Concorde
Concorde is a retired Anglo-French supersonic airliner jointly developed and manufactured by Sud Aviation and the British Aircraft Corporation.
Studies began in 1954 and a UK–France treaty followed in 1962, as the programme cost was estimated at £70 million.
Construction of six prototypes began in February 1965, with the first flight from Toulouse on 2 March 1969.
The market forecast was 350 aircraft, with manufacturers receiving up to 100 options from major airlines.
On 9 October 1975, it received its French certificate of airworthiness, and from the UK CAA on 5 December.
Concorde is an aircraft design with a narrow fuselage permitting four-abreast seating for 92 to 128 passengers, an ogival delta wing, and a droop nose for landing visibility.
It is powered by four Rolls-Royce/Snecma Olympus 593 turbojets with variable engine intake ramps, and reheat for take-off and acceleration to supersonic speed.
Constructed from aluminium, it was the first airliner to have analogue fly-by-wire flight controls.
The airliner had transatlantic range while supercruising at twice the speed of sound for 75% of the distance.
Delays and cost overruns pushed costs to £1.5–2.1 billion in 1976.
Concorde entered service on 21 January 1976 with Air France from Paris-Roissy and British Airways from London Heathrow.
Transatlantic flights were the main market, to Washington Dulles from 24 May, and to New York JFK from 17 October 1977.
Air France and British Airways remained the sole customers with seven airframes each, for a total production of 20.
Supersonic flight more than halved travel times, but sonic booms over the ground limited it to transoceanic flights only.
Its only competitor was the Tupolev Tu-144, carrying passengers from November 1977 until a May 1978 crash, while a potential competitor, the Boeing 2707, was cancelled in 1971 before any prototypes were built.
On 25 July 2000, Air France Flight 4590 crashed shortly after take-off with all 109 occupants and four on the ground killed. This was the only fatal incident involving Concorde; commercial service was suspended until November 2001. The remaining aircraft were retired in 2003, 27 years after commercial operations had begun. Eighteen of the 20 aircraft built are preserved and are on display in Europe and North America.
Development
Early studies
In the early 1950s, Arnold Hall, director of the Royal Aircraft Establishment, asked Morien Morgan to form a committee to study supersonic transport. The group met in February 1954 and delivered their first report in April 1955. Robert T. Jones' work at NACA had demonstrated that the drag at supersonic speeds was strongly related to the span of the wing. This led to the use of short-span, thin, trapezoidal wings such as those seen on the control surfaces of many missiles, or aircraft such as the Lockheed F-104 Starfighter interceptor or the planned Avro 730 strategic bomber that the team studied. The team outlined a baseline configuration that resembled an enlarged Avro 730.This short wingspan produced little lift at low speed, resulting in long take-off runs and high landing speeds. In an SST design, this would have required enormous engine power to lift off from existing runways, and to provide the fuel needed, "some horribly large aeroplanes" resulted. Based on this, the group considered the concept of an SST infeasible, and instead suggested continued low-level studies into supersonic aerodynamics.
Slender deltas
Soon after, Johanna Weber and Dietrich Küchemann at the RAE published a series of reports on a new wing planform, known in the UK as the "slender delta". The team, including Eric Maskell whose report "Flow Separation in Three Dimensions" contributed to an understanding of separated flow, worked with the fact that delta wings can produce strong vortices on their upper surfaces at high angles of attack. The vortex will lower the air pressure and cause lift. This had been noticed by Chuck Yeager in the Convair XF-92, but its qualities had not been fully appreciated. Weber suggested that the effect could be used to improve low-speed performance.Küchemann and Weber's papers changed the entire nature of supersonic design. The delta had already been used on aircraft, but these designs used planforms that were not much different from a swept wing of the same span. Weber noted that the lift from the vortex was increased by the length of the wing it had to operate over, which suggested that the effect would be maximised by extending the wing along the fuselage as far as possible. Such a layout would still have good supersonic performance, but also have reasonable take-off and landing speeds using vortex generation. The aircraft would have to take off and land very "nose high" to generate the required vortex lift, which led to questions about the low-speed handling qualities of such a design.
Küchemann presented the idea at a meeting where Morgan was also present. Test pilot Eric Brown recalls Morgan's reaction to the presentation, saying that he immediately seized on it as the solution to the SST problem. Brown considers this moment as being the birth of the Concorde project.
Supersonic Transport Aircraft Committee
On 1 October 1956, the Ministry of Supply asked Morgan to form a new study group, the Supersonic Transport Aircraft Committee , to develop a practical SST design and find industry partners to build it. At the first meeting, on 5 November 1956, the decision was made to fund the development of a test-bed aircraft to examine the low-speed performance of the slender delta, a contract that eventually produced the Handley Page HP.115. This aircraft demonstrated safe control at speeds as low as, about one-third that of the F-104 Starfighter.Lift is not generated the same way at supersonic and subsonic speeds, with the lift-to-drag ratio for supersonic designs being about half that of subsonic designs. The aircraft would need more thrust than a subsonic design of the same size. Although they would use more fuel in cruise, they would be able to fly more revenue-earning flights in a given time, so fewer aircraft would be needed to service a particular route. This would remain economically advantageous as long as fuel represented a small percentage of operational costs. STAC concluded that an SST would have economic performance similar to existing subsonic types.
