The Rolls-Royce Griffon engine was
designed in answer to Royal Naval
specifications for 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.
Wing types 
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.
= C type =
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 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 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.
= D Type =
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.
= E type =
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 in the outer bays
combined with 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.
or
4 × 20 mm Hispano cannon with 120 rpg
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 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, 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.
The standard armament was now four 20mm
Hispano IIs or the shorter, lighter
Hispano V cannons each with 150 rounds
per gun.
Variants 
= Notes =
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 are the
drawing board design numbers allocated
by Supermarine.
= Mk IV/XX =
On 4 December 1939, the Supermarine
design staff produced a brochure which
mooted the idea of converting the
Spitfire to use the Rolls-Royce Griffon
engine. A top speed of 423 mph at 18,500
ft was predicted. However, constant
problems with the development of the
Griffon meant that the decision to
proceed with building a Spitfire with
this engine didn't come to fruition
until 1942, with the successful flight
trials of the Mk IV.
The Griffon IIB which powered the Mk IV
was a single-stage supercharged engine
of 1,735 hp. Stronger main longerons
were needed to cope with the weight of
the Griffon and it required a bigger
radiator and oil cooler, although it
kept the asymmetric under-wing radiator
layout of the single stage Merlin marks.
The new engine had a lower thrust-line
than the Merlin and was set with a minus
½ degree of downthrust. The lower thrust
line and larger capacity of the new
engine meant that the contours of the
engine cowling were completely changed,
with more prominent blisters over the
cylinder heads, plus a third tear-drop
shaped blister on the upper forward
cowling to clear the magneto, and a
deeper curve down to the spinner, which
was much longer than previous types. The
lower cowling lost its "pigeon-chested"
appearance, with a shallower curve up to
the spinner. A four blade Rotol
propeller of 10 ft 5 in was used. Apart
from these differences the Mk IV
airframe was closely related to that of
the Merlin-powered Mk III. One feature
of the Griffon engine which was to catch
a lot of pilots out was that the
propeller rotated in the opposite
direction to that of the Merlin; i.e.,:
to the left, from the pilot's
perspective, rather than to the right.
This meant that the powerful slipstream
swung the Spitfire to the right on the
ground, requiring the rudder to be
deflected to the left during takeoff.
The Mark IV DP845 first flew on 27
November 1941. It had the full-span C
wing combined with a small tail unit and
retractable tailwheel, and also had
external bracket hinges under the wings,
denoting the installation of braking
flaps. These were soon removed and a
mock up of a proposed six-cannon
armament was fitted, three in each wing.
The aircraft was soon renamed Mk XX, to
avoid confusion with a renamed PR type,
then it became the Mk XII.
Jeffrey Quill, Supermarine's chief test
pilot, was the first to fly the Mk IV/Mk
XII prototype DP845; "... there was
somewhat less ground clearance,
resulting in a slight reduction in
propeller diameter; the power available
for take-off was much greater; and the
engine RPM were lower than in the
Merlin. All this meant that the throttle
needed to be handled judiciously on
take-off but, once in the air, the
aeroplane had a great feeling of power
about it; it seemed to be the airborne
equivalent of a very powerful sports car
and was great fun to fly. Changes of
trim with changes of power were much
more in evidence, both directionally and
longitudinally, and the aeroplane
sheared about a bit during tight
manoeuvres and simulated dog-fights. I
realised at once that we should have to
correct its directional characteristics
and probably its longitudinal stability
also, both of which in due time we
achieved. Indeed, DP485 eventually went
through many phases of development
throughout and I, and others, flew in it
a great deal; it became one of our
favourite aeroplanes."
= Mk XII =
Media related to Supermarine Spitfire
Mark XII at Wikimedia Commons
The Mk XII was the first Spitfire
powered by a Griffon engine to go into
service. The first of 100
Supermarine-built production aircraft
started appearing in October 1942; two
RAF squadrons in total were equipped
with the XII. Mk XIIs were manufactured
from Mk VC and Mk VIII airframes: early
production aircraft had the fixed tail
wheels, Dunlop AH2061 pattern "five
spoke" mainwheels and small elevator
balances. They had a single 85 gal main
fuel tank, giving a short range of
little over 380 miles on internal fuel.
