It is symbolic of the malaise cloaking aviation as it celebrates the centennial of powered flight that, for the first time since Orville and Wilbur Wright made history in 1903, mankind had to settle for flying more slowly than before. Concorde, the airplane that opened supersonic flight to anyone with the means to buy a ticket, will retire this year after 27 years of service with British Airways and Air France. The British flag carrier has said it will operate its last Concorde flight on October 24, five months later than Air France, which terminated its scheduled supersonic transport (SST) operations on May 31.

It was not decrepitude that finished off the crown jewel of the airline fleet, but the alignment of other, less manageable forces.

First, the fiery accident to an Air France Concorde on July 25, 2000, shortly after takeoff from Paris Charles de Gaulle Airport caused the fleet of SSTs to be grounded for 16 months for safety modifications to fuel tanks, tires and wiring runs.

Second, when the modified airplanes returned to service in 2001 with refitted cabins just a couple of months after the September 11 terrorist attacks, the world economy and mood were very different. People who had learned to conduct their business and personal lives without Concorde during the grounding continued to live without it after it returned, some driven away by cost-consciousness, others possibly by lingering fears about the safety of the airplane despite the modifications. Some widely publicized technical problems over the past year (including a repeat performance of a British Airways Concorde shedding rudder parts, and for Air France an engine failure that preceded a sudden and dramatic altitude loss over the Atlantic, and also a major fuel leak in flight) hardly reassured the airplane’s tepid clientele. Load factors fell to levels that could not sustain continued operations, and both airlines reported at the time of announcing the SST’s retirement that neither had made any money since returning the modified airplanes to service.

Third–and this has arguably been the sturdiest nail in Concorde’s coffin–were manufacturer estimates of maintenance costs over the next few years, which exceeded the two airlines’ own estimates by more than $60 million. In combination with the declining revenues, the projected maintenance bills led to only one conclusion: Concorde had reached the end of the road, prematurely in that British Airways had planned to keep flying its modified airplanes until at least 2010.

What massive development costs and truly daunting technological challenges (not to mention legions of anti-SST activists and politicians) had failed to do was eventually accomplished by lack of demand for supersonic travel at the asking price it commanded–about $12,000 round trip between London or Paris and New York.

Rifle Bullets 11 Miles Up

The challenges of designing and building a machine to reliably and regularly transport the traveling public–from top athletes and business executives to rock stars and Mr. and Mrs. Ordinary treating themselves to the trip of a lifetime–at the muzzle velocity of a .22 rifle bullet 11 miles above the ocean were enormous. But in the early 1960s that was the price for Europe to regain the aeronautical lead it had lost to the U.S. with the advent of the successful jetliner. Britain had been first with the de Havilland Comet jetliner, and France was not far behind with the Sud Aviation Caravelle (which, incidentally, used the Comet’s nose and flight deck), but by the time the Comet’s disastrous structural shortcomings had been fixed, the race was already lost to Boeing and Douglas with their respective 707 and DC-8.

Concorde was Europe’s ticket to the next generation of jetliner, an airplane that, if not for the masses at least for the wealthy, would bring  jet fighter speeds to the airlines. Speed had driven just about every advance in aviation thus far, and it seemed entirely logical to expect that a supersonic transport would follow on from the likes of the 707 and DC-8.

Sustained and prolonged supersonic cruise brought with it problems that the designers of military fighters, designed for brief supersonic dashes, never had to confront. (It wasn’t long after service entry that the Concorde fleet had logged more supersonic hours than all the world’s air forces combined had logged since Glamorous Glennis first broke through the wall in 1947.) With the so-called “sound barrier” pushed aside, a supersonic airliner would encounter another equally forbidding obstacle. In its forays up to Mach 1.9, the stainless-steel Bristol 188 had taught British designers the significance of skin surface heat.

Kinetic heat imposes a sustained-speed limit of approximately Mach 2.0 on an aluminum structure. Heat dictates an aluminum SST’s limit speed: at 127 degrees C, the nose probe is the hottest part of Concorde at Mach 2 cruise, followed by the wing leading edges at 99 degrees C. The molecular structure of aluminum suffers from repeated exposure to temperatures generated by flight at more than Mach 2, compromising its strength and durability, and the alternative metals, such as stainless steel or titanium, considered for an SST back in the 1960s were exotic and relatively untried in airplanes.