STAC suggested that two designs naturally fell out of their work, a transatlantic model flying at about Mach 2, and a shorter-range version flying at Mach 1.2. Morgan suggested that a 150-passenger transatlantic SST would cost about £75 to £90 million to develop, and be in service in 1970. The smaller 100-passenger short-range version would cost perhaps £50 to £80 million, and be ready for service in 1968. To meet this schedule, development would need to begin in 1960, with production contracts let in 1962. Morgan suggested that the US was already involved in a similar project, and that if the UK failed to respond, it would be locked out of an airliner market that he believed would be dominated by SST aircraft.
In 1959, a study contract was awarded to Hawker Siddeley and Bristol for preliminary designs based on the slender delta, which developed as the HSA.1000 and Bristol 198. Armstrong Whitworth also responded with an internal design, the M-Wing, for the lower-speed, shorter-range category. Both the STAC group and the government were looking for partners to develop the designs. In September 1959, Hawker approached Lockheed, and after the creation of British Aircraft Corporation in 1960, the former Bristol team immediately started talks with Boeing, General Dynamics, Douglas Aircraft, and Sud Aviation.
Ogee planform selected
Küchemann and others at the RAE continued their work on the slender delta throughout this period, considering three basic shapes - the classic straight-edge delta, the "gothic delta" that was rounded outward to appear like a gothic arch, and the "ogival wing" that was compound-rounded into the shape of an ogee. Each of these planforms had advantages and disadvantages. As they worked with these shapes, a practical concern grew to become so important that it forced selection of one of these designs.Generally, the wing's centre of pressure should be close to the aircraft's centre of gravity to reduce the amount of control force required to pitch the aircraft. As the aircraft layout changes during the design phase, the CG commonly moves fore or aft. With a normal wing design, this can be addressed by moving the wing slightly fore or aft to account for this. With a delta wing running most of the length of the fuselage, this was no longer easy; moving the wing would leave it in front of the nose or behind the tail. Studying the various layouts in terms of CG changes, both during design and changes due to fuel use during flight, the ogee planform immediately came to the fore.
To test the new wing, NASA assisted the team by modifying a Douglas F5D Skylancer to mimic the wing selection. In 1965, the NASA test aircraft successfully tested the wing, and found that it reduced landing speeds noticeably over the standard delta wing. NASA also ran simulations at Ames that showed the aircraft would exhibit a sudden change in pitch when entering ground effect. Ames test pilots later participated in a joint cooperative test with the French and British test pilots and found that the simulations had been correct, and this information was added to pilot training.
Partnership with Sud Aviation
France had its own SST plans. In the late 1950s, the government requested designs from the government-owned Sud Aviation and Nord Aviation, as well as Dassault. All three returned designs based on Küchemann and Weber's slender delta; Nord suggested a ramjet-powered design flying at Mach 3, and the other two were jet-powered Mach 2 designs that were similar to each other. Of the three, the Sud Aviation Super-Caravelle won the design contest with a medium-range design deliberately sized to avoid competition with transatlantic US designs they assumed were already on the drawing board.As soon as the design was complete, in April 1960, Pierre Satre, the company's technical director, was sent to Bristol to discuss a partnership. Bristol was surprised to find that the Sud team had designed a similar aircraft after considering the SST problem and coming to the same conclusions as the Bristol and STAC teams in terms of economics. It was later revealed that the original STAC report, marked "For UK Eyes Only", had secretly been passed to France to win political favour. Sud made minor changes to the paper and presented it as their own work.
France had no modern large jet engines and had already decided to buy a British design. As neither company had experience in the use of heat-resistant metals for airframes, a maximum speed of around Mach 2 was selected so aluminium could be used – above this speed, the friction with the air heats the metal so much that it begins to soften. This lower speed would also speed development and allow their design to fly before the Americans. Everyone involved agreed that Küchemann's ogee-shaped wing was the right one.
The British team was still focused on a 150-passenger design serving transatlantic routes, while France was deliberately avoiding these. Common components could be used in both designs, with the shorter-range version using a clipped fuselage and four engines, and the longer one a stretched fuselage and six engines, leaving only the wing to be extensively redesigned. The teams continued to meet in 1961, and by this time it was clear that the two aircraft would be very similar in spite of different ranges and seating arrangements. A single design emerged that differed mainly in fuel load. More-powerful Bristol Siddeley Olympus engines, being developed for the TSR-2, allowed either design to be powered by only four engines.