Mk. Ia / Ib
In 1939, when the outbreak of World War II was coming closer, it was evident that the fixed pitch 2-blade propeller was far from being a good
solution if the German fighters should be dealt with in a satisfactory manor. This type of propeller was a compromise between a "climb"
propeller and a "cruise" propeller. DeHavilland made a new 3 blade propeller with 2 settings on the blades, so that the power of the engine
could be optimized during cruise, however, climb-performance was reduced - 2,175 ft/min against 2,530 ft/min. This new propeller was inferior
to the contemporary German and Japanese propellers, however, it was a step in the right direction. This propeller became standard equipment.
DeHavilland changed the propellers on the aircraft that were already operational. Rotol (now Messier Dowty) was developing a constant speed
propeller, which really solved the problem. In March 1940, when this propeller was fitted to a Spitfire Mk. I, N3171, things started to
happen: a best climb of 2,905 ft/min. The change to the Rotol propeller was carried out during the Battle of Britain.
When the war broke out it was a Spitfire from 602 sq., which shot down the first enemy aircraft on the 16th October 1939, when a formation
of Junkers JU88's attacked a convoy at Firth of Forth.
Soon, during the aerial combats, problems with frozen weapons occurred. This problem was partly solved by taping the muzzles of the
machineguns and letting the first round remove the tape.
At the beginning the armament with which the Spit was born proved quite effective, however, the Germans quickly found methods of countering
the hailstorm, which the 8 0.303" guns made. The Germans added armour covering the vital areas around the engines and the pilots, fitted
self-sealing and fire retarding fuel tanks. Thus it became harder for the British fighter aircraft to shoot down a German opponent without
having to shoot at the enemy for a long time. The obvious solution was to fit more powerful weapons to the fighters. No one had experience
with large calibre machineguns on aircraft; it was only tested during WW I. The Germans had fitted a 20mm Oerlikon machinegun to the
Messerschmitt Bf109. RAF chose the 20mm Hispano cannon, which was fitted to a modified wing of a Spitfire. During trials a Supermarine
ran into a lot of problems feeding the cannon. It turned out that the wings flexed so much due to the high "G's", which was pulled during
simulated combat, that a shell could get stuck in the in the feeding system and thus caused the cannon to cease firing. Stiffening the main
spars of the wings solved this problem. Fortunately this modification had no influence on the performance and characteristics of the Spitfire.
In November 1940 19 sq. took delivery of modified Spitfires with 20mm cannons and these passed the practical test when Flt/lt Lawson hit a
Bf109 during combat: the German aircraft broke apart in mid-air. This modified model was designated as Mk. Ib.
The vision through the windshield was not too good. The glass, which was used, created optical twisting and thus made it hard to spot the
enemy in good time. From 1941 an other material and design of the windshield was chosen to offer the pilots a better chance to survive....
the pilots were always told that "it is the enemy that you don't see that gets you".
The performance and characteristics of the Spit had always been praised, however, one major complaint had always existed: at speeds exceeding
350 mph (560 km/h) the ailerons became heavy and not too responsive. At high speeds the pilot had to use both hands to operate the ailerons.
This was a big problem because it was hard to manoeuvre the Spit behind an enemy fighter and shoot it down that way. It was determined that
the fabric covered ailerons lost around 65 percent of their effectivity at these speeds. Several solutions were tested but none of them solved
this problem and Supermarine almost gave up cracking this nut, but when a set of all-metal ailerons were tested the Spitfire flew like it had
been reborn. The squadrons were very anxious to replace the old ailerons with the new. Later it turned out that the Bf109 also suffered from
heavy ailerons - even worse than the Spit.
Several versions were built for photo recognisance flights above hostile areas. Those are:
The "original" photo recognisance version. It was fitted with a camera with a 5" lens in each wing. This aircraft did not have larger fuel
capacity than the normal versions.
Had larger cameras and carried an additional 29 gallons (132 litres) of fuel
Was like PR IB but had cameras mounted in a box fitted under starboard wing. It carried 29 gallons of extra fuel in the fuselage and 30 gallons
in an external fuel tank under port wing.
Was the first Spitfire model specifically built for photo recognisance. It carried 2 cameras in the rear fuselage and 114 gallons (518 litres)
of additional fuel in tanks in the leading edges. It also carried the 29 gallons of fuel in the rear fuselage. The PR ID replaced earlier PR I
variants. Later when it was fitted with a Merlin 46 it was re-designated as the PR 5D and then PR IV, which is not to be confused with the Mk. IV.
Only 1 example was built, and was used for low altitude recognisance duties. 1 camera in each wing pointed to the right seen in direction of flight.
It carried 29 gallons of extra fuel in the rear fuselage.
Also had 2 cameras fitted in the rear fuselage together with a 29 gallons fuel tank. An external fuel tank under each wing contained 30 gallons each.
Was also built for low altitude recognisance duties. I carried a camera, which could point either to the right or the left side. 2 cameras in the rear
fuselage pointed down. It also carried a 29 gallons fuel tank in the rear fuselage.
This variant had nothing do with the later "C"-wing, but was built for Air/Sea Rescue Operations. The pilot could jettison a dinghy and supplies of
water and food in order to help a pilot who ended up in the Channel.
The Mk II was actually a Mk. I fitted with a new Merlin XII engine, which was built to take a higher compressor boost at take-off and had a
higher output at altitudes below 17,000 ft by using 100-octane fuel instead of 80-octane. The Merlin XII was equipped with a Coffman cartridge
starter and a 3-blade Rotol constant-speed propeller. (Cartridge-starter: a push on the starter button fires a cartridge, which makes a wheel
turn. At max. rev's the wheel was engaged to the engine which it made turn.) As something new the Mk II had an armour plate fitted behind the
pilot. The Mk II was built at the new "shadow factory" at Castle Bromwich. A Spitfire built there can be recognised by a more pointed spinner.
