There were more spectators than usual on the terraces at Orly airport, south of Paris, on that September afternoon in 1973. They had come to see the making of a piece of aviation history - the climax of the fastestever Transatlantic crossing by a commercial aircraft.

The plane was the Concorde, built jointly by France and Britain in the most imaginative, most challenging, undertaking in aviation history. Yet the crowd was not enormous, nor was there any feeling of great excitement in the air. The technological "miracle" of yesterday had already been accepted, both in France and in Britain, as a simple fact of life today.

In the countries the aeroplane had just been visiting, the picture had been very different. Ten-mile traffic jams had built up around airports as crowds of a hundred thousand and more gathered to look over the creation that was designed to bring faster-than-sound flight within reach of anyone with the price of a plane ticket.

And, suddenly, there it was, a speck in the eastern sky that grew rapidly. As always, the landing configuration - nose drooped, long undercarriage lowered, the typical high-angle approach of the deltawinged aeroplane - gave it the appearance of a great sea-bird.

The crowd had been told to expect Concorde 02, second of the pre-production aircraft, at 1530. It had come in, in fact, a few minutes ahead of time, landing at Orly only 3hr. 33min. after take-off from Dulles airport, Washington - 213 minutes to cover a distance of nearly 3,900 statute miles. Its average speed had been about 1,100 miles an hour, or about 18 miles a minute.

For 2hr. 16min. The aircraft had flown at Mach 2, about 1,350mph, twice the speed of sound, carrying a payload of 25,0001b., made up of test installtions and 32 passengers. In the VIP lounge, newspaper and TV men had gathered to hear about the flight and to interview the crew and passengers who included airline executives, government officials and aviation journalists.

Jean Franchi and Gilbert Defer. captain and co-pilot (as well as being test pilots of Aerospatiale) were professionally unemotional as they gave the details of what had been, for them, an uneventful flight. The passengers were much more ready to enthuse, and it was to the passengers that Robert Hotz, editor of Auiation Week and one of the most experienced journalists present, turned his thoughts.

He wrote: "What is perhaps more important for its (Concorde's) future in airline service is that it has delivered a load of passengers in a remarkably fresh and unfatigued condition that will make them head back toward the 7-8hr. subsonic crossing with the greatest reluctance. "

And that is what Concorde is all about - to get the long-distance air traveller there in half the time. Some people feel that this is a reasonable and even laudable objective: others do not. There is nothing new about this fundamental division. There have always been those who wanted to go faster and those who thought the present speed (of ox-cart, stagecoach, sailing ship) was fast enough.

The debate is, however, sterile. Concorde is now already a fact of aviation life. Twenty years ago, Mach 2 was exclusively for super-fit young fighter pilots. Today, thanks to the technological achievement of Concorde, supersonic flight can be placed at the service of sedentary businessmen and the eldest of elder statesmen.

New ideas in aviation nearly always follow a clearly-defined pattern. First comes experimental research; then, if promising, the idea is taken up, at whatever cost, by the armed forces; finally, its reliability, safety and operating economics improve to the point where the application of the new idea to commercial aircraft becomes a practical proposition. In the past, the time gap between first adoption of the innovation by the military and its introduction into airliner service has been around ten years.

It has taken more than twice as long to move from the first supersonic fighters to the entry into service of Concorde and the Soviet Tu 144. The first fighter capable of exceeding Mach 1 in level flight was the F-100 Super Sabre, which entered service in 1953, and by 1958 the Lockheed F-104 had shown itself capable of sustained flight at Mach 2. The time taken to develop a supersonic airliner is no reflection on the design teams, but simply a measure of the magnitude and complexity of the tasks.

It was as early as 1943 that the British government first issued a specification for an experimental transonic aircraft capable of reaching Mach 1.5 (l,OOOmph) at 36,500ft. By February, 1946, the detail design of this aircraft, the Miles M.52, was nearing completion, but at that point the project was cancelled and substituted by a programme of telemetered transonic flights by air launched models. It was thought that there was too great an element of risk to the human pilot, and it is worth recalling that later in the same year the famous test pilot Geoffrey de Havilland lost his life when the DH 108 broke up during practice for an attempt on the world speed record.

Perhaps, with hindsight, the decision in 1946 to cancel the M52 can be criticised as having been over-cautious since it handed over to the Americans the lead in supersonic experience. At the time, however, the justification for the decision was the general uncertainty surrounding the aerodynamic and controllability effects of what had come to be known, quite inaccurately, as the "sound barrier."

