Supermarine Spitfire

After the first few flights K5054 was returned to the factory, reappearing about 10 days later with an overall pale blue-grey finish, using a high-gloss automotive [Vous devez être inscrit et connecté pour voir ce lien]-[Vous devez être inscrit et connecté pour voir ce lien] applied by people from the Rolls-Royce car plant (there is still some uncertainty over the actual colour).

The tailskid had been replaced by a Dowty manufactured, fully castering tail-wheel unit.

The tailwheel was to be modified several times on the prototype, including using twin tailwheels each smaller than the single wheel which was later standardised.

The engine cowlings had been altered slightly and the angled fin tip had become straight topped - the rudder balance was correspondingly reduced in size.

Undercarriage fairings had now been fitted to the legs.

Although the propeller was still the fixed-pitch, wooden bladed unit the pitch had been changed in an attempt to increase the top speed.

Several different types of propeller unit were to be fitted to the prototype.

Later in 1936, the wings were replaced with a set which, for the first time, incorporated the famous 8 × .303" Browning machine-gun armament.

Also, some time in late 1936, sets of three special "flame dampening" exhaust stacks were fitted to the exhaust ports.

The Spitfire was to fly in this form until 22 March 1937, when a major oil pressure failure led to a "forced-landing" with the undercarriage up.

When K5054 re-emerged from the factory the pale blue finish, which had deteriorated badly, was replaced by the soon to be familiar RAF "Dark Earth"/"Dark Green" camouflage on the top surfaces and a silver finish underneath.

This finish was to be worn for the remainder of the airframe's life.

On 19 September 1938 the Spitfire was flown for the first time with ejector exhausts, developed for the Merlin by
Rolls-Royce.

With these it was found that the exhausts developed 70 pounds of thrust, equivalent to about 70 hp at 300 mph.

K5405 came to the end of its flying life on 4 September 1939 while being tested at [Vous devez être inscrit et connecté pour voir ce lien].

After a misjudged landing K5404 bounced and then tipped over on its back, trapping the pilot Flt Lt. White.

White died four days later because of serious neck injuries which were caused by the design of the anchor point to the Sutton harness; this accident lead to the system being redesigned.

Parts of the prototype went to the Photographic Department at Farnborough where they were used to test camera installations in the wings and fuselage of reconnaissance Spitfires.

Mk I (Type 300)

In 1936, before the first flight of the prototype, the [Vous devez être inscrit et connecté pour voir ce lien] placed an order for 310 Spitfires.

Already the biggest problem facing the entire programme was the inability of Supermarine to build the new fighter in the required numbers.

In spite of the promises made by the Chairman of [Vous devez être inscrit et connecté pour voir ce lien] (the parent company of
[Vous devez être inscrit et connecté pour voir ce lien]) that the company would be able to deliver Spitfire at a rate of five a week, starting 15 months after the order was placed, it soon became clear that this would not happen.

In 1936 the Supermarine company employed 500 people and was already engaged in fulfilling orders for 48 [Vous devez être inscrit et connecté pour voir ce lien] amphibian reconnaissance aircraft and 17 [Vous devez être inscrit et connecté pour voir ce lien] patrol flying boats.

In addition the small design staff, which would have to draught the blueprints for the production aircraft, was already working at full stretch.

Although it was obvious that most of the work would have to be sub-contracted to outside sources, the Vickers-Armstrongs board was reluctant to allow this to be done.

When, finally, other companies were able to start building Spitfire components there were continual delays because either parts provided to them would not fit or the blueprints were inadequate;
the sub-contractors themselves faced numerous problems building components which in many cases were more advanced and complicated than anything they had faced before.

As a result of these problems the first production Spitfire K9788 was not delivered to the RAF until July 1938 with front line service commencing in August 1938.

For a time the future of the Spitfire was in serious doubt, with the Air Ministry suggesting that the programme be abandoned and that Supermarine change over to building the [Vous devez être inscrit et connecté pour voir ce lien] under licence.

The managements of Supermarine and Vickers were able to finally convince the Air Ministry that the problems would be sorted out and, in 1938, an order was placed with the [Vous devez être inscrit et connecté pour voir ce lien] for an additional 1,000 Spitfires to be built at new factory at [Vous devez être inscrit et connecté pour voir ce lien].