Improving current Spitfire variants was very important; a change in production to new variants was demanding and caused halt in the production,
whereas modifications and improvements could easily be implemented while production was running.
The Mk I had the problem that the elevators were too easy to operate causing that the pilot risked either a "red-out" or "black-out". In order
to rectify this problem, a counter weight was added so that the pilot had to use more muscle power to operate the elevators.
Mk IIA (L.R.) - Long Range.
This was a Mk. IIA variant with extended fuel capacity, which gave it better endurance. One hundred of this variant were built.
Although never built as a production variant this mark became one of the important ones.
The Mk. III was a prototype built on a strengthened Mk. I/II airframe and was fitted with a Merlin XX engine. Its wing tips had been removed in
order to improve the roll-rate and flight at low level. Though the Mk III never went into mass production many of the improvements made to this
variant were used on the later Mk. VC (which again was the basis of the Mk. VII, VIII and IX and XIV). Mk. III had a retractable tailwheel, which
was introduced on the Mk. VII.
In 1941 Mk. III, serial no. N3297, was fitted with the new Merlin RM6SM, which was later to become known as the Merlin 60-series. It was also fitted
with a 4-blade Rotol propeller and served as a flying test bed. Late in 1942 N3297 was worn out and started to fall apart; the airframe was not strong
enough to handle all the tests and the Merlin 61 engine.
One single aircraft, which was built as a Mk. III was converted to accept the more powerful Rolls-Royce Griffon IIB engine. It was designated as the
Mk. IV. This prototype flew for the first time in 1941. Mk. IV is not to be confused with the PR IV.
An amusing story is connected to this model. A mentioned earlier Joe Smith at an early stage wanted to test the new Griffon engine in a Spitfire.
It was at Supermarine's own risk when DP845, which was the number of the first of the 2 Mk. IVs built, flew for the first time. At that time it
had been established that the Spitfire Mk. V was no match to the Focke-Wulf 190 or the Bf109F. Hawker had developed their new Typhoon, which was
regarded as the fighter of tomorrow. An air-race between a captured FW190A and a Typhoon was arranged. To participate as a reference aircraft -
and expected looser - Supermarine was asked to provide a Spitfire. Test pilot Jeffrey Quill, who should fly the Spitfire at this race, got the
idea that he could fly DP845, because no one had told him in which Spitfire model he should race. Joe Smith loved the idea. Then the 3 pilots
arrived with their aircraft and it was decided that would fly in formation to a certain spot and turn back and race towards the finish line at
Farnborough, where the VIPs expected to see the Typhoon beat the FW190 and the Spitfire as the hopeless number 3. When the race started the 3
aircraft raced at low altitude towards the finish and Quill unleashed all the power of DP845 and quickly put both the opponents behind him and
won the race with a big margin. This came as a total surprise for the furious VIPs, however, the result spoke for itself and an order for a 100
of this variant designated as the Mk. XII.
Thus the future of the Spitfire was "saved", because the authorities believed that the Spitfire had been developed to its limits.
As mentioned earlier the PR IV is a version derived from Mk. PR ID. It was modified in a way so that it shared the same airframe as the Mk. V.
The PR IV was fitted with a Merlin 46 engine and a 3-blade constant-speed propeller. Later PR IV's were fitted with Merlin 50, 50A, 55 or 56.
It also had about 120 gallons of increased fuel capacity. From 1940 to 1943 230 Mk. I/II were built as or converted to PR IV, which was the
back-bone of the PR-units (Photo Recognisance) for a long period of time until the PR IV was replaced by the Mk. X, XI and XIX.
The first Mk. V was only an updated version of the Mk I/IIA and it was designated Mk. VA. The Mk. VA was still equipped with 8 0.303” machineguns.
The biggest change on the Mk. VA compared to the Mk. I/II was the change from the Merlin III and XII to the new Merlin 45. A modified supercharger
increased the output to 1,470 hp, which improved the the performance of the Mk. VA compared to Mk I/II.
The Mk. VB was also a descendant from the Mk. I/IIB with revised wings which were fitted with 2 20mm canons and 4 0.303” machineguns. The engine
was also a Merlin 45. Except from the armament there were not many changes from VA to VB. The Mk. VB was the most commonly used Spitfire Mk V in
the European theatre. The Mk. VC was the ultimate Mk. V. It had taken around 90,000 man-hours to design the Mk. V, especially the C version. Thicker
skin further strengthened the airframe. The Mk VC was equipped with a new type of “universal” wing, which could house different kinds of armament:
- 8 0.303” machineguns (like the previous marks)
- 2 20mm cannons and 4 0.303” machineguns
- 2 20mm cannons and 2 ½” (12.7mm) machineguns (on later marks)
- 4 20mm cannons
On the 20mm cannon equipped versions the old problem with frozen guns re-occurred. It was no longer enough to heat the weapons with warm air from the
radiator. The system was changed so that additional warm air from the exhaust was led through the pipes down to the weapons. Tests with 2 ½” guns
combined with the 20mm cannons showed the need for further strengthening of the wings. This led to the universal “E”-wing, which was used on later
versions of the Spitfire.