All were fitted with the larger, pointed
tip rudder. The last 45 or so Mk XIIs,
were based on Mk VIIIs with two wing
fuel tanks, each containing a maximum
fuel load of 14 gal, and featured the
larger horn balances, retractable
tailwheel and undercarriage legs with
torque-links, "dished" leg fairings and
the stronger Dunlop AH10019 four spoke
wheels. The wheels were occasionally
fitted with disc-style covers. A later
model IFF was fitted, replacing the
aerials from the tailplane tip to
fuselage with a rod aerial under the
starboard wing. Another important
feature of the Griffon-engine Spitfires
was the entirely flush-riveted finish
which was progressively introduced on
all Spitfires.
The single-stage Griffon engine gave the
aircraft superb low and medium level
performance, although the Mk XII's
performance declined at higher
altitudes: because of this all
production aircraft had "clipped" wings.
In comparative tests with a Mk IX it was
14 mph faster at sea level, but above
20,000 ft it had become slower.
Handling, however, was considered to be
better than previous Spitfire marks, and
the clipped wings conferred excellent
manoeuvrability through enhanced aileron
response.
At low altitude it was one of the
fastest aircraft in the world; in one
speed trial, held at Farnborough in July
1942 DP845 piloted by Jeffrey Quill
raced ahead of a Hawker Typhoon and a
captured Focke-Wulf Fw 190, to the
amazement of the dignitaries present.
On reflection the general scheme became
clear. The Spitfire was to be a sort of
datum pacemaker - 'Mr Average
Contemporary Fighter' - and its job
would be to come in last, the real
excitement of the proceedings being by
how much it would be beaten by the FW
190 and the Typhoon, and which of these
two bright stars would beat the other
and by how much. Outside on the tarmac
at Worthy Down stood the
inoffensive-looking but highly potent
DP485 ...
All went according to plan until, when
we were about halfway between Odiham and
Farnborough and going flat out, I was
beginning to overhaul the FW 190 and the
Typhoon. Suddenly I saw sparks and black
smoke coming from the FW 190's exhaust
... and I shot past him and never saw
him again. I was also easily leaving the
Typhoon behind and the eventual
finishing order was, first the Spitfire,
second the Typhoon, third the FW 190.
This was precisely the opposite result
to that expected, or indeed intended. It
certainly put the cat among the pigeons
and among the VIPs.
However pilots found it difficult to
exploit this advantage in combat as
German pilots were reluctant to be drawn
into dogfights with Spitfires of any
type below 20,000 feet. When the Mk XII
was able to engage in combat it was a
formidable fighter and several Fw 190s
and Bf 109-Gs fell victim to it. The Mk
XII's speed advantage at lower altitudes
again became useful near the end of its
front line service in Summer 1944, in
which it shot down a respectable number
of V-1 Flying Bombs, 82.5 The Mk XII
variant was retired in September 1944.
= Mk XIV =
Media related to Supermarine Spitfire
Mark XIV at Wikimedia Commons
The first Griffon-powered Spitfires
suffered from poor high altitude
performance due to having only a single
stage supercharged engine. By 1943,
Rolls-Royce engineers had developed a
new Griffon engine, the 61 series, with
a two-stage supercharger. In the end it
was a slightly modified engine, the 65
series, which was used in the Mk XIV.
The resulting aircraft provided a
substantial performance increase over
the Mk IX. Although initially based on
the Mk VIII airframe, common
improvements made in aircraft produced
later included the cut-back fuselage and
tear-drop canopies, and the E-Type wing
with improved armament.