This was followed in 1939 by an order for another 200 from [Vous devez être inscrit et connecté pour voir ce lien] and, only a few months later, another 450.

This brought the total to 2,160, making it one of the largest orders in RAF history.

Over the next three years a large number of modifications were made, most as a result of wartime experience.

The early Mk Is were powered by the 1,030 hp (768 kW) [Vous devez être inscrit et connecté pour voir ce lien] engine driving an Aero-Products "Watts" 10 ft 8 in (3.3 m) diameter two-blade wooden fixed-pitch propeller, weighing 83 lb (38 kg).

All Merlin I to III series engines relied on external electric power to start; a well known sight on RAF fighter airfields was the "trolley acc" (trolley accumulator) which was a set of powerful batteries which could be wheeled up to
aircraft.

The lead from the "Trolley Acc" was plugged into a small recess on the starboard side cowling of the Spitfire.

On Supermarine-built aircraft a small brass instruction plate was secured to the side cowling, just beneath the starboard exhausts.

Early on in the Spitfire's life it was found that at altitudes above about 15,000 ft (4,572 m), any condensation could freeze in the guns.

The system of gun heating, described above, was introduced on the 61st production Mk I.

At the outset of World War II, the flash-hiders on the gun muzzles were removed and the practice of sealing the gun ports with fabric patches was instituted.

The patches kept the gun barrels free of dirt and debris and allowed the hot air to heat the guns more efficiently.

When the guns were fired the patches were shot through, these were replaced by the ground-crew during rearming.

Early production aircraft were fitted with a ring and bead [Vous devez être inscrit et connecté pour voir ce lien], although provision had been made for a reflector sight to be fitted once one had been selected. In July 1938, the [Vous devez être inscrit et connecté pour voir ce lien] GM 2 was selected as the standard RAF reflector gunsight and was fitted to the Spitfire from late 1938.

These first production Mk Is were able to reach a maximum speed of 362 mph (583 km/h) at 18,500 ft (5,600 m), with a maximum rate of climb of 2,490 ft/min at 10,000 ft (3,000 m).

The service ceiling (where the climb rate drops to 100 ft/min) was 31,900 ft (9,700 m).

From the 78th production airframe, the Aero Products propeller was replaced by a 350 lb (183 kg) [Vous devez être inscrit et connecté pour voir ce lien] 9 ft 8 in (2.97 m) diameter, three-bladed, two-position, metal propeller, which greatly improved take-off performance, maximum
speed and the [Vous devez être inscrit et connecté pour voir ce lien].

It also started the incremental weight increases which continued through the life of the airframe.

From the 175th production aircraft, the Merlin Mk III, which had a "universal" propeller shaft able to take a de Havilland or [Vous devez être inscrit et connecté pour voir ce lien] propeller was fitted.

Following complaints from pilots a new form of "blown" canopy was manufactured and started replacing the original "flat" version in early 1939.

This canopy improved headroom and enabled better vision laterally, and to the rear.

Late in 1940, a [Vous devez être inscrit et connecté pour voir ce lien] designed quick release mechanism, allowing the pilot to quickly jettison the cockpit canopy, began to be retroactively fitted to all Spitfires.

The system employed unlocking pins, actuated by cables operated by the pilot pulling a small, red rubber ball mounted on the canopy arch.

When freed, the canopy was taken away by the slipstream.

Also in early 1939 the manual hand-pump for operating the undercarriage was replaced by a hydraulic system driven by a pump mounted in the engine bay.

Before this change was made pilots had the awkward task of having to pump the undercarriage up with their right hand while simultaneously trying to keep the Spitire controlled using the left handon the control column.

This often led to a condition known as "Spitfire knuckle" where pilots skinned their hand on the side of the cockpit
while pumping.

Spitfire Is incorporating these modifications were able to achieve a maximum speed of 367 mph (591 km/h) at 18,600 ft (5,700 m), with a maximum rate of climb of 2,150 ft/min at 10,000 ft (3,000 m).

The service ceiling was 34,400 ft (10,500 m).

Un clip sur le proto Spitfire :

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A [Vous devez être inscrit et connecté pour voir ce lien] was fitted in the bay directly behind the pilot. At first this was mounted low in the fuselage.

