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Veteran First World War warrior springs eternal

04 April 2013

Even the tiniest detail counts in any worthy restoration project. Case in point is the venerable Sopwith Dolphin, a restored First World War aircraft, now on display in the Claude Graham-White building at RAF Museum Hendon, which has had a new set of extension springs specially manufactured for its replica Lewis guns.

The single seat Sopwith Dolphin served operationally from January 1918 to July 1919. At its peak, it equipped five Royal Air Force (RAF) Squadrons - the RAF having just been created in April 1918 as an amalgamation of the Royal Flying Corps and its naval equivalent, the Royal Naval Air Service. The aircraft saw service mainly in France, with a handful on home defence duties during the First World War. A total of 1,778 were built in Britain but the model was declared obsolete just three years following the cessation of hostilities in 1921.

John Stoyles, a member of the team that restored the Dolphin, believes it is now the only one in existence. Restoration began as far back as 1968 and was completed early last year after spending eleven years at RAF Museum Cosford. The restoration includes some original parts from different Dolphin aircraft but parts that could not be obtained in this way were manufactured from scratch using original drawings from the manufacturer, Sopwith Aviation.

“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,” says Mr Stoyles, who pays tribute to Lee Spring, which provided two new music wire extension springs for use in the Lewis gun mechanism – and a company that can trace its history back to the time of the Sopwith Dolphin. “The original specification called for 5/16in outside diameter, 2 1/4in 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 together again.

“This is a truly unique application,” says Lee Spring Europe managing director, Chris Petts. “It is another example of how varied the applications of Lee Spring are, and we are delighted to have been 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. Today, Lee Spring is present in Europe, the USA, Mexico and Latin America, and Asia offering over 19,000 different types of compression, die, extension and torsion spring. Other offerings include the LeeP plastic composite, REDUX wave springs, Bantam mini-compression, battery springs and spring kits - all available off-the-shelf.

For more information about the Sopwith Dolphin, click here.

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