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Jets45 Histories

de Havilland DH 106 "Comet"

The very first DH 106 "Comet" at it's roll out in 1949

Specification For Mk I "Comet"
    Engine: 4x de Havilland "Ghost" 50 Mk 1 turbojets making 5,000 lb of thrust each
    Wing Span: 114' 7''
    Length: 93' 9''
    Height: 28' 6''
    Weight: Empty 12,480 lb / Loaded 104,985 lb
    Cruising Speed: 450 mph
    Ceiling: 42,000'
    Range: 1,500 miles
    Crew: 4 & up to 36 Passengers
    Armament: none
The design of the Comet dates from 1942, when the Brabazon committee was set up on the 23/12/1942 to determine what type of civil aircraft would be needed after the war. In 1943 they issued a requirement for a jet-powered mailplane for the North American route, the Type IV it was to carry a ton of cargo at a cruising speed of 400 mph. In 1945 the specifications were revised, to two or more jet engines, the capacity to carry 14 plus passengers over a range of 700 to 800 miles, at an altitude of 30,000' with a speed of 450 mph, the "Comet" was born. A contract was issued to the de Havilland company by the British Ministry of Supply in mid 1946 for the construction of two prototypes. The DH 106 was in advance of any other aircraft then flying, with a fully pressured fuselage, swept wings at 20°, high-pressure refueling and the "Redux" metal-to-metal bonding process, this was used because of the very thin nature of the aluminum alloy skin employed to keep the aircraft's over all weigh down, this was necessary because of de Havilland's insistence on the uses of it's own engines the "Ghost" 50 Mk-I, these were thought by some to be woefully underpowered for an aircraft of such a size.
A design study for the "Type IV " Mail Plane from 1944
The "Comet" production line
The first "Comet" made it's first flight on the 27/7/1949 and in testing all went well, some reservations was voiced over the aircraft's thin "skin" and the fitting and design of the windows, how ever de Havilland's chief designer R.E.Bishop would hear none of it, being more concerned with the aircraft's production schedule, 14 Comet Mk-I's having already been ordered by BOAC. The maiden flight of the first production "Comet" took place on the 9/1/1951 and entered service on the 2/5/1952 flying from London to Johannesburg, the worlds first commercial jet passenger service and years ahead of the Americans. The orders for the Mk-I came in with 50 being ordered by various airlines by the end of 1952. Work on the Mk-2 (fitted with more powerful Rolls-Royce Avon engine) was started and the Mk-3 was announced with a lengthened fuselage it could carry 76 passengers. All seemed well.....
Between October 1952 and January 1954 a number of disastrous accidents took place with the death of 89 people, an attempt was made to blame the accidents on the pilots, but after another "Comet" broke-up in midair all the aircraft then flying were grounded, after a five month investigation by the RAE, the cause of the crashes were pined down to structural weaknesses in the alloy skin around the windows were reinforcing plates were riveted to strengthen the skin around the windows. De Havilland lost all the orders then placed and undertook a major redesign with the square windows being replaced by an oval design, the fuselage was reinforced and the alloy used for the skin being replaced, all this work resulted in the Mk 4, which took to the air on the 27/4/1958 and can be seen as the definitive version of the "Comet" as all the problems relating to the earlier aircraft were resolved. However the damage was done and the "Comet" never recovered it's reputation, only a small number of "Comet MK-4's were sold (around 57) to civilian operators, with the last commercial flight being on the 9/11/1980 by Dan Air.
The first Mk-1 in service 1952 with B.O.A.C
Despite the "Comets" failure as a civilian airliner, it would prove to be a very successful aircraft in the hands of the RAF. The last two unsold airframes were competed as prototypes for a Long Range Maritime Patrol Aircraft (MR) the HS 801, built by Hawker Siddley before its acquisition by BAe, the modified Comet 4C airframes were completed with a shorter fuselage, enlarged underfuselage, stronger landing gear, and other structural improvements. the first flight was on the 27/4/1967 , with the MR-1 entering service in 1969, all together 51 were built, the Nimrod still serves with RAF and in a much upgraded from (MR-4) will continue to do so well into the 21st Century
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