English Electric Canberra
The English Electric Canberra is a British first-generation, jet-powered medium bomber. It was developed by English Electric during the mid- to late 1940s in response to a 1944 Air Ministry requirement for a successor to the wartime de Havilland Mosquito fast bomber. Among the performance requirements for the type was an outstanding high-altitude bombing capability and high speed. These were partly accomplished by making use of newly developed jet-propulsion technology. When the Canberra was introduced to service with the Royal Air Force, the type's first operator, in May 1951, it became the service's first jet-powered bomber.
In February 1951, a Canberra set a world distance record when it became the first jet aircraft to make a nonstop transatlantic flight.
Throughout most of the 1950s, the Canberra could fly at a higher altitude than other aircraft, and in 1957, a Canberra established a world altitude record of with the aid of a Napier "Double Scorpion" rocket motor.
Due to its ability to evade the early jet interceptor aircraft, and its significant performance advancement over contemporary piston-engined bombers, the Canberra became a popular aircraft on the export market, being procured for service in the air forces of many nations both inside and outside of the Commonwealth of Nations. The type was also licence-produced in Australia by Government Aircraft Factories.
In the USA, a modified version was produced by the Martin company as the B-57 Canberra and the significantly updated B-57B.
In addition to being a tactical nuclear strike aircraft, the Canberra proved to be highly adaptable, serving in varied roles such as tactical bombing and photographic and electronic reconnaissance. Canberras served throughout the Cold War, in the Suez Crisis, Vietnam War, Falklands War, Indo-Pakistani wars, and numerous African conflicts. In several wars, each of the opposing sides had Canberras in its air force.
The Canberra served for more than 50 years with some operators. In June 2006, the RAF retired the last three of its Canberras 57 years after its first flight. Three of the Martin B-57 variant remain in service, performing meteorological and re-entry tracking work for NASA, as well as providing electronic communication testing for deployment to Afghanistan.
Development
Background
During the Second World War, a desperate demand for bomber aircraft led to many aircraft being produced by secondary manufacturers via licensed manufacturing arrangements. The English Electric company thus mass-produced thousands of piston-engined bombers, such as the Handley Page Hampden and Handley Page Halifax, and the firm became a well-established British aircraft manufacturer despite having little internal design experience. Sir George Nelson, the chairman of English Electric, decided that the company would seek to remain in the business and produce its own designs. In November 1943, the company was invited to participate in discussions over a prospective bomber that would take advantage of the newly developed jet propulsion technology.In 1944, Westland Aircraft's technical director and chief designer W. E. W. Petter had prepared a design study for a twin-engined fighter-bomber, the P.1056, based on two fuselage-mounted Metrovick F.2/4 "Beryl" engines. The aircraft used a relatively conventional aerodynamic design, Petter having determined that the necessary performance could be attained without adopting swept wings or a swept tail. The authorities doubted its suitability for operations from unprepared fields and at low altitude, but could see its potential as a bomber design; numerous manufacturers refused to take on the design. Petter left Westland to join the English Electric company in December 1944, where he was appointed by Nelson to form a design team and encouraged to develop his design. In 1945, English Electric formalised its own in-house aircraft design team to pursue this design.
The Canberra had its formal origins in a 1944 requirement issued by the Air Ministry for a successor to the de Havilland Mosquito. This requirement, the initial revision being E.3/45, sought a high-altitude, high-speed bomber, which was to be equipped with no defensive armament. According to aviation historians Bill Gunston and Peter Gilchrist, Air Ministry officials are alleged to have had difficulty defining what they sought for the proposed type, which led to several revisions of the requirement. Further specification refinements, including B.3/45 and B.5/47, issued further details such as a three-man crew and other features such as a visual bombing capability. Several British aircraft manufacturers submitted proposals to meet the requirement, including English Electric. The firm was among those companies to be short-listed to proceed with development studies.
By June 1945, the aircraft that was to become the Canberra bore many similarities to the eventual design, despite the placement of a single, centrally mounted turbojet engine; Petter had held discussions with Rolls-Royce Ltd on the topic of the development of a scaled-up derivative of the Nene engine. In late 1945, the design was modified further with a pair of engines being adopted, instead, initially to be set in the wing roots and later to be mounted in a midwing position; this change was made principally due to centre of gravity issues imposed by the position and weight of a heavy bombload and centrally mounted single engine. The new engine position decreased the aircraft's weight by 13% and improved the aircraft's centre of gravity, as well as improved accessibility to the engines and related accessories; its downsides were slight thrust loss from the longer jet pipes and greater yaw during engine-out instances.
