The SST Rise & Fall

In the 1960s there was an international competition to build a supersonic transport (SST), which resulted in the development of two supersonic airliners, the Anglo-French "Concorde" and the Soviet Tupolev "Tu-144". Although the SST was seen as the way of the future, that wasn't how things actually turned out. This document provides a short history of the rise and fall of the supersonic transport.

With the push towards supersonic combat aircraft during the 1950s, aircraft manufacturers began to think about developing a supersonic airliner, what would eventually become known as a "supersonic transport (SST)". In 1961, Douglas Aircraft publicized a design study for an SST that would be capable of flying at Mach 3 at 21,350 meters (71,000 feet) and could be flying by 1970. Douglas forecast a market for hundreds of such machines.

At the time, it wasn't foolish to believe such a forecast was realistic. During the 1950s, commercial air transport had made a radical shift from piston-powered airliners to the new jetliners like the Boeing 707. Going to an SST was simply the next logical step. In fact, as discussed in the next section, Europe was moving even faster down this road than the US. In 1962 the British and French signed an agreement to actually build an SST, the "Concorde". With the Europeans committed to the SST, of course the Americans had to follow, and the US Federal Aviation Administration (FAA) set up a competition for an SST that would be faster, bigger, and better than the Concorde.

Boeing 2707-300 SST

In 1964, SST proposals from North American, Lockheed, and Boeing were selected as finalists. Although North American had built the two XB-70 Valkyrie experimental Mach 3 bombers, which had a configuration and performance similar to that of an SST and were used as testbeds for SST concepts, the company was eliminated from the competition in 1966. Lockheed proposed the "L-2000", which was a double-delta machine with a capacity of 220 passengers, but the winner was Boeing's "Model 2707", the name obviously implying a Mach 2 aircraft that would be as significant as the Boeing 707. Boeing was awarded a contract for two prototypes on 1 May 1967.

The 2707 was to be a large aircraft, about 90 meters (300 feet) long, with a maximum load of 350 passengers. It would be able to cruise at Mach 2.7 over a range of 6,440 kilometers (4,000 miles) with 313 passengers. At first, the 2707 was envisioned as fitted with variable geometry "swing wings" to permit efficient high-speed flight -- with the wings swept back -- and good low-speed handling -- with the wings extended.

Powerplants were to be four General Electric GE-J5P afterburning turbojet engines, derived from the GE J93 engines used on the XB-70, with a maximum afterburning thrust of 267 kN (27,200 kgp / 60,000 lbf) each. The engines were to be fitted into separate individual nacelles under the wing. Further work on the design demonstrated that the swing-wing configuration was simply too heavy, and so Boeing engineers came up with a new design, the "2707-300", that had fixed wings.

However, America in the late 1960s was all but overwhelmed by social upheaval that involved questioning the need to come up with something bigger and better, as well as much increased concerns over the environment. Critics massed against the SST, voicing worries about its sonic booms and the possible effects of its high-altitude cruise on the ozone layer. The US Congress finally zeroed funds for the program on 24 March 1971 after the expenditure of about a billion USD on the project. There were 121 orders on the books for the aircraft when it was cancelled. SST advocates were dismayed, but in hindsight cancelling the 2707-300 was the right decision.

Aerospatiale-BAC Concorde

As mentioned, the British and French were actually ahead of the US on SST plans. In 1955, the British aviation industry and British government agencies had discussions on the notion of an SST, leading to the formation of the "Supersonic Transport Aircraft Committee (STAC)" in 1956. STAC conducted a series of design studies, leading to leading to the Bristol company's "Bristol 198", which was a slim, delta-winged machine with eight turbojet engines designed to cross the Atlantic at Mach 2. This evolved into the somewhat less ambitious "Bristol 223", which had four engines and 110 seats.

In the meantime, the French had been conducting roughly similar studies, with Sud-Aviation of France coming up with a design surprisingly similar to the Bristol 223, named the "Super Caravelle" after the innovative Caravelle twinjet airliner developed by Sud-Aviation in the 1950s. Given the similarity in the designs and the high cost of developing an SST, British and French government and industry officials began talks in September 1961 to see if the two nations could join hands for the effort.

After extensive discussions, on 29 November 1962, the British and French governments signed a collaborative agreement to develop an Anglo-French SST, which became the "Concorde". It was to be built by the British Aircraft Corporation (BAC), into which Bristol had been absorbed in the meantime, and Rolls-Royce in the UK; and Sud-Aviation and the SNECMA engine firm in France. The original plan was to build a 100-seat long-range aircraft for transoceanic operations and a 90-seat mid-range aircraft for continental flights. In fact, the mid-range aircraft would never be built.

