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| Sikorsky S-51 | |
|---|---|
| Name | Sikorsky S-51 |
| Caption | Sikorsky S-51 in flight |
| Type | Utility helicopter |
| Manufacturer | Sikorsky Aircraft |
| First flight | 1946 |
| Introduced | 1946 |
| Primary user | United States Air Force |
| Produced | 1946–1950 |
| Number built | ~300 |
Sikorsky S-51 The Sikorsky S-51 is a post-World War II single-engine, multi-role helicopter developed by Igor Sikorsky's company, Sikorsky Aircraft, and introduced in 1946. Designed as a successor to the Sikorsky R-4 and Sikorsky R-5, it served with United States Air Force, United States Navy, and civilian operators including Los Angeles Airways and Helicopter Air Transport. The S-51 influenced later designs such as the Sikorsky S-55 and Sikorsky H-19, and saw use in roles ranging from search and rescue to air ambulance and agricultural work.
Development began during the closing stages of World War II when demand for rotary-wing aircraft rose among veterans, commercial firms like Pan American World Airways, and military planners from United States Army Air Forces transitioning to the United States Air Force. Igor Sikorsky, influenced by earlier models including the Sikorsky R-6 and the experimental Sikorsky VS-300, guided the S-51 program at Stratford, Connecticut. Early prototypes competed for contracts with designs from Bell Helicopter, Kellett Autogiro, and Piasecki Helicopter; the S-51 first flew in 1946 and received civil certification and military designations such as the H-5 family for different services. Development incorporated lessons from operations with Royal Air Force liaison helicopters and demonstrations for agencies like the Federal Aviation Administration and United States Coast Guard.
The S-51 featured a welded steel-tube fuselage with a fully articulated main rotor and a single Pratt & Whitney radial engine mounted in the nose, similar in lineage to powerplants used by Douglas Aircraft Company transports. The cabin accommodated a pilot and up to three passengers, and the airframe included a tail rotor derived from earlier Sikorsky practice used on the Sikorsky R-4 and Sikorsky R-5. Landing gear was a fixed wheeled type for improved ground handling compared to skid-equipped contemporaries like the Hiller UH-12. Avionics packages were rudimentary by later standards but compatible with navigation aids from firms such as Collins Radio Company and Hughes Aircraft Company used for instrument approaches to fields like LaGuardia Airport and Orly Airport. Structural elements employed alloys sourced from suppliers including Alcoa and manufacturing techniques paralleling those at Boeing and Lockheed Corporation.
Civil operators such as Los Angeles Airways, Helicopter Air Transport, and San Francisco Helicopter Airlines used the S-51 for early scheduled passenger service, pioneering routes linking hubs like Los Angeles International Airport and San Francisco International Airport. Military users included the United States Air Force, United States Navy, Royal Navy, and the Royal Canadian Air Force where it served in air-sea rescue, observation, and utility transport roles alongside types like the Sikorsky H-19 and Piasecki H-21. The S-51 performed medevac missions in peacetime operations supporting institutions such as Massachusetts General Hospital and Johns Hopkins Hospital and aided civil authorities including the New York City Fire Department and Los Angeles County Sheriff's Department. International demonstration tours visited countries including United Kingdom, France, Brazil, Mexico, and Argentina, influencing procurement by Italian Air Force and Spanish Air Force contingents.
Several variants evolved: company civil versions and military designations for different services. The United States Air Force and United States Army used versions designated as H-5 for search and rescue and liaison, while the United States Navy and Royal Navy operated adapted types with maritime radios and rescue hoists. Commercial conversions included passenger-configured S-51s and agricultural adaptations fitted with spray gear used by firms in California and Florida. Licensed or derivative developments influenced successors such as the Sikorsky S-55 and experimental twin-rotor projects from companies like Vertol.
Operators spanned military and civilian organizations: United States Air Force, United States Navy, United States Army Air Forces, Royal Canadian Air Force, Royal Navy, Italian Air Force, Spanish Air Force, Royal Australian Air Force demonstration units, municipal services including New York City Police Department Aviation Unit, commercial airlines such as Los Angeles Airways and Helicopter Air Transport, medical centers including Massachusetts General Hospital and Johns Hopkins Hospital, and civilian owners who flew from heliports at Chicago Midway International Airport and LaGuardia Airport.
Several S-51s are preserved in museums and collections: the Smithsonian National Air and Space Museum holds examples in its archives, the Intrepid Sea, Air & Space Museum displays a restored airframe, the Museum of Flight in Seattle and the New England Air Museum in Windsor Locks, Connecticut exhibit airworthy and static examples, while private restorers and flying museums in California, Florida, and Texas maintain operational S-51s for airshows and film work featuring other types like the Bell 47 and Sikorsky UH-60.
- Crew: 1 pilot, capacity 3 passengers - Length: approx. 31 ft - Rotor diameter: approx. 44 ft - Height: approx. 11 ft - Empty weight: ~2,400 lb - Gross weight: ~3,650 lb - Powerplant: 1 × Pratt & Whitney R-985 Wasp Junior radial engine - Maximum speed: ~100 mph - Range: ~275 miles - Service ceiling: ~13,000 ft - Rate of climb: ~1,000 ft/min
Category:Helicopters Category:Sikorsky aircraft Category:1940s United States helicopters