Another old problem was solved on Mk. VC: the negative G-force cutting the engine. Every time a Spitfire chased an enemy aircraft, which went into
a dive by pushing forward the stick, the Spitfire had problems with engine cutouts and consequent power and speed loss. The negative G’s pressed the
floats in the carburettor to top of their housing and thereby cut off the fuel and thus starving the engine and after that overdosing the engine
with fuel and cause suffocation. So far the Spitfire pilots had to make a half roll before starting the dive. This slowed down the Spitfire during
combat. Therefore a Bf109 could with relative ease dive away from a Spitfire, because the Daimler-Benz engine used in the Bf109 was fitted with
fuel-injection. Many attempts were done to overcome this problem. The best solution to this problem was to fit a restrictor into the fuel line
ensuring that the engine never got more fuel than it could “eat”. It worked quite well, but the problem was not solved until a standard SU AVT40
float carburettor was modified by removing the floats and replacing them with a diaphragm unit. This came as an unpleasant surprise for many German
pilots when they discovered that their old manoeuvre did not work any more. The engines fitted with the the new type of carburettor was designated
as the Merlin 50-series. A Bendix Stromberg injector-carburettor was also tested, however, it increased the fuel consumption at high altitude without
being better than the AVT 40. Later Mk. V’s used an SU injector-carburettor that - depending of the altitude - increased the top speed by 5 mph
(8 km/h) and up to 15 mph (25 km/h) compared to AVT 40 carburetted Spits. Changes on small details on the Spit led to improved performance. It was
determined that by giving better finish especially to the leading edges and certain areas of the fuselage, the top speed could be increased by
6 mph (10 km/h), polishing another 2-3 mph (4 km/h), changed design of the exhaust pipes 6-7 mph (11 km/h), a streamlined rear-view mirror 2-3 mph.
By moving the windscreen armour from the outside to inside of the cockpit another couple of mph were gained. Measuring the efficiency of the
propeller led to modifications, which improved the propeller with approximately 3 percent thus adding 5 mph. All in all the top speed could be
increased by 30 mph which were good if you were in a bad situation or trying to catch up with an enemy fighter.
The Mk. V had performed adequately to match the fighters, which the Luftwaffe had in service so far. The Spitfire had no problems with the Bf109,
which was the most common Luftwaffe fighter, however, in late September 1941 things started to go wrong. A Polish RAF pilot reported seeing a new
German fighter fitted with a radial engine. This turned out to be the Focke-Wulf 190A, which became operational during the following winter. RAF
soon discovered that this was a fighter which any aspect out-classed Fighter Commands best fighter, the Spitfire Mk. V.
In June 1942 RAF got hold of an airworthy FW190. It was tested compared with a Mk. VB from an operational squadron and the results were not encouraging
for the Spitfire. At all altitudes from 0 to 25,000 feet, the FW190 was superior in speed - between 18 mph and 40 mph faster depending on the altitude.
The FW190’s rate of climb was 450 ft/min (140 m/min) better. If you during flight at a high cruise speed started to climb, the difference between
the 2 aircraft was even bigger. When it came to manoeuvrability the FW190 was also superior to the Mk. V except when flying in tight circles. The
conclusion was that if a Spitfire pilot should survive flying over enemy territory, where FW190 could be expected or if the Spitfire-pilot spotted
an attacking FW190, he should firewall the throttle and go into a shallow dive. That way he had the best chance of keeping the FW190 behind him
until he got home or to a safer part of the sky. The Spitfire pilot should never attempt escaping by going into a steep dive; then he would be easy pray.
To compensate for the Spitfires inability to match the FW190, Supermarine cut of a couple of feet of both wing of a Mk. V by removing the wing tips.
Supermarine hoped to make it roll, climb and fly faster. Short wooden wing tips replaced the normal tips. This clip-tip Mk. V rolled faster due to
less inertia of the wings, the speed was improved by 15 mph (25 km/h) but the climb was not improved and the stall speed was increased by 3-4 mph
(5-7 km/h) - the aircraft stalled earlier then the normal Mk. V.
It was also determined that the drag was higher during hard manoeuvring. This version was used for operation in medium altitudes and models with
normal wings in high altitudes. As a vitamin supplement at high altitude operation the Merlin 46 engine was introduced. It gave the best performance
at 14,000ft (4.300m) instead of at 9,250ft (2.820m). With a Merlin 46 fitted the top speed was increased by 6mph at 28,000ft (9.200m).
As a result of this variants of a Mark were built: the LF (low fighter), F (fighter for medium altitudes) (and HF (high fighter) which was introduced
with the Mk. VIII). These variants could have different wing tips and different engines. The Germans used an other philosophy, however, they had 2
equally good aircraft, the Bf109F and FW190. The former took care of work at high altitude and the ladder at medium altitude.
Together with the LF Mk. V came a new term: “The clipped, cropped and clapped Spitty”. The LF Mk. V had “clipped” wings and a Merlin 45M, 50M or 55M
with "cropped" impellers in the supercharger, which allowed operated at a higher boost - +18psi against the normal +12psi - when running at max.
boost. (I.e. the blades in the centrifugal compressor had been cut in order to avoid a compressor stall because the compressor delivered a higher
boost than normal at higher compressor speed.) The "clapping" was pure irony: the LF V's were often old airframes with engines, which had done many
hours of flight. The pilots, who flew this version, were not happy carrying out this sort of operation in such old aircraft. The LF Mk. V had a
10mph higher top speed at altitudes below 4,000 to 5,000ft (1.300-1.700 m) and could climb 700 ft/min faster at these altitudes, however, its
performance decreased rapidly as the aircraft climbed. Equipped with a 250lbs or 500lbs bombs the LF Mk. V was used as a fighter-bomber for low
The Mk. V C was the first model to be equipped with a larger radiator and a better air filter, which enabled it to operate in a warm and dusty
climate such as on Malta and North Africa. The air filter with which the Spits operating in North Africa was fitted, was manufactured by the
company Vokes, and some modification to the air intake were required, because this filter was bigger than the standard one. The Vokes filter thus
created more drag. In North Africa 103. Maintenance Unit at Aboukir changed the system and invented an air filter, which was much smaller and would
fit into a slightly enlarged standard air filter housing. This homemade and unauthorised solution became the basis of air filters on later Spitfire
The German high altitude recognisance aircraft, Junckers Ju 86, was equipped with a pressure cabin and was able to operate at altitudes, which no
available Spitfire could reach. These Ju 86 aircraft could unapproached take pictures and carry out recces over and behind the British lines.
