Supermarine Spitfire. This Supermarine Spitfire Mk VI was one of high-altitude versions of this fighter that first flew in 1941. Developed from the successful Mk V, the new version incorporated 'pointed' extended wing tips, a new four-bladed propeller and partial pressurisation for the pilot. The Mk VI had a ceiling of 11,900m (39,200 ft). Only 100 of these were built. The perceived high-altitude threat from Luftwaffe bombers never materialised and the Mk VI was outperformed by the Mk V at more conventional altitudes. This example is one of the 'Langley aircraft' tested at Langley Air Force Base, Virginia. It is now in the Smithsonian Institution's National Air and Space Museum's collection. Photographed in 1944.