Back Sikorsky S-51 / H-5 / HO3S
1946

Sikorsky S-51

The first helicopter to be built in large numbers was a derivative of the Sikorsky R-5, which started out as a tandem two-seater. The first of five prototypes flew on 18 August 1943 powered by a 450hp Wasp Junior radial. This was followed by 25 YR-5A pre-production models, two of which were assigned to the Navy under the designation HO2S-1. While production of the R-5A was getting under way (34 built), five pre-series aircraft were converted into the R-5E, which had dual control, while at least 20 modified R-5As were later given new, 600hp Wasp Junior engines and redesignated R-5D. From the latter, the S-51 was developed, with a slightly enlarged four-seat cabin and a tricycle landing gear. The first commercial helicopter designed by Sikorsky, it first flew on 16 February 1946 and was certified a month later by the Civil Aviation Agency and delivered to the first customer in August. It was sold to United Air Lines and Los Angeles Airways.

A total of 300 S-51s were built, some with 450hp engines, others with 600hp engines and larger diameter three-blade rotors. The military versions were designated R-5F (11 to the USAF), H-5G (38 fitted with a rescue hoist), H-5H (17 with amphibious wheel/pontoon landing gear), HO3S-1 and S2 (90 in all, naval rescue version). The S-51 had a three-blade articulated rotor, the blades of which could be folded back to facilitate stowage. The first aircraft had manual pitch control; this was later replaced by a hydraulic system. The cabin diameter was also increased.

In 1947, Westland acquired the license to build the S-51 in Britain and produced 139 up to 1953. The British version, named the Dragonfly, had a 550hp Alvis Leonides engine.

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

Sikorsky S-51 / H-5 / HO3S

The S-51 has the distinction of being the first helicopter in the world to fly a regular service, and it did so in the United Kingdom. It flew in British European Airways' colours between Liverpool and Cardiff in June 1950.

Work on the S-51 began in 1943 when the United States Army Air Force put out a requirement for a helicopter bigger and better than the rather crude Sikorsky R-4.

The civil version flew for the first time in February 1946. It could carry four passengers and retained the R-985-AN-5 radial engine of the military version. The Civil Aviation Administration certification was granted a month later and in August 1946 the first customer took delivery. Production lasted until 1951, by which time Sikorsky had built 285 machines.

In December 1946 Westland Aircraft of Yeovil purchased a licence to build the S-51 in Britain. When they ceased production in 1953 they had built 139 machines. The Dragonfly, as the British-built machine was known, had a 520hp Alvis Leonides engine. Westland sold their UK-built helicopters to Belgium, Ceylon, Egypt, France, Iraq, Italy, Japan, Thailand and Yugoslavia. The bulk of these sales were for military use, but Belgium became a European pioneer in the civil field when Sabena bought three.

The S-51 had a three-blade rotor which had flapping and drag hinges and could be folded to facilitate storage. The early machines had manual control for the rotor pitch, later replaced by hydraulic servo-controls with power from a hydraulic pump driven by the tail transmission shaft.

In 1955 Westland produced a conversion of the S-51 which they called the Widgeon. It had a four-blade main rotor with a 520hp Leonides 521 engine, a redesigned cabin and small clamshell nose doors. The first flight was in August 1955 with a Dragonfly converted to Widgeon standard. Westland produced 15 Widgeons and sold them to Ceylon, Jordan, Brazil and the Hong Kong police department. The Widgeon used an S-55 rotorhead which employs an offset flapping-hinge system, thus allowing more latitude in the centre of gravity and the position of cargo or passengers.

The Widgeon was the final development of the S-51 which was becoming obsolete with the rapid changes in helicopter design in the mid 1950s.

