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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

HISTORY

INFO Eduard8

December 2025