Westland WS-51 Dragonfly

WS-51 Dragonfly
Dragonfly HR.3 of 705 Naval Air Squadron Royal Navy in 1955
Role Rescue or communications helicopter
National origin United Kingdom
Manufacturer Westland Aircraft
First flight 5 October 1948
Introduction 1950
Status Retired
Primary users Royal Navy
Royal Air Force
Produced 1949–1954
Number built 149
Developed from Sikorsky H-5
Variants Westland Widgeon

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

Design and development

On 19 January 1947 an agreement was signed between Westland Aircraft and Sikorsky to allow a British version of the S-51 to be manufactured under licence 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.

After delays caused by the need to modify and convert American-drawings to reflect British-sourced items and to replace the engine with a British-built Alvis Leonides 50, the prototype was first flown from Yeovil on 5 October 1948 piloted by Alan Bristow. Only 16 months had elapsed since work had begun on building the prototype registered G-AKTW.

After evaluation initial orders for the British military were placed, thirteen Dragonfly HR.1s for the Royal Navy and three Dragonfly HC.2s for the Royal Air Force.

Operational history

A total of seventy-two Dragonfly helicopters entered service with the Fleet Air Arm of the Royal Navy in the training, air-sea rescue and communications roles. The first unit to be equipped with them was 705 Naval Air Squadron, which is believed to be the first all-helicopter squadron to be formed outside of the United States. The Dragonfly was the first British-built helicopter to be used by the navy and the first to operate from a British ship in trials on RFA Fort Duquesne in 1951. A Dragonfly led the helicopter section of the flypast at the Coronation Review of the Fleet in 1953.

A planned upgrade the navy's Dragonflies to the Widgeon standard with a larger cabin, to be known as the Dragonfly HR.7, was dropped in 1957 due to defence cuts. It was replaced in British service by the Westland Whirlwind, another derivative of a Sikorsky design, in the late 1950s. Dragonflies were used in relief operations in the North Sea flood of 1953 and a number were used by the Royal Air Force for casualty evacuation during the Malayan Emergency.

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.

Variants

Westland/Sikorsky WS-51
Prototype.
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. 13 built, some modified later as HR.5s.
Dragonfly HC.2
Casualty evacuation helicopter for the Royal Air Force similar to the commercial Mark 1A, 2 built and one-conversion from a civil Mark 1A.
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, 71 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 with Alvis Leonides 23/1 engine and updated to instruments and avionics. 25 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, 36 built.
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, 15 built.

Operators

Military and government operators

Ceylon
Egypt
Iraq
Italy
Japan
Japan Maritime Self Defence Force S-51
Thailand
United Kingdom
British European Airways Sikorsky S-51 in 1953
Yugoslavia

Civil operators

Belgium
Japan
United Kingdom

Surviving aircraft

WS-51 Mk.1A in Royal Thai Air Force Museum in December 2014

Australia

Brazil

Japan

Malta

Netherlands

HR.5 on static display at the Aviodrome in Lelystad, Netherlands.

Serbia

Sri Lanka

Thailand

United Kingdom

HR.1 at the FAA Museum in Yeovilton, England.

Venezuela

Specifications (WS-51 Mk.1A)

Westland Dragonfly HR3

Data from Jane's all the World's Aircraft 1955–56

General characteristics

  • Crew: 1
  • Capacity: 3 passengers (useful load 530 lb (240 kg)
  • Length: 57 ft 6.5 in (17.54 m) overall
  • Fuselage length: 41 ft 1.75 in (12.54 m)
  • Height: 12 ft 11.375 in (3.95 m)
  • Empty weight: 4,366 lb (1,980 kg) HR Mk.1,
  • Gross weight: 5,700 lb (2,585 kg)
  • Max takeoff weight: 5,870 lb (2,663 kg)
  • Fuel capacity: 83 imp gal (100 US gal; 380 L) in 2 fuselage tanks
  • Powerplant: 1 × Alvis Leonides 521/1 9-cylinder air-cooled radial piston engine (6lb boost), 520 hp (390 kW)
  • Main rotor diameter: 49 ft (15 m)
  • Main rotor area: 1,885 sq ft (175.1 m2)

Performance

  • Maximum speed: 103 mph (166 km/h, 90 kn) at sea level
  • Cruise speed: 85 mph (137 km/h, 74 kn)
  • Range: 300 mi (480 km, 260 nmi) in still air with 20 minutes fuel reserves
  • Service ceiling: 11,000 ft (3,400 m)

See also

Related development

Related lists