The Mk XIV differed from the Mk XII in
that the longer, two-stage supercharged
Griffon 65, producing 2,050 hp, was
mounted 10 inches further forward: the
top section of the engine bulkhead was
angled forward, creating a distinctive
change of angle to the upper cowling's
rear edge. A new five bladed Rotol
propeller of 10 ft 5 in in diameter was
used, although one prototype JF321 was
fitted with a six bladed contra rotating
unit. The "fishtail" design of ejector
exhaust stub gave way to ones of
circular section. The increased cooling
requirements of the Griffon engine meant
that all radiators were much bigger and
the underwing housings were deeper than
previous versions.
The cowling fasteners were new, flush
fitting "Amal" type, and there were more
of them. The oil tank was increased in
capacity from 6 to 10 gal.
To help balance the new engine the radio
equipment was moved further back in the
rear fuselage and the access hatch was
moved from the left fuselage side to the
right. Improved VHF radio equipment
allowed for the aerial mast to be
removed and replaced by a "whip" aerial
further aft on the fuselage spine.
Because the longer nose and the
increased slipstream of the big
five-bladed propeller a new tail unit,
with a taller, broader fin and a rudder
of increased area was adopted.
The first batch of aircraft to fly with
the Griffon 60 series engines were six
converted Mk VIIIs JF316 to JF321 which
were designated Mk VIIIG. The first one
of these was flown by Jeffrey Quill on
20 January 1943:
"Changes to the aircraft were restricted
to those essential to enable it to
accept the new engine ... I found that
it had a spectacular performance doing
445 mph at 25,000 ft, with a sea-level
rate of climb of over 5,000 ft per
minute. I remember being greatly
delighted with it; it seemed to me that
from this relatively simple conversion,
carried out with a minimum of fuss and
bother, had come up with something quite
outstanding ... The MK VIIIG, with
virtually the same tail surfaces both
vertical and horizontal as the Merlin MK
VIII, was very much over-powered and the
handling in the air was unacceptable for
an operational type ... I soon realised
that a new throttle box would be needed
giving a much greater angular travel for
the hand lever ... The next essential
... was an improvement in the
directional stability and control and a
new fin was drawn out with a substantial
increase in area and a much larger
rudder and fitted to the second aircraft
JF317. This, though not ideal, produced
a very marked improvement in directional
characteristics and we were able to
introduce minor changes thereafter and
by various degrees of trimmer tab and
balance tab to reach an acceptable
degree of directional stability and
control. The enlarged fin of JF317 had a
straight leading edge but for production
a more elegant curved line was
introduced."
One prototype, JF321, was fitted and
tested with a Rotol six-bladed
contra-rotating propeller unit; although
this promised to eliminate the
characteristic swing on take-off the
propeller unit was prone to failure. The
pitch control mechanism controlled the
pitch on the front propeller;
... and this was transmitted to the rear
propeller through the transitional
bearing mechanism. If this failed the
pitch of the rear propeller was no
longer under control and might do
anything which was potentially
dangerous.
A similar contra-rotating propeller unit
was later used on production Seafire 46
and 47s.
When the new fighter entered service
with 610 Squadron in December 1943 it
signified a new leap forward in the
evolution of the Spitfire. Jeffrey Quill
flew the first production aircraft,
RB140 in October 1943:
"So the Mk XIV was in business, and a
very fine fighter it was. It fully
justified the faith of those who, from
the early days in 1939, had been
convinced that the Griffon engine would
eventually see the Spitfire into a new
lease of life ... It was a splendid
aeroplane in every respect. We still had
some work to do to improve its
longitudinal and directional
characteristics, but it was powerful and
performed magnificently. The only
respect in which the XIV fell short was
in its range."
It could climb to 20,000 ft in just over
five minutes and its top speed, which
was achieved at 25,400 ft, was 446 mph.
In operational service many pilots
initially found that the new fighter
could be difficult to handle,
particularly if they were used to
earlier Spitfire marks. Don Healy of 17
Squadron, based at Madura recalled that
the Mk XIV was;
a hairy beast to fly and took some
getting used to. I personally preferred
the old Mk Vs from a flying standpoint
... Even with full aileron, elevator and
rudder, this brute of a fighter took off
slightly sideways.
