De Havilland Comet

The de Havilland DH 106 Comet was the first production commercial jetliner.[N 2] Developed and manufactured by de Havilland at its Hatfield, Hertfordshire, United Kingdom headquarters, the Comet 1 prototype first flew on 27 July 1949. It featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wings, a pressurised fuselage, and large square windows. For the era, it offered a relatively quiet, comfortable passenger cabin and showed signs of being a commercial success at its 1952 debut. A year after entering commercial service the Comets began suffering problems, with three of them tearing apart during mid-flight in well-publicised accidents. This was later found to be due to catastrophic metal fatigue, not well understood at the time, in the airframes. The Comet was withdrawn from service and extensively tested to discover the cause; the first incident had been incorrectly blamed on adverse weather. Design flaws, including dangerous stresses at the corners of the square windows and installation methodology, were ultimately identified; consequently the Comet was extensively redesigned with oval windows, structural reinforcement and other changes. Rival manufacturers meanwhile heeded the lessons learned from the Comet while developing their own aircraft. Although sales never fully recovered, the improved Comet 2 and the prototype Comet 3 culminated in the redesigned Comet 4 series which debuted in 1958 and had a productive career of over 30 years. The Comet was adapted for a variety of military roles such as VIP, medical and passenger transport, as well as surveillance; the most extensive modifica

ion resulted in a specialised maritime patrol aircraft variant, the Hawker Siddeley Nimrod. Nimrods remained in service with the Royal Air Force (RAF) until June 2011, over 60 years after the Comet's first flight. On 11 March 1943 the Cabinet of the United Kingdom formed the Brabazon Committee to determine Britain's airliner needs after the conclusion of the Second World War.[5] One of its recommendations was for a pressurised, transatlantic mailplane that could carry one long ton (1.0 t) of payload at a cruising speed of 400 mph (640 km/h).[6] Challenging the widely held scepticism of jet engines as too fuel-hungry and unreliable,[N 3] committee member Sir Geoffrey de Havilland, head of the de Havilland company, used personal influence and his company's expertise with jet aircraft to specify a turbojet-powered design.[5] The committee accepted the proposal, calling it the "Type IV" (of five designs),[N 4] and awarded a production contract to de Havilland under the designation Type 106 in February 1945.[9] First-phase development of the DH 106 focused on short and intermediate range mailplanes with a small passenger compartment and as few as six seats, before being redefined as a long-range airliner with a capacity of 24 seats.[6] Out of all the Brabazon designs, the DH 106 was seen as the riskiest both in terms of introducing untried design elements and for the financial commitment involved.[5] Nevertheless, the British Overseas Airways Corporation (BOAC) found the Type IV's specifications attractive, and initially proposed a purchase of 25 aircraft; in December 1945, when a firm contract was laid out, the order total was revised to 10.