The people at 103. M.U. once again went into action. A Mk. VC was stripped of all equipment except for 2 machine-guns. The compression ratio of
its Merlin 46 engine was increased by hand, the Aboukir air filter housing was modified so that a larger oil tank could be fitted, home made
extended wing tips were fitted and a 4-blade deHavilland propeller was fitted. One day in this special Spitfire, in more than 50,000ft (15.5km)
and without pressure cabin an almost 40 years old English fighter pilot pursued one of the Ju86 aircraft. Troubled by the “bends” (decompression sickness),
which caused temporarily paralysation, with iced windshield and frozen controls he manoeuvred up behind the German JU86 and shot it down. On the back
to the base he could enjoy the view - from Syria to Benghazi and from the Aegean Sea and down the Suez Canal. About this special Spitfire no technical
data is available. The Mk. V was a flying test bench where different types of external fuel tanks and jettisonable hoods were tested - things that
were used on later variants.
From 1943 the Mk. V was withdrawn from front-line service in Europe, and later Marks took over its part, however, it remained in front-line service
in Asia until the end of the war.
Mk. VB as seaplane
One Mk with floats was made for use in areas where there were no airfields. It was fitted with a Merlin 45 engine, a 4-blade Rotol propeller
and an enlarged vertical stabiliser. An anti-spin parachute fitted at the rear of the fuselage could bring the aircraft out of an unpleasant situation.
A Mk. V was adopted by the Royal Navy and re-named "Seafire". Please see below.
All in all the Mk. V (A, B and C) was one of the 3 most important Marks of the Spitfire with a total of 6,479 aircraft built.
Mk. VI (PR VI).
The Bf109s ability to fly higher than the Spitfire I, II and V together with the highflying pressurised recognisance aircraft, which the Germans
sent over the British Isles proved the need of a fighter aircraft capable of operation at 40,000ft + (more than 13 km). It would take a pressure
cabin to secure the pilot tolerable working conditions. The Spitfire was chosen because of the strength of its airframe. A Mk. V was fitted with
a Merlin 47 engine, a 4-blade propeller with a diameter of approx. 11.5 ft (3,5m) and a Marshall cabin blower (compressor, which pressurised the
cockpit equal to an altitude of 28,000 - 30,000 feet. In order to make the cockpit airtight the Mk. VI was fitted with a pressure bulkhead placed
behind the pilots armour plate, rivet holes and joint were sealed with rubber material and an inflatable rubber seal was fitted around the hood.
Extended wingtips increased the lift and reduced vortex.
Mk. VI had a ceiling of 40,500ft and a top speed of 350mph (560 km/h). The problem with the Mk. VI was that it did not have a sliding hood like
all other models; it was bolted on to the aircraft when the pilot was strapped in prior to starting, however, the the pilot could jettison the
hood in emergency. A sliding hood was tested on the Mk. VI; however, it was not introduced until the Mk. VII.
Mk. VII (PR VII og FR VII).
Mk. VII had its roots in the Mk. VI and was the first proper high-altitude interceptor. This model flew for the first time in April 1942 and
140 of them were built. It was equipped with the new 1,565hp Merlin 61 engine with 2-stage compressor and a 4-blade propeller. It was also
built as F VII with a Merlin 64 and a HF VII with a Merlin 71 engine both with an output of 1,650hp. The F and HF were capable of a top
speed of 407 mph (652 km/h). The new Merlin 60-series needed more cooling than the earlier single-stage Merlins. Therefore 2 symmetrical
radiator housings were placed under the wings. Starboard housing contained a radiator element for the engine coolant and an element for the
intercooler (see the chapter "Engines"). Port housing also contained a radiator element for engine coolant and an oil cooler. This together
with the heavier engine increased the weight in front of the centre of gravity and in order to compensate for this the vertical stabiliser
was made a bit longer and the rudder was larger. The wing spar and the undercarriage were strengthened.
Behind the outlet of the cabin blower the tubing parted in 2 so that one tube led to the cockpit and the other tube to a hose, which was
connected to the inflatable rubber seal, which sealed and made the hood airtight. The windshield, the hood and the window behind the pilot
were double glassed. There was air between the 2 layers of glass and in order to prevent mist, a small hose interconnected the 3 units. A
small container was filled with moisture absorbing crystals. These crystals were blue but when they had absorbed moisture they turned pink.
After each flight the ground crew could check the crystals and replace them if needed.
The fighter and recognisance version FR VII had its roots in the PR IV and was equipped with a Merlin 45 or 46 and was armed with 8 0.303”
machineguns. 16 of these were later converted to the low-level model PR XIII fitted with a Merlin 32 engine.
This model, which Jeffrey Quill thought was best Merlin-powered Spitfire, had incorporated all the modifications from the Mk. VII; however,
it did not have a pressure cabin and was therefore used for operation at medium and low altitude. 1,658 were built in 3 variants all with
retractable tail wheel. The F VIII had standard “C” wings and a Merlin 61, 63 or 63A, the HF VIII had “C” wings and a Merlin 70 and finally
the LF VIII had clipped wings and a Merlin 66. The HF and LF versions were both capable of a top speed of 416mph (665 km/h). The Mk. VIII,
which was introduced at a later stage then the Mk. IX, was operational in August 1943. The Mk. VIII was also built with “E” wings (see under Mk. IX).
