The world's first commercial jetliner
Design work began in 1946 under Ronald Bishop and the intention was to have a commercial aircraft by 1952. The de Havilland DH. 106 Comet 1 first flew on 27 July 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 clean, low-drag design of the aircraft featured many design elements that were fairly uncommon at the time, including a swept-wing leading-edge, integral wing fuel tanks, and four-wheel bogie main undercarriage units designed by de Havilland. The airliner underwent almost three years of tests and fixes and the first commercial flight did took place to Johannesburg on 2 May 1952 with Boac.
The jet airliner proved to be around twice as fast as contemporary aircraft, like the Constellation, and with almost 30'000 passengers carried in the first year. Orders began pouring in from airlines including from Canadian Pacific Airlines (2 aircraft), Air France (3 aircraft), and Union Aéromaritime de Transport (UAT) (3 aircraft). And not only did the aircraft attract just commercial operators; the Royal Canadian Air Force (RCAF) became the first military in the world to introduce jet transports when it placed an order for two Comet 1s.
Large picture windows and table seating accommodations for a row of passengers afforded a higher degree of comfort and luxury as compared to other airliners of the period. Amenities included a galley that could serve hot or cold food and drinks plus a bar along with separate men's and women's toilets. Emergency provisions included several life rafts stored in the wing roots near the engines along with individual life vests stowed under each seat.
For ease of training and fleet conversion, de Havilland designed the Comet's flight deck layout with a degree of similarity to the Lockheed Constellation, an aircraft that was in service at the time with key potential customers such as BOAC. The cockpit included full dual-controls for the captain and first officer, while a flight engineer controlled various key systems, including the fuel, air conditioning, and electrical systems. The navigator occupied a dedicated station with a table across from the flight engineer.
The first sign of a flaw in the Comet came on 2 May 1953 when a Comet 1 G-ALYV crashed in a severe tropical storm six minutes after taking off from Calcutta/Dum Dum, India killing all 43 on board. Further crashes followed. On 10 January 1954, 20 minutes after taking off from Ciampino, Comet G-ALYP broke up in flight and crashed into the Mediterranean off the Italian island of Elba, with the loss of all 35 on board. There was no obvious reason for the crash, and the fleet was grounded while the Abell Committee met to determine potential causes of the crash.
Then on 8 April 1954, Comet G-ALYY, On charter to South African Airways, was on a leg from Rome to Cairo (of a longer flight from London to Johannesburg), when it crashed in the waters near Naples The fleet was immediately grounded once again and a large investigation board was formed under the direction of the Royal Aircraft Establishment (RAE). Royal Navy was tasked with helping to locate and retrieve the wreckage so that the cause of the accident could be found.
Engineers subjected an identical airframe, G-ALYU, to repeated re-pressurization and over-pressurization and after 3,057 flight cycles (1,221 actual and 1,836 simulated), YU failed due to metal fatigue near the front port-side escape hatch. Investigators began considering fatigue as the most likely cause of both accidents and initiated further research into measurable strain on the skin. It was 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 sudden depressurization and catastrophic structural failure.
All remaining Comets were either scrapped or modified and the program to produce a Comet 2 was put on hold. The Comet 2 had a slightly larger wing, higher fuel capacity and more powerful Rolls Royce Avon engines which all improved the aircraft's range and performance. Following the Comet 1 disasters, these models were rebuilt with heavier gauge skin and rounded openings. 12 of the 44-seat Comet 2s were ordered by BOAC for the South Atlantic route. The first production aircraft (G-AMXA) flew on 27 August 1953. Although these aircraft performed well on the South Atlantic routes, their range was still not suitable for the North Atlantic. All but four Comet 2s were allocated to the RAF. Eight Comet C2 transport aircraft and two Comet T2 crew trainers were delivered to the RAF beginning in 1955.
Comet 2 sub-variants
- Comet 2X: Limited to a single modified Comet Mk 1 powered by four Rolls-Royce Avon 502 turbojet engines and used as a development aircraft for the Comet 2 series;
- Comet 2E: Two Comet 2 airliners were fitted with Avon 504s in the inner nacelles and Avon 524s in the outer ones. These aircraft were used by BOAC for proving flights during 1957–1958;
- Comet T2: The first two of 10 Comet 2s for the RAF were fitted out as crew trainers, with the first aircraft (XK669) flying for the first time on 9 December 1955;
- Comet C2: Eight Comet 2s originally destined for the civil market were completed for the RAF as transports and assigned to No. 216 Squadron; and
- Comet 2R: Three Comet 2s were modified for use in radar and electronic systems developments, and were assigned to No. 192 and No. 51 Squadrons. The 2R series was also equipped to monitor Warsaw Pact signals traffic and operated in this SIGINT role from 1958.
G-ANLO was the only flying Comet 3, and took part in a marathon round-the-world promotional tour in December 1955, flown by John Cunningham. It was modified with reduced span wings as the Comet 3B and was displayed at Farnborough in September 1958. The other Comet 3 was used for structural and technology testing during development of the similarly sized Comet 4.
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. 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 4 October 1958.
That flight was the first scheduled trans-Atlantic passenger jet service, beating Pan American's inaugural 707 service by three weeks. 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 27 June 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. In total, 76 Comet 4 family aircraft were delivered from 1958 to 1964. Although BOAC retired its Comet 4s from revenue service in 1965, other operators (of which Dan -Air was the largest and last) continued flying commercial passenger services with the aircraft until 1980.
Although the Comet was the first jetliner in service, the interruption of commercial service and the damage to the aircraft's reputation caused by the Comet 1 fatigue failures meant that the jetliner market was dominated by Boeing , which flew the first prototype 707 in 1954, and Douglas , which launched the DC-8 program in 1955. Only fifteen airlines ever used the Comet, the proposed Comet 5 was never built, and the Comet 4s were slowly withdrawn from service. A few additional aircraft were used by the military, but only the Nimrod, a Comet derivative.
The last Comet flight was conducted in 1997 by a Comet 4C that had been owned by the British government.
East African Airways
Middle East Airlines
Union Aeromaritime de Transport
United Arab Airlines / Egyptair
Ministry of Aviation
Royal Aircraft Establishment
Royal Air Force
Summary of the Comet