Info EDUARD

Monthly magazine about history and scale plastic modeling.

Strana 9

of Spitre Mk.V until November 1943 and gradually delivered
a total of 140 Mk.Vb and 495 Mk.Vc. Except for several initial
production Mk.Vb all Westland-built Spitres featured the inner,
integrated armor glass. Westland-built Mk.Vc featured specic
wing cannon upper covers shaped as bulges with attened sides
and front not used by any other manufacturer.
Spitfire Mk. V modernization
During the two and half years of Spitres Mk.V production, the
airframe was gradually developed and improved. Already at the
beginning of manufacture they featured thicker armor in com-
parison to Mk.I and Mk.II. The oil cooler was soon replaced with
a larger one featuring a circular intake which was retroactively
installed on the rst batch of Spitres Mk.V, converted from
Mk.I and Mk.II, and became one of the features distinguishing
Spitres Mk.V. At the same time the armament of eight 0.303
Browning machine guns was abandoned. Only 94 Mk.Va, with
such armament, were manufactured, while 6,370 Mk.Vb and
Mk.Vc, armed with two 20mm Hispano cannons and four 0.303
Browning machine guns left the assembly lines.
The problems with weapons freezing at the higher altitudes per-
sisted on Spitres Mk.V. Therefore, the weapons compartment
heating was enhanced by introducing the heat from the engi-
ne exhausts which was visually distinguishable by an additional
pipe running through the exhausts, entering the engine cover
from the last one and running through the fuselage and wing
leading edge to the cannons. The exhaust pipes were gradually
changed as well. The rst Spitres Mk.V featured the same ex-
hausts as Mk.I and Mk.II. Then the various types of pipes with
rectangular openings (sh tails) were introduced. In the end of
production and after overhaul the “ves” received six indepen-
dent exhaust pipes as featured on Spitres Mk.IX.
Canopy
The windshield, which originally featured the armored glass
mounted on its outside, was in later “ves” modied so as the
armored glass was integrated into it in a way that it was no lon-
ger sticking out. The sliding portion of the canopy was modied
as well. In the later production batches it was not only bulging
upwards but to the sides as well (Malcom hood, modication nr.
461). This new canopy lacked the small hinged window. Most
Spitres were equipped with laminated pilot seats.
Radio equipment
The rst Spitres Mk.V converted from Spitres Mk.I were still
tted with TR.9D shortwave radios with a wire antenna stret-
ched between the antenna masts behind the cabin to the top
of the rudder. The new-built production aircraft were alrea-
dy equipped with the new TR.1133 and later TR.1143 VHF ra-
dios, which replaced the older units from the summer of 1941.
The TR.1133 and 1143 had no wire antenna, so the serial
aircraft equipped with them had the antenna mast on top of
the rudder deleted. Similarly, the rst of the converted Mk.Vs
had the IFF R.3002 identication Friend or Foe device, soon
replaced by the newer IFF device ARI 5000. Both had wire an-
tennas between the fuselage sides and the leading edge of
the elevator. The IFF antenna on later Spitres was located on
the lower surface of the right wing half. From November 1941,
the A.1271 radio navigation system for radio beam guidance on
landing was also gradually introduced.
Engine modifications
Several engine versions powered Spitres Mk.V. Besides the
essential Merlin 45, the high altitude Merlin 46 with a more
powerful compressor providing higher manifold pressure at high
altitudes.But the original assumption that the combats with
Luftwae will move up to higher altitudes did not materialize
and quite the opposite happened, many missions then took pla-
ce at lower altitudes. So, the low altitude version Merlin 45M
was developed and tuned for the optimal performance at low
altitudes.
The carburetor development is a story on its own. The origi-
nal drawback of the Merlin III carburetors SU A.V.T.40, during
negative G maneuvers an intermittent fuel supply interruption
occurred, was partially eliminated by means of RAE restrictor
a.k.a. Tilly’s orice, named after its inventor, Beatrice Shilling.
But it was not a perfect solution. The problem was fully resol-
ved by introducing a membrane-type carburetor designed by
Rolls-Royce and introduced into the production in 1942. They
were installed in Merlin 50 and 55 powering Spitres Mk.Vc.
