Fanning the flames
"So what’s a jet engine? It’s simply anything that emits a jet of fluid out of one end, generating an equal and opposite force going in the other direction. A jet engine compresses the air around it and uses this compressed air to burn its fuel.
Sound is a movement of the air. The air can carry information at around 750 mph-no faster. Hit the air at a higher speed, and it doesn’t have time to get out of your way. It explodes. Many objects exceed the speed of sound eg. the tips of propellers. If your blades are long enough, and spin fast enough, the tips exceed the speed of sound. When this happens, the air, which would normally be fanned behind the blade, producing forward motion, simply explodes, constantly, producing a standing wave, a shock wave that generates turbulence just forward of the blade. It’s not as serious as it sounds: you’ll stay aloft well enough. But you won’t go any faster, and your fuel consumption will deteriorate.
Supersonic flight is different from subsonic flight. At supersonic speeds, aircraft get hot. This is because the air doesn’t have time to get out of the way of the aircraft. It piles up. Because of all this air piling up in front of them, planes travelling at supersonic speeds run into problems similar to faced by seagoing vessels. Waves of thick air, called shock waves, cling to a supersonic craft, the way a bow wave sticks to the front of a boat. (Bow waves are shock waves: waves in water move so slowly, it’s relatively easy for a boat to throw up a shock wave in front of itself). As early as 1933, wind-tunnel tests had shown German researchers that as air gathers in front of a plane traveling at supersonic speed, its shock wave spreads behind it as a cone. A plane’s wings have to stay inside the cone, or the shock wave will put such pressure on the control surfaces, they can’t be operated. This is a problem for designers; if the plane’s wings are too long, they’ll cease to work at supersonic speeds and the plane will crash. If they’re too short, however, the plane might not be able to get off the ground at all! Designing a wing that will function at subsonic and supersonic speeds is no easy task; but the work on the problem had begun long before supersonic planes were ever built.
Dietrich Kuchemann, a Gottingen native, found himself developing ideas of supersonic flight. He had been planning to study pure physics at the university under the celebrated mathematician Max Born, a family friend, and one of the founders of quantum mechanics. When Born, a Jew, was expelled from the university under pressure from the Nazi regime, Kuchemann was left casting around for other things to study. Gottingen was home to Germany’s largest institute of aerodynamics. There Kuchemann-somewhat to his own surprise stumbled upon his life’s work: aerodynamics. During the war, Kuchemann designed the intakes for Germany’s earliest jet fighters. It was important work, but it still left him time to develop ideas of his own about wave drag, wingless planes and supersonic flight. Following Germany’s defeat, Kuchemann was picked up by Operation Surgeon, a no-nonsense British programme that removed German scientists and technicians. Kuchemann thrived in England and by the late 1940s, the aerodynamic department of the RAE read like a Who’se Who of German aeronautical design. The primary purpose of the RAE was to research and develop new types of aircraft for the British government. What kind of aircraft would the post-war future demand? British aeroplane manufacturers and the RAE responded with three truly terrifying warplanes: the V bombers ;these planes were Britain’s core Cold War deterrent until submarines equipped with the Polaris missiles came into service in 1969.
Engineers at British Aircraft Corporation (BAC) also responded with the TSR-2, strike aircraft featuring extremely fancy ground-following terrain radar, infra- red cameras, side looking radar and a sophisticated autopilot. Following cancellation of the TSR-2 project and freed from deadlines, Kuchemann and his colleagues picked up their old work on the theory of high-speed flight and built a series of test aircraft to study the problem of wing design. They were now expert at swept-back triangular wing layouts, called delta wings. Delta wings had a surface area that could keep them in the air at normal speeds; pushed beyond the speed of sound, their swept back shape kept them within the cone of the shock wave. The main problems were takeoff and landing. The takeoffs and landings angles with wings like these were incredibly sharp.Veterans of the TSR-2 project saw a way to save some of their hard work, by adapting their warplane design to create a viable civilian aircraft. The stage was set for a remarkable meeting of minds and a remarkable new aircraft. In 1961, Peter Thorneycroft, then Minister of Aviation, spoke to Cabinet. His excitement was palpable. He was proposing that the government develop a supersonic passenger jet. With it, Thorneycroft believed, “Britain has an opportunity . . . of gaining the leadership we so narrowly missed with the Comet.”