During the early stages of design, the aircraft had grown from being roughly the same size as the Mosquito to being around double its weight. Although jet-powered, the Canberra design philosophy was very much in the Mosquito mould, providing room for a substantial bomb load, fitting two of the most powerful engines available, and wrapping it in the most compact and aerodynamic package possible, an example being a leading edge formed of a single sheet of light alloy wrapped around to 40% of chord, sitting on Redux-bonded stiffeners through which the ribs were passed, the panels secured with adjustable eye-bolts, enabling a highly accurate wing profile to be maintained from the leading edge to main spar without any external joints or fastenings. Also in line with the Mosquito philosophy, the Canberra by design dispensed with defensive armament, which had historically proven unequal to fighter aircraft, and the resulting performance gain permitted the Canberra to avoid air-to-air combat entirely.
On 7 January 1946, the Ministry of Supply placed a contract for the development and production of four English Electric A.1 aircraft. It continued to be known as the English Electric A.1 until it was given the name "Canberra" after the capital of Australia in January 1950 by Sir George Nelson, chairman of English Electric, as Australia had become the aircraft's first export customer.
Prototypes and first flights
The Air Ministry specification B.3/45 had requested the production of four prototypes. On 9 January 1946, English Electric received a contract to produce four prototypes, which received the Society of British Aerospace Companies designation A.1; work commenced on the construction of these prototype aircraft in that same year, which were all built on production jigs. Progress was slow, however, due to several factors, such as the protracted development of the Avon engine that powered the type; in October 1947, in response to Rolls-Royce's difficulties, English Electric elected to have the second prototype modified to use the existing Nene engine in place of the Avon. The implementation of postwar military cutbacks also served to slow development.Another external issue that affected development was the failure of the Telecommunications Research Establishment to produce the radar bombing system for the aircraft in a timely fashion. This required a redesign in 1947, changing the aircraft's nose to accommodate a glazed tip for visual bombing by a bomb aimer, which in turn required the cockpit to be restructured to facilitate the ejection system of the additional crewmember. In 1948, the design team relocated to Warton Aerodrome, Lancashire, establishing a flight-test organisation and assembly facilities there.
Ultimately, the first of these prototypes, VN799, conducted its maiden flight on 13 May 1949. Piloted by Roland Beamont, the aircraft is claimed to have handled well, with the exception of rudder overbalance. This initial flight was flown with Avon engines, the decision to perform the type's first flight with the Avon-equipped first prototype or the Nene-equipped second prototype, VN828, was not made until weeks beforehand. On 9 November 1949, the second prototype, VN828, the first to be equipped with the Nene engine, performed its first flight. The third and fourth followed within the following eight weeks.
Flight testing of the prototypes proved to be vice-free and required only a few modifications. The changes included the installation of a glazed nose to accommodate a bomb-aimer, due to the advanced H2S Mk9 bombing radar being unavailable for production, the turbojet engines were replaced by more powerful Rolls-Royce Avon R.A.3s, and distinctive teardrop-shaped fuel tanks were fitted under the wingtips. Refinements were also made following early flight testing to the rudder and elevator to reduce instances of buffeting, after which it is claimed that the Canberra handled much like a fighter, proving to be atypically manoeuvrable for a bomber.
The project had found considerable support from the government in the late 1940s. In March 1949, in advance of the maiden flight of the first prototype, English Electric received an instruction to proceed for production. By the time the first prototype had flown, the Air Ministry had placed orders for 132 production aircraft in bomber, reconnaissance, and training variants. On 21 April 1950, the first production-standard aircraft, designated as the Canberra B.2, conducted its maiden flight, piloted by Beamont. Proving to be free of problems, this first flight was almost immediately followed by the mainstream manufacturing of production Canberras. In May 1951, the Canberra entered RAF squadron service, No. 101 Squadron being the first to receive the type. In a testament to the aircraft's benign handling characteristics, the transition programme for the Canberra consisted of only 20 hours in the Gloster Meteor and three hours in a dual-control Canberra trainer. Matthew Materia of Smiths Industries was pivotal in a secret Australian Government mission to fit an autopilot system to the Canberra bomber, Australia's major air defence