In spite of the difficulties pilots
appreciated the performance increases.
Wing Commander Peter Brothers, O/C
Culmhead Wing in 1944-1945 and a Battle
of Britain veteran;
It was truly an impressive machine,
being able to climb almost vertically -
it gave many Luftwaffe pilots the shock
of their lives when, having thought they
had bounced you from a superior height,
they were astonished to find the Mk XIV
climbing up to tackle them head-on,
throttle wide open!
F Mk XIVs had a total of 109.5 gal of
fuel consisting of 84 gal in two main
tanks and a 12.5 imp gal fuel tank in
each leading edge wing tank. In
addition, 30, 45, 50 or 90 gal drop
tanks could be carried. The fighter's
maximum range was just a little over 460
miles on internal fuel since the new
Griffon engine consumed much more fuel
per hour than the original Merlin engine
of earlier variants;. By late 1944,
Spitfire XIVs were fitted with an extra
33 gal in a rear fuselage fuel tank,
extending the fighter's range to about
850 miles on internal fuel and a 90 gal
drop tank. Mk XIVs with "tear-drop"
canopies had 64 gal. As a result, F and
FR Mk XIVEs had a range that was
increased to over 610 miles, or 960
miles with a 90 gal drop tank.
The first test of the aircraft was in
intercepting V1 flying bombs, and the Mk
XIV was the most successful of all
Spitfire marks in this role. When 150
octane fuel was introduced in mid-1944
the "boost" of the Griffon engine was
able to be increased to +25 lbs,
allowing the top speed to be increased
by about 30 mph to 400 mph at 2,000 ft.
The Mk XIV was used by the 2nd Tactical
Air Force as their main high-altitude
air superiority fighter in northern
Europe with six squadrons operational by
December 1944.
One problem which did arise in service
was localised skin wrinkling on the
wings and fuselage at load attachment
points; although Supermarine advised
that the Mk XIVs had not been seriously
weakened, nor were they on the point of
failure, the RAF nevertheless issued
instructions in early 1945 that all F
and FR Mk XIVs were to be
retrospectively fitted with clipped
wings.
Spitfire XIVs began to arrive in the
South-East Asian Theatre in June 1945,
too late to operate against the
Japanese. It was this type which was
rumoured to have been buried at an
airfield in Burma after the war.
= FR Mk XIV =
Late in 1944 a number of high-back
full-span Mk XIVEs were converted by the
Forward Repair Unit to have a single
camera fitted, facing to port or
starboard; a conversion identical to
that used on the FRU-converted FR Mk
IXC. To achieve this a new hatch,
similar to the radio hatch on the port
side, was installed on the starboard
side, and both hatches were fitted with
camera ports in streamlined blisters.
Otherwise this version of the FR Mk XIVE
was essentially the same as the standard
aircraft. These field-converted aircraft
were allocated to 430 squadron RCAF.
Later, purpose-built conversions, also
known as the FR Mk XIVE, had the later
cut-down rear fuselage with its tear
drop–shaped canopy, port and/or
starboard camera ports, and an
additional rear fuel tank of 34 gallons
which extended the Spitfire's range to
about 610 miles on internal fuel.
Because it was used mainly at low
altitudes the "production" FR Mk XIVE
had clipped wingtips.
In total, 957 Mk XIVs were built, over
430 of which were FR Mk XIVs. After the
war, second hand Mk XIVs were exported
to a number of foreign air forces; 132
went to the Royal Belgian Air Force, 70
went to the Royal Indian Air Force and
30 of its reconnaissance variant went to
the Royal Thai Air Force.
= Mk XV and Mk XVII =
The mark numbers XV and XVII were
reserved for the naval version, the
Seafire, in an effort to reconcile the
Spitfire numbering scheme with that of
the Seafire.
