The aviation industry is one of the most capital intensive and competitive industries in the world. Airlines and operators have always been on the lookout for the next source of competitive advantage. This happened in the 1950s, where after World War II, the jet engine started to find application in commercial aviation. With the production of transonic jetliners like the Boeing 707 that reduced ticket prices while opening different parts of the globe for travel, the demand for aircrafts that could break the sound barrier and travel at supersonic speeds increased in Britain and the US (Bohme et al., 2019). In response to the demand, Douglas Aircraft designed and released the concept of the first supersonic transport aircraft in 1961. The aircraft, according to Chittum (2018), was designed to cruise at Mach 3 and FL710. The British government, through the Supersonic Transport Aircraft Committee and Sud-Aviation in France were faster than their American counterparts. While the former designed and produced the Bristol 233, a supersonic transport that could cruise at Mach 2 and had a capacity of 110 passengers, the latter designed a similar aircraft that was called the Super Caravelle (Petrescu, 2020). The design, production, and maintenance cost for a supersonic transport aircraft was prohibitive for both governments. In 1962, the British and French government signed an agreement over the design, production, and operation of a supersonic airliner, which was later known as the Concorde. During its service life, only 20 aircrafts were built. With the exception of Flight 4590, the Concorde owed its excellent flight record to its revolutionary engineering. Unfortunately, only one fatal crash was needed to end the dream of a commercial supersonic airliner that would have disrupted the aviation industry. Even then the success and downfall of the Concorde represents a significant milestone in the history of aviation.
Aircraft Specifications
The Concorde is a unique aircraft concept with its trademark dart-like drooping nose and low delta wings. It is the only commercial aviation aircraft with four afterburning turbojet engines, distributed equally under the wings (Fife, 2016). Each engine could produce 163 KN of thrust, with the added capability to for 17% extra thrust with the afterburners (Chittum, 2018). The engines and the aircraft were designed to withstand high environmental and aerodynamic loads. As a result, the inlet was configured with an electric de-icing system and variable inlet and outlet to optimize thrust production, maximize efficiency, and minimize wave drag at supersonic speeds (Fife, 2016). Furthermore, the delta wings were not designed with flaps that could increase drag during landing while reducing lift-off speed at take-off. As a result, the engines were configured with thrust reversers to aid slow the aircraft down during the final ground roll after landing.
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Most modern aircrafts use composite materials to build primary and secondary structures. However, the Concorde was primarily built with aluminium alloys for most of its structure. Some of the primary structures that required high strength were built with steel. On the other hand, the engines, especially the combustion chamber, turbine, and afterburner were built with titanium and high temperature nickel alloys (Malek et al., 2020). These materials were required to ensure safe operations at cruise speeds up to Mach 2. To remain operational, however, the Concorde had to carry enough fuel for all four engines over long distances. As a result, the Concorde was designed with a fuel carrying capacity of 119786 liters distributed in different parts of the aircraft (Osterer & Stamm, 2021). For instance, each wing had five tanks while the fuselage was built with four tanks. Having an aircraft design where the fuel was distributed meant that the center of gravity was would shift as the aircraft weight changed. The situation was worse for the Concorde because the center of gravity would also shift depending on the aircraft’s attitude. As a result, the fuel feed system was built with complex cross-feed that would prevent the pumps from emptying one tank without redistributing the weight to avoid destabilizing the aircraft.
Other important design specifications were a wingspan of 25.56 meters and a wing area of 385.25 meters squared. The Concorde was 62.1 meters long and 11.4 meters high, with an empty weight of 78,700 kg and a maximum take-off weight (MTOW) of 185,065 kg. The aircraft could cruise at 2180 kmph (1345 mph) with a service ceiling of 18,300 meters (60,000 ft) and a range of 6580 km. at such high cruise speeds and altitude, the Concorde needed high fidelity and redundant flight control systems. For instance, all flight controls on the wings were controlled with redundant hydraulic system and the tail fin was a two-section rudder, both for redundancy and to add to the trim capability of the aircraft. The retracting landing gear was designed in a tricycle configuration with 2 by 2 four-wheel bogies, antiskid system, and carbon disk brakes (Fife, 2016; Chittum, 2018). On the avionics side, the Concorde featured an automatic flight control system with redundant radios and inertial navigation systems (INS). In other words, the Concorde was a marvel f engineering, both at its time and by today’s standards.
