|Dragonfly HR.3 of 706 Squadron Royal Navy in 1955|
|Role||rescue or communications helicopter|
|Status||retired; several examples preserved|
|Primary users||Royal Navy
Royal Air Force
|Developed from||Sikorsky H-5|
Design and development
In December 1946 an agreement was signed between Westland Aircraft and Sikorsky to allow a British version of the S-51 to be manufactured under license in the United Kingdom. These would be powered by the 500 hp Alvis Leonides radial engine. A modified version was also developed by Westland as the Westland Widgeon, but it was commercially unsuccessful.
The Dragonfly entered service with the Royal Navy in 1950 in the air-sea rescue role. A number were also used by the Royal Air Force for casualty evacuation. It was replaced in British service by the Westland Whirlwind, another derivative of a Sikorsky design, in the late 1950s.
Fifty-one civilian WS-51s were produced. Examples were used by Pest Control Ltd for crop spraying and others were flown as executive transports by Silver City Airways, Evening Standard Newspapers and Fairey Aviation. Exported aircraft operated in Japan, Belgian Congo, Mexico and Norway.
- Westland/Sikorsky WS-51
- Dragonfly HR.1
- Air-sea search and rescue helicopter for the Royal Navy powered by a 540 hp (400 kW) Alvis 50 radial piston engine. Thirteen built, some modified later as HR.5s.
- Dragonfly HC.2
- Casualty evacuation helicopter for the Royal Air Force similar to the commercial Mark 1A, three built.
- Dragonfly HR.3
- Air-sea search and rescue helicopter for the Royal Navy. Similar to the Dragonfly HR.1, but fitted with all-metal rotor blades, 58 built some later modified as HR.5s.
- Dragonfly HC.4
- Casualty evacuation helicopter for the RAF similar to the Dragonfly HR.3 with all-metal rotor blades, 12 built.
- Dragonfly HR.5
- Air-sea search and rescue helicopter for the Royal Navy similar to the Dragonfly HR.3. Modified from HR.1 and HR.3.
- Westland-Sikorsky WS-51 Mk.1A
- Civil transport helicopter powered by a 520 hp (388 kW) Alvis Leonides 521/1 radial piston engine. Built by Westland in the United Kingdom.
- Westland-Sikorsky WS-51 Mk.1B
- Civil transport helicopter powered by a 450 hp (336 kW) Pratt & Whitney R-985 Wasp Junior B4 radial piston engine.
- Sabena - Three helicopters
- Royal Egyptian Air Force - Two helicopters as VIP transports.
- Royal Iraqi Air Force - Two helicopters
- Italian Air Force - Three helicopters
- Royal Ceylon Air Force - Two helicopters
- Japan Air Self Defense Force - Three helicopters
- 153rd Rescue Squadron
- Tohuku Electrics - Two helicopters for power line inspection.
- Royal Thai Air Force - Four helicopters
- Empire Test Pilot's School
- Royal Air Force
- Central Flying School
- No. 194 Squadron RAF
- Fleet Air Arm
- SFR Yugoslav Air Force - Ten helicopters
- Dragonfly HR.3 WG751 on display at the Chatham Historic Dockyard, Chatham, United Kingdom.
- Dragonfly HR.5 WN403 on display at the Fleet Air Arm Museum at RNAS Yeovilton in Somerset, United Kingdom
- Dragonfly HR.3 G-AJOV on display at the Royal Air Force Museum Cosford, Shropshire, United Kingdom
- WS-51 Mk.1B 11503 on display at the Yugoslav Aeronautical Museum at Nikola Tesla Airport, Belgrade, Serbia.
- Dragonfly Mk.1A WS-51 H1-4/96, (cn WA/H/120) at Royal Thai Air Force Museum, Don Muang AFB.
- Dragonfly HR.5 WG724 on display at the North East Aircraft Museum, Sunderland, United Kingdom
- Dragonfly HR.5 on display at the Sri Lanka Air Force Museum, SLAF Ratmalana, Sri Lanka
- Dragonfly HR.5.Mk.5 On display at (The Helicopter Museum) Weston-super-Mare (North Somerset), (United Kingdom)
- Westland/Sikorsky S-51 Dragonfly - Museu Eduardo André Matarazzo, Bebedouro, SP, Brasil.
Specifications (Dragonfly HR.1)
Data from 
- Crew: 1 (pilot)
- Capacity: 3 (passengers)
- Length: 57 ft 6½ in (17.54 m)
- Main rotor diameter: × 48 ft 0 in (14.63 m)
- Height: 12 ft 11½ in (3.95 m)
- Main rotor area: 1809.56 ft2 (168.11 m2)
- Empty weight: 4380 lb (1987 kg)
- Gross weight: 5870 lb (2663 kg)
- Powerplant: 1 × Alvis Leonides 50 radial piston, 540 hp (403 kW)
- Maximum speed: 95 mph (153 km/h)
- Range: 300 miles (483 km)
- Service ceiling: 12,400 ft (3780 m)
- Related development
- Related lists
- Jackson, 1974, pp 618-619
- Orbis 1985, page 3080
- The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing.
- Jackson, A.J. (1974). British Civil Aircraft Since 1919 - Volume Three. Putnam & Company Limited. ISBN 0-370-10014-X.
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