Supermarine Scimitar - Design and Development

Design and Development

The Scimitar stemmed from a number of designs from Supermarine for a naval jet aircraft, initially to a requirement for an undercarriage-less fighter aircraft to land on flexible "sprung" rubber decks, which would allow for a lighter and simpler structure. Supermarine's design to meet this requirement was the Type 505, featuring a thin, straight wing and a V-tail (or "butterfly tail") to keep the tail surfaces away from the jet exhausts, and to be powered by two Rolls-Royce Avon turbojets, mounted side-by-side in the fuselage. In 1948, the Admiralty had second thoughts about the undercarriage-less fighter, and Supermarine reworked their design by including a nosewheel undercarriage, becoming the Type 508. The Vickers-Supermarine Type 508 was the first Scimitar ancestor, and shared the basic layout of the Type 505, i.e. a twin-engined straight-winged type with V-tail. Pitch control was by moving the whole tail, with elevators for additional pitch control when working in tandem, and to replace the rudder on a conventional tail when working differentially. Ailerons were fitted to the wings for lateral control, and both leading and trailing edge flaps were also fitted to the wings. An order for three Type 508s was placed in November 1947, to Specification N.9/47.

The first Type 508 made its maiden flight from Boscombe Down airfield on 31 August 1951, with the aircraft carrying out carrier trials aboard HMS Eagle in May 1952. The second aircraft had significant differences, carrying a cannon armament, and different enough in detail to be redesignated the Type 529, flying for the first time on 29 August 1952. One unusual modification was the larger tailcone that was to accommodate a proposed tail-warning radar. The maximum speed of the straight-winged Type 508 and 529 was relatively modest, with the Type 529 reaching 607 mph (977 km/h), and it had already been decided when the Type 508 first flew to redesign the third prototype with swept wings to improve performance. The resulting Type 525 also featured conventional swept tail surfaces as well as blown flaps to reduce the aircraft's landing speed, and first flew on 27 April 1954. It later crashed but the basic design had already proved sound enough to proceed with an outwardly fairly similar looking aircraft, the Type 544, to specification N.113. A total of 100 were ordered although the Royal Navy had changed the specification to a low level strike aircraft with nuclear capability rather than a dedicated fighter.

The first of the Type 544s serving as prototypes for the later production series flew on 19 January 1956. The aircraft evolved more with the third Type 544 incorporating different aerodynamic changes and a stronger airframe strengthened for the new low level role - to quote Flight; "To permit uninhibited manoeuvring in thick turbulent air at low levels while carrying heavy loads of strike weapons, the structure is extremely sturdy". Various aerodynamic "fixes" to try and counter pitch-up effects at high speed and altitude included flared-out wingtips and wing fences. The tailplane was also changed from dihedral to anhedral. The combined modifications led to the final Type 544 being considered the "production standard". The first production Scimitar flew on 11 January 1957.