The Mk. VIII had also internal extra fuel tanks in the roots of the wing. This gave it a longer range. Mk. VIIIs only served with squadrons
that were stationed outside England.
As earlier mentioned when the Germans introduced the FW190 in 1941 the Mk. V was not doing well and Supermarine was planning to develop a radically
changed version of the Spitfire. Since both Mk. VII and VIII still were not ready, an interim version was developed. The airframe was a Mk. VC,
which was adapted to a Merlin 60 engine, which had been developed for a bomber aircraft, the Vickers Wellington VI. The Merlin 61, which the engine
was called after the necessary modifications had been carried out, had the new 2-stage compressor, which boosted the max. output to 1,600hp.
The Merlin 61 had an output of 1,020hp at 30,000ft where the Merlin 46 only was capable of 720hp, which is almost a 42 pct. increase. When 19,000ft
was reached, the compressor was automatically switched to High Blow and that gave a considerable kick in the back. The top speed was around 412mph
(660 km/h), the best climb was 3,950ft/min. (1.306m/min) and from 0-20,000ft (6.600m) 6 min. and 15 sec. (LF Mk. IXE). This turned the Mk. IX into
a much different aircraft than the Mk. V. However, due to the new 2-stage compressor the Merlin 61 was somewhat thirsty, which reduced the aircrafts
range. Therefore it was necessary to increase the fuel capacity; on late Mk. IX's an extra fuel tank was fitted behind the pilot. However, this
caused the centre of gravity to move and gave the Spitfire longitudinal instability. At speeds above 144mph (230 km/h) the Spitfire became increasingly
unstable and as the speed increased it demanded constant work with the controls to keep it flying in a straight line because it could not be
trimmed sufficiently. After some time when the new rear tank was half empty, the Spitfire started to behave normally again. Therefore a Spitfire
could not engage in combat before that; it was recommended that this fuel tank should be completely empty before any combat.
The Mk. IX was built in 4 variants. Variant Mk. IXA, which had nothing to do with the "A"-wing, got the official designation F Mk. IXC, which was
the original Mk. IX with Merlin 61 or 63 engine. The next variant was Mk IXB, which also did not have anything to do with the "B"-wing, was officially
designated as the LF Mk. IXC and was fitted with a Merlin 66. "LF" had in this case nothing to do with clipped wings, but only referred to the tuning
of the engine. The compressor cut in at a lower altitude than on the "F"-variant and gave its maximum output at 22,000 ft / 6,710 meters in order to
match the FW190. Later the HF Mk. IXC, which was fitted with a Merlin 70, came about. This engine was tuned for high altitude operation. In 1944 a
small number of Mk. IX were modified to the variant FR IX, which was fitted with a camera - a few of these were stripped of weapons and armour.
In the fall of 1944 the Spitfire was modified with the new "E"-wing. The model was also equipped with the new Mk. II gyro gun sight, which made
deflection shooting much more efficient.
The first Mk. IXs from S/N MH312 and on had the rounded tail and "C" wings and later S/Nos. from HNxxx had "E" wings. S/Nos. RK833 and on furthermore
got the pointed rudder, which the Mk. VIII got later. S/Nos. from TD175 through TE343 were built with low back and teardrop hood (see the picture of
the low back Mk. XIV). The low back was introduced in February 1945. As mentioned the "C" wing was later replaced by "E" wing on which the 2 0.303"
guns (2 in each wing) had been replaced by 1 ½" (12,7mm) gun which was placed on the inside of the 20mm canon.
The earlier mentioned improvement in performance closed the gap between the Spitfire and FW190. However, the initial tests of the Mk IX had proved
that the Mk. IX still could not follow the FW190 before Rolls-Royce had their hands on the Merlin 61 once more. It was necessary to increase the boost
from +12psi to +15psi. Then the 2 fighters had almost identical performance. At level flight the 2 fighters depending of the altitude changed to be
5-6 mph quicker that the other. Generally the Spitfire was quicker but only marginally. During climb up to 22,000ft the Mk. IX was a little faster,
, above 22,000ft the Mk. IX climbed away from the FW190. The FW190 could still dive away from the Mk. IX but not as easy compared to Mk. V. The FW190
had better manoeuvrability than the Mk. IX, but flying in curves the Mk. IX could still turn sharper. An FW190 could get away from an attack from a
Spitfire by turning, then rolling to the opposite and dive away in a turn to the opposite direction. The FW190 still accelerated better than the
Mk. IX and therefore the Spitfire pilot had to keep his aircraft at high speed and avoid altitudes between 18,000ft and 22,000ft (5500/6700m) where
the FW190 had a small advantage over the Mk. IX. In real life it was the best pilot who came out on top.
The first Mk IXs became operational at 64 squadron in July 1942. In the beginning many German pilots mistook the Mk. IX for a Mk. V because they looked
much alike, except for the slightly longer nose, because the Merlin 60s were longer then the 40s.
Many people say that the first Mk. IXs with the round tail are the most beautiful of the Spitfires. The British fighter-ace, Johnnie Johnson, who flew
the Mk. IX in combat thought that the Mk. IX was the best and most harmonic of the Spitfire-models, which he flew. He had 38 kills in Spitfires - many
of them in Mk. IX S/N EN398.
Even though Mk. IX was meant as a temporary solution to an acute problem 5,665 of them were built.
