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Westland Dragonfly (WS-51)

Light Utility Helicopter [ 1950 ]

Fewer than 135 of the Westland WS-51 Dragonfly series helicopter were produced for the British military and others during the early-1950s.

Authored By: Staff Writer | Last Edited: 08/24/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

For a period in its history, Westland Aircraft of the United Kingdom produced, under license, the Sikorsky "S-51" helicopter product as the WS-51 "Dragonfly". This light utility-minded platform was operated in the Search & Rescue (SAR) and communications roles for its time in service and 133 of the type were produced by Westland from the period spanning 1949 to 1954. A first-flight of a prototype was had on October 5th, 1948 and service introduction occurred in 1950.

Rather than develop a helicopter system from scratch, Westland managed to secure a production agreement with Sikorsky for the S-51 in December of 1946. The aircraft retained all of the form and function of the original including its rather utilitarian appearance, three-bladed main rotor and three-bladed tail rotor. The wheeled tricycle undercarriage was fixed in place and the forward section of the fuselage contained a series of window panels for excellent vision out-of-the-cockpit. The helicopter was essentially a no-frills product that could be handed different over-battlefield roles.

Beyond the WS-51 prototype - the sole example completed - were several major variants: The HR.Mk 1 was the standard SAR platform of which thirteen were built for the British Royal Navy (RN) and these were powered by 1 x Alvis 50 radial piston engine 540 horsepower. The HC.Mk1 served the British Royal Air Force (RAF) in the casualty evacuation role - only two were procured. The HR.Mk 3 was used by the RN in the air-search and SAR roles and finished with all-metal rotor blades. Some seventy-one were built. The HC.Mk 4 was another casualty evacuation helicopter developed to serve the RAF and these were given the same all-metal rotor blades with production reaching twelve units in all. The HR.Mk 5 was another air-search / SAR platform and used by the RN. These were built up from existing HR.Mk 1 and HR.Mk 3 models.

Two civilian transport forms also emerged in time, these being the WS-51 Mk 1A and WS-51 Mk 1B. The former carried an Alvis "Leonides" 521/1 series radial engine of 520 horsepower and the latter was finished with a Pratt & Whitney R-985 "Wasp Junior" B4 radial engine of 450 horsepower. Production totaled 36 and 15, respectively.

Once in circulation, the series gave good service and was eventually taken on by the militaries of Egypt, Hong Kong, Italy, Thailand and Yugoslavia as well. Commercial/civilian market operations were seen with helicopter through Belgium and the United Kingdom.

The Dragonfly was directly succeeded in British Royal Navy service by the Westland "Whirlwind" helicopter - another locally-produced licensed product from Sikorksy (the S-55/H-19 "Chickasaw").©MilitaryFactory.com
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Service Year

United Kingdom national flag graphic
United Kingdom

Not in Service.


National flag of Belgium National flag of Czechia National flag of Egypt National flag of Italy National flag of the Netherlands National flag of Thailand National flag of the United Kingdom National flag of Yugoslavia Belgium; Czech Republic; Egypt; Hong Kong; Italy; Netherlands; Thailand; United Kingdom; Yugoslavia
(OPERATORS list includes past, present, and future operators when applicable)
Special-Mission: MEDical EVACuation (MEDEVAC)
Extraction of wounded combat or civilian elements by way of specialized onboard equipment and available internal volume or external carrying capability.
Special-Mission: Search & Rescue (SAR)
Ability to locate and extract personnel from areas of potential harm or peril (i.e. downed airmen in the sea).
General transport functionality to move supplies/cargo or personnel (including wounded and VIP) over range.
Commercial Aviation
Used in roles serving the commercial aviation market, ferrying both passengers and goods over range.
VIP Service
Used in the Very-Important-Person (VIP) passenger transport role, typically with above-average amenities and luxuries as standard.
Intelligence-Surveillance-Reconnaissance (ISR), Scout
Surveil ground targets / target areas to assess environmental threat levels, enemy strength, or enemy movement.

57.6 ft
(17.55 m)
48.1 ft
(14.65 m)
13.0 ft
(3.95 m)
Empty Wgt
4,409 lb
(2,000 kg)
5,875 lb
(2,665 kg)
Wgt Diff
+1,466 lb
(+665 kg)
(Showcased structural values pertain to the Westland Dragonfly production variant)
Installed: 1 x Alvis Leonides 50 series radial piston engine developing 540 horsepower and driving a three-bladed main rotor and three-bladed tail rotor.
Max Speed
96 mph
(155 kph | 84 kts)
12,402 ft
(3,780 m | 2 mi)
301 mi
(485 km | 898 nm)

♦ MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030

(Showcased performance specifications pertain to the Westland Dragonfly production variant. Performance specifications showcased above are subject to environmental factors as well as aircraft configuration. Estimates are made when Real Data not available. Compare this aircraft entry against any other in our database or View aircraft by powerplant type)

Supported Types

(Not all ordnance types may be represented in the showcase above)
WS-51 "Dragonfly" - Base Series Designation
Dragonfly HR.Mk 1 - SAR variant; Alvis 50 radial engine of 540 horsepower; 13 examples built.
Dragonfly HC.Mk 2 - MEDEVAC variant for RAF; 2 examples completed.
Dragonfly HR.Mk 3 - SAR variant for RN; all-metal blades; 71 examples completed.
Dragonfly HC.Mk 4 - MEDEVAC variant for RAF; all-metal blades; 12 examples completed.
Dragonfly HR.Mk 5 - SAR variant for RN; built from HR.Mk 1 and HR.Mk 3 stock.
WS-51 Mk 1A - Civilian market form with Alvis Leonides 521/1 radial engine of 520 horsepower; 36 completed.
WS-51 Mk 1B - Civilian market form with Pratt & Whitney R-985 Wasp Junior B4 radial engine of 450 horsepower.; 15 examples completed.

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