The Westland WS-51 Dragonfly helicopter was built by Westland Aircraft and was an Anglicised licence-built version of the American Sikorsky S-51.

Westland Aircraft was a British aircraft manufacturer located in Yeovil, Somerset. Formed as a separate company by separation from Petters Limited just before the start of the Second World War, Westland had been building aircraft since 1915. During the war the company produced a number of generally unsuccessful designs, but their Lysander would serve as an important liaison aircraft with the Royal Air Force. After the war the company focused on helicopters, and was merged with several other British firms to create Westland Helicopters in 1961.