A restored First World War aircraft now on show at RAF Museum Hendon, features a new set of extension springs manufactured by Lee Spring for use on the replica Lewis guns.
The Sopwith Dolphin served operationally from January 1918 to July 1919. At its peak, this single seat fighter equipped five RAF Squadrons, mainly in France with a handful on home defence duties during the First World War. A total of 1,778 Sopwith Dolphins were built in Britain but the model was declared obsolete in 1921.
“We believe that our Dolphin is now the only one in existence,” said John Stoyles, part of a team who restored the Dolphin now on display in the Claude GrahamWhite building at the RAF Museum Hendon.
The world's first single seat multi-gun fighter the Dolphin represented a departure from traditional Sopwith fighter design. In place of the rotary engines so characteristic of the Triplane and Camel, the Dolphin was equipped with a stationary 200hp geared Hispano-Suiza in-line engine.
The Dolphin's unusual wing layout with its 'backwards stagger' was designed to provide the pilot with excellent all round visibility. This was achieved by placing the upper wings low on top of the fuselage, the pilot being positioned with his head in the centre where he was afforded a clear and uninterrupted view.
Restoration started in 1968 and was completed in early 2012 after 11 years at RAF Museum
Cosford. The restoration includes some original parts from different Dolphin aircraft but any unavailable parts were primarily manufactured using original Sopwith Aviation (the manufacturer) drawings.
“The Sopwith Dolphin was the first four gun fighter, having two Vickers machine guns (pointing forwards) and two Lewis guns inclined on the top of the aircraft,” explained Stoyles, revealing that Lee Spring provided two new music wire extension springs for use in the Lewis gun mechanism. “The original specified spring was 5/16 o/d, 2?in long 20g steel wire, but the Lee Spring replacements were very similar and did the job admirably.”
Helical extension springs are loaded in tension and feature hooks or loops to allow a pull force to be applied. Usually, extension springs are attached at both ends to other components which, when they move apart, the spring tries to bring them together again.
“This is a truly unique application” says Chris Petts, Managing Director at Lee Spring, Europe. It is another example of how varied the applications of Lee Spring are, and we are delighted to be part of such an historic restoration project."
Founded in 1918, Lee Springs shares a similar heritage, opening in Brooklyn, New York the same year that the Sopwith Dolphin first went into operation. To learn more about the Sopwith Dolphin visit http://www.rafmuseum.org.uk/research/collections/sopwith-dolphin-5fi