If materials were limiting, so were aerodynamics. Wings that worked at high supersonic speed were treacherous at low speed, and vice versa, and yet Concorde would have to operate from the same runways as other jetliners. The slender-delta configuration, attributable to research by Dietrich Kuchemann (a former Messerschmitt engineer), Eric Maskell and Johanna Weber, was the key to success in conjunction with another newly discovered aerodynamic foible called controlled flow separation. This was a vital revelation, and it contradicted then-current thinking, which held that the smooth flow of air over an airfoil was essential to lift and stability, and that dire consequences attended its loss.

Delta wings such as Concorde’s have an extremely low aspect ratio (in the region of 0.5:1), and engineers thought initially that this would prevent takeoff and landing on the power of wing lift alone. Some of the early research for an SST produced miserable numbers: for example, a 300,000-pound airplane would be capable of flying the Atlantic supersonic but with enough payload for only 15 passengers.

One of the turning points was the discovery that controlled flow separation from the delta’s leading edge over virtually the entire angle-of-attack range produced a pair of highly stable conical vortices that had the combined effect of increasing lift and reducing drag. (Lockheed followed this path for its proposed SST, and Boeing dropped its early swing-wing design in favor of a fixed delta.) In the ogival delta (so called because the leading-edge sweep describes the gentle S-shaped curve of an ogee) the disparate demands of high-speed and low-speed flight were met in one fixed wing–a wing that also happened to be strikingly elegant. In short, the accepted aerodynamic principles of heavier-than-air flight were of little consequence to a successful SST.

Concorde as Political Weapon

Apart from leading Europe’s assault on U.S. dominance of the world aerospace market, Concorde was also the spearhead of Anglo-French political and industrial relations. The French and the British had rarely seen eye to eye on anything. How on earth could they tackle this formidable job together, saddled with other handicaps such as the language barrier, metric versus Imperial units of measurement and the physical barrier of the Channel? The program was to set the stage for Airbus and other intra-European collaborative projects. “Two heads are better than one, even if one is French,” a British Aircraft Corporation (now BAE) engineer is alleged to have said early on. Neither country could afford to develop an SST alone, based even on the wildly optimistic initial cost estimates. Some sources maintain that the French were reluctant at first to collaborate, but that the British held the trump card with the Bristol Siddeley Olympus engine.

The official starting point was a meeting of the Supersonic Transport Advisory Committee (STAC), led by Sir Morien Morgan, in November 1956. Negotiations with the French resulted in the signing of the Anglo-French Supersonic Aircraft Agreement on Nov. 29, 1962. There was no design leader and decisions were to be thrashed out by committees. An unusual document between two nations, the agreement contained no break clause, making it absolutely binding. This was at the insistence of the British, who expected the French would try to pull out at a later stage. As it turned out, the reverse was the case. In the years ahead, British commitment to the program vacillated, while France maintained an almost unwavering dedication to its completion.

To Gen. Charles de Gaulle, president of France, Concorde was a prestige project aimed at ending U.S. domination of the skies; to UK prime minister Harold Macmillan, Concorde represented his vision of a united Europe. It was his ticket to acceptance in the European Economic Community (predecessor to today’s European Union) and a tangible gesture to de Gaulle, who was strongly opposed to Britain’s entry. Politics was both Concorde’s lifeblood and its specter of death. De Gaulle made it clear that the future success of the Concorde program would be part of the process on which Britain would later be deemed ready to become a full member of the EEC. Subsequent British governments were either cool toward the project or hell bent on canceling it.

The Anglo-French SST was first called Concorde in public by de Gaulle during the very same speech in which he pronounced his famous “non” to Britain’s entry into the EEC. Concorde, meaning “a harmonious state of agreement,” was aptly named in terms of the project’s aspirations, but it hardly reflected the partners’ emotions of the moment.

The marriage was strained early on when the two countries tried to decide on the size and range of the SST. France wanted a medium-range airplane and Britain a long-range airplane, and the plan initially was to build both. But by 1964 France concurred, after Pan Am and other airlines had taken options on the long-range airplane, and the team concentrated on a long-range SST capable of crossing the Atlantic. The expected cost of getting the airplane into production was £220 million split about equally over eight years.