The phenomenon of the compressibility drag rise which occurs as an aircraft approaches the speed of sound was first examined by the German scientist Adolf Busemann in 1933. Before the advent of the gas turbine engine with its far~greater thrust, it was thought that this sharp increase in drag could well place an upper limit on aircraft speed.

For an appreciation of basic supersonic design philosophy, some understanding of the nature of the compressibility drag problem is necessary. As an aircraft is propelled through the atmosphere by the thrust of its engines, the resistance of the air exerts a force upon it. This force is made up of two components: one is lift, which normally acts vertically on the aircraft, and the other is drag, acting in a direction opposed to the aircraft's motion. The measure of an aircraft's aerodynamic efficiency is its lift/drag ratio.

When it is moving through the air an aircraft sends out pulses in all directions. As these are sound pulses, their speed is the speed of sound at the altitude at which the aircraft is flying. So long as the aircraft's speed is below the speed of sound, some of these pulses move ahead of the aircraft and give warning to the molecules of air, which rearrange themselves to give the aircraft a relatively unimpeded passage.

But as the aircraft begins to approach the speed of sound, the situation changes radically. No warning pulses can now get ahead of the aircraft, and it has therefore to start forcing its way through the air in much the same way that a ship forces its way through the sea. It has to start compressing the air it meets as it moves forward. The ship creates a bow wave, and the aircraft creates a shock wave cone with its apex at the aircraft nose. Because of the nature of this greatly increased air resistance, there is a corresponding increase in drag (compressibility or "wave drag" as it is sometimes called) and, in the transonic speed range, an inevitable sharp falling-off in aerodynamic efficiency.

The Royal Aircraft Establishment, Farnborough, had been in the forefront of supersonic research in Britain and took the initiative in the discussions leading to the setting up in 1956 of the Supersonic Transport Aircraft Committee, a body which can be fairly claimed to have signposted the way for the future development of supersonic transport in Britain. It had as its chairman the deputy director of RAE, Mr M. B. (later Sir Morien) Morgan, and among its members were some of the best brains in British aviation. It was a truly national committee with representation from the ministries, the airlines and all the important British aircraft and aero-englne companies.

Under the auspices of the STAC, research into various aspects of supersonic transport design was pursued by technical sub-committees. By March, 1959, the work had progressed to a point where the committee was able to report its broad recommendations on the two types of supersonic airliner it thought should be developed. One was a 100-seat aircraft with a cruise speed of Mach 1.2 (800mph) and a maximum range of 1,500 miles. The other was a 150seat aircraft cruising at Mach 1.8 (1,200mph) with a Transatlantic range of approximately 3,500 miles.

The British concept

Following receipt of the report, the Ministry of Aviation awarded contracts for the study of various possible configurations for the long-range aircraft. For the time being the medium-range type was put on the shelf, and it was left to the French to revive the proposal for such an aircraft later.

From the wind-tunnel research and theoretical work done under these first feasibility study contracts, it became clear that the slender delta wing planform had advantages over all the other shapes being considered. Furthermore, and contrary to earlier predictions, the aerodynamic efficiency of this planform tended to improve up to about Mach 2.2.

It remained to decide what would be the best fuselage-wing combination to exploit the potential of the delta planform. A joint feasibility study, awarded to Hawker-Siddeley Aviation Ltd. and Bristol Aircraft Ltd., settled the issue. Hawkers investigated a proposal for a fuselage integrated in a wing of deep cross-section while Bristol studied a proposal for a discrete fuselage associated with a thin wing. When the results of the two studies were compared, the "discrete" configuration was found to have definite advantages over the "integrated" version for use in a first generation supersonic airliner in the size and speed bracket contemplated.

Under a design study contract, BAC proposed the Bristol type 198, a slender delta aircraft similar in configuration to that which Bristol - merged in the newly formed BAC in 1960 - had made for its feasibility study. It was powered by six Olympus turbojets mounted beneath the wing it had a Transatlantic range and a 130passenger payload- and its maximum takeoff weight was about 380,0001b.

Doubts about the weight of the Bristol 198, which increased the intensity of the sonic boom, and reservations about the intake design problems and economics of a six-engine installation, caused the government to call for a proposal for a smaller transport This was the Bristol Type 223, with four Olympus engines, capable of carrying 100 passengers over a Transatlantic range and with a maximum takeoff weight of 250,0001b. This last was an all-British design.

