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The de Havilland Comet of Britain was the world's first commercial jet airliner. It is infamous for being the first to experience the metal fatigue of jet aircraft due to high flight altitudes. Despite that, the Comet and its military derivative, the Nimrod, enjoyed long and productive careers. History The origins of the Comet lie in the report produced by the Brabazon Committee during the war. It looked forward to Britain's post war airliner needs and one of the aircraft identified as needing research was for a 100-seat jet airliner which was known as the "Type IV". That Geoffrey de Havilland, head of the de Havilland company, was on the committee and de Havilland were working on jet fighters for the RAF was not unrelated. Design work began in 1946 under Ronald Bishop and the intention was to have a commercial aircraft by 1952. The DH 106 Comet first flew on 27 July 1949. At the controls was de Havilland test pilot, John Cunningham, the same man who set a new altitude record two years later in a de Havilland DH 100 Vampire. The design was similar to other airliners except that four of the new, albeit underpowered, de Havilland Ghost 50 Mk1 turbojets were mounted within the wings, in pairs close to the fuselage; this was thought to prove the aircraft more aerodynamic when flying at high speeds. (Unfortunately, the metal skin of the Comet was thinned to compensate for the lack of thrust from the Ghost turbojets; the consequences of this proved disastrous and will be discussed later.) The airliner underwent almost three years of tests and fixes and the first commercial flights did not begin until 22 January 1952 with British Overseas Airways Corporation (BOAC). It became an instant hit with the elite market at whom it was aimed. The first passenger flight was in May from London Heathrow Airport to Johannesburg. The airliner proved to be around twice as fast as contemporary craft and with almost 30,000 passengers carried in the first year over fifty Comets were ordered. Design
Design flaws Two separate incidents involving Comets occurred near the end of 1952 and beginning of 1953: a BOAC flight failed to become airborne at Ciampino airport near Rome, Italy on 26 October 1952, resulting in minor injuries to passengers, while a Canadian Pacific Airlines Comet 1A collided with a bridge and was destroyed with all hands on takeoff from Karachi, Pakistan next March. These were attributed to a loss of lift from the leading edge of the plane's wing, which was subsequently redesigned. The first indication of a more serious design flaw, however, came later, on 2 May 1953 when a Comet 1, again of BOAC crashed soon after take-off from Calcutta (now Kolkata), India; further crashes (January and April 1954) off the Italian island of Elba and in Stromboli with no clear cause led to the entire fleet being grounded for investigation. In February 1955, the remnants of the Italian crashes were brought to the surface. Analysis showed the cause of the crashes to be metal fatigue: after thousands of pressurised climbs and descents, the fuselage metal (which was thinner than standard due to the need to save weight, resulting from the aircraft's underpowered de Havilland Ghost engines) around the Comet's distinctive rectangular, large windows would begin to crack and eventually cause explosive decompression of the cabin and catastrophic structural failure. All remaining Comets were either scrapped or modified with window rip-stop doublers and the program to produce a Comet 2 with more powerful Rolls-Royce Avon engines was put on hold. Some Comet 2s were modified to alleviate the fatigue problems and served with the RAF as the Comet C.2. The Comet did not resume commercial airline service until 1958, when the much-improved Comet 4 was introduced. Comet 1 The Comet 1 was the first model of the Comet produced. An update Comet 1A was offered, and some of these were modified to Comet 1XB standard, with strengthened fuselages and round windows, in the wake of the fatigue accidents. Comet 2 The Comet 2 was a development of the Comet 1, featuring a slightly larger wing, and more powerful Rolls-Royce Avon engines, which improved the aircraft's range and performance. The Comet 2s were allocated to the RAF, where they were known as the Comet Mk. 2s. Eight Comet C.Mk 2 transport aircraft and two Comet T.Mk 2 crew trainers were delivered to the RAF in 1955. Comet 3 The Comet 3 was a lengthened Comet, with greater capacity and greater range. In the wake of the fatigue accidents, orders dried up, and only two Comet 3s were built, only one of which flew, the other being used for structural testing. The Comet 3 paved the way for the similarly sized Comet 4, serving as a test bed for new technology being developed for that aircraft. Comet 4 The Comet 4 included many modifications compared to the original Comet 1. It used a strengthened fuselage and round windows to alleviate the metal fatigue problems of the Comet 1. The Comet 4 was also a considerably larger aircraft, 5.64 m (18 ft 6 in) longer than the Comet 1 and typically seating 74 to 81 passengers, compared to the Comet 1's 36 to 