In October 1964 the Conservative government of Harold Macmillan was voted out of office. Harold Wilson’s Labour government was in, and swinging a budgetary ax
at the pride of British technology: the TSR.2 (a highly advanced supersonic terrain-following bomber powered by basically the same engines destined to propel Concorde); a supersonic derivative of the P.1127 vertical-takeoff fighter, which became the Harrier; and Concorde. (Wilson’s cancellation spree fueled conspiracy theories in Britain that he was a Soviet agent.)

The right-of-center de Gaulle was enraged and had no intention of letting Britain wriggle out of its obligations to the SST treaty. (Just in case, however, he is thought to have sounded out Germany, Sweden, Holland and Belgium for their support in the event of British withdrawal, and even to have approached the Russians about replacement engines.)

Wilson was in the embarrassing position of probably being taken to the International Court of Justice in The Hague if he pulled out. He would likely also have been ordered to pay half the development costs with nothing to show for them (which, as it transpired, would have been much cheaper in the long run than paying half of
the £1.6 billion final price tag, a figure that in the mid-1970s equated to about $3.25 billion). Wilson bowed to the consequences and Concorde survived.

By the spring of 1965 Concorde was taking shape in aluminum, but in 1968 it had another scrape with mortality when the Labour government cut spending sharply. In 1970 Wilson called a general election and lost to the (basically pro-Concorde) Conservatives. Flight testing was proceeding well, following the 1969 maiden flights of the countries’ prototypes on March 2 (French) and April 9 (British) under the commands of André Turcat and Brian Trubshaw, respectively.

In 1971 Concorde was again threatened by two events: the bankruptcy of Rolls-Royce, which had absorbed Bristol Siddeley and was responsible for Concorde’s Olympus 593 afterburning turbojets along with Snecma of France; and the cancellation of the Boeing 2707 SST, which raised the question of whether or not the U.S. would grant landing rights to Concorde after canceling its own SST–apparently and partially on the grounds of environmental damage.

The environmental lobby was active in Britain, too, in the form of the Anti-Concorde Project. SSTs were portrayed as monstrous symbols of pollution, elitism and nationalization (synonymous in the group’s view with socialism) that would shatter the earth asunder with sonic booms, bring on the fourth ice age (or melt the polar ice cap– opinion differed), destroy the ozone layer and thereby cause skin cancer, not to mention hearing loss and cardiovascular, glandular, respiratory and neurological changes in the defenseless humanity below. Perhaps if all the world’s major airlines had ordered Concorde fleets, the environment would have suffered measurably. But in the end only 14 airplanes entered service.

Stratospheric Costs

Concorde’s development costs ballooned beyond either country’s wildest imaginings.

Around the time Concorde entered service in 1976, Flight International published the “launch investment” (engine and airframe research & development and nonrecurring production tooling) between 1962 and 1976 as £1.2 billion (about $8 billion today, equally divided between Britain and France). This figure did not include production costs of $960 million (about $3.2 billion, 2003 dollars) for 16 production aircraft at $60 million ($193 million) each. (The exchange rate on the day Concorde entered service–Jan. 21, 1976–was £1= $2.025.) All told, Concorde’s development and production costs could be said to have cost each man, woman and child in Britain and France about £17 ($34 then, about $110 now). Spread over 14 years, that’s roughly the price of a few beers each year per person (lemonade for the kids).

The cost increases are now generally attributed to inflation, currency fluctuations,
the complexities of joint development and to several major redesigns along the way. In 1964 the wing area grew by 20 percent and maximum takeoff weight went up to 330,000 pounds. A year later, the preproduction configuration had 130 seats. By the end of 1967 another redesign took max weight to 367,000 pounds, and the wingtips and leading edges were further refined for less drag. The tail grew in length, a new nose-visor design appeared and fuel capacity was increased. Another year later, max takeoff weight was up to 385,000 pounds and fuel capacity was increased again, as was the length of the rear fuselage. In 1971 the team made more changes to the engine intake control system–one of the most expensive and time-consuming problems encountered. It was not until the close of 1975, by which time the development airplanes had flown nearly 5,500 hours, that the French and British aviation authorities issued certificates of airworthiness.

Airline service began on Jan. 21, 1976, from London to Bahrain (British Airways) and Paris to Rio de Janeiro via Dakar (Air France). After much deliberation over landing rights, Concorde flights to New York from London and Paris began in 1977.