Propeller
Spitres Mk.V manufactured at mother company Supermarine
mostly featured De Havilland Hydromatic Type 5/29A, 5/39,
45/1 and 45/4 propellers which diered primarily in a pitch.
These propellers demanded careful maintenance and pitch
control assembly tended to freeze at high altitudes. The same
propellers were installed on Spitres Mk.V manufactured by
Westland. Spitres Mk.V manufactured by CBAF were traditio-
nally equipped with more reliable and popular propellers Rotol
RX5/14 and RX5/24 with metal blades, later with propellers
RX5/10 with wooden blades Jablo of a slightly smaller diameter
(3.12 meters compared to 3.28 meters of metal propeller).
Spitres Mk.Vc equipped with the four-bladed propellers could
be encountered during the second half of the conict.
Exhausts
The early Spitres Mk.V featured the exhausts with straight,
oval orice same as Spitres Mk.I. These were fairly prompt-
ly replaced by new exhausts with attened orice known as
shtail. Several variations of this type of exhaust are known.
With the introduction of 20 mm caliber Hispano cannons to Spit-
re Mk.Vb equipment it was found out that the current weapons’
heating system using the oil cooler hot air was insucient and
the cannons were freezing at the higher altitudes. Therefore,
the heating was enhanced by the hot air from the pipe running
through the exhausts exiting behind the last exhaust pipe, en-
tering the fuselage in front of the fuel tank, running through
the fuselage to the wing leading edge and further to the can-
nons. These pipes were a trademark of Spitres Mk.Vb. Spitres.
Mk.Vc received the electrical heating of the guns therefore
the aforementioned pipe was missing from their exhaust sets.
In theory because it can still be recognized in many Mk.Vc pho-
tographs. These were probably Mk.Vc converted from Mk.Vb
mating the new C wings with the old Mk.Vb fuselages
Ailerons
There were continuing problems with the fabric-covered aile-
rons on Spitres Mk.V, dating back to Spitres Mk.I and Mk.II.
Even though the all-metal ailerons were designed and tested
in the end of 1940, in the middle of 1941 they were still not
installed as a standard on the aircraft leaving the assembly li-
nes. Therefore, not only Mk.Vs converted from Mk.I and Mk.II
featured fabric-covered ailerons but the rst mass-produced
“ves” as well. Only after the Air Ministry interference in June
1941 the all-metal ailerons were introduced into the mass pro-
duction which signicantly improved the dog-ghting ability
of the Spitres that were equipped with them. This case shows
the cumbersome process of implementing technical improve-
ments into a large-scale production. The situation was so se-
rious, and nonsensical, that the American units equipped with
Spitres Mk.V supposedly replaced the fabric-covered ailerons
with plywood-covered ones.
Spitfire Mk.Vc
Spitre Mk.Vc represented the logical combination of all gra-
dual modications of the original Spitre design. Besides the
modernized bulged sliding canopy and armored glass integrated
internally into the windshield , the most important and funda-
mental change was a newly-designed and strengthened wing
(called the Universal wing or c type). Traditionally, the ability
to house variety of weapons installations is considered a main
advantage. These options were eight machine guns (variant a),
two cannons and four machine guns (variant b) or four cannons
(variant c only possible in the new c type wing but c isn’t the
designation of this option). In fact, out of all these, variant b,
two cannons and four machine guns, was absolutely dominant.
Four cannons installation was rarely used because heavy ca-
nnons had signicantly negative impact on the aircraft ight
characteristics so if the four cannons had been installed at the
factory regardless, usually two of them, mostly at inner locati-
ons, were removed at the unit level. Variant a. was practically
never installed on Spitres Mk.Vc. An important change was the
introduction of the belt-fed Hispano II cannons allowing for lar-
ger ammunition load (120 bullets per cannon as opposed to 60
bullets with the older, drum-fed Hispano Mk.I (as on the earlier
b type wing). These cannons were also less prone to jamming.
The visual indication of their installation was a missing bulge
under the cannon well which on Spitre Mk.Vb appeared in two
forms, straight, symmetrical on the older airframes and kid-
ney-shaped, asymmetrical on the newer aircraft. In comparison,
the upper bulge above the cannon well on Mk.Vc appeared in at
least three dierent shapes based on the anticipated armament
variant and was also subject to a certain improvisation at the
unit level. Another fundamental change was the landing gear
re-design, featuring strengthened gear legs’ attachments and
increased rake, moving the wheels 5 cm forward in compari-
son to the older Spitre versions. This solution improved the
aircraft stability during taxiing and ground maneuvers and
was visually recognizable by a new, elliptical wheel well shape.