Starting in the N30 series the regulator was repositioned to the rear of the seat bulkhead, appearing low in the rear transparency.

From N32, the regulator, which was under a black, cylindrical cover, was secured to the bulkhead directly behind the pilot's headrest.

Other changes were made later in 1939 when a simplified design of [Vous devez être inscrit et connecté pour voir ce lien] was introduced and the "rod" aerial mast was replaced by a streamlined, tapered design.

Also, to improve protection for the pilot and fuel tanks, a thick, laminated glass, bullet proof plate was fitted to the curved, one piece windscreen and a 3 mm thick cover of light alloy was fitted over the top of the two fuel tanks.

From about mid-1940, 73 pounds (33 kg) of armoured steel plating was provided in the form of head and back protection on the seat bulkhead and covering the forward face of the glycol header tank.

In addition, the lower petrol tank was fitted with a fire resistant covering called "Linatex", whach was later replaced with a layer of self-sealing rubber.

In June 1940 de Havilland began manufacturing a kit to convert their two pitch propeller unit to a [Vous devez être inscrit et connecté pour voir ce lien].

Although this propeller was a great deal heavier than the earlier types (500 lb (227 kg) compared with 350 lb (183 kg)) it provided another substantial improvement in take-off distance and climb rate.

Starting on 24 June de Havilland engineers began fitting all Spitfires with these units and by 16 August every Spitfire and [Vous devez être inscrit et connecté pour voir ce lien] had been modified.

"Two step" rudder pedals were fitted to all frontline Spitfires; these allowed the pilot to lift his feet and legs higher during combat, improving his "[Vous devez être inscrit et connecté pour voir ce lien]" threshold and allowing him to pull tighter sustained turns.

Another modification was the small rear view mirror which was added to the top of the windscreen: an early "shrouded" style was later replaced by a simplified, rectangular, adjustable type.

MK IIa

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Starting in September 1940, [Vous devez être inscrit et connecté pour voir ce lien] equipment was installed.

This weighed about 40 lb (18 kg) and could be identified by wire aerials strung between the tailplane tips and rear fuselage.

Although the added weight and the aerials reduced maximum speed by about two mph (three km/h), it allowed the aircraft to be identified as "friendly" on radar: lack of such equipment was a factor leading to the [Vous devez être inscrit et connecté pour voir ce lien].

At about the same time new [Vous devez être inscrit et connecté pour voir ce lien] T/R Type 1133 radios started replacing the [Vous devez être inscrit et connecté pour voir ce lien] TR9 sets.

These had first been fitted to Spitfires of [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien] in May 1940, but ensuing production delays meant the bulk of Spitfires and Hurricanes were not fitted for another five months.

The pilots enjoyed a much clearer reception which was a big advantage with the adoption of Wing formations throughout the RAF in 1941.

The new installation meant that the wire running between the aerial mast and rudder could be removed, as could the triangular "prong" on the mast.

Weight increases and aerodynamic changes led to later Spitfire Is having a lower maximum speed than the early production versions.

This was more than offset by the improvements in take-off distance and rate of climb brought about by the constant speed propeller units.

During the [Vous devez être inscrit et connecté pour voir ce lien] Spitfire Is equipped with constant-speed propellers had a maximum speed of 353 mph
(568 km/h) at 20,000 ft (6,100 m), with a maximum rate of climb of 2,895 ft/min at 10,000 ft (3,000 m).

Although the Merlin III engine of Spitfire Is had a power rating of 1,030 hp (768 kW), supplies of 100 [Vous devez être inscrit et connecté pour voir ce lien] fuel from the United States started reaching Britain in early 1940.

This meant that an "[Vous devez être inscrit et connecté pour voir ce lien]" of +12 pounds per square inch was available for five minutes, with pilots able to call on 1,310 hp (977 kW) at 3,000 rpm at 9,000 feet (2,743 m).

This boosted the maximum speed by 25 mph (40 km/h) at sea level and 34 mph (55 km/h) at 10,000 ft (3,000 m) and improved the climbing performance between sea level and full throttle height.

The extra boost wasn't damaging as long as the limitations set forth in the pilot's notes were followed.

As a precaution, however, if the pilot had resorted to emergency boost, he had to report this on landing and it had to be noted in the engine log book.

The extra boost was also available for the Merlin XII fitted to the Spitfire II.