Supermarine Spitfire

The Spitfire will always be compared to its main adversary, the [Vous devez être inscrit et connecté pour voir ce lien];
both followed similar design philosophies of marrying a small, streamlined airframe to a powerful liquid-cooled [Vous devez être inscrit et connecté pour voir ce lien]

Design and development


R. J. Mitchell's 1931 design to meet [Vous devez être inscrit et connecté pour voir ce lien] for a new and modern fighter capable of 251 mph (404 km/h), the [Vous devez être inscrit et connecté pour voir ce lien], resulted in an open-cockpit monoplane with bulky gull-wings and a large fixed,
spatted [Vous devez être inscrit et connecté pour voir ce lien] powered by the 600 horsepower (450 kW) [Vous devez être inscrit et connecté pour voir ce lien] engine.

This made its first flight in February 1934.

This aircraft was a big disappointment to Mitchell and his design team, who immediately embarked on a series of "cleaned-up" designs, using their experience with the [Vous devez être inscrit et connecté pour voir ce lien] seaplanes as a starting point.

Of the seven designs tendered to F/30, the [Vous devez être inscrit et connecté pour voir ce lien] biplane was accepted for service.

Le Type 224

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

Mitchell had already begun working on a new aircraft, designated Type 300, based on the Type 224. With a retractable gear and the wingspan reduced by 6 ft (1.8 m), the aircraft was submitted to the Air Ministry in July 1934, but again was not accepted.

The design evolved through a number of changes, including an enclosed cockpit, oxygen-breathing apparatus, even smaller and thinner wings, and the newly-developed, more powerful Rolls-Royce [Vous devez être inscrit et connecté pour voir ce lien] V-12 engine, later named the Merlin.

In November 1934, Mitchell, with the backing of Supermarine's owner, Vickers-Armstrongs, started detailed design work on the Type 300.

Type 300

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

The Air Ministry issued a contract AM 361140/34 on 1 December 1934, providing [Vous devez être inscrit et connecté pour voir ce lien]10,000 for the construction of Mitchell's "improved F7/30 design".

On 3 January 1935, the Air Ministry formalised the contract and a new Specification F10/35 was written around the
aircraft.

In April 1935 the armament was changed from two .303 in (7.7 mm) [Vous devez être inscrit et connecté pour voir ce lien] in each wing to four .303 in (7.7 mm) [Vous devez être inscrit et connecté pour voir ce lien], following a recommendation by Squadron Leader Ralph Sorley of the Operational Requirements section at the Air Ministry.

On 5 March 1936 the prototype (K5054) took off on its first flight from [Vous devez être inscrit et connecté pour voir ce lien] (later [Vous devez être inscrit et connecté pour voir ce lien] Airport).

At the controls was [Vous devez être inscrit et connecté pour voir ce lien], chief test pilot for Vickers (Aviation) Ltd., who was reported in the press as saying "Don't touch anything" on landing.

This eight minute flight came four months after the maiden flight of the contemporary Hurricane.

K5054 was fitted with a new propeller and Summers flew the aircraft on 10 March; during this flight the undercarriage was retracted for the first time.

After the fourth flight a new engine was fitted, and Summers left the test-flying to his assistants, [Vous devez être inscrit et connecté pour voir ce lien] and George Pickering.

They soon discovered that the Spitfire was a very good aircraft, but not perfect.

The rudder was over-sensitive and the top speed was just 330 mph (528 km/h), little faster than [Vous devez être inscrit et connecté pour voir ce lien]'s new
Merlin-powered Hurricane.

A new and better-shaped wooden propeller meant the Spitfire reached 348 mph (557 km/h) in level flight in mid-May, when Summers flew K5054 to [Vous devez être inscrit et connecté pour voir ce lien] and handed the aircraft over to Squadron Leader Anderson of the [Vous devez être inscrit et connecté pour voir ce lien] (A&AEE).

Here, Flight Lieutenant Humphrey Edwardes-Jones took over the prototype for the RAF.

He had been given orders to fly the aircraft and then to make his report to the Air Ministry as soon as he landed.

Edwardes-Jones made a positive report; his only request was that the Spitfire be equipped with an undercarriage position indicator.

