Last revised: 19 November 1995
The Westland Wyvern began life as a 'Torpedo Fighter', intended to operate as daylight fighter and torpedo bomber. The concept itself was less odd than it might seem. Multi-role aircraft are an obviously advantageous concept for carrier forces, because the ship can carry only a strictly limited number of aircraft. The Wyvern fitted in the trend that fighter-bombers replaced light and medium bombers, and torpedoes had already been carried by the Focke-Wulf Fw 190A-5/U14 and the Blackburn Firebrand. The particularly disappointing career of the latter aircraft should have been a warning, however.
The Wyvern began life with specification N.11/44, issued in November 1944; this called for a fighter with a Rolls-Royce Eagle piston engine, but capable of accepting a turboprop; carrier-capable and armed with four 20-mm cannon, eight rockets, and three 450 kg bombs, a 825 kg mine or a 20-in torpedo. The RAF thought about ordering the same aircraft as a land-based escort fighter for some time, but abandoned it in favour of jet fighters.
John Digby was responsible for the Westland design, chosen by the RN. It had half-elliptic wings not unlike those of the Tempest and slightly of inverted-gull configuration. The inner section was fitted with sizable Fairey-Youngman flaps; the outer section had plain flaps and ailerons. The fuselage was clean, if sizable; the 3550 hp, 24-cylinder, sleeve-valve liquid-cooled Eagle engine was installed with a 'beard' radiator and underwing oil coolers. It wasn't exactly close-cowled, but the sloping engine cowling certainly gave the pilot a good forward view, preventing one of the most undesirable characteristics of single-engined propeller fighters. An eight-bladed, contra-rotating propeller was to pull the big fighter forward. Because of the bulky engine installation, a large tail had to be fitted.
First flight was made by TS371 on 12 December 1946, flown by Harold Penrose. It was followed by five other prototypes and ten Wyvern TF.1 pre-series aircraft. Except the first prototype all were fitted with ejection seats. They immediately began to build a bad record, with numerous emergencies and two complete groundings; problems with engine and propeller seem to have been responsible for most of them. The Eagle-engined version was soon abandoned in favour of the turboprop-engined developments.
The concept of a turboprop-engined strike fighter was not uncommon in itself. In the USA the Douglas A2D Skyshark was built as a possible replacement for the AD Skyraider; but it had to be abandoned because of the unreliability of the Allison T40 engine. In the USSR the Tupolev Tu-91 attack aircraft was abandoned after Stalin's death, together with the carrier building programme.
The available engines for the Wyvern were the Rolls-Royce Clyde and the Armstrong Siddeley Python. The Clyde was a twin-spool engine, with one spool driving a centrifugal compressor and the other the propeller and an axial compressor. The Clyde delivered at least 4030 hp, with a potential for much more. The Clyde was used for prototype VP120. The radiator and underwing oil coolers were removed, a smaller tail was fitted, and a six-bladed contraprop installed. The engine had twin exhausts, one on each side of the fuselage, over the wing. It first flew on 18 January 1945, and showed to be excellent. Production had to be canceled however, simply because Rolls-Royce refused to build the Clyde engine in series! Rolls-Royce was committing itself fully to jet engines.
The Python was an older design and lower-powered (3760 hp), with a reverse-flow, 14-stage axial compressor. The first Python-engined Wyvern TF.2 was VP109 and flew on 22 March 1949, with an eight-bladed Rotol propeller, but otherwise similar to VP120. Oil coolers were placed in the extended wing roots. It was followed by a second prototype and a few T.3 two-seat trainers. Experiences with the engine were far from satisfactory, unreliability and a slow reaction speed making the aircraft unpopular. If it had been available, Westland would probably have liked to return to the Eagle engine; but that was not possible, and twenty Python-engined TF.2s were built. Carrier trials began on 21 June 1950.
Four converted and 87 new-built aircraft were delivered of the most important Wyvern version, the TF.4, later renamed S.4. The TF.4 had numerous small changes. The recognition characteristic was the cut-off engine inlet, the propeller spinner then protruding much further forward. Small rectangular fins were added to the tailplane, changes were made to the ailerons, Martin-Baker Mk. 2B ejection seats were installed, and the cockpit was reinforced. Later modifications included perforated dive brakes, a flat windscreen, and provisions for tip tanks.
The Wyvern entered service with 813 Sqn in May 1953, replacing the Firebrand. 813 Sqn was based later on the Eagle and the Albion. Other Wyvern units were 827, 830 and 831. In November 1956 the 830 and 831 Squadron took part in the Suez campaign. Only 830 seems to have made combat flights, losing 2 aircraft in 79 sorties. In March 1958 the last Wyvern unit, 813, was disbanded. Total Wyvern production had been 127.