The Rolls-Royce Griffon engine was designed in answer to Royal Naval specifications which required an engine capable of generating good power at low altitudes. The concepts for adapting the Spitfire to take the new engine had begun as far back as October 1939; Joseph Smith felt that "The good big 'un will eventually beat the good little 'un." and Ernest Hives of Rolls-Royce thought that the Griffon would be "a second power string for the Spitfire." The first of the Griffon-engined Spitfires flew on 27 November 1941.
Although the Griffon-engined Spitfires were never produced in the large numbers of the Merlin-engined variants they were an important part of the Spitfire family and, in their later versions, kept the Spitfire at the forefront of piston-engined fighter development.
This article describes the Griffon-powered Spitfire variants.
The majority of Spitfires, from the Mk VIII on, used three basic wing types — the C through to the E types. Unless otherwise noted all Griffon-engined Spitfire variants used the strengthened Dunlop AH10019 "four spoke" pattern mainwheels. With the increasing use of hard-surfaced runways in the post-war years many Spitfires were either manufactured, or retro-fitted with, larger mainwheels which were of a "three spoke" pattern. These were used on modified undercarriage legs which had reduced "toe-in' for the axles, which reduced tyre scrub.
Also known as the "Universal wing" the new design was standard on the majority of Spitfires built from mid 1942. This wing was structurally modified to reduce labour and manufacturing time plus it was designed to allow mixed armament options; A type, B type, or four 20 mm Hispano cannon.
The undercarriage mountings were redesigned and the undercarriage doors were bowed in cross section allowing the legs to sit lower in the wells, eliminating the upper-wing blisters over the wheel wells and landing gear pivot points. Stronger undercarriage legs were raked 2 inches (5.08 cm) forward, making the Spitfire more stable on the ground and reducing the likelihood of the aircraft tipping onto its nose. During production of the Mk VIII and Mk IX a new undercarriage leg was introduced which had external v-shaped "scissor-links" fitted to the front of the leg; this also led to small changes in the shape of the undercarriage bay and leg fairings. Several versions of the Spitfire, including Mk XIV and Mk XVIIIs had extra 13 gallon integral fuel tanks in the wing leading edges between the wing-root and the inboard cannon bay.
The Hispano Mk IIs were now belt fed from box magazines allowing for 120 rpg (the "Chattellerault" system). The fairings over the Hispano barrels were shorter and there was usually a short rubber stub covering the outer cannon port. Redesigned upper wing gun bay doors incorporated "teardrop" shaped blisters to clear the cannon feed motors, and the lower wings no longer had the gun bay heating vents outboard of the gunbays. In order to provide room for the belt feed system of the cannon the inner machine gun bays were moved outboard to between ribs 13 and 14. As the Spitfire was no longer to be used as a night fighter, the retractable landing lights were no longer fitted.
These were specifically made for the Photo-Reconnaissance Spitfires, including the PR XIX; no armament was fitted and the "D" shaped leading edges of the wings, ahead of the main spar, were converted into integral fuel tanks, each carrying 66 gallons. To avoid the expansion of fuel in hot weather damaging the wing, pressure relief valves, incorporating small external vent pipes, were fitted near the wing tips.