designing Overture so that airlines will be able to offer fares similar to today’s long-haul, business-class travel," it adds.
The company estimates that when Overture enters service in the mid-2020s, more than 65 million passengers will fly business class on the 500 transoceanic routes that make sense for a supersonic service. This demand, Boom predicts, will require 1,000 to 2,000 Overture airliners.
Mach 2.2 is the fastest a passenger plane can fly before the heat caused by air friction becomes too much for the existing certified materials that make up a passenger aircraft, according to aeropsce engineers.
So is supersonic flight around Mach 2 the limit for commercial passenger travel? Some companies don't think so.
One outfit with its eyes on the ultra-fast travel prize is SpaceWorks Enterprises, based in Atlanta. SpaceWorks is developing the X60A, "an air-dropped liquid rocket, specifically designed for hypersonic flight research to mature technologies", John Bradford, the company's president and chief operating officer, tells The National.
"SpaceWorks is very interested in high-speed, point-to-point travel via atmospheric flight and we have been designing potential systems that could achieve this for over a decade," he says. While he agrees there are a number of other entrants emerging for this market, he admits the financial viability for these ventures is still extremely challenging. "The fuel costs alone for these systems can be thousands of dollars per passenger, not including the cost for development, manufacturing, operations, and of course profit," he says.
Mr Bradford acknowledges there are also regulatory challenges with land overflight at hypersonic speeds, but says there are "viable technological solutions".
Another player emerging in the hypersonic market is Reaction Engines, a privately held company based in Culham, Oxfordshire, UK. It employs over 200 staff across its sites in the UK and US. The key factor boosting a hypersonic flight's efficiency is its engine's ability to process air in high temperatures, according to the company.
Reaction is developing the technologies needed for what it refers to as an advanced combined cycle air-breathing rocket engine class called Sabre (Synergetic Air-Breathing Rocket Engine), designed for the next generation of hypersonic flight and space access vehicles.
And it, too, seems to have the financial muscle to become a significant driver of the ultra-fast travel market. According to Zacks Equity Research, Reaction Engines has secured investments of about $130m from Boeing's venture capital arm HorizonX, BAE Systems and Rolls-Royce over the past four years. The company has also received a $78m funding assurance from the UK government.
In February Reaction announced its air-breathing rocket engine successfully passed the first phase of high-temperature testing. The precooler technology it is developing "will enable a wide variety of high-speed flight and advanced propulsion systems", it says.
"This is a hugely significant milestone which has seen Reaction Engines' proprietary precooler technology achieve unparalleled heat transfer performance," says Mark Thomas, chief executive of Reaction Engines, adding that the technology has applications across emerging areas "such as very high-speed flight [and] hybrid electric aviation".
To replicate the conditions of hypersonic speeds, Rection's TF2 test facility uses a General Electric J79 turbojet engine formerly used in a McDonnell Douglas F-4 Phantom aircraft to provide high-temperature airflow. The firm is also in the final stages of constructing its TF1 test facility at Westcott, Buckinghamshire, UK, where it will undertake ground-based testing of a Sabre engine core.
Boeing is also at the vanguard of hypersonic development.
For the aerospace giant, hypersonic passenger travel is among its most serious projects. “It may not be as hard as people think it is,” says Boeing chief technology officer Greg Hyslop, although he adds: “It’s still going to be hard.”
Boeing unveiled its hypersonic passenger plane concept in June in Atlanta at the 2018 Aviation and Aeronautics Forum hosted by the American Institute of Aeronautics and Astronautics.
"We're excited about the potential of hypersonic technology to connect the world faster than ever before," Kevin Bowcutt, Boeing's senior technical fellow and chief scientist of hypersonics, said at the time. "Boeing is building upon a foundation of six decades of work designing, developing and flying experimental hypersonic vehicles."
But whenever Mach-plus passenger travel becomes a reality again, Concorde is unlikely to be replaced in the hearts of many British aviation and design enthusiasts. In 2006, the aircraft won The Great British Design Quest to choose the nation's favourite British design since 1900. Organised by BBC2's The Culture Show and the Design Museum, the jet garnered the vast majority of the 211,792 votes cast.
And in future, for those who won't be able afford a trip on a supersonic or indeed hypersonic passenger jet, perhaps the words of the late UK MP Tony Benn regarding the First Lady of supersonic commercial aviation will provide some solace: "Whenever a Concorde flies, people look at it, it's very graceful, it's very beautiful, it is a symbol of peace and international understanding."