Supermarine Spitfire (late Merlin-powered variants)

The British Supermarine Spitfire was facing several challenges by mid-1942. The debut of the formidable Focke-Wulf Fw 190 in late 1941 had caused problems for RAF fighter squadrons flying the latest Spitfire Mk Vb. Rolls-Royce engineers were already working on a new version of the Merlin incorporating a two-stage supercharger; the combination of the improved Merlin and the Spitfire Mk Vc airframe in a "stop-gap" design allowed the RAF to combat the Fw 190 on equal terms.

In a second stream of development Supermarine was working on an improved, reinforced, Spitfire airframe which incorporated several new features and was designed for the Merlin 60 and 70 series engines. This new airframe later formed the basis for the Rolls-Royce Griffon powered Spitfires. This article presents a history of the Spitfire powered by two-stage engine variants and also describes some of the "drawing board" projects and experimental Spitfires. The Griffon powered variants are described in a separate article.

Wing types

The majority of the Spitfires from the Mk VIII on, used three basic wing types; C, D and E

C type

Also known as the "universal wing" the new design was standard on the majority of Spitfires built from mid 1942. The design of the wing was altered to reduce labour and manufacturing time and carry various armaments: A type (8 x .303 machine guns, 4 per wing), B type (4 x .303 machine guns (2 per wing) and 2 x 20mm Hispano cannons (1 per wing), or four 20 mm Hispano cannon.

The undercarriage mountings were redesigned and the undercarriage doors were bowed in cross-section allowing the legs to sit lower in the wells, eliminating the upper-wing blisters over the wheel wells and landing gear pivot points.