While nobody questions the technical achievement of carrying 100 people at the speed of a rifle bullet, sipping champagne and eating canapés off fine china while clad only in shirtsleeves, Concorde was an economical flop when evaluated by conventional airline accounting yardsticks. The British government sold British Airways its seven Concordes for one pound each because that was the only way the airline would agree to operate them; Air France, too, was given its seven airplanes.

Even without amortization of true purchase price, it was clear to both airlines
that Concorde was going to be an abnormally expensive airplane to operate and maintain. Lay observers, who tend to lace their revelation with shock at such profligacy, have noted many times that Concorde burns as much fuel to carry 100 people across the Atlantic as a 747 burns to carry 400. There should be no surprise there: such is the price of speed. By the simple laws of physics, fast is more energy-hungry than slow.

Environmental questions aside, the vast majority of the world’s airlines did not greet the SST with open arms. The concept emerged at a time when the economics of the subsonic jetliner were just beginning to tap a huge market. Having invested many millions of dollars in jetliners that had rendered their relatively youthful piston fleets obsolete overnight, the airlines could not afford premature obsolescence again. Concorde also broke the historical pattern of ever lower operating costs per seat mile; its payload is only 6 percent of max takeoff weight, versus about 20 percent for the 747, and by the time Concorde was ready for service, fuel was expensive.

In the end, British Airways at least made Concorde operations profitable for many years before the July 2000 accident, largely because it successfully supplemented its scheduled transatlantic operations with worldwide charter ops. Concorde’s strikingly beautiful shape and even its distinctive turbojet noise caused it to be welcomed just
about wherever it went on these world-wide odysseys.

Operating a Thoroughbred

Concorde not only looks like no other jetliner; it flies like no other jetliner. The flight deck is about the size of a long-range business jet’s, plus a sidesaddle seat for the flight engineer, but it has a few gauges and knobs and dials that are unique. No other civilian airspeed indicator has numbers this high (Mach 2 at 60,000 feet equates to about 1,350 mph, or one statute mile every 2.7 seconds, or 19 nm per minute), and trim is accomplished not by moving control surfaces but by the flight engineer’s shifting fuel. Concorde introduced fly-by-wire to the civil fleet, and autothrottle helps the pilot manage the balancing act that is flying Concorde, a task that calls for unusual precision.

Concorde’s wing has no leading-edge or trailing-edge high-lift devices; with some secondary function for enhancing low-speed lift, the trailing-edge surfaces are for pitch and roll control only. The airplane is essentially an elongated flying wing, and simply by changing its angle of attack it can provide an airspeed envelope vastly wider than that of any other civil aircraft. Indicated airspeed at Mach 2.0 at 60,000 feet is 400 knots, after a transatlantic-mission rotate speed of 190 knots indicated. The true-airspeed envelope is unique in the airline world, stretching from 190 knots at rotation (and 205 knots as the eight mainwheels leave the runway) to 1,150 knots.

The disadvantage of Concorde’s slender-delta configuration is its reliance on prodigious quantities of power–both to reach the required 190-knot takeoff speed in the confines of existing civil airports, and to maintain flight at the high angles of attack required at approach and landing speeds (some 13 degrees on final approach, with the pilot maintaining a pitch angle above the horizon of exactly 10.5 degrees). Typical final approach speed is 155 to 160 knots, but at noise-sensitive airports such as New York’s John F. Kennedy the speed is kept at 190 knots down to 800 feet (about 2.5 miles from the threshold) because less power is required to maintain the glideslope at the higher speed. Concorde’s distinctive “droop snoot” nose lowers to maintain visibility for the crew at these extreme nose-high angles.

On a Boeing 747 cruising at Mach 0.85, the center of lift is about eight inches farther aft than where it started out. On Concorde at Mach 2, the center of lift has migrated aft by a massive seven feet. The designers recognized early that the drag of deflecting control surfaces for pitch trim was unacceptable, and the correct center-of-gravity (c.g.) position on Concorde is maintained by pumping 12 tons of fuel into the tailcone (through a pair of four-inch-diameter pipes) as the speed increases, then forward again to the forward trim tank as the airplane decelerates for the descent and landing. While this transfer of fuel is aerodynamically elegant, it renders 12 tons of fuel unusable during the supersonic portion of the flight, with an attendant penalty on range. At subsonic speeds the fuel can be used, but it doesn’t carry the airplane nearly as far as it would have if burned at Mach 2.

