Supermarine Spitfire Mk.Ia

Supermarine gained their experience in fast and maneuverable aircraft with their design which won the Schneider Trophy Air Races. But the concept of the Spitfire really began way back in 1930 when Supermarine submitted their design (Westland and Blackburn Aircraft Companies also submitted designs) in relation for the construction of an all metal type fighter aircraft that would have a fabric covered wing area as well as tailplane sections. This was to comply with specification F.7/30.

The wings were of gull wing design, the fixed undercarriage had streamlined fairing over the wheels, and it was powered by a single Rolls Royce Goshawk engine which provided just 600 horsepower giving the Type 224 a top speed of only 228 miles per hour (367 kph). Armament was two .303 guns in the fuselage and one in each of the wheel fairing. The 224 first took to the air on 19th February 1934, and because of its poor performance it failed to be accepted as a potential fighter aircraft. Supermarine had great plans for the Type 224, but because of its failure in every department, the company had to do something quick to be able to prove to the authorities that they were capable of producing a good hard working fighter aircraft.

Supermarine knew that Sydney Camm was now in the process of designing the Hurricane at Hawker's works at Weybridge. So Reginald Mitchell set about designing a completely new type of aircraft. They stayed with the required specifications as called by F.7/30 in producing a metal bodied cantilever type fighter aircraft. Mitchell decided that the wings should be metal as well as the fuselage believing that fabric covered wings on an aircraft with a metal body at high speed would provide the aircraft with weak spots. The cockpit of the aircraft was enclosed and formed part of the design lines of the body, while the narrow undercarriage was retractable with the wheels being lifted into wheel wells under the wings.

The design was a streamlined, yet strong, aircraft that had all areas that would cause any form of resistance to wind removed. It was claimed, as the aircraft made its early test flights that not only did this Type 300 look exciting it was yet the most attractive aircraft ever designed. By the end of 1934 the Type 300 was eventually ordered as a prototype, and it was put through a further series of strenuous tests. By 1935, the aircraft with its Rolls Royce PV12 now glycol cooled engine (this engine was later to be known as the Merlin), and four .303 Browning machine guns in each wing gave a performance good, or maybe even better than expected.

The aircraft flew on official tests in March 1936, the name Type 300 was dropped and the name Spitfire was officially adopted. Initial production of the Spitfire Mk.I began in 1937. It was powered by the Rolls-Royce Merlin II of 1030 hp. This gave the Mk I a speed of 355 mph, a climb rate of 2515 ft/min, and a very high ceiling of 34,556 ft. It came equipped with no fewer than 8 .303 Vickers K machine guns, 4 in each wing.

The first 77 Mk I's had a two-bladed, fixed-pitch propeller. Subsequent aircraft received three-bladed, two-position airscrews, with fine pitch for takeoff and coarse pitch for cruising, and these were subsequently retrofitted to the earlier aircraft. Taller pilots found the headroom very restrictive and this led to the original flat cockpit canopy being replaced by the bulged version which was to become a feature of all future marks. Other improvements included the provision of an armor plated windscreen and 6mm armor panels on the rear engine bulkhead and behind the pilot's seat. Heating for the guns was also installed after it was found that they froze at high altitude.

The original armament of eight .303 Browning machine guns had been chosen because of the ready availability of this weapon but, in June 1939, two 20mm Hispano cannon were fitted to the Mk I for trails. These proved unsuccessful as the Hispano had been designed to be mounted on top of a fighter's engine block which would be solid enough to absorb the recoil. Thirty Mk I's were equipped with the twin 20mm cannons at the expense of the .303 Brownings. To distinguish the two, the Spitfire Mk I's equipped with machine guns were designated IA's, while those that had the cannons fitted were designated IB's.

At the outbreak of the Second World War, the Mk I's were the mainstay of Fighter Command along with the Hurricane and it was these that flew in Norway, in France and formed the protective cover at Dunkirk. But in June 1940, just prior to the fall of France, the Spitfire Mk I gave way to a faster and more powerful Mk II with its Merlin Mk XII power plant. In all, 1,537 Spitfire Mk IA's were built. Eventually the production of Spitfires was to become a flood that totalled 20,334 Spitfires and 2,556 related new build Seafire naval fighters. A degree of muiti-role capability was to result from the development of low-altitude clipped wings (prefix LF), and high-altitude increased-span wings (HF), the standard wing being identified as (F), and with variations of armament within these wings comprising eight machine guns (suffix A), two cannon and four machine guns (B), four cannon (C) and two cannon, two 12.7 mm (0.50 in) machine-guns and up to 1,000 lbs (454 kg) of bombs (E).

GB Planes and Specifications