Staff Writer (Updated: 7/6/2016):
NOTE 1: While the Spitfire production line relied on roman numeral "marks" to identify each type, these did not necessarily appear in chronological order as one might suspect. After 1942, the Royal Air Force moved away from Roman numeral designation marks.
NOTE 2: The Spitfire was primarily produced with four various wing types which directly dictated available armament options. The Type A wing fitted 8 x 7.7mm Browning machine guns while the Type B wing allowed 2 x 20mm Hispano cannons along with 4 x 7.7mm machine guns. The Type C proved the "universal win" fit intended to speed production and allow for flexible armament options: 8 x 7.7mm machine guns, 2 x 20mm cannons with 4 x 7.7mm machine guns or 4 x 20mm cannons. Additionally provision for 250lb bombs was added. The final wing - the D Type - was generally fitted to reconnaissance models which lost their wing armament and gained additional internal fuel stores for increased ranges.
Supermarine Spitfire Development
Headed by engineer Reginald J. Mitchell, the small Supermarine concern developed several award-winning racing seaplanes during the interwar years prior to its development of the excellent Spitfire fighter aircraft series. When the chance came to produce a new modern fighter aircraft for the Royal Air Force, qualities of these racers were implemented into the new fighter to create an instant classic including the identifiable elliptical wings which assisted in maximizing lift. Design work began in 1935 and the single prototype, known as the K5054 (company Type 300), went airborne for the first time on March 5th, 1936 with a Rolls-Royce Merlin II/C engine of 900 horsepower under the hood driving a two-bladed propeller. The aircraft exhibited vary clean lines with its long nose assembly housing the engine and the cockpit just aft at center. Aft of the fuselage was a raised spine which allowed for more internal volume at the expense of obstructed rear views. The wings were low-set monoplane assemblies with their distinct elliptical shape that was so pronounced in the design. The empennage was conventional with a curved vertical tail fin and applicable curved horizontal planes. The undercarriage utilized a narrow-track design in which the weight of the aircraft was displaced through the fuselage into the landing gear legs as opposed to mounting these under the wings as in other aircraft. Both main landing gears were full retractable with a tail wheel at the rear. Armament would be concentrated across several bays held each wing and primarily consisting of machine gun armament though this would change over time. The type proved so promising early on that it was immediately placed on order for 370 examples as the Spitfire Mk I, adopted for service on August 4th, 1938. Ultimately, the Spitfire series would comprise a total of 20 major production marks - a stunning achievement for a single aircraft, though undoubtedly helped by the prospect of world war.