= Mk XVIII =
Media related to Supermarine Spitfire
Mark XVIII at Wikimedia Commons
The Mk 18 was a refinement of the Mk
XIV. It was identical in most respects
including engine and cockpit
enhancements, but it carried extra fuel
and had a revised, stronger wing
structure. Its handling was also nearly
identical and so it was not put through
any performance tests. Like the Mk XIV
there were fighter and fighter
reconnaissance variants built.
The Mk 18 missed the war. It was built
up until early 1946 but it was not until
January 1947, that an RAF squadron, 60
Squadron which operated from RAF
Seletar, Singapore, was re-equipped with
the variant. Later, other squadrons in
the Far East and Middle East would
receive them. Some 300 F Mk 18s and FR
Mk 18s were built, before production
ended in early 1946. The Mk 18s saw
little action apart from some
involvement against guerrillas in the
Malayan Emergency. The Royal Indian Air
Force purchased 20 ex-RAF Mk 18s in
1947.
= Mk XIX =
Media related to Supermarine Spitfire
Mark XIX at Wikimedia Commons
The Mk XIX was the last and most
successful photographic reconnaissance
variant of the Spitfire. It combined
features of the Mk XI with the Griffon
engine of the Mk XIV. After the first 25
were produced, later aircraft were also
fitted with the pressurised cabin of the
Mk X and the fuel capacity was increased
to 256 gallons, three-and-a-half times
that of the original Spitfire This
version was the type 390.
The first Mk XIXs entered service in May
1944, and by the end of the war the type
had virtually replaced the earlier Mk
XI. A total of 225 were built with
production ceasing in early 1946, but
they were used in front line RAF service
until April 1954.
In 1951, Hainan Island was targeted at
the behest of U.S. Naval Intelligence
for RAF overflights, using Spitfire PR
Mk 19s based at Kai Tak Airport in Hong
Kong. The last operational sortie by a
Mk 19 was in 1963 when one was used in
battle trials against an English
Electric Lightning to determine how best
a Lightning should engage piston-engined
aircraft. This information was needed in
case RAF Lightnings might have to engage
P-51 Mustangs in the Indonesian conflict
of the time.
= Mk XX =
Mark XX was given to the original Mk IV
Griffon engine prototype DP845 to avoid
confusion with the retitled Spitfire PR
Mk IVs.
The second Mk XX, DP851, initially had a
Griffon II engine and made its first
flight in August 1942. In December, it
was refitted with a Griffon 61 and
re-designated as a Mk 21 initial
prototype.
= Mk 21 =
Media related to Supermarine Spitfire
Mark 21 at Wikimedia Commons
By early 1942, it was evident that
Spitfires powered by the new two-stage
supercharged Griffon 61 engine would
need a much stronger airframe and wings.
The proposed new design was designated
the Mk 21. At first the Mk 21 displayed
poor flight qualities that damaged the
otherwise excellent Spitfire reputation.
The wings were completely redesigned
with a new structure and using
thicker-gauge light alloy skinning. The
new wing was torsionally 47% stiffer,
allowing an increased theoretical
aileron reversal speed of 825 mph. The
ailerons were 5% larger, and were no
longer of the Frise balanced type,
instead being attached by continuous
piano-hinges. They were extended by
eight inches, meaning that with a
straighter trailing edge, the wings were
not the same elliptical shape as in
previous Spitfires. The Mk 21 armament
was standardised as four 20mm Hispano II
cannon with 150 rpg and no machine guns.
The Griffon engine drove an 11 ft
diameter five-bladed propeller, some 7
inches larger than that fitted to the Mk
XIV. To ensure sufficient ground
clearance for the new propeller, the
undercarriage legs were lengthened by
4.5". The undercarriage legs also had a
7.75 inch wider track to help improve
ground handling. The designers then
devised a system of levers to shorten
the undercarriage legs by about eight
inches as they retracted, because the
longer legs did not have enough space in
which to retract. These same levers
extended the legs as they came down. The
larger diameter four spoke mainwheels
were strengthened to cope with the
greater weights; post-war these were
replaced by wider, reinforced three
spoke wheels to allow Spitfires to
operate from hard concrete or asphalt
runways. When retracted the wheels were
now fully enclosed by triangular doors
which were hinged to the outer edge of
the wheelwells.
