Comet 3 & Comet 4
The Comet was completely reengineered and emerged as a much changed and improved aircraft in 1958. An extensively developed variant of the earlier Comet 1 and 2, the world's first pressurised jet airliner, the De Havilland Comet 3 (G-ANLO) flew for the first time on 19th July 1954 and was in reality an extensively developed aircraft, derived from the earlier Comet 1 and 2. Fuselage length was increased by 15' 5" to provide accommodation for up to 58 passengers (although this was further increased with the introduction of the Comet 4) plus the addition of wing pinion fuel tanks which were introduced to provide extended range capability. Many regard the Comet 3 as the most attractive in appearance of all the Comets although trials indicated that it lacked the range required for North Atlantic operations.
Only two Comet 3s were ultimately built,with “G-ANLO”, the only airworthy Comet 3, being demonstrated at the Farnborough Airshow in September 1954. The other Comet 3 airframe was not completed to production standard and it was instead used primarily for ground-based structural and technology testing for the development of the Comet 4 series. “G-ANLO” became a flying testbed and it was later modified with Avon RA29 engines. In 1961, it was assigned to the Blind Landing Experimental Unit (BLEU) at RAE Bedford for use in automatic landing system experiments. When finally retired in 1973, the airframe was then used for foam arrester trials before the fuselage was salvaged at BAE Woodford to serve as the mock-up for the Nimrod variant.
Development flying and route proving with the Comet 3 allowed accelerated certification of what was destined to be the most successful variant of the type, the Comet 4. All airline customers for the Comet 3 subsequently cancelled their orders and switched to the Comet 4, which was based on the Comet 3 but with improved fuel capacity.
The design had progressed significantly from the original Comet 1, growing by 5.64 m (18 ft 6 in) and typically seating 74 to 81 passengers as compared to the Comet 1's maximum of 44. Eventually up to 119 passengers could be accommodated in a special charter seating package developed for the the later 4C series. The Comet 4 was considered the definitive series, having a longer range, higher cruising speed and higher maximum takeoff weight. These improvements were possible largely because of Avon engines possessed twice the thrust of the Comet 1's Ghosts.
The Comet 4 was the main production variant utilised by BOAC. The Comet 4 had the required performance for non-stop services from London to New York, this service being inaugurated on 4th October 1958. BOAC ordered 19 Comet 4s in March 1955, while American operator Capital Airlines ordered 14 Comets in July 1956. Capital's order included 10 Comet 4As, a variant modified for short-range operations with a stretched fuselage and short wings, lacking the pinion (outboard wing) fuel tanks of the Comet 4. However, due to financial problems and a subsequent takeover by United Airlines, Capital would never actually operate the Comet.
In addition to the BOAC fleet, export sales were also made to Aerolineas Argentinas (6 aircraft) and East African Airways (3 aircraft). However, the need for a higher capacity aircraft was identified by Capital Airlines in the USA (although their order was subsequently cancelled). The aircraft that duly emerged was the Comet 4B which was specifcially for BEA operations. This variant can readily distinguished by its longer fuselage section (118 ft compared with 111 ft 6 in) and the lack of the wing pinion fuel tanks. 18 were built: 14 for BEA and 4 for Olympic Airways.
The final version the Comet 4C combined the fuselage of the Comet 4B with the wings of the Comet 4 to produce a long fuselage variant with pinion tanks. The Comet 4C was notably successful in the export market with sales to Misrair, Mexicana, Aerolineas Argentinas, Sudan Airways, Kuwait Airways and Middle East Airlines.
The prototype Comet 4 completed its first flight on 27 April 1958, received its Certificate of Airworthiness on 24 September 1958, and was then delivered to BOAC the following day. The Comet 4 enabled BOAC to inaugurate the first regular jet-powered trans-Atlantic services on 4 October 1958 between London and New York (although it still required a fuel stop at Gander International Airport, Newfoundland, on west-bound North Atlantic crossings). By the time the flaw had been corrected and the new Comet 4C had been produced, de Havilland's jet had lost its lead to the Boeing 707 and the Douglas DC-8. The Comet 4, was not really competitive with the new generation of jet transports coming into use at that time, and only 74 were built.
While BOAC gained publicity by being the first to provide trans-Atlantic jet service, by the end of the month, rival Pan American World Airways was flying the Boeing 707 alongthe same route, and, by 1960, the Douglas DC-8 as well. The American jets proved to be larger, faster, longer-ranged, and significantly more cost-effective to operate than the Comet. After analyzing effective route structures for the Comet, BOAC reluctantly began looking for a successor to the Comet and, by 1958, had already entered into an agreement with Boeing to purchase the 707. The commercial success of the Comet was limited, but it was the first jet transport and represented a large step forward in our concepts of air transportation and its utility. It is unfortunate that the pioneering work of the designers and builders of the Comet was not rewarded with greater success. The Comet, in highly modified form, survives today as a marine reconnaissance aircraft known as the Nimrod.
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