When the design study contract was awarded in 1960, the government made it a condition that BAC should actively explore the possibilities of international collaboration on the project. It was already apparent that there would be heavy demands on finance, manpower, and research and development facilities in developing a supersonic airliner, and there were obvious advantages in sharing the load with another nation if agreement on the basic design principles could be reached.

Approaches were therefore made by BAC to the United States, Germany and France. There was little interest shown in the USA where at that time there was a widespread conviction that the first-generation supersonic civil transport should be based on the Mach 3 B 70 bomber. Germany's reaction was that their industry was not ready to face the challenge of a supersonic airliner just yet and they would require more time to consider such a step.

The French concept

French response was very different. Their industry was in good heart and justifiably proud of the Caravelle. Today rear-engined jetliners are accepted as the norm for short and medium-haul operation, but it was not always so. The Caravelle was the first of the breed and there was much skepticism in Britaln and the USA about the configuration before the aircraft proved itself.

France, too, had been investigating the feasibility of developing a supersonic transport, and their thinking had been running on parallel lines to that of the British. The French company Sud-Aviation had a prominent role in this activity. Just as Bristol was merged into BAC, so Sud-Aviation became part of the nationalised SNIAS group, familiarly known as Aerospatiale. It was these two groups that were to become joint airframe contractors for Concorde.

Sud-Aviation and Dassault had already announced that they were concentrating their effort on a medium-range aircraft. The name they gave to their proposal, the Super-Caravelle, was significant, but it was not only their recent Caravelle experience that coloured their thinking. They considered, with some justification, that long range would be a difficult initial design objective for any supersonic transport and that it would be better to concentrate first on the more easily achievable medium range, extending the range as operating experience was acquired.

The British, on the other hand, were firmly of the view that Transatlantic range was a fundamental requirement for supersonic operation. Whatever the difficulties and it was accepted that they would be great - it was in the long-range market that the best prospects for a supersonic transport lay, because it was only on sector lengths exceeding 1,500 miles that the timesaving advantages of the higher cruise speed began to show themselves.

When, in accordance with the 1961 design study contract, BAC raised the subject of collaboration with Sud-Aviation, the French company was quite prepared for serious discussions, but on the basis that there would be two different types of aircraft. Later in 1961, BAC and Sud-Aviation each put in proposals for long-range and medium-range aircraft, but these still showed the differences in the approach to key design problems. By this time, there had also been direct consultation between the French and British governments on the subject and the companies' proposals did not go far enough to meet the governments' wish for joint working.

The Anglo-French compromise

The leaders of the two design teams had been in regular consultation, however, and were gradually coming to a closer understanding of the othera' viewpoint and motivation This steady movement towards an agreement was a long, and sometimes wearing, process, but it helped to lay the foundation for the years of joint working that lay ahead.

By the Farnborough Air Show in September, 1962, agreement was so close that a model of the proposed aircraft was shown on the BAC stand. This attracted much Press and public attention, and there was some speculation that the expected AngloFrench agreement to build an SST (supersonic transport) might be announced. But there were still two months to wait.

The four men who had been most closely concerned wlth the direction of the joint design studies and discussions were, on the British side, Dr A. E. (later Sir Archibald) Russell, technical director of BAC's Filton Division, and Dr W. J. Strang, chief engineer of Filton Division and, on the French side, Pierre Satre and Lucien Servanty, technical director and chief engineer respectively of Sud-Aviation. Each of the four was an aeronautical engineer of international standing.

In October in a small office in Paris, a final move was made in the protracted negotiations. Bill Strang and Lucien Servanty were closeted for a whole day, with a single draughtsman and drawing board, and instructed to come out with a common three-view general arrangement drawing for the long-range and medium-range aircraft. They succeeded, although it would be hard to imagine two men more unlike in temperament, background and personality. Lucien Servanty was a forceful and fiery character, who did not suffer fools gladly. Bill Strang is an equable, quiet-spoken man, who leads rather than drives his team. They were, one might have thought, a fairly unlikely pair to work together as collaborators on the most difficult technological project ever tackled in Europe.

Yet this partnership, like many others in the Concorde organisation, grew and flourished on the firm basis of mutual respect for the other's intellect and integrity. When Servanty died in 1973, soon after 02 had made the first Concorde non-stop crossing of the North Atlantic, Bill Strang wrote in Flight International:

"Lucien Servanty was, above all, a dedicated engineer. He combined a wide intellectual grasp of his subject with a great capacity for absorbing detail. Setbacks never daunted him. They were accepted as a challenge and always his first step was to analyse the situation in depth in order to isolate the underlying causes of the problem.

