The first Griffon-engined prototype was originally designated Mark IV but, as other types were required before it could be fully developed, the aircraft was specified as the Mark XX. Quill has recorded that, in July 1942, he was asked to take part in a comparison test with the new Hawker Typhoon and a captured Fw190. He chose the new Griffon-engined prototype, DP845, which had first flown in the previous November and caused quite a stir: while the Fw190 had to drop back due to engine trouble, Quill was able to leave the leave the Typhoon well behind.
Mark XII (100 Built)
The Mark XII became the first production version of a Griffon-engined Spitfire. It was intended for low-level operation and used the single-stage Griffon III, with clipped wings as standard. It was based on the VC airframe, but had the newer, pointed, broad-chord fin and rudder. Some of the earlier XIIs had fixed tailwheels, but the distinguishing feature of all Griffon-engined types was the engine cowling – now modified with blisters over the cylinder banks of the new engine to leave a trough down the centre of the longer nose to assist the forward view of the pilot. With the new engine and new fin and rudder, the length of the type was now extended to 31ft 10in.
Nevertheless, the Mark XII was an improvised machine with a poor rate of climb because of its single-stage supercharged engine. It was only built in limited numbers and was phased out in September 1945. The Spitfire Mark IX was still the most useful all-round fighter.
Mark XIII
See the photo-reconnaissance section below.
Mark XIV (957 Built)
The Mark XIV was required in order to improve on the high-altitude performance of both the Mark IX and the Mark XII. This was achieved with the fitting of a Griffon 65 engine with two-stage supercharging. The new power unit now made separate high or low-altitude versions unnecessary. Indeed, with the new two-stage engine, it was very successful at low level against the German V1s and was also the main superior high-altitude fighter until the end of the war.
However, the Mark XIV was another interim type, with some directional instability, as with the previous Griffon mark, and so the required fin and rudder area eventually produced the first thorough redesign of these components. The power of the latest Griffon engine now required a five-bladed propeller and the radiators were slightly deeper.
Quill reported that it called for vigilant flying – particularly because, as part of a move towards standardisation, the Griffon engine rotated in the opposite direction from the Merlin and so the swing during take-off was not only more powerful but was now to the right. Also, only slight throttle movements resulted in a dramatic surge of power. Nevertheless, Quill’s first impression of the new machine was expressed in his phrase ‘quantum jump’, for the performance was spectacular: 445mph at 25,000ft and a climb of over 5,000ft per minute.
The new mark was the first Spitfire in the fighter-reconnaissance (FR) category, which signified the use of standard fighters equipped with cameras and operating as fighter-reconnaissance aircraft. It could be equipped with four cannons and could carry bombs, so it could claim to have the best all-round performance of any current fighter apart from range. Later versions had the improved rear-view ‘teardrop’ canopy with the lower fuselage decking.
It was the last substantial production run of any type of Spitfire and the last version to see significant action. The first Mark XIVs were produced in time to take part in the invasion of Europe in June 1944, and one had the distinction of being the first aircraft to shoot down the formidable Messerschmitt Me262 jet fighter.
Many hundreds were sent to assist with the Pacific War, but this ended before many saw active service.
Mark XV
See the Seafire section below.
Mark XVI (1,053 Built)
From September 1944, a version of the Mark IX was produced, powered by the low-rated Merlin 66 built under licence by the Packard Motor Co. of Detroit. It came with the ‘E’ wing and the modified ‘rear-view’ fuselage. Clipped wings were standard as the machine was to be used mainly for ground attack. It had the separate LF XVIE designation.
Mark XVII
See the Seafire section below.
Mark 18 (300 Built)
(NB: from 1943, it became the RAF convention to use Arabic numerals, rather than the Roman numerals used for previous marks.)
The Mark 18 was very similar to the Mark XIV, also powered by the Griffon 65 (later replaced with the 67 version) and it incorporated the later aspects of the Mark XIV, including the rear-view fuselage and retractable tailwheel. The wings, however, were a redesigned unit with a strengthened centre-section and with a wider track undercarriage; fuel capacity was also increased.
As it was produced two years after the Mark XIV, it was too late for wartime service; it did, nevertheless, see action as late as 1951 against Communist forces in Malaya.
Mark 19
See the photo-reconnaissance section, below.
Mark XX
For the Mark XX (so designated because it was proposed before the use of Arabic mark numerals) see the introduction to the Griffon-engined Spitfires above.
Mark 21 (121 Built)
The Mark 21 was similar in many ways to the Mark 18, but the wings were of the extended span type. It was soon supplied with the first completely revised wing in which the familiar Mitchell outline was significantly altered – with half-rounded tips, and redesigned and larger ailerons.
RAF test pilots did not consider it an improvement on the Mark XIV as an all-round machine and advised that ‘no further attempt should be made to perpetuate the Spitfire family’. On the other hand, Quill found the new mark to have ‘a tremendous lightness of control’ and ‘revelled in aerobatics at speeds that would have been impossible before’. The major redesign work involved had been put in hand by 1942 but this mark was only operational at the end of 1944. It was not produced in large numbers because the war ended soon after its production began.