A week later, on 3 June 1936, the Air Ministry placed an order for 310 Spitfires, before any formal report had been
issued by the A&AEE; interim reports were later issued on a piecemeal basis.

Le K 5054 sans peinture

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

The British public first saw the Spitfire at the [Vous devez être inscrit et connecté pour voir ce lien] air-display on Saturday 27 June 1936.

Although full-scale production was supposed to begin immediately, there were numerous problems which could not be overcome for some time and the first production Spitfire, K9787, did not roll off the [Vous devez être inscrit et connecté pour voir ce lien], [Vous devez être inscrit et connecté pour voir ce lien] assembly line until mid-1938.

The first and most immediate problem was that the main Supermarine factory at Woolston was already working at full capacity fulfilling orders for [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien] flying boats.

Although outside contractors were supposed to be involved in manufacturing many important Spitfire components, especially the wings, [Vous devez être inscrit et connecté pour voir ce lien] (the parent company) were reluctant to see the Spitfire being manufactured by outside concerns and were slow to release the necessary blueprints and sub-components.

As a result of the delays in getting the Spitfire into full production, the Air Ministry put forward a plan that production of the Spitfire be stopped after the initial order for 310, after which Supermarine would build [Vous devez être inscrit et connecté pour voir ce lien].

The managements of Supermarine and Vickers were able to persuade the Air Ministry that the problems could be overcome and further orders were placed for 200 Spitfires on 24 March 1938, the two orders covering the K, L and N
prefix serial numbers.

Airframe


In the mid-1930s, aviation design teams worldwide started developing a new generation of all-metal, low-wing fighter aircraft.

The French [Vous devez être inscrit et connecté pour voir ce lien] and Germany's [Vous devez être inscrit et connecté pour voir ce lien], for example, were designed to take advantage of new techniques of [Vous devez être inscrit et connecté pour voir ce lien] construction and the availability of new high-powered, liquid-cooled, in-line aero engines.

They also featured refinements such as retractable undercarriages, fully enclosed cockpits and low drag, all-metal wings (all introduced on civil airliners years before but slow to be adopted by the military, who favoured the simplicity and manoeuvrability of the biplane).

Mitchell's design aims were to create a well-balanced, high-performance bomber interceptor and fighter aircraft capable of fully exploiting the power of the Merlin engine while being relatively easy to fly.

At the time, no enemy fighters were expected to appear over Great Britain—to carry out the mission of home defence, the design was intended to climb quickly to meet enemy bombers.

The Spitfire's airframe was complex: the streamlined, [Vous devez être inscrit et connecté pour voir ce lien] fuselage featured a large number of [Vous devez être inscrit et connecté pour voir ce lien] built up from a skeleton of 19 [Vous devez être inscrit et connecté pour voir ce lien], starting from the main engine bulkhead (frame number one) to the tail unit attachment frame.

Aft of the engine bulkhead were five half-frames to accommodate the fuel tanks and cockpit.

From the seventh frame, to which the pilot's seat and (later) armour plating was attached, to the nineteenth, which
was mounted at a slight forward angle just forward of the tailfin, the frames were oval, each reducing slightly in size, and each with numerous holes drilled through them to lighten them as much as possible without weakening them.

The U shaped Frame 20 was the last frame of the fuselage proper and the frame to which the tail unit was attached.

Frames 21, 22 and 23 formed the tailfin; frame 22 incorporated the tailwheel opening and frame 23 was the [Vous devez être inscrit et connecté pour voir ce lien] post.

Before being attached to the main fuselage the tail unit frames were held in a jig and the eight horizontal tail formers were riveted to them.

A combination of 14 [Vous devez être inscrit et connecté pour voir ce lien] and two main longerons helped form a light but rigid structure to which sheets of [Vous devez être inscrit et connecté pour voir ce lien] stressed skinning were attached.

The fuselage plating was 24, 20 and 18 [Vous devez être inscrit et connecté pour voir ce lien] in order of thickness towards the tail, while the vertical fin structure was completed using short longerons from frames 20 through 23, before being covered in 22 gauge plating.

There was ample room for camera equipment and fuel tanks which were to be fitted during the Spitfire's operational service life.

MK I

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