Fuel placement on the SST is as integral a part of the control system as the elevons, and the flight engineer is essential to the continued controllability of the machine. Fuel shifting plays a role in low-speed handling, too. For takeoff and landing, Concorde’s c.g. is deliberately kept a little farther aft than it need be, calling for a balancing application of down elevon–which increases camber and bestows on the airplane some of the effects of trailing-edge flaps. Incidentally, the Russian Tupolev
Tu-144 SST, whose sole victory was to beat Concorde into the air by first flying on the last day of 1968, achieved the same effect by having canard foreplanes just downwind of the flight deck. By generating a small amount of lift far ahead of the c.g., they created a tendency to pitch up that called for a balancing application of down elevon.

Engines

Concorde’s stalwart Rolls-Royce/Snecma Olympus 593 turbojets are 1960s technology, and a prime culprit for the airplane’s severe operating economics. Their noise is distinctive, whether it be the insistently powerful humming whine they emit during mere taxiing or the thunderous (and literally gut-shaking if you’re close enough) roar of an afterburner takeoff at 400,000 pounds. They breathe through 11-foot-long intakes equipped with ramps and spill doors to cope with supersonic intake flow, and they each eject their 38,050 pounds of thrust through hinged variable exhaust nozzles, called clamshells or buckets.

The intakes and their ramps set up shock waves that, in a distance of just 11 feet, slow the incoming air to Mach 0.5 from Mach 2. In the event of an engine failure at supersonic speed, Concorde banks the “wrong” way because the spill door vents all that intake air downward, imparting a rolling moment away from the dead engine.

In the process of slowing the intake air, the ramps also compress the air and raise its temperature, meaning that the engine’s own compressors have less work to do. However, changes in air temperature and pressure during cruise disturb the wave pattern in the intakes. Computers sense these changes and fine-tune the position of the ramps to maintain the correct airflow into the engine. Likewise, changes in engine power settings require changes to the airflow.

The Tu-144’s reliance on afterburners for sustained supersonic cruise contributed greatly to its early demise. The cores of its Kuznetsov NK144 low-bypass (one-to-one) turbofans were too small for the Tu-144 to sustain Mach 2 without continuous reheat, with the attendant fuel-flow and range penalties. However, the Russians were very close to making their SST work.

Concorde’s afterburners are lit for takeoff, then cut 60 seconds later for noise abatement. The flight engineer lights them again at high subsonic Mach for acceleration through Mach 1 and leaves them burning until Mach 1.7. Concorde then accelerates in dry thrust to Mach 2.0.

Sonic Boom

Engine noise on takeoff has not been Concorde’s only anti-social trait. There is also the matter of the sonic boom, which banished the SST from exercising the SS in its name over land. The transatlantic routes are designed to allow Concorde to accelerate to supersonic speed as soon as practical while not booming the coastal population too loudly. Residents and vacationers on Martha’s Vineyard, an idyllic island off the coast of Massachusetts, have been able to set their watches by the distinctive boom as Concorde heads east to Europe each morning. There are other, more flukish examples of booming, such as the transatlantic yachtsman who was stooping, with lighted match in hand, to ignite the oven in his sailboat’s galley when Concorde’s boom reached the surface of the ocean, convincing him momentarily that he had blown himself up.

The End

So the year is 2003, the end is in sight for the first-generation SST, and museums are lining up for the 13 remaining airplanes. Plenty of critics inside and outside aviation have pilloried Concorde for its development and operating costs, but few (in aviation circles, at least) hold anything but awe for the technical ground the airplane broke in an era when slide rules, not 2.2-GHz computers, powered design offices. By NASA’s admission at the time, making Concorde work was no less a feat than putting men on the moon.

Both feats were achieved in an era when technology was pursued for technology’s sake. At some point that era faded, and today it seems the populace (and perhaps more important, shareholders) are more impressed with information bytes than with technology bites. Other than Dassault’s continued work on the concept of a supersonic business jet (the NetJets fractional ownership program has expressed interest), which may or may not lead to a real airplane, there is nothing on the horizon to take Concorde’s place, and for the first time in the history of aviation, air travelers beyond this fall will be forced to recall how fast premium air travel used to be.