Mark 22 (268 Built)
The Mark 22 was also completed very late – in 1945 – and its development from the Mark 21 was so seamless that no prototype, as such, was necessary. The main difference between the two variants was the increased fuel capacity of the later mark.
While the Mark 21 still retained the balloon type of cockpit hood and its associated rear fuselage decking, the later machine was equipped from the outset with a final rear-view fuselage and canopy configuration. A redesigned wing and tailplane was fitted and a fourth type of fin.
Mark 23
The Mark 23 was never built.
Mark 24 (74 Built)
Given the revised wing and tail planforms and increased fuel capacity, the resultant manoeuvrability and increased range made the Mark 24 the ‘ultimate Spitfire’, and showed how far it had been possible to develop Mitchell’s prototype of 1936. One does, however, tend to agree with Quill: ‘The genius passed on by Mitchell had died. The beautiful symmetry had gone; in its place stood a powerful, almost ugly fighting machine.’
This final Spitfire came off the production line in February 1948.
Photo-Reconnaissance Spitfires
As with the naval Seafire (see below), the photo-reconnaissance version had never been envisaged by Mitchell, although the ‘Speed Spitfire’, a modified Mark I which failed to establish a new speed record, set the pattern for highly polished and unarmed Spitfires being developed for the reconnaissance role.
Various rather ad hoc camera placings, usually under the wings, and different fuel tankage arrangements were indicated by designations PR IB to PR IG, with the D long-range version becoming developed as the PR IV, which was the mainstay of the RAF Reconnaissance Unit until 1941, and 229 were built.
PR VI (6 Built)
The PR VI was a special conversion of Mark VI fighters sent to the Middle East in 1942 for PR work.
PR VII
See PR IG, which was used for low-level work and so retained its armour.
PR Mark X (16 Built)
The PR Mark X saw the use of the new, more powerful
Merlin 61 for PR work, with the usual bulletproof windscreen deleted in favour of a plain, curved one. This, in combination with wing leading edges without gun ports, gave an increase of 5mph in speed over a standard Mark IX fighter. The Mark XI appeared before the PR Mark X as the latter had a pressurised cockpit and this involved a longer developmental period.
PR Mark XI (471 Built)
The PR Mark XI had the fuselage camera installations of the long-range PR Mark IV, later augmented by a camera fitted in a blister under each wing, just outboard of the wheel well. As this long-range mark was also fully tropicalised, it not only served in Europe but was also employed in the Middle East and the Pacific. As a result, it was the main PR variant of the Second World War and could be regarded as the most effective RAF photo-reconnaissance aircraft.
It achieved the highest wartime speed of any Spitfire when being tested at Farnborough. On 27 April 1944, Squadron Leader ‘Marty’ Martindale dived from 40,500ft to a speed of 606mph (Mach 0.89) before the engine blew up. He glided safely back to the airfield, despite almost no forward vision owing to a heavily oiled windscreen.
PR Mark XIII (26 Built)
The PR Mark XIII signified an advance on the PRVII low-level reconnaissance aircraft and was, essentially, a Mark V fitted with a special low-altitude rated Merlin 32 and a 30 gallon drop tank. It appeared in 1943 – by which time standard fighters were also being equipped, additionally, with cameras and operated as fighter-reconnaissance (FR) aircraft.
PR Mark 19 (225 Built)
The PR Mark 19 was the only Griffon-powered PR variant. The Griffon 65 was later replaced by the Griffon 66, and the aircraft had a pressurised cockpit, now that cruising at increased height was possible. The leading-edge fuel tanks were increased by 20 gallons on each side, giving a total internal petrol capacity of 256 gallons, often supplemented by a 90 or 170 gallon drop tank.
This airframe, which was produced in May 1944, and, with the full advantage of the Griffon engine, resulted in one of the most outstanding of all the Spitfire variants. With a top speed of 460mph, it was one of the fastest piston-engined aircraft of all time and could cruise at 370mph and at 40,000ft, beyond the reach even of the German jets at the end of the war – or, indeed, beyond the reach of any jet until the early 1950s. Flight Lieutenant E.C. Powles claimed a climb to 51,550ft and an emergency dive, when his cabin pressurisation failed, to a speed of Mach 0.96 (NB: not with a machine fitted with a later revised wing, but with the last mark to embody the classic elliptical wing of Mitchell’s original design).
It was produced in time for the closing stages of the war in Europe and saw limited service in the Pacific and Far Eastern areas. In 1957, a Meteorological Flight of Mark 19s was finally phased out.
The Seafires
At the beginning of the war, naval aviation was underdeveloped – attributed, by C.G. Grey, to the senior Admirals being ‘definitely anti-air-minded’ and being ‘solid ivory from the jaws up, except for a little hole from ear to ear to let useful knowledge go in and out’. And he attributed the sinking of the Prince of Wales and the Repulse off the coast of Malaya and the prolonged hunting of the Bismarck, Scharnhorst and Prinz Eugen to lack of effective naval aircraft.
