Westland Wyvern TF Mk 2 / S Mk.4

Almost a year before the first flight of the Wyvern TF Mk 1, the Naval Air Staff had decided to sponsor development of Britain's first turboprop-powered shipboard fighter by ordering three prototypes of the (W.35) Wyvern TF Mk 2, to Specification N.12/45. Two were to be powered by the Armstrong Siddeley Python and the third by a 4500hp Rolls-Royce Clyde. In the event, the former engine was to be preferred for production aircraft. In overall configuration and armament the Wyvern TF Mk 2 closely resembled the Mk 1, although there were differences in detail, and the first flight of the Clyde-engined prototype was made on 18 January 1949, followed by the first with a Python on 22 March 1949. Flight testing soon showed the need for modifications, noticeably to the tail unit with the progressive introduction of a larger tailplane, more fin area, dihedral on the tailplane and, eventually, finlets. Prolonged testing and development also proved necessary to achieve a satisfactory engine/propeller/throttle response system for the special demands of carrier landings, involving the two Python prototypes and most of 20 pre-series TF Mk 2s ordered in 1948 (together with a single W.38 Wyvern T Mk 3 two-seat training version). The first pre-series TF Mk 2, with a Python 2, flew on 16 February 1950, and, in June that year, became the first British turboprop aircraft to engage in carrier deck landings, aboard HMS Illustrious. The final seven pre-series aircraft were completed as Wyvern S Mk 4s, this being the designation of the definitive variant with all the handling and engine modifications, and the primary mission changed to strike. The S Mk 4 was powered by a Python 3 rated at 3670hp plus 535kg residual thrust. Production of 87 Wyvern S Mk 4s ensued, and deliveries to the first FAA squadron (No 813) began during 1953. Three other squadrons subsequently flew the Wyvern S Mk 4, front-line service continuing until March 1958. Operational use of the Wyvern during the Suez campaign in 1956 marked the only occasion on which British turboprop-powered aircraft saw combat use.

3-View

A three-view drawing of Wyvern S Mk.4 (800 x 548)