"Once he had made up his mind, he was prepared to support his opinions vigorously, deploying an impassioned array of arguments. He was always a loyal friend and ally. Sometimes we were together against 'the rest.' Sometimes we were ourselves in disagreement, and I believe a partnership such as ours would have been of little value if this had not happened from time to time. But however tough the in-fighting, as soon as we left the office Lucien would at once become the charming and cultivated host I knew so well."

The joint proposal which finally emerged from the inter-company discussions was for a slender-delta-winged monoplane, with common dimensions but different internal layouts for the medium- and the long-range versions. The medium-range aircraft was to seat 100 passengers and would take-off at a maximum of 220,0001b., and the long-range had a capacity of 90 passengers and an all up weight of 262,0001b.

A review was made of the design, production and research facilities available for the joint project, and general agreement was reached on the allocation of responsibilities between the two companies. At last, on November 29, 1962, an agreement was signed in London by Julian Amery, Minister of Supply, and Geoffroy de Courcel, the French Ambassador to Britain, by which the two governments undertook to finance the development and building of a supersonic airliner. Everything would be shared - costs, work, and proceeds of sales.

Before the signing of the treaty, BAC and Sud-Aviation had agreed in principle on how the work of developing and producing the airframe of the supersonic airliner should be shared between them. One of the companies' first tasks now was to convert this general understanding into a definitive agreement. They had to produce an acceptable and practical plan for enabling the design and production work to be broken down and allocated, on a 6040 split to France and Britain. It took long meetings and much hard bargaining to agree on a manufacturing break-down but, in general, the division of responsibilities then formulated still holds good today.

The airframe work was divided 60-40 in favour of France because the balance of work on the engine was weighted in favour of Britain. By November, 1962, the engine selected for the Concorde, the supersonic version of the Bristol-Siddeley Olympus, was already being developed. Engines were in existence and running on the test-bed, and whatever adjustments might be made in the new programme to allow joint AngloFrench development of the Olympus 593, the British work content would be greater than the French.

Agreement on the airframe breakdown enabled BAC and Sud-Aviation to begin the allocation of work within their own groups. Each of the factories concerned was given full responsibility for detail design and manufacture of the component or components allocated to it. The BAC factories which received Concorde sub-assembly work were Weybridge, Filton, Hurn and Preston, the Sud-Aviation factories were St Martin, Toulouse, Bouguenais, St Nazaire and Bourges.

Plans were also made for two final assembly lines to be established, one in Britain and the other in France. In series production, the odd-numbered Concordes are assembled in the St Martin plant at Toulouse and the even-numbered at the Filton works of BAC. There is, however, no duplication at the sub-assembly stage. For example, all the nose fuselages (Sections 10 and 11) are built at Weybridge, all the centre fuselage wing components (Section 14) are produced at Marignane.

In structural design, BAC was made responsible for the front fuselage including the flight deck, the engine nacelles, air intakes and engine mountings, the rear fuselage, fin and rudder. It had design responsibility as well for the following systems: electrics, oxygen, fuel, engine instrumentation, engine controls, fire, air conditioning distribution and de-icing. Sud-Aviation's share of the structure comprised the entire centre fuselage section, the wings including elevons, and the landing gear. The French company was also given design responsibility for the hydraulics, flying control, navigation, radio and air-conditioning supply systems.

Working together

With this clearly-defined division of overall responsibilities and the firm allocation of sub-assembly responsibilities, work could be started across a wide front. Numbers of people deployed on the project increased steadily until the total, including those employed by sub-contractors and suppliers, reached nearly 50,000. Most of these thousands were able to get on with their work without reference to anyone except their immediate superiors. But their efforts could only be effective so long as there was coordinated direction at the top and close liaison at all executive levels throughout the international organisation. This organisation worked well because a few scores of pairs of people, French and British, learned to work in partnership.

Without firm handling, one aspect of the collaboration arrangements could have been a source of serious friction. Although it was never precisely defined, there was a general understanding that Sud should lead on the design side of the project and that BAC should be leaders on the manufacturing side. But the first few months' working together made it clear that joint direction would be necessary. Therefore, the two leaders of the project, General Andre Puget, President of Sud-Aviation, and Sir George Edwards, chairman of BAC, who held the chairmanship of the Aircraft Committee of Directors in rotation for several years, decided to take all major executive decisions jointly, having talked out the problem between them. On paper, the committee had a chairman and a vice-chairman; in practice, it had two chairmen.