The navy’s first all-metal monoplanes were the relatively slow Blackburn Skua dive-bomber, and the even slower Roc. The later Fairey Fulmar was far too large and unwieldy when it came up against the new single-seat opposition now based on the other side of the Channel, and so the Admiralty had requested a navalised version of both the Spitfire and the Hurricane.
Some sixty Hurricanes were put into service as a stopgap but, by mid-1942, mounting losses made it urgent that Spitfires should be finally employed. So it came about that the first Seafires were basically Spitfire Vs fitted with arrester hooks and, because they were fitted with the B wing, were designated Seafire IB and IIB.
The Mark II was also equipped for catapult launching and, because of the harsher nature of seaborne landings, was now given a strengthened undercarriage. The designation Seafire IIC signaled the fitting of the ‘universal’ wing to this version, followed by FR IIC which signified the installation of cameras. This aircraft entered service in June, 1942, and its first action was in support of Albacore bombers during Operation Torch. (In total, 372 Seafires I and II were produced.)
Seafire Mark III (1,250 Built)
The Seafire Mark III (not to be confused with the Spitfire III prototype) saw the introduction of folding wings, which allowed its use on a wider variety of vessels. Because of the extensive modification required to the wings, the Mark III did not become operational until late 1943 and it was still in service at the end of the war with Japan.
Seafire Mark XV (390 Built)
The Seafire Mark XV was the first naval version to be equipped with the Griffon engine and was basically a Seafire Mark III airframe with manually operated folding wings, a Spitfire Mark VIII tail and retractable tailwheel, and on later aircraft, a newly designed spring-loaded ‘sting’ deck arrester hook, involving a modification to the rudder. It finally began appearing in September 1944.
Seafire Mark XVII (233 Built)
The Seafire Mark XVII was the first naval type with the later cut down fuselage and rear-view canopy, and it now had a curved windscreen and was equipped for rocket-assisted take-offs. With the previous folding wing arrangement retained, but with a strengthened main spar and long-stroke undercarriage, this mark can therefore be regarded as the first dedicated carrier-Spitfire.
It began to appear in September 1945, four years after the first improvised naval versions but too late for wartime service. However, it did gave the navy its first 400mph machine.
Seafire Mark 45 (51 Built)
The Seafire Mark 45 appeared soon after the Mark XVII, despite its much higher mark number – which had been allocated to allow for future Spitfires which were, in fact, never produced. It was 45mph faster than the previous type, but its more powerful Griffon 61 engine produced a swing on take-off which was not exactly ideal for carrier operation. Some later aircraft were fitted with contra-rotating airscrews which, together with an increase in rudder area, made a considerable improvement.
Seafire Mark 46 (25 Built)
The above modifications, with a tail destined for the future Spiteful fighter, constituted the Mark 46 although it did not have folding wings, as there had not been time to develop such an arrangement for the new type of wing of the Spitfire Mark 21 on which it was based.
Seafire Mark 47 (90 Built)
The Seafire 47 combined the improvements of Marks 45 and 46, and was also finally equipped with a powered wing-folding geometry. The air intake filter was now faired into the lower engine cowling, with the duct opening positioned just behind contra-rotating propellers. Combined with a top speed of 452mph, it can be seen as the most comprehensive naval revision of the Spitfire land plane and an impressive illustration of how far it had been possible to develop Mitchell’s original conception. It saw service in the Korean War.
(N.B. On the website www.airhistory.org.uk/spitfire/home.html (accessed 24.11.14), the author admits that it will probably never be possible to give a definitive listing, ‘owing to errors and omissions in official records’. Thus even his impressive record of the serial numbers and service history of every machine identified cannot guarantee the number of various makes are entirely accurate.)
APPENDIX 3
SUPERMARINE WOODEN HULLS
One of the fortuitous circumstances in R.J. Mitchell’s career was joining a firm which had experience of a method of flying boat hull construction of considerable potential, while wooden hulls were in vogue.
It is perhaps necessary to give some detail of this technique of sophisticated marine know-how which was so important in the early career of the young chief designer from the landlocked Potteries and from a background in locomotive engineering. However, an adequate account was considered to be too detailed for inclusion in the main body of this book and so it is given here. A further reason fo
r the inclusion of this detail is that visitors to the RAF Museum at Hendon may appreciate better this early technique, as exemplified in the splendidly restored Supermarine Southampton hull (see photograph overleaf).
As described in Chapter 1, the workforce of the Pemberton-Billing firm were largely ‘Kemp boatyard men’ and that his PBI hull was ‘of round construction, built by small boat methods, with closely spaced wooden ribs of half inch square section like girl’s hoops, joined by longitudinal stringers and covered by two layers of mahogany or cedar wood planking, laid so that the outside layer was sloping the opposite way to the inner layer’. There was a layer of doped fabric between, and the whole was fastened by brass screws or copper nails.
With the outbreak of the First World War, an Admiralty design team had joined the yacht designer, Linton Hope, at Woolston to further develop flying boat hull construction and so the basic structure with which Supermarine afterwards continued was established.
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