The initial contract specified the construction of two flight prototypes, two static-test prototypes, and two preproduction aircraft. BAC was responsible for development and production of:

• The three forward fuselage sections.
• Rear fuselage and tailfin.
• Engine nacelles and engine installation.
• Electrical system, fuel system, and oxygen system.
• Sound and thermal insulation.
• Fire warning and extinguishing systems.

Sud-Aviation was responsible for development and production of:

• The rear cabin section.
• Wings and flight control surfaces.
• Hydraulic systems.
• Flight controls.
• Navigation avionics.
• Radios.
• Air conditioning.

Design of the automatic flight control system was subcontracted by Aerospatiale to Marconi, now GEC-Marconi, in Britain and SFENA (now Sextant Avionique) in France. Final assembly of British Concordes was at Filton and of French Concordes was at Toulouse.

Airlines began to place options for purchase of Concordes in June 1963, with service deliveries originally expected to begin in 1968. This proved a bit over-optimistic. Prototype construction began in February 1965.

Concorde first flight

The initial "001" prototype was rolled out at Toulouse on 11 December 1967, but it didn't perform its first flight for another 15 months, finally taking to the air on 2 March 1969, with a flight crew consisting of Andre Turcat, Jacques Guignard, Michel Retif, and Henri Perrier.

The first flight of the "002" prototype took place from Filton on 9 April 1969. Flight trials showed the design to be workable, though it was such a "bleeding edge" machine that there were a lot of bugs to be worked out. First supersonic flight by 001 wasn't until 1 October 1969, and its first Mach 2 flight wasn't until 4 November 1970.

The first preproduction machine, "101", performed its initial flight from Toulouse on 17 December 1971, followed by the second, "102", which performed its initial flight from Filton on 10 January 1973. The first French production aircraft, "201", performed its initial flight from Toulouse on 6 December 1973, by which time Sud-Aviation had been absorbed into Aerospatiale. The first British production machine, "202", performed its initial flight from Filton on 13 February 1974, both machines well exceeding Mach 1 on their first flight. These two production machines were used for flight test and never entered commercial service.

14 more production machines were built, the last performing its initial flight on 20 April 1979, with seven Concordes going into service with British Airways and seven into service with Air France. The Concorde received French certification for passenger operations on 13 October 1975, followed by British certification on 5 December 1975. Both British Airways and Air France began commercial flights on 21 January 1976. The Concorde was finally in service.

There has never been a full accounting of how much it cost the British and French governments to get it there, but one modern estimate is about 1.1 billion pounds in 1976 values, or about 11 billion pounds or $18.1 billion USD in 2003 values. Of the 20 Concordes built, six never carried any paying passengers. In fact, only nine of the production machines were sold at "list value". The other five were simply given to British Airways and Air France for literally pocket change, apparently just to get them out of the factories.

The initial routes were London to Bahrain, and Paris to Rio de Janiero via Dakar. Service to Washington DC began on 24 May 1976, followed by flights to New York City in December 1977. Other routes were added later, and there were also large numbers of charter flights, conducted mostly by British Airways.

The manufacturers had obtained options for 78 Concordes, most prominently from the US carrier Pan-American, but by the time the aircraft was ready to enter service interest had evaporated. Sonic boom ensured that it could not be operated on overland routes, a consideration that had helped kill off the mid-range Concorde, and even on the trans-Atlantic route the thundering noise of the four Olympus engines led to restrictions on night flights to New York City, cutting the aircraft's utilization on the prime trans-Atlantic route in half.

The worst problem, however, was that the 1970s were characterized by rising fuel prices that rendered the thirsty SST uneconomical to operate. It required 3.5 times more fuel to carry a passenger in the Concorde than in a Boeing 747 with its modern, fuel-efficient high-bypass turbofans. The Americans had been sensible to kill off the Boeing 2707-300. Even if the environmental threat of the machine had been exaggerated, the 2707-300 would have never paid itself off.

There was some muttering in Britain and France that Pan-Am's cancellation of its Concorde orders and the restrictions on night flights into New York City were part of a jealous American conspiracy to kill the Concorde, but Pan-Am had simply done the numbers and wisely decided the Concorde didn't make business sense. Pan Am had analyzed use of the Concorde on trans-Pacific flights, such as from San Francisco to Tokyo, and quickly realized that its relatively limited range meant refueling stops in Honolulu and Wake Island. A Boeing 747 could make the long-haul trip without any stops, and in fact would get to Tokyo faster than the Concorde under such circumstances. First-class customers would also have a much more comfortable ride on the 747.