Bill Gunston "The Illustrated Encyclopedia of Commercial Aircraft", 1980

Sikorsky S-51

Technical data for S-51

Crew: 1, passengers: 3, engine: 1 x Pratt & Whitney R-985-AN-5 Wasp Junior rated at 336kW, main rotor diameter: 14.94m, length with rotors turning: 13.70m, fuselage length: 12.45m, height: 3.95m, take-off weight: 2263kg, empty weight: 1720kg, max speed: 166km/h, range: 480km

Comments 
Ruben Cudicio, rubenlc=speedy.com.ar, 29.08.2011

En la Republica Argentina estos helicopteros fueron inicialmente adquiridos por el Estado para combatir las plagas de langostas.
En el año 1962 tuve la oportunidad de hacer el curso y volar aproximadamente 100 horas en la Base Oficial de Aviacion Civil.
El riesgo mayor durante su operacion era tocar con el rotor de cola y perder el control total, asi fué como perdimos dos aeronaves y en el incendio sus dos pilotos. otra consideracion importante era aterrizar con velocidad tipo
avion cuando no se habia colocado el lastre convenientemente y de acuerdo a los pasajeros transportados.Un gran recuerdo para mi humilde experiencia de helicopteros en contraposicion a mis 21000 horas de diferentes tipos de avion.

Alec Moore, quart-of-ale=anygoodpub.com, 20.08.2011

Great shots of this in the movie 'The Bridges At Toko-Ri'

polo, poloalobabab=yahoo.com, 16.06.2011

I have a s51 tail and rotor motor for sale. please email me for pics and any other info. thanks Joe

Mark, mhvond2=optonline.net, 23.04.2011

I have a tail rotor blade for this helicopter and am interested in selling it.

Timothy Tredwell, tbird05=live.com, 27.12.2010

I was just writing my grandson to thank him for a tie with P-51, P-38 etc. on it. I decided to tell him about my first helicopter ride in a Sikorsky S-51. A business man from around Rye, NY buzzed our pastures in Old Westbury Long Island and then landed next door. In 1948, I was in 8th. grade and just returning from school, so I ran to the next pasture and the pilot offered three of us a ride. We went up 400 feet and headed east. Immediately I was lost because the trees formed a canopy over Bacon Road. This was great for show and tell in school---and I can never forget Silorsky!!!! My next door neighbor was Albert C. Bostwick who was a partner with John D. Rockefeller in Standard Oil Co. TT

kiran, napstervkk=gmail.com, 20.04.2009

will u send me model sketch of your project let me know something about your project please

joseph sokola, a67gtx=yahoo.com, 24.03.2009

I have a s51 tail and rotor motor for sale. please email me for pics and any other info. thanks Joe

alex, life-=km.ru, 22.03.2009

Sikorsky from Ukraine... and study in Kiew Polytechnic Universety

Henk Cruijff, hjcruijff=hotmail.com, 27.08.2008

What material were the rotor-blades of the S-51 made of originally? I understand that later they were made of aluminum, but originally something else?

Nick Drummond, nickdrummond=hotmail.com, 09.04.2008

The importance of this helicopter is often under-estimated, because it only enjoyed a few short years of production before it was superseded by other Sikorsky designs. But its contribution to the development of the helicopter as we know it today was significant. Arguably better known in the UK than the USA, it was an extremely advanced design for its time and a brilliant example of American aero-engineering skill. Moreover, it created an operational blueprint for military helicopters that exists to this day. Its use as Air-Sea Rescue helicopter is particularly noteworthy. During the 1950s, this iconic machine achieved an almost cult status first for rescuing downed pilots in Korea, something which had never been done before, and then off the coast of the UK through numerous rescues of shipwrecked yachtsmen. The S-51's robustness and reliability were impressive given that there were no precedents for the engineering solutions it incorporated. Not all piston-engined helicopters proved to be as reliable. Those familiar with this helicopter have nothing but a deep affection for the old Dragonfly. It was truly a machine that saved lives.

Keith Besherse, waafcdr=hotmail.com, 02.11.2007

It would be nice if to this paragraph:
Work on the S-51 began in 1943 when the United States Army Air Force put out a requirement for a helicopter bigger and better than the rather crude Sikorsky R-4.
You added a comment like, "Sikorsky responded with the VS..."

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FACTS AND FIGURES

© Westland built the R-5 under licence in Britain as the WS.51 Dragonfly, for the RAF, Royal Navy and civil operators.

© Nine HO3S-1s were used by the US Coast Guard as HO3S-1Gs.

© HO3S-1s served with distinction in the Korean War with Squadron HU-1.

© In 1950 Sikorsky built and tested a single XHO3S-3 with a redesigned rotor head and blades.

© Two XR-5As were fitted with British instruments to an RAF requirement.

© The R-5B, R-5C and HO3S-2 were planned variants later cancelled.


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