angel falqués: Supersonic flight: will it ever rise out of the ashes of Concorde?

A British Airways Concorde takes off for a test flight from London's Heathrow Airport.

You could tell without looking up that Concorde was on its final approach to Heathrow: its Rolls Royce Olympus turbojets made the same roar on landing as others did taking off. It was a treat just to watch it in flight, and many of us assumed one day that supersonic flight would be the norm, not a novelty.

Concorde’s crash just outside Paris on 25 July, 2000 was actually just the symbolic end for the world’s only supersonic airliner. It may have been ahead of its time, but paradoxically it was already out of date and out of touch. Weighed down with political and economic baggage, Concorde was grounded in 2003, which seemed to signify the end of commercial supersonic travel (SST).

Maybe Concorde had made us complacent. Just as the Apollo generation assumed we’d have moon bases by now, having SST since the 1960s meant we thought everything could only get sleeker and quicker. Instead, we got bigger and cheaper. Instead of ramjets, we got Ryanair.

Air France Concorde jet crashes near Paris.

With a cruising altitude of 19,812 metres (65,000 feet) – nearly twice the height of other airliners – and a speed of 1345.6mph (more than twice the speed of sound) Concorde flew 100 souls higher and faster than modern fighter jets, making the journey from London to New York in just three and a half hours. That this herculean Anglo-French collaboration – between the French state-owned aerospace manufacturer Aerospatiale and its British counterpart BACB – got airborne amid such stern competition from the US and Russia in a cold-war-driven age of one-upmanship is a marvel.

The short lived Soviet Tupolev Tu-144 launched in December 1968, stealing Concorde’s thunder by just two months. It was so similar the Anglo-French team suspected espionage. But the sleek exterior concealed a flight deck stuffed with archaic levers and instrumentation. Clearly an exercise in propaganda, the Tu-144 had no practical use: the communist USSR did not tolerate Concorde’s jetset customer base and it had nowhere to fly to. So it became a supersonic workhorse, ferrying mail across the USSR. A fatal crash at the 1973 Paris Air Show ended Russia’s supersonic passenger effort.

A British Airways Concorde took off from London's Heathrow airport less than 24 hours after one of the aircraft crashed in Paris killing 113 people.

Boeing’s 2707 was the USA’s attempt, a supersonic behemoth designed to fly some 300 people at mach 3 (over 2,300mph). By flying faster it could make more trips, its designers reckoned, and it would pay off. But, like a later 1990 NASA-led project, the High Speed Civil Transport, it never left the drawing board. Huge technological, environmental and economic hurdles meant that no one – Boeing especially – wanted to build it and, crucially, no one wanted to buy it.

Those hurdles are partly why we aren’t blasting supersonically to Sydney and back in time for tea today. Peculiar things happen when you hit the speed of sound. Sound waves and air compress at the nose, creating an aerodynamic barrier that increases wave drag fourfold, and needs a lot of power (and fuel) just to penetrate. And when it does, the shockwave begets the infamous sonic boom.

A visitor walks past Concorde at the National Museum of flight in Scotland

Scientists had known about this since at least 1964, with the notorious Operation Bongo II experiments, in which the US air force conducted a series of supersonic test flights 65,000ft over Oklahoma City, to determine whether the sonic boom would still be audible at ground level.

Following 10,000 complaints of broken windows and shattered plaster, nearly every state banned supersonic flights in their airspace, scuppering dreams of an east-west supersonic shuttle. To this day, supersonic flight is banned over land in the US and Europe, and it was years before the US supreme court would even allow Concorde to come in over the Atlantic.

The sun sets on Concorde after the final flight into Filton, Bristol for the very last time, after a special flight from Heathrow Airport to the site where the supersonic plane was made

There are other flies in the supersonic ointment. Flying this fast superheats the aircraft, so it must be made of special – and expensive – composites such as titanium alloys, or carbide ceramic materials that can withstand temperatures of 3,000C. The faster you go, lift and drag increases, requiring aerodynamic wings, a thinner fuselage, and a much higher cruising height where the air is thin.

But the higher you fly the bigger the engines needed to cram in enough air. This means you need a lot of fuel, which ultimately, results in poor range. Even Concorde was only just capable of the transatlantic trip, and it showed SSTs weren’t worth flying on routes shorter than three hours, which cut out a lot of routes.

Concorde was a supersonic passenger airliner created jointly by the French and British. Here is pre-production prototype landing with nose drooped and under carriage lowered at the Farnborough Air show in 1974.

Boeing 747 taking off over roof tops near London Heathrow Airport in 1971.

So how did Concorde have the freedom of the skies for 27 years? It helped that British Airways put up with it as a flagship loss-leader until 1980, when two of its pilots took over Concorde and hiked the price to about £8,000 a ticket – to any normal customer base this might have been a suicidal move, but to a luxury market not exactly counting the pennies, the rise didn’t seem to matter. Suddenly, Concorde was “reassuringly expensive’’. Over its lifetime, it made BA profits of about £750m.

But the French did not followed suit and was going bust. Eventually they grounded their Concorde, and when legacy firm Airbus announced it was to stop making and servicing the parts, it was the beginning of the end for the British plane too.

Concorde officially entered service in 1976, with a maximum speed over twice the speed of sound (1,354 mph at cruise altitude). The plane type was retired in 2003, three years after the crash of Air France Flight 4590, in which all passengers and crew were killed. It cost so much for a ticket, few people could ever afford to fly this way.

Air travel had already moved on. The concept of “luxury” travel now meant reclining seats, space and comfort, and suddenly Concorde’s narrow fuselage looked cramped. Recliners and TVs? Forget it. Concorde was an outdated notion of prestige that left sheer speed the only luxury of supersonic travel.

Air travel was becoming democratised, something Boeing spotted as early as the 1960s. The future was bigger, not faster, resulting in the Boeing 747. Fifty years later a jumbo can still carry more than three times as many passengers, with the same fuel, as Concorde, and at a fraction of the price. In the tortoise and hare air travel race, the tortoise is winning.

A keen plane spotter at the stands under the model of Concorde at Heathrow, London terminal awaiting the arrival of the final Concorde flight arriving at Heathrow airport, from New York, marking the end of an era of supersonic travel.

But the race isn’t over. New technology has opened up exciting possibilities.

Lockheed Martin and Aerion have developed a concept aircraft that can fly at Mach 1.2 with no sonic boom – technology they’ve tested on an F15 fighter jet. The drawback: it can only work on small aircraft, which means Aerion will be a business jet.