Supermarine Swift

During 1945, the Second World War came to a close and a new post-war Labour government, headed by Clement Attlee, came to power in Britain.[1] The incoming Attlee government's initial stance on defence was that no major conflict would occur for at least a decade, and thus there would be no need to develop or to procure any new aircraft until 1957. In accordance with that policy, aside from a small number of exceptions such as what would become the Hawker Sea Hawk for the Royal Navy, the majority of Specifications issued by the Air Ministry for fighter-sized aircraft during the late 1940s were restricted to research purposes.[2] Aviation author Derek Wood refers to this policy as being: "a fatal error of judgement which was to cost Britain a complete generation of fighters and heavy bomber aircraft".[1]

In part, the Swift had its origins in the experimental fighter prototypes that had been developed. Specifically, a number of Supermarine-built prototypes had been ordered under Specification E.41/46, which had sought the production of an experimental fighter aircraft furnished with a swept wing. The first of those prototypes was designated as the Type 510, which was heavily based on the straight-wing Supermarine Attacker, an early jet aircraft which was procured by the Fleet Air Arm (FAA) of the Royal Navy. The principal difference from the Attacker was that it had been modified with a swept wing configuration.[3] During 1948, the Type 510 had conducted its maiden flight, a year after the first navalised prototype Attacker had flown. That flight made it the first British aircraft to fly with both swept wings and a swept tailplane. In trials for the Fleet Air Arm, the Type 510 was also the first swept-wing aircraft to take off from and land on an aircraft carrier.

During the late 1940s, in the face of the emerging Cold War, the RAF came to recognise that it would urgently require the development and procurement of fighters equipped with features such as swept wings. That need was felt to be so pressing that it was willing to accept interim fighter aircraft while more capable fighters were being developed.[4] In 1950, with the outbreak of the Korean War, Britain's heavy involvement in that conflict led to a flurry of orders being placed. In particular, the RAF felt that a pair of proposed fighter aircraft from Hawker Aircraft and Supermarine were of great importance and, in the same year, ordered the proposed fighters "off the drawing board".[5] The Supermarine design was designated as the Type 541, and was essentially an advanced development of the earlier Type 510 experimental aircraft.[3]

The initial order placed in 1950 for 100 aircraft was intended to serve as an insurance policy in the event that Hawker failed to produce a viable aircraft. The two aircraft became known as the Supermarine Swift and the Hawker Hunter respectively.[5] In early 1946, the Type 541 order was increased to 150 aircraft, while the Air Ministry had hopes that it would be able to enter service in advance of the rival Hunter. However, the development of both the Swift and the Hunter were protracted, having encountered several considerable technical challenges. According to Wood, that was in part due to a failure to procure interim aircraft equipped with swept wings, or to proceed with development of the Miles M.52.[3] Wood describes the Swift as being "literally an attempt to squeeze a quart into a pint pot, with 30mm Aden guns, an afterburner, power controls, adequate fuel and a respectable high subsonic performance".[3]

Swift FR.5 landing at the Farnborough air show in 1955

The Type 541 replaced its predecessors' Rolls-Royce Nene centrifugal flow turbojet engine with the axial-flow Rolls-Royce AJ.65 turbojet, which became the famed Avon series. The fuselage, which had been given a cross section suitable for the Nene engine, was not redesigned for the narrower AJ.65 and Avon engines, and retained a somewhat portly appearance. The plane was also equipped with a tricycle undercarriage. A pair of Type 541 prototypes were produced. The first made its maiden flight in 1951 and the second during the following year.

Production of the Swift had been declared to be a "super-priority" item under a policy created by Sir Winston Churchill, who had regained the position of Britain's prime minister in 1951, as a means of increasing projects considered to be of vital military importance. According to Wood, volume manufacturing commenced in advance of the implementation of modifications based on the results of flight experiences with the prototypes: "too much had been asked for in too little time and production aircraft were rolling off the production line before a major redesign could be accomplished".[3]

The first production variant was a fighter designated the Swift F Mk 1, of which 18 were eventually built. It was powered by a single 7,500 lbf (33.4 kN)-thrust Avon 109 engine and carried an armament of two 30 mm ADEN cannons. On 25 August 1952, the first flight of a production standard Swift F 1 took place. Peter Thorne, who had been appointed as the senior RAF test pilot for the incoming Swift in 1954, came to doubt the aircraft's suitability. Thorne and several other pilots noted the Swift had unusual handling qualities, as well as a troublesome engine.[6]

Swift.F.1 test aircraft operated by Vickers-Armstrong in 1953

The second variant was the Swift F Mk 2, of which 16 were built. It was practically the same as the F 1, except for being fitted with two extra ADENs and the leading edge of the wing being altered from straight to a compound sweep configuration.[3] However, the addition of the cannon caused problems, because the structural modifications required to house the increased ammunition load led to dangerous handling characteristics, and it was clear that more thrust was required from its engine. Numerous further modifications were required to resolve the problems.[3]

The third Swift variant was the F Mk 3, of which 25 were built, powered by an Avon 114 engine with reheat. It was never put into operational service with the Royal Air Force and was used as an instructional airframe. The next variant was the F Mk.4, which included a variable incidence tailplane, intended to correct the handling problems that the Swift suffered from. It did fix the problem, but it was found that reheat could not be ignited at high altitude, adding to the Swift's list of problems.

The next in the line, the FR Mk 5, had a longer nose to accommodate a number of cameras to allow a reconnaissance role, as well as other modifications to its structure. The FR 5 also reverted to the F 1's twin ADEN cannon armament. It first flew in 1955 and entered service the following year, performing reconnaissance mainly at low level, making the reheat problem at high altitude irrelevant.

Two further variants were designed. The PR Mk 6 was an unarmed photo reconnaissance plane. However, its use was short-lived, due to the ever-present reheat problems. The last variant was the F Mk 7, which was the first Swift model to be fitted with guided missiles, the Fairey Fireflash air-to-air missile, and was powered by a new model of the Avon engine. Only fourteen F 7 aircraft were built and none ever entered service with the RAF, being relegated – along with its prototype missiles – to conducting guided-missile trials duties only.

In 1953, as a response to growing RAF interest in developing transonic aircraft to serve as a stopgap while the next generation of supersonic fighters were being developed, both Supermarine and Hawker proposed derivatives of their respective Swift and Hunter aircraft.[7] By that time, the shortcomings of the Swift were not yet apparent, which perhaps had allowed Supermarine to gain the RAF's favour for its proposal, designated as the Type 545, over the rival Hawker P.1083. The Type 545 had been drawn up to conform with the requirements given by Specification F.105D. It was to have been capable of attaining Mach 1.3. powered by an Avon engine, promising superior performance to that of the P.1083.[8] The Type 545 bore a resemblance to the Swift, although it was a complete redesign, having an area-ruled fuselage and wing changes. In 1955, work on the project was cancelled, in part due to the considerable difficulties experienced with the Swift.[9]

• Andrews, C. F.; Morgan, E. B. (1987). Supermarine Aircraft since 1914 (2nd ed.). London: Putnam. ISBN 0-85177-800-3.
• Buttler, Tony. X-Planes of Europe II: Military Prototype Aircraft from the Golden Age 1946–1974. Manchester, UK: Hikoki Publications, 2015. ISBN 978-1-90210-948-0
• Winchester, Jim. The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters. London: Amber Books, 2005. ISBN 1-904687-34-2
• Wood, Derek. Project Cancelled. Macdonald and Jane's Publishers, 1975. ISBN 0-356-08109-5