The Royal Danish Air Force had 38 HF Mk. IXE in service in the years 1947-1952. One of these, owned by Toejhusmuseet, is at display at Dansk
Veteranflysamling at Stauning airport. See "41-401".
TR.IX (2-sædet Mk. IX)
A number of 2-seat trainers were built after the war, in which the green pilots could learn how to handle a powerful fighter like the Spitfire.
Many pilots, who learned the trade during the Battle of Britain, got 10 minutes briefing and a few hours in a single seat Spitfire after 50 hours
of training in a Tiger Moth before they were sent into combat.
Mk. PR X.
This version was developed from the Mk. VII and therefore had a pressure cabin, retractable tail wheel and pointed vertical stabiliser and rudder.
The wings were from Mk. VC and they had integral leading edge fuel tanks. PR X was unarmed, but carried cameras pointing to the side or down. The
engines were Merlin 64 or 71. The enlarged oil tank, which was fitted under the engine, gave the Mk. X a characteristic "chin". For some reason the
model was not used much and was removed from service quite early.
When the Focke-Wulf 190 turned up, it was necessary to replace the trusty PR. IVs, because they had the same performance problems as the Mk. V's.
The need for a new photo recognisance version was so bad, that 1st PRU (Photo Recognisance Unit) modified 15 Mk. IX aircraft to PR XI. Supermarine
quickly moved this work to a factory at the outskirts of the air base at Aldermaston not far from Reading.
The PR XI was a Mk. IX without armament and most of the armour of the Mk. IX. Like the PR IV D it was fitted with wings with integral leading edge
fuel tanks and had the enlarged oil tank like the PR. X and therefore also had the characteristic "chin". The P XI's of Aldermaston got a retractable
tail wheel from the Mk. VII and VIII; the converted Mk. IX did not have this feature. The windshield was replaced with a 1-piece rounded one (see
the picture of the Mk. XIX).
The PR XI was a major improvement compared to the PR IV: equipped with Merlin 63 or 70 engines the top speed was depending of the altitude between
50 and 66 mph faster, climbed 1340ft/min faster, climbed to 30,000ft (9.200m) in only 8 min. and 20 sec. and had a service ceiling of 44,000ft (13.500m).
Since the PR XI was not pressurised the pilots could not fly at that altitude for a long period of time.
A PR XI was used at RAE in Farnborough for high-speed tests and in 1944 during a dive the speed of 606mph (970km/h) (Mach 0.89) was reached. At this
occasion the propeller reduction gear broke and the propeller was lost, however, the pilot saved himself and the aircraft and made a normal landing
The pilots who flew the PR aircraft were individualists contrary to the "normal" fighter pilots, who were depending on each other. The PR pilots
went on sorties maybe 600-700 miles into enemy territory to take pictures of targets in order to plan an air raid or evaluate the damage done during
an air raid.
The RDAF had 3 PR XI's.
From the beginning the Spitfires fitted with the more powerful 12-cylinder 36,7 litre Rolls-Royce Griffon engine were supposed to have Mark numbers
from XX and up, however, the first Griffon-powered Spitfires ended up with Mark number XII. Like many other versions it was based on Mk. VC, however,
with a strengthened airframe and clipped wings. Later serial numbers had the pointed broad rudder and retractable tail wheel of Mk. VII. It was armed
with 2 20mm canons and 4 0.303" machineguns. A 100 of this model was built with either Griffon II or Griffon IV single-stage supercharged engines
with a maximum output of 1,735hp. The engines were tuned for low-level operation in order to deal with German low level sneak attacks over Southern
England carried out by FW190s. The Mk. XII became operational in the spring of 1943. Because the Griffon was bigger the Mk. XII was the only Spitfire
that got 3 humps in the top cowling behind the propeller (the centre hump covered the magneto) and for the same reason it was also longer than the
Mk. V. The upper fuel tank had to be smaller than on the Mk. V.; however, on this model range was not the issue, because it was meant for defensive use.
Mk. FR XIII.
I have only been able to find very little information about this mark. It was designed for low-level photo recognisance. It was a development of the
Mk. V/VII, but the engine was a Merlin 32, which which was designed for operation at very low level. The wings were of the normal C type and had
provisions for drop-tanks and were fitted with 4 0.303" machineguns. Only 18 were built.
Tests of a Mk. VIII with a Griffon engine had been so promising that another "temporary" model was built. It was designated as the Mk. XIV and 957 were built.
It was the most potent of all the Spitfires built in large numbers. The airframe, which had the retractable tail wheel from the Mk. VIII, was made longer to
house the bigger and heavier Griffon engine. The vertical stabiliser was enlarged by stretching it forward in order to compensate for the heavier engine and
the torque of the new and larger 5-blade Rotol propeller. The movement of the throttle lever was made longer, because the throttle quadrant had always been
the same as it was on K5054 back in 1936, where the output of the engine was only half of the Mk. XIV. When the throttle lever was moved just a little bit
forward it gave an enormous change of power thus making it very difficult to adjust the power setting. The new trottle arrangement made power adjustment easier.
The engine was a 2,035hp 2-stage Griffon 65, which made the Mk. XIV reach a top speed of 450mph (721 km/h) at 26,000ft (7.930m). The climb had also been
improved compared to the Mk. IX: 4,580ft/min against 3,950ft/min). The model was fitted with either "C" or "E" wings of the clipped type. From the beginning
the wings were of the normal type, however, soon they were clipped because the heavier wing load caused the skin near the fuselage to buckle.
The Mk. XIV was so fast that it was put up against the German V1 flying terror bomb (Vergeltungswaffe 1). The Mk XIV was credited with 300 V1-kills. The Mk.