At BAC, Archibald Russel, a notorious perfectionist led the effort to create a British supersonic passenger plane. What he came up with would carry about 100 passengers across the Atlantic at around twice the speed of sound, or Mach 2, a term that remembers the German physicist Ernst Mach, who did so much important early work on shock waves. The Bristol 223 boasted four Olympus engines, based on those originally developed for the Vulcan bomber, a curiously scooped delta wing shape, courtesy of Dietrich Kuchemann, and a droopy nose to cope with those sharp takeoffs and landings it helps if the pilot can see the runway.
When I say that the Concorde was a remarkable plane, I am not for a second forgetting its limitations. It lacked range, which lost it lucrative routes to the west coast of the US and Johannesburg. It carried only a hundred people. And it wasn’t very comfortable: whoever dreamed up its plank-narrow seating never predicted today’s ever expanding waistlines. The legroom on offer wasn’t much better than you’d have got in economy class; and God help a tall person who tried to stand upright in the thing. BA made an effort, bless them, with their doll’s-house Wedgewood crockery and stunted silverware, but Concorde was never going to be a comfort option.
At its maximum cruising height of 60,000 feet, the air is so thin that a sudden loss of pressure might well have knocked everyone out before they could get to their oxygen masks. Concorde’s windows were made annoyingly small in an attempt to keep the air in for longer, giving passengers those vital extra seconds. The plane flew so high, there was a dial in the cockpit recording the amount of ionizing radiation hitting it from space.
Concorde flew faster than the Earth spun; flying from east to west across the Atlantic, you could beat the clock and land before you arrived. It flew so fast, a commercial jet flying in the same direction would look to Concorde’s passengers as though it was flying backwards. Air compressed by the plane’s passage heated the windows in the cockpit so much; they became too hot to touch. The whole aircraft swelled in the heat of its supersonic passage, and a gap opened up on the flight deck between the flight engineer’s console and the bulkhead. Retiring flight engineers used to place their hats in the gap before it cooled; the caps are there to this day.
Concorde was a plane to capture the imagination of an entire industry always assuming, of course, that the industry had any imagination. It turned out to be a big assumption. The Anglo-French consortium that built the plane secured a hundred non-binding orders, but a series of near-fatal coincidences knocked them for six. Bad enough that Concorde should go on sale at the height of the 1973 oil crisis; what really did for the initial orders (from the likes of Pan Am, United, Lufthansa all the major global players of the day) was the dreadful and spectacular crash of somebody else’s plane. Some people say that the Soviet Tupolev Tu-144 the world’s first supersonic passenger jet, beating the Concorde to the grid by two months. The Tu-144 was unveiled at the Paris Le Bourget air show on June 3, 1973. While in the air, it dipped violently, broke up and crashed, destroying fifteen houses and killing all six people on board and eight more on ground. The accident has never been fully explained. Tu-144 flew without trouble within the Soviet Union for years afterwards. In any event, the Tu-144 was done for commercially; and the Concorde, because it bore an obvious resemblance to the Tu-144, suffered by association.
The environmental movement was getting going around this time, and one of its first targets was the noise pollution from the aircraft. Concorde was particularly vulnerable because whenever it exceeded the speed of sound, a little of the air it displaced would explode. Over the years, aircraft designers have worked out ways to minimize this sonic boom, but at the time, it was popularly supposed that the sound barrier was some sort of real physical barrier that these newfangled supersonic aircraft simply had t punch through. No wonder some feared the future the Concorde was ushering ina cacophonous new world, its skies a-tremble with booms and bangs and the ever more raucous drones of ever more powerful engines! Noise abatement was a serious issue whose time had come, but it’s a pity that Concorde should have been made a target. I was far from being the loudest plane in the sky, a point well made in the US Supreme Court in 1977, when the ban on Concorde imposed by New York’s Port Authority was finally thrown out.