Construction of the Concorde
As a joint collaborative project between the British and French government, the production of the Concorde was divided between different manufacturing giants in their respective countries. For instance, the British Aircraft Corporation and Rolls-Royce represented the UK, while Sud-Aviation and SNECMA represented France. As per the agreement between the two countries, two flight prototype, preproduction and static-test aircrafts were built. The British Aviation Corporation (BAC) was responsible for producing the engines, electrical, fuel, and oxygen systems, and the fuselage. Sud-Aviation, on the other hand, was responsible for producing the hydraulic systems, the wing, avionics, flight control system, and radio. Sextant Avionique and GEC-Marconi were contracted to build the automatic flight control systems. The assembly for the aircrafts were done in two locations: Filton and Toulouse. By 1979, fourteen of the 20 aircrafts had been built and were divided equally between British Airways and Air France. Certifications for commercial operations were finished by October 13th 1975 and December 5th in the same year for Air France and British Airways (Fife, 2016). Formal commercial operations began on January 21 1976. The aircraft was retired from service in October 24 2003 after the fatal crash of Air France Flight 4590. While there are no clear records to indicate the exact amount both governments paid for the design and production of the 20 aircrafts, Chittun (2018) estimates that the two countries spent approximately $18 billion in 2003 currency.
Concorde Operations
As soon as the Concorde entered into service, it started to fly different routes. For instance, British Airways flew the Concorde between London and Bahrain while Air France flew their fleets between Paris and Rio, with a layover in Dakar. The first flight to the US (Washington DC) was not accomplished until midyear 1976 followed by New York at the end of the next year (Chittun, 2018). While the plane was in service, other routes were added to meet the demand for supersonic transport. British Airways, however, did not limit their operations to commercial flights. The airline also started to charter flights, thus increasing the routes through which the Concorde flew through by the time all fleets were grounded. By the time the aircraft was retired from service, the all the models had logged 155,000 flight hours (105,000 from British Airways and the rest from Air France, the two main operators; Fife, 2016). One of the aircrafts operated by Air France had successfully completed 5845 flights, logging 17, 723 flight hours. That aircraft was said to have logged more flight time at supersonic speeds than any other military aircraft in the world at that time (Fife, 2016). While there is no way to validate the statement, the number of flight hours logged goes to demonstrate how much the demand for a supersonic transport aircraft was at the time. The last formal flight for the Concorde in Europe was on November 23 2003 where the aircraft looped around London, Filton, and Clifton as the last display of its might to enthusiasts and the world. In the US, the last flight happened a day earlier, where the aircraft flew over the Statue of Liberty before ending up on display at Intrepid Air Museum. These were the very last flights of the Concorde, whose engines have never been started since then.
For 24 years between 1974 and 2000, the Concorde became one of the few aircrafts in service with a perfect safety record. That record would have been maintained if the Concorde flew by Air France (AF4590) had not crashed during take-off from Charles de Gaulle airport. Air crash investigations revealed that the main cause of the fatal accident was a titanium strip that was part of runway debris. When the aircraft rolled over the strip, its tires blew, causing a piece of the rubber to hit the lower surface of the wing, perforating a fuel tank. The take-off failed with the Concorde catching fire and crashing shortly after. Immediately after the crash, all Concorde fleets were grounded awaiting the results of the investigations.