XIV was also the first aircraft ever to shoot down a jet-powered fighter - the German Messerschmitt Me262.
In the spring of 1944 the Mk. XIV became operational with 610 Sq. That was 8 years after the prototype had flown for the first time. In that period of time
the Spitfire was almost twice as heavy, had the double amount of horsepower and its 20mm and 12.7mm weapons could fire a one second burst of 3.6 kilos
against Mk. I's 4 0.303s 1.2 kilos. RAF compared the Mk. XIV with different aircraft and the results would have made Mitchell happy. At altitudes between
0 to 5000ft and 15,000 to 20,000ft the Spitfire Mk. XIV was only 40mph faster than the FW190A, but at all other altitudes it was more than 60mph faster.
Compared to the long-nosed FW190D with Jumo 213E engine the 2 aircraft had identical top speed. At all altitudes Mk. XIV could climb away from both FW190A
and D and since it had kept the manoeuvrability of earlier Marks it could still out-turn the FW190 (a little slower in a right turn because of the torque
of the massive propeller). However, the FW190 still rolled faster than the Mk. XIV. All in all the Mk. XIV was superior to the FW190 in most disciplines.
to the Mk. XIV the Bf109G was out-classed in any aspect. The Mk. XIV did not leave the Hawker Typhoon and North American P-51 Mustang anything to come for.
The only problem with the Mk. XIV was its short range. Drop-tanks solved the problem, but a big external fuel tank tied to belly reduced its manoeuvrability,
but even with a 90-gallon external fuel tank it could still follow and out-manoeuvre a FW190 and Bf109. One should keep in mind that the main idea behind
the Spitfire was a defensive fighter aircraft.
After flying the Mk. XIV for the first time Johnnie Johnson said that it was a nice and fast aeroplane, which wasn't a Spitfire any longer. On the other
hand Jeffrey Quill thought that it was the best Spitfire mark ever built. As earlier mentioned the Mk. XIV was faster than earlier marks and the torque
of the propeller was high that it took constant trimming of the controls during flight. With increasing speed it became increasingly tail-heavy and had
to be trimmed nose fully down in order to maintain level flight. According to Johnnie Johnson pulling out of a dive was a violent experience. Many
experienced Spitfire-pilots that were checked out on the Mk. XIV at first experienced the take-off as an unpleasant thing because the propeller turned
the opposite way of the Merlin-powered Spitfires. An experienced Spitfire-pilot tells that the first time he took off in a Mk. XIV he did not get it
airborne until it had made a 90 degrees turn on the ground during take-off. Someone forgot to tell him that the prop turned the other way.
The Mk. XIV was also built in a low-back variant with teardrop hood, which gave the pilot a better view. Please see below in the section about Mk. XVIII
for pictures of low-back Griffon engine powered Spitfires. One can maintain that the low-back was not faithful to Mitchell's original beautiful Spitfire,
but it was indeed still a beautiful and efficient fighter aircraft. One should remember that the Spitfire was a weapon of war and England had been
fighting with the back against the wall and in order to survive. England was dependant of the success of machines like the Spitfire. The Spitfire's
success was dependant of constant "product improvement".
This mark number was never used.
A Mk. XVI with serial numbers RR, SM and TB was in fact equal to a Mk. IXE with serial numbers from RK883. It was fitted with an American licence
built Merlin 66 - Packard Merlin 266. Like on the Mk. IX with Serial numbers from TD175 through TE343 serial numbers starting with RW, SL, TD and
TE had the low back and tear drop hood, which gave the pilot a better view.
The low back was introduced in February 1945. The XVI only had “E” wings with clipped tips. Shortly after the model became operational, the rate
of loss in units equipped with the Mk. XVI went up. When examining a Mk. XVI, which had done an crash landing, it was established that a batch of
Packard Merlins had a serious fault, which could cause a sudden fire. The model was built along side with the Mk. IX.
Mk. F XVII.
This model number was not used either
Mk. F XVIII og FR XVIII.
This model was a development of the Mk. XIV with low back. The engine was still a Griffon 65. The airframe and undercarriage were strengthened,
enabling the aircraft to carry more fuel. The model was used as a fighter-bomber. Mk. XVIIIs were used for recognisance under the designation
FR. XVIII. 100 F XVIII and 200 FR. XVIII were built and both had either “C” or “E” wings. The XVIII became operational in 1947 and was only
used by units serving outside England.
For PR work a Mk. XIV was fitted with extended “C” wings and cameras. The engine was either still a Griffon 65 or a Griffon 66. It had a pressurised
cockpit a rounded windshield without the normal armour and was naturally without armament. The fuel capacity was increased which gave the Mk. XIX a
range of 1,300 nautical miles. It was a major improvement compared to its predecessor, the PR Mk. X/XI.
The Mk. XIX is probably the piston engined aircraft, which has flown at the highest speed and at the highest altitude. The official service ceiling
of the XIX was 42,500 ft / 12,962 meters, but in Hong Kong, where a XIX was used for meteorological flights, a pilot nursed the aircraft up to
51,550 ft / 15,722 meters, where he kept it flying at stall speed (108 kts / 200 km/h). Suddenly a light came on warning the pilot of a pressure
cabin problem. The pilot decided to get down to a safe altitude as quickly as possible. During the wild dive the elevators locked and he was not
able to pull out of the dive until he pushed forward the stick instead of pulling it. When examining the
meteorological equipment it was determined
that he during the dive had reached Mach 0.94 (690 mph / 1104 km/h) at 15,000 ft / 4,575 meters.
Mk. XIX became operational in the summer of 1944 and became the most used recognisance aircraft used in the 2nd half of the war. It was not replaced until 1954.
