In late 1944, the Bristol Aircraft Company established a Helicopter Department at Filton and recruited designer Raoul Hafner from the Airborne Forces Experimental Centre where he had been leading a rotorcraft research team. Work was immediately initiated on the design of a 4-seat helicopter for both military and civilian use and, by 1946, a prototype machine emerged. Powered by a Pratt & Whitney Wasp Junior engine, this aircraft took to the air for the first time on 25th April 1947 with test pilot H A Marsh at the controls. Two years later, on 25th April 1949, a second prototype became the first British helicopter to be granted a Certificate of Airworthiness. A third and final prototype designated the Bristol 171 was equipped with a more powerful Alvis Leonides rotary engine and it was this machine that formed the basis of a Mk 3 production version of which 15 were built for evaluation by RAF, Army Air Corps and British European Airways.
The military version of the Bristol 171 entered service with No 275 Squadron RAF as the Sycamore HR14 on 13th April 1953 and went on to serve with a total of 9 squadrons in a variety of roles. Although primarily used for search and rescue and casualty evacuation duties, it proved the importance of the helicopter for transporting troops and supplies into harsh terrain inaccessible to fixed wing aircraft and road vehicles. As such, the Sycamore proved invaluable during the Malaysian Campaign and Cyprus Emergency of the 1950s and in other trouble spots including Kenya and Aden. Meanwhile, in the civil arena the Bristol Type 171 was used for transport, mountain rescue and mining survey work – both in the UK and Australia.
Apart from its RAF service, the Sycamore was operated by the Australian, German and Belgian armed forces. A total of 180 aircraft were built with production finally drawing to a halt in 1959. Several aircraft survive in Museums today and Red Bull is currently restoring a machine to airworthy status at its Saltzburg Airport facility.