In other respects, the first production
Mk 21s used the same basic airframe as
the Mk XIV. The first true Mk 21
prototype, PP139 first flew in July
1943, with the first production aircraft
LA187 flying on 15 March 1944. However
the modifications over the Mk XIV made
the Mk 21 sensitive to trim changes.
LA201's poor flight control qualities,
during trials in late 1944 and early
1945, led to a damning report from the
Air Fighting Development Unit: "... it
must be emphasised that although the
Spitfire 21 is not a dangerous aircraft
to fly, pilots must be warned ... in its
present state it is not likely to prove
a satisfactory fighter. No further
attempts should be made to perpetuate
the Spitfire family."
Supermarine were seriously concerned
because Castle Bromwich had been
converted to produce Mk 21s, and more
were coming off the production lines
daily. Jeffrey Quill commented that "The
AFDU were quite right to criticise the
handling of the Mark 21 ... Where they
went terribly wrong was to recommend
that all further development of the
Spitfire family should cease. They were
quite unqualified to make such a
judgement and later events would prove
them totally wrong."
After intensive test flying the most
serious problems were solved by changing
the gearing to the trim tabs and other
subtle control modifications, such that
the Mk 21 was cleared for instrument
flying and low level flight during
trials in March 1945. An AFDU report on
LA215 issued that month noted that the
Spitfire 21 was now much easier to fly;
General Handling The modifications
carried out to this aircraft have
resulted in an improvement of the
general handling characteristics at all
heights ... Conclusions The critical
trimming characteristics reported on the
production Spitfire 21 have been largely
eliminated by the modifications carried
out to this aircraft. Its handling
qualities have benefitted to a
corresponding extent and it is now
considered suitable both for instrument
flying and low flying. It is considered
that the modifications to the Spitfire
21 make it a satisfactory combat
aircraft for the average pilot.
Spitfire 21s finally became operational
on 91 Squadron in January 1945. 91
Squadron had little opportunity to
engage the enemy before the war ended,
but scored a rare success on 26 April
1945, when two Spitfire Mk 21s shot up
and claimed to have sunk a German midget
submarine which they caught on the
surface. With the end of the war most
orders for the Mk 21 were cancelled and
only 120 were completed. In 1946 40
Spitfire 21s were delivered to
Shoeburyness; once there their leading
edges were removed and destroyed in
"lethality" tests. Some aircraft had
less than five hours flying time.
= Mk 22 =
Media related to Supermarine Spitfire
Mark 22 at Wikimedia Commons
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.
= Mk 23 =
The Mk 23 was to be a Mk 22
incorporating a revised wing design
which featured an increase in incidence,
lifting the leading edge by 2 inches. It
was hoped that this would improve the
pilot's view over the nose in flight and
increase the high speed and dive
performance of the aircraft. The
modified, hand-built wing was first
fitted to a Mk VIII JG204 which was
tested from July 1944. However the tests
were disappointing and, after
discussions at Supermarine, it was
decided to build a new prototype using
the Mk 21 prototype PP139: in this form
the prototype was designated F Mk 23,
and was to be renamed the Supermarine
Valiant. However the new wing gave less
than perfect handling characteristics
and so the Mk 23 was never built from
the Mk 22 airframe as intended.
= Mk 24 =
Media related to Supermarine Spitfire
Mark 24 at Wikimedia Commons
The final Spitfire variant, the Mk 24,
was similar to the Mk 22 except that it
had an increased fuel capacity over its
predecessors, with two fuel tanks of 33
gal each installed in the rear fuselage.
