Questions tagged [de-havilland-comet]

The de Havilland Comet was a narrowbody four-engine jetliner (its turbojet engines, unlike those of most later jetliners, were buried within the wing roots rather than being mounted in separate pods) built by de Havilland from 1949 to 1964; it was the first jetliner in the world to fly (with its maiden flight on 27 July 1949), and also the first to enter commercial airline service (on 2 May 1952 with BOAC). However, as the first-ever jetliner, it suffered from more than the usual teething troubles; the first of these were two crashes on takeoff (in October 1952 and March 1953, the latter of which became the first fatal jetliner crash) which revealed problems with the design of the wing's leading edge.

In early 1954, a far more serious problem reared its head: two Comets disintegrated in midair (one in January, the other in April), and the resultant investigation revealed that its design (aggravated by errors in manufacturing) considerably increased the fuselage's susceptibility to fatigue damage. As a result, the Comet was withdrawn from commercial service, not to resume revenue flights until the introduction of the Comet 4 in September 1958. Although the Comet 4 quickly distinguished itself as the first jetliner to make a commercial transatlantic flight, its primacy in the jetliner market was brief; the very next month, the boeing-707 entered service, followed in September 1959 by the Douglas dc-8. Both of these American jets were larger and longer-ranged than the Comet, and quickly displaced it from long transoceanic routes. The Comet was shifted to shorter routes, primarily within Europe, the Middle East, and Latin America, where it hung on for several years; it lasted longest with British operator Dan-Air, which operated the last revenue Comet flight in November 1980. A few Comets continued to fly in military service after this, with the last-ever flight by a Comet taking place on 14 March 1997.

There were four major versions of the Comet, although only two ever operated in commercial service:

• The Comet 1 was the first and smallest variant, seating only 36 to 44 passengers and with a range of just 2,400 km (1,300 nmi); this was necessitated by its use of low-powered de Havilland Ghost engines, as the preferred engine, the Rolls-Royce Avon, was not yet available. The Comet 1 was also the only Comet version built with square, rather than round, windows; following the two 1954 midair Comet 1 disintegrations, all future Comets were redesigned to use round windows in an effort to reduce fatigue stresses around the window frames, while the remaining airline Comet 1s were withdrawn from service and scrapped (although a few military Comet 1s were extensively rebuilt to Comet 1X/1XB standard, with thicker skin and round windows, and remained in service into the 1960s). A total of twelve baseline Comet 1s (including the two Comet prototypes) and nine of the Comet 1A (a subvariant with more powerful engines) were built, with four Comet 1As later being converted into 1Xs or 1XBs.
• None of the sixteen Comet 2s ever saw revenue airline service, although a few conducted proving flights for BOAC, carrying only crew; most of the twelve produced were given to the Royal Air Force, where they served into the 1970s. The first Comet 2s were basically Comet 1s with Avon engines (which had become available in the interim) instead of Ghosts, right down to the square windows; when the results of the Comet 1 investigation came in, they were rebuilt with thicker fuselage skin and round windows, while later Comet 2s came straight from the factory with these modifications already in place. The more powerful engines gave the Comet 2 a much longer range (4,200 km [2,300 nmi]) than the Comet 1, plus a greater maximum weight and a higher top speed (although they also necessitated that the engine exhausts be reconfigured to prevent heat damage to the fuselage behind the wings). The Comet 2 was otherwise similar to the Comet 1, with the exception of a slightly longer fuselage.
• Only one flightworthy Comet 3 was built, first flying in July 1954. Although a (stretched, with considerably more powerful engines) derivative of the Comet 2, it was not rebuilt with thicker skin, and, thus, was incapable of being safely pressurized; as a result, it was destined to serve only as a testbed, first for the Comet 4, and, later, for various other technologies, before being retired in 1973.
• The Comet returned to revenue service with the Comet 4, which first flew in April 1958 and entered revenue service that September. It was mostly similar to the Comet 3, but featured a fully-redesigned fuselage structure with considerably thicker skin (which allowed it to safely carry passengers) and considerably larger fuel tanks (which allowed it to fly up to 5,190 km [2,800 nmi] at a time, finally giving it the range to cross the Atlantic). The Comet 4 came in three variants: the baseline Comet 4, the Comet 4B (a shorter-range, higher-capacity version with shorter wings and a stretched fuselage), and the Comet 4C (which combined the larger wings of the baseline 4 with the stretched fuselage of the 4B and added additional "slipper" fuel tanks under the outer wings). The Comet 4 typically carried 70 to 80 passengers, but could accommodate up to (in the 4C's case) 119. 75 were built (29 baseline 4s, 18 4Bs, and 28 4Cs) before production shut down in 1964.

The Comet was later developed into the Hawker Siddeley Nimrod maritime patrol aircraft, which entered service in 1969 and was finally retired in June 2011.

For more information on the Comet, see Wikipedia.