of Spitfire 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 Spitfires featured the inner,

integrated armor glass. Westland-built Mk.Vc featured specific

wing cannon upper covers shaped as bulges with flattened sides

and front not used by any other manufacturer.

Spitfire Mk. V modernization

During the two and half years of Spitfires Mk.V production, the

airframe was gradually developed and improved. Already at the

beginning of manufacture they featured thicker armor in comparison 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 first batch of Spitfires Mk.V, converted from

Mk.I and Mk.II, and became one of the features distinguishing

Spitfires 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 persisted on Spitfires Mk.V. Therefore, the weapons compartment

heating was enhanced by introducing the heat from the engine 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 first Spitfires Mk.V featured the same exhausts as Mk.I and Mk.II. Then the various types of pipes with

rectangular openings (fish tails) were introduced. In the end of

production and after overhaul the “fives” received six independent exhaust pipes as featured on Spitfires Mk.IX.

Canopy

The windshield, which originally featured the armored glass

mounted on its outside, was in later “fives” modified so as the

armored glass was integrated into it in a way that it was no longer sticking out. The sliding portion of the canopy was modified

as well. In the later production batches it was not only bulging

upwards but to the sides as well (Malcom hood, modification nr.

461). This new canopy lacked the small hinged window. Most

Spitfires were equipped with laminated pilot seats.

Radio equipment

The first Spitfires Mk.V converted from Spitfires Mk.I were still

fitted with TR.9D shortwave radios with a wire antenna stretched between the antenna masts behind the cabin to the top

of the rudder. The new-built production aircraft were already equipped with the new TR.1133 and later TR.1143 VHF radios, 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 first of the converted Mk.Vs

had the IFF R.3002 identification Friend or Foe device, soon

replaced by the newer IFF device ARI 5000. Both had wire antennas between the fuselage sides and the leading edge of

the elevator. The IFF antenna on later Spitfires 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 Spitfires 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

Luftwaffe will move up to higher altitudes did not materialize

and quite the opposite happened, many missions then took place 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 original 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 orifice, named after its inventor, Beatrice Shilling.

INFO Eduard - January 2022

But it was not a perfect solution. The problem was fully resolved 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 Spitfires Mk.Vc.

Propeller

Spitfires Mk.V manufactured at mother company Supermarine

mostly featured De Havilland Hydromatic Type 5/29A, 5/39,

45/1 and 45/4 propellers which differed 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 Spitfires Mk.V manufactured by

Westland. Spitfires Mk.V manufactured by CBAF were traditionally 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).

Spitfires Mk.Vc equipped with the four-bladed propellers could

be encountered during the second half of the conflict.

Exhausts

The early Spitfires Mk.V featured the exhausts with straight,

oval orifice same as Spitfires Mk.I. These were fairly promptly replaced by new exhausts with flattened orifice known as

fishtail. Several variations of this type of exhaust are known.

With the introduction of 20 mm caliber Hispano cannons to Spitfire Mk.Vb equipment it was found out that the current weapons’

heating system using the oil cooler hot air was insufficient 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, entering the fuselage in front of the fuel tank, running through

the fuselage to the wing leading edge and further to the cannons. These pipes were a trademark of Spitfires Mk.Vb. Spitfires.

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 photographs. 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 ailerons on Spitfires Mk.V, dating back to Spitfires 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 lines. Therefore, not only Mk.Vs converted from Mk.I and Mk.II

featured fabric-covered ailerons but the first mass-produced

“fives” as well. Only after the Air Ministry interference in June

1941 the all-metal ailerons were introduced into the mass production which significantly improved the dog-fighting ability

of the Spitfires that were equipped with them. This case shows

the cumbersome process of implementing technical improvements into a large-scale production. The situation was so serious, and nonsensical, that the American units equipped with

Spitfires Mk.V supposedly replaced the fabric-covered ailerons

with plywood-covered ones.

Spitfire Mk.Vc

Spitfire Mk.Vc represented the logical combination of all gradual modifications of the original Spitfire design. Besides the

modernized bulged sliding canopy and armored glass integrated

internally into the windshield , the most important and fundamental 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 cannons had significantly negative impact on the aircraft flight

characteristics so if the four cannons had been installed at the

factory regardless, usually two of them, mostly at inner locations, were removed at the unit level. Variant a. was practically

eduard

9