De Havilland Comet

History

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 July 27, 1949. The design was similar to other airliners except that four of the new, albeit underpowered, de Havilland Ghost 50 turbojets were mounted within the wings, in pairs close to the fuselage. The airliner underwent almost three years of tests and fixes and the first commercial flights did not begin until January 22, 1952 with BOAC. 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.

Related Topics:
1946 - 1952 - July 27 - 1949 - Turbojet - January 22 - BOAC - London Heathrow Airport - Johannesburg

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Design flaws

The first sign of a flaw in the Comet came on May 2, 1953 when a Comet crashed soon after take-off from Calcutta; further crashes (January and April 1954) with no clear cause led to the entire fleet being grounded for investigation. Only after the remnants of the Italian crash were brought to the surface and analysed was it found in February 1955 that, as suspected, metal fatigue was the problem: after thousands of pressurized climbs and descents, the thin fuselage metal around the Comet's distinctive right-angled, large windows would begin to crack and eventually cause explosive decompression of the cabin and catastrophic structural failure.

Related Topics:
May 2 - 1953 - Calcutta - 1954 - 1955 - Metal fatigue - Explosive decompression

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All remaining Comets were either scrapped or modified 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.

Related Topics:
Rolls-Royce - Avon - RAF

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Comet 4

The Comet did not resume commercial airline service until 1958, when the much improved Comet 4 was introduced.

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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.

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BOAC ordered 19 Comet 4s in March 1955, despite the Comet 1's problems. The Comet 4 first flew on April 27, 1958, and deliveries to BOAC began that September. BOAC initiated Comet 4 service with a flight from London to New York via Gander on October 4, 1958. That flight was the first scheduled trans-Atlantic passenger jet service, beating Pan Am's inaugural 707 service by three weeks.

Related Topics:
1955 - October 4 - 1958 - Pan Am

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Comet 4B and 4C

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 June 27, 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 October 31, 1959, and Mexicana started Comet 4C services in 1960.

Related Topics:
British European Airways - June 27 - 1959 - 1960 - Mexicana

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Examples are on display at the Mosquito Aircraft Museum.

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Hawker-Siddeley Nimrod

The Nimrod, a military Electronic Reconnaissance and maritime patrol aircraft, is a larger and heavily modified variation of the Comet 4 design that entered service in 1967 and is only now reaching the end of its service life. As such it is the only large aircraft still in service that has engines buried within the wing roots rather than slung beneath the wings or mounted either side of the rear fuselage.

Related Topics:
Nimrod - Fuselage

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