No. 10200. Sopwith 5F.1 Dolphin (E4764) Canadian Air Force
Aeroplane Photo Supply (APS) Photo No. 2471

Sopwith 5F.1 Dolphin

11/30/2010. Designed to provide the pilot with the best possible view in tactically important directions, the 5F.1 Dolphin was unusual in being a two-bay equi-span biplane with negative stagger. The pilot was seated with his head in the open framework connecting the upper main planes.

Primarily of fabric-covered wire-braced wooden construction with an upper centre section of steel tube, the Dolphin was powered by a 200 hp Hispano-Suiza geared eight-cylinder water-cooled engine in its initial production form.

Armament consisted of two fixed and synchronized 0.303 in (7.7 mm) machineguns and either one or two machineguns of similar caliber mounted over the wing centre section and movable, but usually firing forwards and upwards. The prototype was flown in late May 1917, the first production contract was placed in the following month, on June 29, and quantity deliveries to the RFC began late in the year.

The first Dolphin squadron was deployed to France in February 1918, and the decision was taken to license-build a version for the USAAS in France. This, the Dolphin Mk.II powered by a 300 hp Hispano-Suiza engine, was to be manufactured by the SACA (Societe Anonyme des Constructions Aeronautiques) and the USAAS anticipated taking delivery of 2,194 by mid 1919. In the event, only a few Dolphin Mk lIs were completed before the Armistice prompted cancellation of all contracts.

Difficulties with the reduction gear of the original 200 hp engine led to the conversion of many to direct drive, aircraft fitted with the modified power plant being designated Dolphin Mk.III and some engines having their compression ratio raised to boost output to 220 hp. Production of the Dolphin totaled 1,532 aircraft, of which all but 121 were built during 1918. Both Dolphin Mk.I and Mk.III were finally withdrawn from RAF service mid 1919. The following data relate to the Dolphin Mk.III.

Created November 30, 2010