||Fighter/ Fighter reconnaissance/ Photo reconnaissance.
||27 November 1941 (Mk IV)
||October 1942 (Mk XII)
||Royal Air Force
||Seafire, Spiteful, Seafang
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 Spifire 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.
Structurally unchanged from the C wing. The outer machine gun ports were eliminated, although the outer machine gun bays were retained and their access doors were devoid of empty cartridge case ports and cartridge case deflectors. The inner gun bays allowed for two weapon fits;
- 2 × 20 mm Hispano Mk II cannon with 120 rounds-per-gun (rpg) in the outer bays.
- 2 × .50 cal Browning M2 machine guns, with 250 rpg in the inner bays. With of the relocation of the Hispano to the outer gun bay the blisters covering the feed motors were moved outboard on the gun bay doors.
- 4 × 20 mm Hispano cannon with 120 rpg (this configuration was rarely fitted.)
The 20 mm Hispano cannon were moved outboard and a more effective .50 calibre Browning .50 cal M2/AN heavy machine gun with 250 rpg was added to the inner gun-bay replacing the outer Browning .303s. The first trial installation of the installation (modification 1029) was made in BS118, a Mark XI in November 1943. This armament later became standard for all Spitfire Mk XIVs used by 2 TAF as fighters. The improved armament was more effective for both air-to-air engagements and air-to-ground attacks.
The Mk XII flew operationally with their rounded wingtips replaced by shorter, squared off fairings; the single-stage supercharger of the Griffon II or IV used in the Mk XIIs meant that it was rated and used as a low altitude fighter, and the LF prefix used by Merlin-powered Spitfires was never applied. Starting in early 1945 most Spitfire Mk XIVs also used clipped wingtips, mainly in an effort to reduce wrinkling of the wing's skin; again the LF prefix was not applied to these aircraft.
Redesigned late wing
As the Spitfire gained more power and was able to fly at greater speeds the possibility was that pilots would encounter aileron reversal so the Supermarine design team set about redesigning the wings to counter this possibility. The original wing design had a theoretical aileron reversal speed of 580 mph (930 km/h), which was somewhat lower than that of some contemporary fighters. The new wing of the Spitfire F Mk 21 and its successors was designed to help alleviate this problem; the wing's stiffness was increased by 47%, and a new design of aileron using piano hinges and geared trim tabs meant that the theoretical aileron reversal speed was increased to 825 mph (1,328 km/h).
The standard armament was now four 20mm Hispano IIs or the shorter, lighter Hispano V cannons each with 150 rounds per gun.
The Mark numbers used in the aircraft designations did not necessarily indicate a chronological order; for example, the Mk IX was a stopgap measure brought into production before the Mks VII and VIII. Some Spitfires of one mark or variant may have been modified to another; for example, several of the first Mk VBs were converted from Mk IBs; the first Mk IXs were originally Mk VCs.
Up until the end of 1942, the RAF always used Roman numerals for mark numbers. 1943-1948 was a transition period during which new aircraft entering service were given Arabic numerals for mark numbers but older aircraft retained their Roman numerals. From 1948 onwards, Arabic numerals were used exclusively. Thus, the Spitfire PR Mk XIX became the PR 19 after 1948. This article adopts the convention of using Roman numerals for the Mks I-XIX and Arabic numerals for the Mks 21-24. Type numbers (such as type 361) are the drawing board design numbers allocated by Supermarine.
Mk 22 (type 356)
The Mk 22 was identical to the Mk 21 in all respects except for the cut-back rear fuselage, with the tear-drop canopy, and a more powerful 24 volt electrical system in place of the 12 volt system of all earlier Spitfires. Most of the Mk 22s were built with enlarged tail surfaces, similar to those of the Supermarine Spiteful. A total of 287 Mk 22s were built: 260 at Castle Bromwich and 27 by Supermarine at South Marston.
The Mk 22 was used by only one regular RAF unit, 73 Squadron based on Malta. However 12 squadrons of the Royal Auxiliary Air Force used the variant and continued to do so until March 1951. The Mk 22 was also used at Flying refresher schools. In May 1955 the remaining F.22s were declared obsolete for all RAF purposes and many were sold back to Vickers-Armstrongs for refurbishment and were then sold to the Southern Rhodesian, Egyptian and Syrian Air Forces.
After the destruction of the main Itchen and Woolston works by the Luftwaffe in September 1940, all Supermarine manufactured Spitfires were built in a number of "Shadow Factories"; by the end of the war there were ten main factories and several smaller workshops which built many of the components. A fuller explanation can be found in Supermarine Spitfire. The main Castle Bromwich factory was also aided by a smaller number of the shadow factories. The breakdown of production figures is taken from Air International 1985, p. 187. Information as to when the first production aircraft emerged is from the serial number lists provided in Morgan and Shacklady 2000. Because the first XIVs were converted from existing Mk VIII airframes the first true production serial No. is listed. Protracted development of the Mk 21 meant that this variant did not reach operational service until January 1945.
Production by Mark
|F Mk XII
||First Mk XII 13 October 1942
|F Mk XIV, FR Mk XIV
||First Mk XIV RB142 28 October 1943
|F Mk XVIII
||First Mk XVIII June 1945
|PR Mk XIX
||First Mk XIX RM626 May 1944
|F Mk 21
||First Mk 21 LA187 27 January 1944
|F Mk 22
||Supermarine, Castle Bromwich
||(27) + (260); 287
||First Mk 22 March 1945
|F Mk 24
||First Mk 24 March 1946