44. It also had a longer range, higher cruising speed, and higher maximum takeoff weight. These improvements were possible largely due to the use of Rolls-Royce Avon engines with over twice the thrust of the Comet 1's de Havilland Ghosts. BOAC ordered 19 Comet 4s in March 1955, despite the Comet 1's problems. The Comet 4 first flew on 27 April 1958, and deliveries to BOAC began that September. BOAC initiated Comet 4 service with a flight from London to New York via Gander on 4 October 1958. That flight was the first scheduled trans-Atlantic passenger jet service, beating Pan Am's inaugural 707 service by three weeks. Two other variants of the Comet 4 were developed. The Comet 4B included a stretched fuselage and shorter wings; it was targeted to the fairly short-range operations of British European Airways, which placed an initial order for it in 1958. The Comet 4B first flew on 27 June 1959, and BEA inaugurated services with it in April 1960. The final Comet 4 variant was the Comet 4C, with the longer fuselage of the Comet 4B but the larger wings and fuel tanks of the original Comet 4, which gave it a longer range than the 4B. It first flew on 31 October 1959, and Mexicana started Comet 4C services in 1960. Comet 5 The Comet 5 was a proposed development that would have been a marked improvement over the previous models. Features of the design included a wider fuselage allowing 5 abreast seating, a wing with greater sweep, and pod mounted Rolls-Royce Conway engines, all producing a similar configuration to the Boeing 707 and Douglas DC-8 which were being developed on the other side of the Atlantic. Support from the Ministry of Transport was not forthcoming, and the project did not proceed. Ironically, BOAC, backed by the Department, went on to order Conway powered Boeing 707s. Hawker Siddeley Nimrod The Comet 4 was heavily modified to become the Hawker-Siddeley Nimrod, a military plane which has been the Royal Air Force's primary maritime patrol aircraft since 1969. Before its introduction, maritime patrol aircraft generally used piston or turboprop engines because of better fuel economy, which gave longer flight duration and range. The Nimrod is powered by turbofans, two of its four Spey engines being able to be shut down in flight to reduce fuel consumption and allow extended "loiter" time, the four engines used together allowing for a high-speed "dash" to a suspected submarine contact. Nimrod was originally designed and built by Hawker-Siddeley who had incorporated de Havilland, but is now produced by BAE Systems (formerly British Aerospace which had been formed out of Hawker-Siddeley and other companies). Nimrod serves the RAF in two variants: the Maritime Reconnaissance (MR) role, currently as the MR.2 variant, and the Reconnaissance (R1) variant, with an electronic intelligence (ELINT) gathering capacity; officially, these were originally coyly designated "radar calibration aircraft". The R1 is distinguished from the MR2 by the lack of a MAD boom. A new Nimrod, the Nimrod MRA4, is entering service. Production and service summary In total, 76 Comet 4 family aircraft were delivered from 1958 to 1964. Although BOAC retired its Comet 4s from revenue service in 1965, other operators (of which Dan-Air was the largest and last) continued flying commercial passenger services with the aircraft until 1980. The last Comet flight was conducted in 1997 by a Comet 4C that had been owned by the British government. Although the Comet was the first jet airliner in service, the interruption of commercial service and the damage to the aircraft's reputation caused by the Comet 1 fatigue failures led to the domination of the jetliner market by Boeing, which flew the first prototype 707 in 1954, and Douglas, which launched the DC-8 program in 1955. Also, for a brief period, the Soviet Union's Tupolev Tu-104 was the only jet airliner flying commercially. Both the 707 and DC-8 had better ranges and passenger accommodations as compared to the Comet, and the American manufacturers also had the huge advantage of a large (and often highly patriotic) domestic airline market. The USA has enjoyed a large share of the commercial jetliner market ever since, with their only real competition coming from the later formed Airbus consortium (although Tupolev still manufacture jet airliners at a slow pace). Only fifteen airlines ever used the Comet. The proposed Comet 5 was never built, and the Comet 4 was slowly withdrawn from service. Comet 1 The only complete surviving Comet 1 is a Comet 1XB on display at the RAF Museum Cosford. It is painted in BOAC colours and displays the registration , although it never flew for that airline, having been delivered to Air France, and then to the Ministry of Supply after conversion to 1XB standard. The nose of BOAC Comet 1A is displayed at London's Science Museum, while the fuselage of Air France Comet 1A F-BGNX is preserved at the De Havilland Aircraft Heritage Centre in Hertfordshire. Comet 4 Operators Military Operators Royal Air Force Royal Canadian Air Force Specifications (Comet 1) Specifications (Comet 4) Related content | |||||||||
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