The second of the single-stage Griffon II powered Mk. IV prototypes with a 4 blade propeller had fitted new and strengthened wings and a revised
fuselage. It flew for the first time in August 1942 and got renamed to Mk. 20.....
... but later the aircraft was fitted with a 2-stage Griffon 61 and the name was changed again - this time to Mk. 21. Unfortunately this
prototype was lost in a crash, which killed the pilot. The second Mk. 21 prototype flew for the first time in July 1943, however, it differed
from the first prototype by having ailerons with trim-tabs, 5-blade propeller and fairings around the main undercarriage, so that the undercarriage
was completely covered when retracted. The vertical stabiliser was also enlarged. The engines on the production Mk. 21s were Griffon 64 or 85.
The wings looked different from the well known elliptic wings of the earlier Spitfires, however, their improved aerodynamics allowed even higher
speeds. It was armed with 4 20mm cannons and became operational shortly before the end of the war. Due to instability Supermarine had to make
extensive changes to the model before it was accepted by RAF. Mk. 21 was faster and climbed better that the Mk. XIV, but its flight characteristics
were not as pleasant as the Mk. XIV's.
A single Mk. 21 fitted with a Griffon 85 was tested with a 6 blade contra-rotating propeller, however, it was not used on production aircraft because
the system was unreliable and heavy. A revised system was used on the Seafire 47 with great success.
Basically the Mk. 22 was a Mk. 21, however, with a low back and teardrop hood. At a later stage the Mk. 22 was built with an even larger vertical
stabiliser. It was the most important post-war variant, which remained in service until March 1951.
This project should have been a Fighter version with laminar flow wing; however, it never got off the drawing board. However, the wings were tested on a Mk. 22.
The Mk. 24 was a Fighter version, which was conceived just after the war and it was the last Spitfire model to be produced. It was like the Mk. 22, but it
had 2 extra fuel tanks in the rear fuselage. The wings were fitted with mountings, which could carry 6 60lbs rockets. Late production aircraft were fitted
with short Mk. V Hispano cannons. The model was retired from service in January 1952.
Spiteful og Seafang
The final development of the Spitfire changed it so radically that the name changed too. The wing was changed and the undercarriage extended the opposite
way of that of earlier models. It still had a Griffon engine at it was capable of a top speed of 525mph (840km/h). It came about too late to become a production
Seafire Mk I
Versions of the Spitfire were built for use on aircraft carriers under the name Seafire. The inwards extending undercarriage was a drawback when it came to
landing on the deck of an aircraft carrier, however, the Spitfire still found its way to the NavyThis was a development of the Spitfire Mk. VB. It had an
arrestor hook fitted under the fuselage behind the wings. It did not have folding wings and was therefore difficult to stow below deck. The engine was a
Merlin 32, 45 or 46. It was armed with 8 0.303” machine-guns.
Seafire Mk II
The Mk. II was in fact a Seafire Mk. I, however, it had the “universal” wing with 20mm/0.303” combination or 4 20mm cannons. Like on the Mk. I they could
not fold. It could carry 2 bombs under the wings. The engines were Merlin 32, 45, 46, 48, 40, 50 or 55.
Seafire Mk. III
This was a Mk. II with folding wings.
The Mk. XV was in fact a Spitfire Mk. XII and was equipped with a Griffon III or V-engine. The arrestor hook on this model was moved to the back of the
fuselage to avoid conflicts between the tail wheel and the arrestor wire.
Seafire Mk. XVII
The Royal Navy wanted to improve the Seafire in the same way as the low-back Spitfire Mk IX, XIV and XVI. A Seafire XV was sent for modification and returned
with a low back and bobble hood. The capacity of the fuel tanks was also increased. Later the rounded windscreen was added. Unfortunately this created some
unpleasant reflections, however, this was solved by painting the upper part of the fuselage matt black.
The low back caused the same stability problems as it did with the low-back Spitfires. This was solved by increasing the vertical stabilzer. Seafire XVII
was strengthened compared earlier Seafires (and Spitfires) to cope with landings on the deck of an aircraft carrier. These landings can only be described
as controlled crashes - the aircraft is flown down onto deck with a bang. The stroke of the struts was made longer in order to be able to absorb the high
force of the impact of the landing. The main spar of the wing onto which the main landing gear is attached was also strengthened. The folding mechanism of
the wings is operated manually and it takes 6 men for the job. The Mk. XVII was short-lived as the spear head of the Royal Navy.
Seafire Mk. 45
The privately owned company Cunliffe-Owen Aircraft Ltd. had converted a Spitfire Mk. 21 to naval use and it got the name Seafire Mk. 45. The fairings,
which covered the undercarriage, were changed in order to avoid problems with the arrestor wires. The model did not have folding wings.
Seafire Mk. 46
This was the Royal Navy’s equivalent to the Spitfire Mk. 22, however, it had counter-rotating propellers and like the Mk. 45 it did not have folding
wings. It was built as an interim version before the Mk. 47 was available.
Seafire Mk. 47
This was the last of the Seafire models. It had hydraulic folding wings. The Seafire Mk. 47 was built as a Fighter Recognisance variant (FR.).
Jet-powered fighters such as the Gloster Meteor and DeHavilland Vampire took over the part of being the fastest fighters in the Royal Air Force.
The sound barrier had been broken and fighters and fighter-bombers that were able to break the sound barrier were now in demand because the
Cold War had broken out and a technological race between the western and the eastern powers was going on.
The piston engine could not compete in this race.
20,334 Spitfires and 2,455 Seafires were built before production ceased in October 1947 and thus ending an era... the piston had been overtaken
by the turbine.