After investigations were done, an airworthiness directive (AD) was issued for operators of the remaining Concorde aircrafts, mainly Air France and British Airways, to retrofit their fuel tanks to increase their safety. The modifications were not limited to lining the tanks with rubber, but also improving the safety of the electrical and avionics systems (Chittum, 2018). Other operators also switched their tires to some that would not blow due to sharp runway debris. Note that the fatal crash of Flight 4590 was also due to human factors. For instance, before taking off on its last flight, AF4590 was overloaded and was carrying excess fuel. As a result, the aircraft’s COG was altered where it shifted aft. Such a shift would make the aircraft hard to control as it would naturally pitch up. Furthermore, some last-minute maintenance was performed on the aircraft. According to Chittum (2018), the crew requested that the thrust motor on one engine be replaced. The maintenance crew were working under pressure as they worked with a very short deadline. Such compounding factors acted individually, but collectively resulted in the fatal accident that took the lives of all that were on board.
Why did the Concorde Fail?
Most sources in aviation history cite the AF4590 crash as the main reason why the Concorde ended the possible future of commercial supersonic flight. However, while it was a significant event, it was not the only reason. After all, commercial flights on the Concorde resumed in November 2001 and continued for another two years before the entire fleet was retired from service. Like many other aircraft models, fatal crashes are not the main reason to end the flights for the aircrafts. Case in point, the recent crashes that led to the grounding of the entire fleets of Boeing 737 Max due to software error did not result in the aircraft being retired from service (Johnston & Harris, 2019). Instead, Boeing had to correct the errors, have the aircraft recertified to be airworthy and train all the pilots and crews to use the new systems. Despite the pandemic, Herket et al. (2020) notes that the orders for the aircraft model are picking up. Therefore, there must have been other reasons that led to the Concorde’s premature retirement.
Poor Fuel Economy
The Concorde was an aircraft in competition with other successful subsonic and transonic aircrafts like the Boeing 707 and 747. The Concorde’s main strength was its supersonic speed, where it could fly the same distance as other commercial airliners in half the time. By cruising at supersonic speeds, however, the Concorde’s fuel economy was pure. According to Chittun (2018), the Concorde’s fuel consumption was over thrice that of the Boeing 747, despite the former carrying significantly fewer passengers than the latter. The global oil crisis that happened in the 1970s also exacerbated the situation, where the operational costs for the Concorde increased compared to other models. Therefore, interested operators could only place orders, but never went through with the purchase intentions. Fuel costs would not have been a significant problem to some operators, like Pan America (Pan Am). However, unfair regulations reduced the value proposition for the aircraft. For instance, the FAA and other US regulatory bodies restricted the Concorde from making night flights (take-offs and landings) in New York, despite the city being on one of the aircraft’s main routes to the US.
Fewer Passengers
At the design stage, two variants were planned for: a 100 seat long-range aircraft and a 90 seat optimized for continental flights, such as between airports in the US. The former variant was only built while the later was left at the design stage. Even then, the Concorde’s carrying capacity was significantly lower than its competing subsonic and transonic airliners. For instance, the Boeing 747 could carry up to 416 passengers on the same route and consume significantly less fuel at transonic speeds. If Concorde operators were to break even and or turn a profit, the tickets had to be expensive. As a result, not all passengers could afford to pay a ticket on the Concorde. In contrast, the 747 had a 3 class layout, thus accommodate different passengers on the same flight. In other words, despite its unique value proposition, the Concorde could not succeed when other competing aircraft models were cheaper to buy and operate. The only recorded time where the ticket prices for the Concorde were not a limiting factor was after Air France and British Airways announced the dates of their last flights. To be part of the last people to have flown in the Concorde, tickets were fully booked, but the demand was still high.