Undercarriage retraction was already standard on all Mk.V Spit-
res with a hydraulic pump driven by the engine. The wings and
fuselage design were strengthened by the application of thicker
sheet metal skin and later Mk.Vc batches featured ush rivets
on the rear fuselage. The later aircraft also featured the hori-
zontal tail surfaces with modied weight balance, pressurized
fuel tanks, submersible fuel pump in the bottom tank and six
single exhaust pipes on each side of the engine. Later Spitres
Mk.Vc batches were almost exclusively powered by Merlin en-
gines series 50 and 55/56 with membrane-type carburetor. Mo-
reover, Merlin 55/56 featured the separate piston blocks. Their
specic versions were distinguished by compressors tuned for
the optimal output at various operational altitudes.
Short wing/low level
Spitfires LF Mk.V
In the course of 1942, the number of both defensive and oen-
sive, low altitude missions increased. It led to the requirement
to modify Spitre Mk.V design in order to optimize their low al-
titude performance. Low level Spitres LF Mk.Vb and LF Mk.Vc
received Merlin engines series M (Merlin 45M, 50M and 55M)
with smaller compressor diameter which gave the engine the
highest output at low altitudes. In case of Merlin 45M it was
1,585 hp (1,182 kW) at 838 meters altitude. Another modicati-
on was the wing’s strengthening design by means of two strips
on the wing upper surfaces above wheel wells area. Some of
the Spitres LF Mk.V received “clipped wings”, in fact shorter
wingtips reducing the wingspan to 9.8 meters. This modi-
cation improved the rate-of-roll and moderately increased the
maximum speed. The wingtips varied, both short and long ones
could be installed. Therefore, the short wingtips do not deci-
dedly identify the LF version.
Auxiliary fuel tanks
There were several types of auxiliary tanks of dierent ca-
pacity developed in order to extend Spitre Mk.V range. The
smallest one was 30gal (136 liters) tank introduced into service
in September 1941 extending the range to 1167 km. It was fo-
llowed by a larger, 45gal tank (204.5 liters). Both tanks were
of so-called blister-type (also known as slipper-type) referring
to the tank’s curved outline on the bottom and upper at sur-
face mating with fuselage and wing’s center-plane. Both were
droppable. The cylinder-shaped 45gal tanks were also used. In
Malta, 44gal (200 l) cylindrical tanks from Hurricanes Mk.II were
used, attached in pairs, next to each other under the fuselages.
In the end of 1941, 90gal (409 l) non-droppable y-over tank
was introduced extending the range to 1,988 km. In 1942 even
170gal (773 l) y-over tank arrived extending the range to 2,334
km, however at the cost of signicantly worse ight characte-
ristics. Both of these tanks were of the blister-type, there was
also a cylindrical 170gal y-over tank. In the actual operations,
since the middle of 1942, the combination of 29gal (132 l) tank
mounted in the fuselage behind the cockpit and a 170gal drop
tank was used. This combination allowed an extended range to
2,615 km at the maximum altitude of 4,575 m.
Tropical filters
In the dusty tropical and sub-tropical environments, the engi-
ne was subject to potential damages caused by sucked-in dust.
To lower this risk Vokes company designed a voluminous, fully
covered lter which formed a typical chin under the aircraft
nose. The worsened aerodynamics together with the lower
pressure of the entering air on such modied aircraft resulted
in the maximum speed drop by approximately 12 kph, which
was actually better value than the anticipated drop by 37 kph.
These tropicalized versions were quite widely used in both Me-
diterranean and Far East theaters of operations. Tropicalized
Early production Spitre Mk.V manufactured in October 1941 with symmetrical lower bulges under the cannon well, enlarged
cooler, older canopy style with exterior armor and hinged window hatch. The aircraft still lacks the armament, it’s equipped with
the De Havilland propeller and newer type of radio Tr.1133 (photo: Simon Erland).
HISTORY
INFO Eduard
9
December 2025
Info EDUARD