Intervention at chairman level was not often required. Indeed, Sir George has suggested dryly that one of the secrets of the success of the Concorde industrial collaboration was that the Committee of Directors did not meet very often. In contrast, other Anglo-French pairs at executive level needed to keep in daily contact by executive aircraft, telephone, telex or data link. In many cases, collaboration led to firm friendships.

There were, of course, incompatibilities and friction. Two large independent engineering organisations, each jealously proud - with good reason - of its reputation and skill, were being compelled to join forces on a project for which both had done much spadework. Some of them thought of it as a shotgun marriage. There were bound to be personality problems, but that would have been equally true had BAC been working with another British company or Sud with another French one.

The language barrier

Undoubtedly, some of the problems of professional pride were exacerbated by language difficulties and by differences in national temperament. Early meetings on any subject tended to divide on purely national lines, but in the long run nationality factors played a surprisingly small part. Men who worked through the "running-in" period of the collaboration are often asked how the problem of the language barrier was overcome. Their reply is usually on the lines that, if you could not find a way round the barrier, you just barged through it.

Because Sud-Aviation had been building Caravelles for the international market, many of their engineering and sales executives spoke good English, and that gave them a head start over their British opposite numbers whose French was, in the main, at the rusty sixth-form standard. A number of BAC men have since acquired a working knowledge of French, however, particularly in their professional field, so that many meetings can be conducted bilingually, with the French and the British speaking in their own language without immediate translation.

One British custom which never ceased to bemuse the French is the ready use of Christian names. This was underlined at the end of a meeting at which agreement had been reached on a specially complicated point. The leader of the British group said: "Jean, just so that both sides are clear on what has been agreed, why not get Honorine in and dictate a note on the subject?" The Frenchman replied: "D'accord, mais qui est Honorirle?"

Honorine was his own secretary, but, although she had worked for him for three years, her French chief still knew her as "Mademoiselle Dupont."

Double standards

As the project moved onwards, more and more people in both countries grew convinced on two points - that Concorde was well worthwhile, and that Britain and France had a much better chance of seeing the programme through to success by working together than by going it alone. At bottom, it was the strength of these convictions that enabled the Concorde team to push doggedly ahead through all the crises and vicissitudes of the decade that followed.

One technical question frequently asked is: What happens about the two standards of measurements in France and Britain? The simple solution to this problem was to allow both sides to work in the scales to which they are accustomed. A common system of numbering engineering drawings was established before manufacture of the prototype aircraft began. French drawings were dimensioned in metric measurements, and British drawings in feet and inches. At interface points in the structure, the relevant drawings were dimensioned in both scales.

A minor, but not unimportant, requirement was to find a suitable name for the aircraft. When the collaboration began, the design was being referred to by the British as the "SST" or the "223," a reference to the Bristol type number. Neither title could be regarded as inspired or inspiring. The French used the terms "TSS" (transport supersonique) or, quite frequently, "Super-Caravelle." There were those in Britain who felt that they could not accept the implications of the latter name.

One Sunday afternoon in January, 1963, the suggestion that the aircraft should be called "Concorde" emerged from an informal family conference in the home of a BAC executive. It was arrived at by the simple process of thumbing through Roget's Thesaurus. At this family discussion, the first reaction to the suggestion of "Concorde" was the question: "With the 'e,' of course?" To which the answer was: "Yes."

When the suggestion was put forward officially, the British side approved it tentatively and then submitted it to the French. There were some preliminary murmurs of approval but the subject was regarded as a matter for decision by "higher authority." It is ironic that the first indication that the name had been officially adopted in France came in the famous speech by General de Gaulle in which he dashed Britain's hopes of joining the Common Market. In it, the French President mentioned "the Concorde supersonic airliner" and said there was no reason why this kind of scientific and industrial collaboration between the countries of the Six and Britain should not continue.

So the project had a name. Or, rather, it had two names for the British government soon decreed that in this country the spelling "Concord" should be used This trifling difference proved to be a small but recurring source of friction for several years. But at the roll-out of the first Con corde prototype at Toulouse in December, 1967, Mr Anthony Wedgwood Benn, then British Minister of Technology, finally resolved what he described as the only disagreement with France that had occurred during the years of co-operation on the project. He had decided, he said, that the British "Concorde" should from now on also be written with an "e."