de Havilland DH.106 Comet

The worlds first jet-powered passenger airline, the de havilland DH.106 Comets reign was short-lived for the program suffered major setbacks by way of accidents and fatalities.

Detailing the development and operational history of the de Havilland DH.106 Comet Narrow-Body Passenger Airliner Aircraft.  Entry last updated on 5/17/2018. Authored by Staff Writer. Content ©www.MilitaryFactory.com

The de Havilland DH.106 "Comet" holds the distinction of becoming the world's first commercial marketplace passenger jet airliner. The design originated from work begun during World War 2 (1939-1945) in 1943 looking to the future of British passenger air travel. Including prototypes used in the flight-testing phase of the program, a total of 114 Comets were completed with primary customers being BOAC, British European Airways, Dan-Air, and the Royal Air Force (RAF). The last example was retired on March 14th, 1997. A first-flight, in prototype form, was recorded on July 27th, 1949.

The Comet enjoyed a period of early success and high-level publicity, giving the British a head start in the jet-driven, passenger-hauling marketplace but the series was done-in by equally high-profile crashes and accidents. This period eventually allowed competitors in the United States to take-over with their own storied designs. For the British, the Comet did influence another major Cold War player, the Hawker Siddeley "Nimrod" (detailed elsewhere on this site) of the late-1960s as forty-nine of these were built for the RAF to a maritime patrol standard..

Comet Development
During the Comet's design study phase, several forms of the what would become the DH.106 emerged including a version with twin tail booms, one with canard foreplanes, and another lacking horizontal tailplanes altogether while relying on a wide-area, swept-back wing mainplane. Many of these early offerings were influenced by "blank canvas" thinking in the late-World War 2 period as it revolved around the prospect of jet-powered flight. As the decade wore on, however, the Comet's design began to materialize along more traditional lines - giving us the tried-and-true jet airliner form still in play today.

Comet Walk-Around
A tubular fuselage was envisioned to act as the center point of the aircraft in which a short nosecone gave pilots excellent vision over the frontal section. The passenger section then took up most of the internal volume of the tube which tapered at the aft-end to form the empennage. The tail unit consisted of a single, rounded vertical tail fin complemented by low-set horizontal planes. The wing mainplanes were also set low, this at about midships, and featuring sweepback of the leading wing edges. Within each wingroot was buried paired turbojet engines, aspirated through ports at the wing leading edges and exhausting through ports beyond the trailing edges. Their position within the wing allowed the aircraft to retain considerable aerodynamic efficiency by basic streamlining. For ground-running, multi-wheeled landing gear members were used which were wholly retractable.

Comet Variants
There were four notable series variants in the Comet line named simply as "Comet 1", "Comet 2", "Comet 3, and "Comet 4". The original 40-seat Comet 1 emerged in production through a dozen airframes and were detailed with square windows, the overall appearance based heavily on the original de Havilland prototype. However, by this time, the design had incorporated multi-bogie main landing gear members over the original's single-wheeled forms. Original models were fielded with 4 x Ghost 50 Mk 1 series turbojet engines but these later gave way to 4 x Ghost FGT3 series engines.

From this initial model arrived the Comet 1A which increased performance allowing for greater take-off weights, speed, and range. Ten examples followed to the standard. The Royal Canadian Air Force (RCAF) was the recipient of a pair of Comet 1 models and these were taken on with reinforced skins and operated under the Comet 1X name. The follow-up Comet 1XB standard was nothing more than the Comet 1A with a strengthened fuselage understructure and more rounded windows.

The Comet 1 series enjoyed a maximum speed of 460 miles per hour with an MTOW of 110,000lb, a range out to 1,500 miles, and a cruising altitude of 42,000 feet. With these specifications, it clearly outpaced prop-driven developments of the period - garnering much interest from a public thirsty for flight.

The Comet 2 was given modified wing mainplanes which incorporated greater surface area and switched to more powerful Rolls-Royce "Avon" turbojets to better handle proposed cross-Atlantic / overwater routes. This also increased operational ranges but not to the extent required for such travel. The variant was some three feet longer than the original Comet 1 and was also differentiated by having the rounded windows of the later Comet 1 marks. The initial Comet 2 went airborne for the first time on August 27th, 1953 and deliveries followed in 1955. Variants went on to include the one-off Comet 2X development model (with its RR Avon 502 turbojets), a pair of Comet 2E aircraft (with mixed RR Avon 504/Avon 524 turbojet parings), a pair of Comet T2 marks (to serve the RAF as crew trainers), eight RAF-bound Comet 2C platforms, and a trio of Comet 2R developmental-minded platforms.

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