Supermarine Spitfire Mk I

From racing seaplanes to a fighter

Supermarine’s chief designer Reginald J. Mitchell had designed the racing seaplanes that won the Schneider Trophy; the S.6B won it outright for Britain in 1931. When his first fighter attempt, the open-cockpit Type 224, failed, he drew an entirely new aircraft using the lessons of those racers.

The name "Spitfire" was suggested by Vickers chairman Sir Robert McLean. Mitchell did not live to see his aircraft enter service: he died of cancer in June 1937, aged 42. His deputy Joseph Smith carried the design on and led the team that developed the Spitfire throughout the war.

The elliptical wing

The wing that became the Spitfire’s signature was thin and therefore low in drag; its elliptical shape kept induced drag low while leaving room at the root for the undercarriage and guns. The Canadian engineer Beverley Shenstone had a large share in its aerodynamics.

The all-metal stressed-skin structure and the complex curved wing made it hard to build. The first orders ran late, and mass production only gathered pace as the factories got used to the design.

The Battle of Britain

In 1940 the Spitfire Mk I was the closest British match for the Bf 109 E. The Spitfire turned tighter; the Bf 109 was better in the climb and the dive, and it carried cannon. The Merlin’s float carburettor cut the engine out for a moment under negative g, so German pilots could escape by pushing over into a dive.

Two changes just before and during the battle made the Spitfire markedly stronger: constant-speed propellers and 100-octane fuel, which allowed higher boost. The ailerons were light at low speed but grew ever heavier at high speed, making it hard to roll in a dive.

Later versions

The Spitfire was developed throughout the war: in 1941 the more powerful, cannon-armed Mk V; in 1942 the Mk IX with a two-stage supercharged Merlin as an answer to the Fw 190; later, versions with the larger Griffon engine. The carrier version was called the Seafire. Production continued until 1948, and the Turkish Air Force was among the Spitfire’s users.