Supermarine Spiteful

The Supermarine Spiteful was a British fighter aircraft designed by Supermarine during the Second World War as a successor to the Spitfire. Powered by a Rolls-Royce Griffon engine, it had a radical new wing design to allow safe operations at higher speeds and incorporating inwards-retracting undercarriage. Other changes included a larger fin to improve the marginal stability of Griffon Spitfires. Development of the wing was formalised by Air Ministry specification F.1/43; as well as a new aircraft, there was an expectation the wing could be used as a replacement for the elliptical wing on Spitfire production.

The Spiteful was ready for production as the war was ending but in testing had shown only marginal improvements over existing types and was now being overtaken by jet-powered designs. Of the original order for 150 Spitefuls, only 19 were built. The Royal Navy opted for a navalised variation of the Spiteful type, the Supermarine Seafang, but few of those were built either. The wing developed for the Spiteful was used for the Supermarine Attacker jet.

Design and development

Background

In 1942, to improve the rolling characteristics of the Supermarine Spitfire, the British Air Ministry asked Supermarine to devise a new wing for the aircraft and to incorporate a laminar flow wing section in the new design. By November that year, the company's chief designer, Joseph Smith, was working on the new wing. It became clear to the Supermarine design team that the Spitfire's performance at speeds greater than was compromised by the aeroelasticity of its elliptical wing. R.J. Mitchell's original elliptical design had been regularly strengthened and modified during the war to cope with increases in engine power, but if the Spitfire was to fly still higher and faster, a radical new design of wing would be needed. The design progressed in collaboration with the National Physical Laboratory at Teddington.

In September 1942, Supermarine used Specification No 469, which outlined the first steps towards designing the Type 371, later named the Spiteful. Specification No 470 was issued by Supermarine on 30 November,

Specification 470 described how the wing skins were to be relatively thick, aiding rotational stiffness, which was needed for good aileron control at high speeds. Although the prototype was to have a dihedral of 3° it was intended that this would be increased in subsequent aircraft. To improve the aircraft's ground handling, the Spitfire's outward-retracting undercarriage was replaced with one that was inward-retracting, so that the wheels were further apart. This eliminated a weakness in the original Spitfire design which had made it comparatively difficult to land.

The Air Ministry was impressed by the proposals. In February 1943 it issued Specification F.1/43 for a single-seat fighter with a laminar flow wing; there was also to be provision made for the pilot to have for good visibility, for the wings to fold, to meet possible Fleet Air Arm requirements, for an armament of 4 × cannon, and for the propellers to be contra-rotating. Specification F.1/43 stated that the new fighter was to use a fuselage based on a Spitfire Mk VIII. Three aircraft with contra-rotating propellers were ordered under the specification which was largely experimental to test the wing and a contra-rotating propeller. Supermarine was initially left to decide whether to use a Merlin or Griffon; this was altered to the first two aircraft were to be built with Griffons and the third with a Merlin, all with the contra-rotating propeller. The specification also called for the wing to be used on Mark VIII or Mark 21 Spitfire airframes (with Merlin and Griffon engines respectively) with the expectation that it would be used on production lines from the end of 1944. However, the changes to the wing spar spacing meant the wing would not be a straight replacement. Internally Supermarine identified the wing as the Type 371 which—by extension—was used to refer to the aircraft design as a whole.

Prototype trials

The new wing was fitted to a modified Spitfire XIV (serial NN660)—the specification having been amended by the Air Ministry from its original instruction for a Mk VIII fuselage to be used. The Mk XIV was chosen so that the new wing could be directly compared with the earlier elliptical wing. The aircraft was planned to fly for the first time on 15 March 1944, but delays to the construction of the new wing meant that the aircraft could not be delivered on time.

NN660 was first flown by Supermarine's chief test pilot Jeffrey Quill from Vickers' flight development site at RAF High Post, Wiltshire, on 30 June 1944. Although the new Spitfire's speed performance was comfortably in excess of an unmodified Spitfire XIV, the wing displayed issues at the stall which, although acceptable, did not come up to the high standards of the Spitfire's earlier elliptical wing. NN660 crashed on 13 September 1944 during an improvised low altitude mock-combat with a standard Spitfire XIV. The test pilot Frank Furlong was killed.

The Admiralty expressed an interest in the aircraft for use as a naval fighter and issued specification E.1/45 around it.

Supermarine Seafang

During the mid-1940s there was some uncertainty over whether jet aircraft would be able to operate from the Royal Navy's aircraft carriers so it was decided to develop a naval version of the Spiteful, to specification N.5/45, subsequently named the Seafang. The initial prototype was a converted Spiteful XV (RB520) with an arrestor hook fitted. The first full Seafang prototype was VB895. This was followed by 10 Seafang F.Mk 31, two of which were marked up as further prototypes (VG471 and VG474). The final fully navalised F Mk 32 version differed in that it had folding wingtips, a "sting"-type arrester hook, and two three-blade contra-rotating propellers. However, only the two prototypes (VB893 and VB895) are known to have been completed. With the introduction of the Supermarine Attacker from August 1951, the need for the Seafang disappeared.