Aircraft Data Sheet: WS-55 Whirlwind (1952)

First flight:	12th November 1952
Rotor diameter:	16.15m/53ft 0ins
Length:	18.94m/62ft 1ins
Max weight:	3,402kg/ 7,500lb
Max speed:	175kph/95knots
Power:	One 600shp/447kW Pratt & Whitney Wasp R-1340-40(600hp) or One 750shp/559kW Wright Cyclone R-1300-3
Accommodation:	Two pilots plus ten
No Built:	289

After the Dragonflies had entered service, Westland announced the agreement between Sikorsky had been finalised to build Sikorsky S-55 for the British Forces, the Westland built a version of the Sikorsky S-55 was used for Search and Rescue, Transport and Anti-submarine duties. Initial versions designated Series 1, followed closely the engineering of the US original, and were powered by the 600hp/447kW Pratt and Whitney engine.

Later, 750hp/559kW (de-rated) Alvis Leonides Major engines was fitted producing a Series 2 of improved performance. Whirlwinds were supplied to the RAF to operate in the Rescue and Transport roles. The Royal Navy used the aircraft for SAR and anti-submarine duties. Two Whirlwind HCC Mk8 aircraft were used by The Queens Flight.