Supermarine Southampton
The Supermarine Southampton was a British military flying boat designed by R. J. Mitchell and built by Supermarine for the Royal Air Force. Developed from Mitchell's civilian Swan, it entered service in August 1925 and became the RAF's principal inter-war patrol flying boat, famous for long-distance formation cruises such as the Far East Flight of 1927-28. The RAF took eighteen wooden-hulled Mk Is and forty-eight metal-hulled Mk IIs, and the type served for eleven years; the restored wooden fuselage of one Mk I is on display at the RAF Museum in London.
Why It Mattered
History of War identifies the Southampton as the RAF's first flying boat designed after the First World War, and the RAF Museum calls it one of the most successful flying boats the service ever used. It arrived when the RAF was looking to replace its First World War Felixstowe flying boats, and R. J. Mitchell's development of his civilian Swan design proved an immediate success. Its standing rested on reliability: the museum records an eleven-year service life, a span only the Sunderland later exceeded. The type became famous for long-distance formation flights across the Empire, above all the Far East Flight's cruise from Felixstowe to Singapore in 1927 and 1928.
Design Notes
Mitchell based the Southampton on his single Swan flying boat, and the type was ordered off the drawing board in August 1924. It was a two-bay biplane with a triple fin and rudder and two engines carried between the wings; a crew of five served three Lewis gun positions, in the nose and amidships. The Mk I had a wooden hull with a double bottom, and its aircraft were powered by two Napier Lion V engines. The Mk II replaced the wooden structure with a single-skin metal hull: the new hull was 500 lb lighter, and it avoided the extra weight a wooden hull took on as it soaked up water. Powered by 500 hp Napier Lion VA engines, the lighter Mk II gained more than 500 miles of range.
Operational History
The first of the six aircraft ordered in August 1924 made its maiden flight on 10 March 1925. The type entered service that summer with No. 480 (Coastal Reconnaissance) Flight; the RAF Museum dates the entry to August 1925. A second order for twelve more Mk Is was placed in July 1925, and all eighteen aircraft had been delivered by the end of 1926. The RAF's later deliveries were forty-eight metal-hulled Mk IIs, and in a programme begun in 1929 the surviving wooden-hulled aircraft were rebuilt with metal hulls. History of War counts 78 Southamptons in all, the majority of them Mk IIs. The flights that made the type's name were long-distance cruises, flown partly as flag-waving exercises and partly to gain experience of operating flying boats in remote waters. The most famous took four Far East Flight aircraft 27,000 miles between October 1927 and 11 December 1928, travelling from Felixstowe to Singapore via the Mediterranean and India and circumnavigating Australia. At Singapore the flight was reformed as No. 205 Squadron. Wikipedia records that exports followed: eight aircraft were sold to Argentina for coastal reconnaissance patrols, six were bought by Turkey, Australia bought two ex-RAF Mk Is, and the Imperial Japanese Navy bought one aircraft, later converted into an 18-passenger airliner. The Southampton remained in RAF service for eleven years.
Afterlife
The Southampton's development line outlived the type itself: History of War records that the later Mk IV became the Scapa and the Mk V the Stranraer. History of War also presents the Southampton as the first in Mitchell's series of successful military flying boats. What survives of the type is the restored wooden fuselage of the Mk I N9899. The RAF Museum lists N9899 on display at its London museum, in Hangars 3 and 4. The hull is wooden, as the Mk I hulls were.