Noise Levels
Jet engines are machines that emit significant levels of noise pollution. Though efforts were underway (and still are) to reduce the noise figures for a jet engine, the problem appears to be intractable. Supersonic flights add an extra layer of complexity, where the sonic boom produces disturbances that made living or working next to the airports where the Concorde took off and landed a challenge. The characteristic nature of sonic booms is that they spread out spatially according to their shape. A conical sonic boom, for instance, will spread out equally in a conic shape. Furthermore, the sonic boom produced by the Concorde was not a single shockwave, but a combination of several produced due to disturbances in local air flow over specific parts, such as the wing tips, leading edges, and engine inlets, among others. Alone, the sonic boom could not affect the aircraft’s operation. However, the noise it produced meant that if would not find wide application in continental flights. Furthermore, some airports, like in New York banned night flights because a passing Concorde disturbed the peace. As a result, the Concorde’s utilization dropped, which lowered revenues while maintaining operational costs.
Range
As discussed in a previous section, the Concorde had a range of 6850 km. Compared to other competing models, like the Boeing 747 with a range of 13,940 km, the Concorde’s flight performance was worse. A good example is a flight between San Francisco and Tokyo. A Boeing 747 would make the flight continuously, owing to its larger size and higher fuel economy. After all, the aircraft was forced to refuel if its destination was twice its range. In comparison, the Concorde would be forced to make a refuelling stop at Honolulu and Wake Island. In the end, the Concorde would end up consuming more fuel compared to the Boeing 747. Furthermore, the stops would negate the Concorde’s speed advantage, where a Boeing 747 would arrive first if the two took off from San Francisco at the same time.
In summary, the Concorde is one of the best aircrafts to have been built in the history of aviation. The aircraft has a wingspan of 25.56 meters and a wing area of 385.25 meters squared. The Concorde was 62.1 meters long and 11.4 meters high, with an empty weight of 78,700 kg and a maximum take-off weight (MTOW) of 185,065 kg. The aircraft could cruise at 2180 kmph (1345 mph) with a service ceiling of 18,300 meters (60,000 ft) and a range of 6580 km. By the time the aircraft was retired from service, the all the models had logged 155,000 flight hours (105,000 from British Airways and the rest from Air France, the two main operators; Fife, 2016). One of the aircrafts operated by Air France had successfully completed 5845 flights, logging 17, 723 flight hours. Furthermore, the Concorde is one of the few aircrafts in aviation history with a relatively clean safety record. Though the crash of Flight 4590 tarnished this record, the aircraft continued to operate safely for another two years after is resumed flight in 2001. From an analysis of the causes of the accident with AF4590, it is clear that come of the limitations were designed into the aircraft. For instance, the designers focused more on making the aircraft supersonic that they forgot to consider the reduced range and fuel economy. Overall, the lessons learned from the accident and the aircraft in general influenced the future of aviation in various ways. For instance, the certification procedures for new aircrafts became stricter as regulatory authorities sought to reduce previous regulatory oversight.
References
Böhme, F., Cadete, S., & Dannet, G. (2019). Concorde 2.0: Ongoing Supersonic Projects. In TMAL02 Expert Conference (Vol. 8, No. 4, pp. 21-23).
Chittum, S. (2018). Last Days of the Concorde: The Crash of Flight 4590 and the End of Supersonic Passenger Travel (Vol. 3). Smithsonian Books.
Fife, M. (2016). Commercial Aviation in Britain in the 1970s . Amberley Publishing Limited.
Herkert, J., Borenstein, J., & Miller, K. (2020). The Boeing 737 MAX: lessons for engineering ethics. Science and engineering ethics , 26 (6), 2957-2974.
Johnston, P., & Harris, R. (2019). The Boeing 737 MAX saga: lessons for software organizations. Software Quality Professional , 21 (3), 4-12.
Malek, B., Mabru, C., & Chaussumier, M. (2020). Fatigue behavior of 2618-T851 aluminum alloy under uniaxial and multiaxial loadings. International Journal of Fatigue , 131 , 105322.
Osterer, H., & Stamm, P. (2021). Concorde. In Adrian Frutiger–Typefaces (pp. 150-155). Birkhäuser.
Petrescu, R. V. V. (2020). About Supersonic Flight and Mach 3 Flying.