The Port Authority of New York & New Jersey was mainly worried about irate townspeople raising hell over noisy Concordes waking them up in the middle of the night. These "townspeople" were assertive New Yorkers, after all, and they had been pressuring the Port Authority with various complaints, justified or not, over aircraft operations from Idlewild / Kennedy International Airport since 1958. In fact there were few jetliners noisier than the Concorde, and in another unfortunate irony the new high-bypass turbofans used by airliners such as the 747 were not only much more fuel-efficient than older engines, they were much quieter, making the Concorde look all that much worse in comparison.

Some Europeans were not surprised by the Concorde's problems. In 1966, Henri Ziegler, then head of Breguet Aviation of France, commented with classic French directness: "Concorde is a typical example of a prestige program hastily launched without the benefit of detailed specifications studied in partnership with airlines."

Ziegler would soon become the first boss of Airbus Industries, which would rise to effectively challenge mighty Boeing for the world's airliner market. Airbus was established on the basis of such consultations between aircraft manufacturers and airlines. The Concorde program would have important lessons for Airbus, though mostly along the lines of how not to do things. The full duplication of Concorde production lines in the UK and France was seen as a particular blunder that substantially increased program costs. Airbus took the more sensible strategy of having different elements built in different countries, and then transporting them to Toulouse for final assembly and flight check.

The Concorde was a long, dartlike machine with a low-mounted delta wing and four Orpheus afterburning turbojets, with two mounted in a pod under each wing. It was mostly made of aircraft aluminum alloys, with some steel assemblies, but featured selective high-temperature elements fabricated from Iconel nickel alloy. It was designed for a cruise speed of Mach 2.2. Higher speeds would have required much more extensive use of titanium and other high-temperature materials.

The pilot and copilot sat side-by-side, with a flight engineer behind on the right, and provision for a fourth seat. The crew flew the aircraft with an automatic flight control system, guiding their flight with an inertial navigation system backed up by radio navigation systems. Avionics also included a suite of radios, as well as a flight data recorder.

The nose was drooped hydraulically to improve the forward view during takeoff and landing. A retractable transparent visor covered the forward windscreen during supersonic cruise flight. There were short "strake" flight surfaces beneath the cockpit, just behind the drooping nose, apparently to help ensure airflow over the tailfin when the aircraft was flying at high angles of attack.

Each of the four Rolls-Royce / SNECMA Olympus 593 Mark 610 engines was rated at 169.3 kN (17,255 kgp / 38,050 lbf) thrust with 17% afterburning. The engine inlets had electrical de-icing, variable ramps on top of the inlet throat, and auxiliary inlet / outlet doors on the bottom.

Each engine was fitted with a bucket-style variable exhaust / thrust reverser. The Olympus had been originally developed in a non-afterburning form to the Avro Vulcan bomber, and a Vulcan had been used in trials of the Concorde engines. The Concorde used afterburner to get off the ground and up to operating speed and altitude, and then cruised at Mach 2 on dry (non-afterburning) thrust. It was one of the first, possibly the first, operational aircraft to actually cruise continuously at supersonic speeds. Interestingly, at subsonic speeds the aircraft was inefficient, requiring high engine power that drained the fuel tanks rapidly.

Total fuel capacity was 119,786 liters (26,350 Imperial gallons / 31,645 US gallons), with four tanks in the fuselage and five in each wing. Fuel trim was maintained by an automatic system that shuttled fuel between trim tanks, one in the tail and a set in the forward section of the wings, to maintain the proper center of gravity in different flight phases.

The wing had an elegantly curved "ogival" form factor, and a chord (ratio of cross-sectional height to width) of 3% at the wing root, and featured six hydraulically-operated elevon control surfaces on each wing, organized in pairs. The tailfin featured a two-section rudder, apparently to provide redundancy and improve safety. The Concorde had tricycle landing gear, with a twin-wheel steerable nosewheel retracting forward, and four-wheel bogies in a 2-by-2 arrangement for the main gear, retracting inward. The landing gear featured carbon disk brakes and an antiskid system. There was a retractable tail bumper wheel to protect the rear of the aircraft on takeoff and landing.