There were also zero-point fittings for
rocket projectiles under the wings. All
had the larger "Spiteful" tail units:
modifications were also made to the trim
tab gearings in order to perfect the F
Mk 24's handling characteristics. The F
Mk 24 achieved a maximum speed of 454
mph, and could reach an altitude of
30,000 ft in eight minutes, putting it
on a par with the most advanced
piston-engined fighters of the era.
Although designed primarily as a
fighter-interceptor aircraft, the
Spitfire proved its versatility in
several different roles. In fighter
configuration the F Mk 24's armament
consisted of 4 × short-barrelled Mk.5 20
mm Hispano cannon – operational
experience had proved that the hitting
power of these larger weapons was
necessary to overcome the thicker
armoured plating encountered on enemy
aircraft as the war progressed. The
aircraft also served successfully in the
fighter-bomber role, being capable of
carrying 1 × 500 lb and 2 × 250 lb
bombs, with rocket-projectile launch
rails fitted as standard. Late
production aircraft were built with the
lighter, short-barrelled, electrically
fired Mark V Hispano cannon.
A total of 81 Mk 24s were completed, 27
of which were conversions from Mk 22s.
The last Mk 24 to be built was delivered
in February 1948. They were used by only
one RAF squadron, 80 Squadron, until
1952. Some of the squadron's aircraft
went to the Hong Kong Auxiliary Air
Force where they were operated until
1955.
Introduced into service in 1946, the F
Mk 24 differed greatly from the original
Spitfire Mk I in many respects and was
twice as heavy, more than twice as
powerful and showed an increase in climb
rate of 80% over that of the prototype,
'K5054'. These remarkable increases in
performance arose chiefly from the
introduction of the Rolls-Royce Griffon
engine in place of the famous Merlin of
earlier variants. Rated at 2,050 hp, the
12-cylinder Vee liquid-cooled Griffon 61
engine featured a two-stage
supercharger, giving the Spitfire the
exceptional performance at high altitude
that had been sometimes lacking in early
marks.
Production 
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. 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.
Specifications Spitfire 
General characteristics
Crew: one pilot
Length: 32 ft 8 in
Wingspan: 36 ft 10 in
Height: 10 ft
Wing area: 242.1 ft2
Airfoil: NACA 2209.4(tip)
Empty weight: 6,578 lb
Loaded weight: 7,923 lb
Max. takeoff weight: 8,488 lb
Powerplant: 1 × Rolls-Royce Griffon 65,
supercharged V12 engine, 5-bladed
Jablo-Rotol propeller
2,050 hp at  8,000 ft
Performance
Maximum speed: 448 mph,
Combat radius: 400 nmi
Ferry range: 950 nmi(1,090 mi, 1,815 km)
Service ceiling: 43,500 ft
Rate of climb: 3,650 ft/min
Wing loading: 32.72 lb/ft2
Power/mass: 0.24 hp/lb
Armament
Guns: ** 2 × 20 mm Hispano Mk II cannon,
120 rpg.
4 × 0.303 in Browning machine guns, 350
rpg. 
Replaced by 2 x .50 in M2 Browning
machine guns 250 rpg Mk XIVE.
Bombs: 2 × 250 lb bombs
See also 
British military history of World War II
Rolls-Royce Merlin and Griffon
Supermarine
Allied technological cooperation during
World War II
Related development
Supermarine S.6B
Seafire
Spiteful
Seafang
References 
= Citations =
= Bibliography =
= Videography =
External links 
Manual: A.P. 1565T & W-P.N. Pilot's
Notes for Spitfire XIV & XIX
The Spitfire Site
The Spitfire Society
Alan Le Marinel hosts Supermarine
Spitfire
Spitfire Performance Testing
Spitfire/Seafire Serial Numbers,
production contracts and aircraft
histories
Spitfire, Warbird Alley  – Information
about Spitfires still flying today]
K5054 – Supermarine Type 300 prototype
Spitfire & production aircraft history
The Spitfire: Seventy Years On –
Includes images of the factory
National Heritage Warbird Foundation
