Supermarine Spitfire

Spitfire Floatplanes (types 355 & 359)


With the German invasion of Norway in April 1940 the RAF took an interest in the concept of using [Vous devez être inscrit et connecté pour voir ce lien]
fighters in areas where airfields were not immediately available.

To this end a Spitfire Mk I R6722 was taken in hand at the [Vous devez être inscrit et connecté pour voir ce lien] factory to be modified and mounted on [Vous devez être inscrit et connecté pour voir ce lien] floats.

Tank tests were carried out at [Vous devez être inscrit et connecté pour voir ce lien], using a 1/7th scale model, it was found that the concept was basically sound, although the vertical tail surfaces would need to be enlarged to counter-balance the side area of the floats.

The end of the Battle of Norway and the need for as many Spitfires as possible meant that R6772 was converted
back to an ordinary fighter without being flown

With the entry of Japan into the war the concept was revived in early 1942.

A Spitfire V W3760 was fitted with a pair of floats 25 ft 7 in (7.8 m) long, mounted on cantilever legs.

This aircraft was powered by a Merlin 45 driving a four bladed propeller of 11 ft 3 in (3.43 m) diameter (3.4 m).

A Vokes filter was fitted to the carburettor air intake and under the tail an extra fin extension was added.

Other changes included external lifting points forward of and behind the cockpit and a spin-recovery parachute with a rudder balance-horn guard.

The Spitfire floatplane was first flown on 12 October 1942 by Jeffrey Quill.

Soon afterwards the Vokes filter was replaced by an Aero-Vee filter, similar to that on later Merlin 61 series aircraft, which was extended to prevent water entry, and full Mk VB armament was installed.

Two more VBs EP751 and EP754 were converted by Folland and all three floatplanes were transported to Egypt, arriving in October 1943.

At the time it was thought that the floatplanes could operate from concealed bases in the [Vous devez être inscrit et connecté pour voir ce lien] Islands, disrupting supply lines to German outposts in the area which relied on resupply by transport aircraft.

This scheme came to naught when a large number of German troops, backed by the Luftwaffe, took over the British held islands of [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien].

No other role could be found for the floatplane Spitfires, which languished in Egypt, operating from the [Vous devez être inscrit et connecté pour voir ce lien].

Specifications for the VB based floatplane included a maximum speed of 324 mph (521 km/h) at 19,500 ft (521 km/h at 5,943 m), a maximum rate of climb of 2,450 ft/min at 15,500 ft (12.45 m/s at 4,724 m) and an estimated service ceiling of 33,400 ft (10,180 m).

In the spring of 1944, with the prospect of use in the Pacific Theatre, a Spitfire IX MJ892 was converted to a floatplane.

This used the same components as the earlier Mk VB conversions.

Jeffrey Quill wrote:

"The Spitfire IX on floats was faster than the standard Hurricane.
Its handling on the water was extremely good and its only unusual feature was a tendency to "tramp" from side to side on the floats, or to "waddle" a bit when at high speed in the plane."

Soon after testing started the idea of using floatplane fighters was dropped and MJ982 was converted back to a landplane.

Five aircraft were converted:

• Mk I - [Vous devez être inscrit et connecté pour voir ce lien]
  
• F.Mk Vb - W3760
  
• Mk V - EP751 and EP754
  
• Mk IXb - MJ892
  

Supermarine 312 : This was the basic Mk I Spitfire adapted to take four 20 mm Oerlikon cannon mounted in modified wings.

The radiator and oil cooler were moved from under the wing to a duct under the fuselage.

This was R J Mitchell's last design before his death in 1937.

Supermarine 324, 325 and 327 :

These were designs for twin-engined fighters which used the same construction techniques and the same elliptical wing [Vous devez être inscrit et connecté pour voir ce lien] as the Spitfire.

All three designs used tricycle undercarriages with the primary engines being Merlins with an alternative being the [Vous devez être inscrit et connecté pour voir ce lien].

The 324 and 325 were intended to carry an armament of 12 .303 calibre Brownings in groups of six in each outer wing while the 327 had the armament changed to six 20 mm Hispanos mounted in the wingroots.

The 324 and 327 used conventional tractor engines while the 325 used pusher engines.

L'usine en 1924

[Vous devez être inscrit et connecté pour voir cette image]

Supermarine Spitfire (Griffon powered variants)

[Vous devez être inscrit et connecté pour voir ce lien]


The [Vous devez être inscrit et connecté pour voir ce lien] engine was designed in answer to [Vous devez être inscrit et connecté pour voir ce lien] specifications which required 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; [Vous devez être inscrit et connecté pour voir ce lien] felt that "The good big 'un will eventually beat the good little 'un." and [Vous devez être inscrit et connecté pour voir ce lien] of [Vous devez être inscrit et connecté pour voir ce lien] 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 Spifire at the forefront of piston-engined fighter development.

This article describes the Griffon-powered Spitfire variants.

Un MK 22

[Vous devez être inscrit et connecté pour voir cette image]

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 [Vous devez être inscrit et connecté pour voir ce lien]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.

Un Rolls Royce Griffon

[Vous devez être inscrit et connecté pour voir cette image]

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 (5.08 cm) forward, making the Spitfire more stable on the ground
and reducing the likelihood of the aircraft tipping onto its nose.

The Hispano Mk IIs fitted in all cases were now belt fed from box magazines allowing for 120 rpg (the "Chattellerault" system).

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.

All later Spitfires had smaller, more streamlined blisters.

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.

During a turning combat the effectiveness of the outboard machine guns was low because if the aircraft was pulling 'G' the flexing of the wings meant that the rounds scattered in a large cone.

As the Spitfire was no longer to be used as a [Vous devez être inscrit et connecté pour voir ce lien], the retractable landing lights were no longer fitted.

Several versions of the Spitfire, starting with the H.F Mk VIIs had extra 13 gallon integral fuel tanks added to the wing leading edges between the wing-root and the inboard cannon bay.

Although many earlier Spitfires had been modified to carry bomb racks capable of carrying 250 lb (113 kg) bombs the first Spitfires to be specifically modified for the fighter-bomber role (known as Modification 1209) were those of the [Vous devez être inscrit et connecté pour voir ce lien]

The first Mk IX Spitfires started being used in the role in June 1944.

D Type


These were specifically made for the Photo-Reconnaissance Spitfires; no armament was fitted and the "D" shaped leading edges of the wings, ahead of the main spar, were adapted to become integral fuel tanks.

These were fitted to the Mk XIX.

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 (rpg) in the outer bays.
  
• 2 × [Vous devez être inscrit et connecté pour voir ce lien] 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 (this configuration was rarely fitted.)
  

The 20 mm Hispano [Vous devez être inscrit et connecté pour voir ce lien] were moved outboard and a more effective .50 calibre [Vous devez être inscrit et connecté pour voir ce lien] with 250 rpg was added to the inner gun-bay replacing the outer Browning .303s.

The first trial installation of the installation (modification 1029) 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.

Browning M2 cal 50

[Vous devez être inscrit et connecté pour voir cette image]

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 asa low altitude fighter, and the L.F 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 L.F 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 [Vous devez être inscrit et connecté pour voir ce lien] 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 (930 km/h), 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 [Vous devez être inscrit et connecté pour voir ce lien] and geared [Vous devez être inscrit et connecté pour voir ce lien] meant that the theoretical aileron reversal speed was increased to 825 mph (1,328 km/h).

The standard armament was now four 20mm Hispano IIs or the shorter, lighter Hispano V cannons each with 150 rounds per gun.