Maximum capacity was in principle 144 passengers with a high-density seating layout, but in practice seating was not more than 128, and usually more like 100. Of course all accommodations were pressurized and climate-controlled, and the soundproofing was excellent, resulting in a smooth and quiet ride. There were toilets at the front and middle of the fuselage, and galleys front and back. Customer service on the flights placed substantial demands on the stewards and stewardesses because the flights never lasted more than a few hours.

The two prototypes had been slightly shorter and had been fitted with less powerful Olympus engines. A "Concorde B" was considered, with airframe changes -- including leading edge flaps, wingtip extensions, modified control surfaces, and 4.8% more fuel capacity -- and significantly improved Olympus engines that provided incrementally better fuel economy, allowing a trans-Pacific flight with a single stop, and greater dry thrust, allowing takeoffs without noisy afterburner. However, the Concorde B still couldn't operate over land and it still couldn't compete with modern subsonic jetliners in terms of fuel economy. It never got off the drawing board.

Concorde crash at Gonesse

On 25 July 2000, an Air France Concorde was departing from the Charles de Gaulle airport outside Paris when one of its tires hit a piece of metal lying on the runway. The tire disintegrated and a piece of rubber spun off and hit the aircraft, setting up a shockwave that ruptured a fuel tank. The airliner went down in flames and crashed near the town of Gonesse, killing all 109 people aboard and four people who had the bad luck to be in the impact area. All 12 surviving Concordes were immediately grounded pending an investigation.

Safety modifications were made to all seven British Airways and all five surviving Air France Concordes. The bottom of the fuel tanks, except those in the wing outboard of the engines, was fitted with flexible Kevlar-rubber liners to provide them with a limited "self sealing" capability; minor safety modifications were made to some electrical systems; and new "no blowout" tires developed by Michelin were fitted. British Airways also implemented a previously planned update program to fit their seven aircraft with new passenger accommodations.

The Concorde returned to flight status on 7 November 2001, but it was a hollow triumph. The economics of even operating the Concorde, let alone developing it, were marginal, and with the economic slump of the early 21st century, both Air France and British Airways were losing money on Concorde flights. In the spring of 2003, Air France announced that they would cease Concorde operations as of 31 May 2003, while British Airways would cease flights by the end of October 2003. The announcement led to unprecedented levels of passenger bookings for the final flights.

Air France's most worked aircraft, named the "Fox Alpha", had performed 5,845 flights and accumulated 17,723 flight hours. One Air France technical manager claimed that the British and French Concorde fleets had accumulated more supersonic time than all the military aircraft ever built. That may be an exaggeration -- how anyone could compile and validate such a statistic is a good question -- but it does illustrate the unique capabilities of the aircraft. Interestingly, spares were never a problem, despite the age and small numbers of Concordes, as large inventories of parts had been stockpiled for the machines.

It was a sign of the Concorde's mystique that the aircraft were in great demand as museum pieces. Air France CEO Jean-Cyril Spinetta said: "We had more requests for donations than we have aircraft." One ended up on display at the Charles de Gaulle Airport near Paris, while another found a home at the US National Air & Space Museum's Steven F. Udvar-Hazy Center at Dulles International Airport in Washington DC. In something of an irony, one of the British Concordes was given to the Museum of Flight at Boeing Field in Seattle, Washington.

Concorde last flight

The last operational flight of the Concorde was on 24 October 2003, with a British Airways machine flying from New York to London. British aviation enthusiasts flocked to Heathrow to see the arrival. As it taxied off the runway it passed under an honorary "water arch" created by the water cannons of two fire engines. During the type's lifetime, Air France had racked up 105,000 hours of commercial flight operations with the Concorde, while British Airways had run up a tally of 150,000 hours.

On 25 November 2003, a Concorde that had landed at Kennedy on 10 November was hauled up the Hudson river on a barge past the Statue of Liberty for display at New York City's Intrepid Air Museum. New Yorkers turned out along the waterfront to greet the arrival.

The very last flight of a Concorde was on 26 November 2003, when a British Airways Concorde took off from Heathrow, performed a ceremonial loop over the Bay of Biscay and then flew back to Filton, where it was to be put on display. The aircraft performed a "photo op" by flying over Isambard Kingdom Brunel's famous chain suspension bridge at Clifton, not far from Filton; as the crew taxied the airliner after landing, they hung Union Jacks out the windows and raised the nose up and down to please the crowd of 20,000 that was on hand. When the Olympus engines were shut down for the very last time, the crew got out and handed over the flight logs to HRH Prince Andrew in a formal ceremony.

Author: Greg Goebel