An all-metal construction, single-engine, single-seater monoplane fighter. The Spitfire (Prototype K5054) made its first flight on March 6, 1936, and mass production began in May of 1938. In August of the same year, the plane entered the service of the RAF. It would become one of the best fighters of World War II.
The Mk.I variant was equipped with type A wings and eight wing-mounted Colt-Browning Mk.II .303 (7.7mm) machine guns. From the 194th plane onward, a Rolls-Royce Merlin III engine was used instead of the original Merlin II. The first production Spitfire had a twin-blade wooden propeller. From the 74th plane onward, a three-bladed De Havilland 5/21 propeller was used instead. The De Havilland 5/20, also a three-bladed metal propeller, became standard by the end of 1939, and was used on the majority of Spitfires.
The first Spitfires had a primitive targeting system consisting of a ringed sight, but by July of 1939 a more sophisticated collimator sight, the GM2 Mk.II, began to be used. Machines already released were refitted with the new sights when possible.
With the advent of the Spitfire Mk.IB, with type B wings, in 1940, the older planes received the designation Mk.IA.
The Spitfire Mk.IA fighters fought from the very first day of the war onward, and were particularly active in the Battle of Britain. They were in part responsible for the RAF's victory over the Luftwaffe. In 1941, they were replaced with the Spitfire Mk.V. A total of 1,567 Mk.I planes were produced.