The biggest brakes on the Concorde’s future turned out to be the operators themselves. Concorde the aeroplane that wanted to be a rocket planewas a proposition so futuristic, so controversial, so odd, neither company quite knew what to do with it. They both made the same mistake. They treated Concorde like a regular passenger jet, only they stuck it on a pedestal: flying Concorde across the Atlantic was business as usual, they said, except that it was exclusive, it was expensive, it was. . . well, unaffordable.
n the last six months of Concorde’s life, BA woke up. Someone there finally realized why people flew the Concorde. People flew the Concorde for the experience. It wasn’t the workhorse the designers had imagined and the airlines had wanted. It was something quite different: a pleasure craft. Demand for air travel slumped following the attacks of 11 September 2001, damaging an industry already injured by rocketing fuel costs. The first-class cabins of flag-carrier airlines were even emptier than usual. BA and Air France committed themselves to withdrawing the Concorde from service so they could fill up their empty first-class seats.
On 25th July 2000, during takeoff from Gonesse, France, Air France Flight 4590 rolled over a strip of titanium part of a thrust-reverser that had, only minutes before, fallen from a Continental Airlines DC-10. This fragment punctured a tyre on the Concorde’s left wheel assembly. The tyre exploded, hitting the fuel tank and snapping an electrical cable. The tank fractured and fuel spilled out over the sparking wire. A fire broke out, and the landing gear refused to retract. Unable to gain height or speed, the plane pitched up violently, then rocketed into the Hotel in Gonesse, killing all hundred passengers and nine crew, and four people on the ground.
It was the Concorde’s only fatal accident, and it did not stop Concorde flying; but it did make abandoning the aircraft easier. It was while Concorde was grounded following the Gonesse crash that BA and Air France noticed something interesting: regular users of their supersonic service were buying first-class seats on their regular jets and they seemed to be staying loyal to the companies that operated them. The penny dropped: if BA and Air France killed Concorde, they would not just save money on maintenance; they would make their other long-haul flights more profitable. They wouldn’t even lose any passengers, because there were more than enough empty seats in their first and business-class cabins to accommodate the demand from former Concorde flyers. It made a brutal sort of sense, and times for the airline industry were hard in 2003.
Critics claim that Concorde was a white elephant: expensive to develop (which it certainly was), expensive to maintain (true, but exaggerated) and expensive to operate (absolute nonsense). Concorde was a sports car. You don’t buy sports car for its fuel economy. So what if a 747 is four and a half times more fuel-efficient than Concorde? A fully booked 747 is more fuel efficient than a family saloon! Playing with numbers is easy. The point is to ask what these vehicles are for, and to operate them responsibly. Concorde wasn’t what either its designers or its operators expected. In thrilling crews and passengers and lookers-on, it served to introduce us to a new model of the air industry: a way of doing things that took the out of long-haul flying.
Entertainment leads us into the future. Novelty and fun, more than anything else-more even than the ambitions and fears of nations are the engines that carries us there. Concorde was never going to usher in a world of Concords, any more than the Delahayes and Bugattis of the 1930s were going to usher in a world crawling with racing cars. The challenge today, for those of us inspired by Concorde’s example, is to create supersonic passenger planes that are faster, cheaper and kinder to the environment.
Concorde was made out of the most advanced materials of its day. They were, most of them metals; its children will be woven out of resins. Concorde burned fossil fuel by the barrel-load; its children will burn engineered fuels that have a minimal effect on the environment. Concorde climbed as high as it could, then slugged its way through the air; its children will escape the earth’s atmosphere entirely, increasing their speed and saving the atmosphere from harm. Concorde cut the journey times out of its competitors by more than half; its children will carry passengers from new York to Sydney in under two hours. Concorde promised a future in which all parts of the earth were accessible,
Excerpts from: Reach for the Skies by Richard Branson, Virgin Books 2010, Great Britain.
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