The Sikorsky R-4 was the first Allied mass produced helicopter and the United States Air Force's first service helicopter. [1] [2]
Development
The original military model, the XR-4, was developed from the famous experimental VS-300 helicopter, invented by Igor Sikorsky and publicly demonstrated in 1940. The XR-4 made its initial flight on 13 January 1942 and as a result of its successful flight tests, the United States Army Air Forces ordered three YR-4As and 27 YR-4Bscitation needed for service testing and flight training.
The VS-316 was designated the R-4, under the United States Army Air Forces' series for "Rotorcraft". In 1947, with the birth of the United States Air Force, the series was changed to "H" for "Helicopter", and the R-4 became the H-4.
Operational history
The R-4 was first used in combat in May 1944. In a letter to a friend, Col. Philip G. Cochran, commanding officer of the 1st Air Commando Group, wrote "Today the 'egg-beater' went into action and the damn thing acted like it had good sense."[3] The R-4 showed such promise that the AAF ordered 100 R-4Bs.
Of these 30, one went to Burma and one to Alaska, while several others were assigned to the United States Navy, United States Coast Guard and Royal Navy who named it the Gadfly. In Royal Air Force service it was called the Hoverfly. The R4 equipped the first British military unit to be equipped with helicopters, the Helicopter Training School, formed in January 1945 at RAF Andover.
Variants
External differences noted in photos: Some R-4s had the tail wheel located at the extreme aft end of the boom near the tail rotor while others had it positioned at the mid-point of the boom. Additionally, some had short "stub" exhaust pipes from the engine while others had a much longer one which extended vertically and then aft above the main landing gear struts.
- XR-4
- One prototype Model VS-316A with a crew of two and dual controls, 165hp R-500-3 engine, became XR-4C
- YR-4A
- Version with larger rotor diameter and a 180hp R-550-1 engine, three built.
- YR-4B
- Version with detailed changes, redesignated YH-4B in 1962, 27 built for development testing followed by a further batch of 14, seven to US Navy as HNS-1s. Redesignated YH-4B in 1947
- R-4B
- Production version with 200hp R-550-3 engine, redesignated H-4B in 1962, 100 built including 20 for the US Navy and 45 for the Royal Air Force. Redesignated H-4B in 1947
- XR-4C
- Prototype XR-4 re-engined with 180hp R-550-1 engine with the larger YR-4A type rotor.
- HNS-1
- Three YR-4Bs and 22 R-4Bs transferred to the US Navy, two diverted to the United States Coast Guard.
- Hoverfly I
- UK military designation of the R-4 for the Royal Air Force and Royal Navy, 52 delivered and one later transferred to the Royal Canadian Air Force.
Operators
 Canada- Royal Canadian Air Force
 United Kingdom
 United States
Survivors
Specifications (R-4B)
General characteristics
- Crew: 1
- Length: 33 ft 8 in (10.2 m)
- Rotor diameter: 38 ft (11.5 m)
- Height: 12 ft 5 in (3.8 m)
- Empty weight: 2,098 lb (952 kg)
- Loaded weight: 2,581 lb (1,170 kg)
- Powerplant: 1× Warner R-550 piston, 200 hp (149 kW)
Performance
See also
Related development
References
Notes
Bibliography
- Myall, Eric and Sturtivant, Ray (ed.). The Hoverfly File. Tunbridge Wells, Kent, UK: Air-Britain (Historians) Ltd., 1998. ISBN 0-85130-262-9.
External links
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USAAC/USAAF/USAF/Joint Service Helicopter designations 1941- |
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USN helicopter designations pre-1962 |
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| Helicopter, Anti-submarine |
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| Helicopter, Crane |
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| Helicopter, Observation |
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| Helicopter, Trainer pre-1948 |
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| Helicopter, Trainer 1948-1962 |
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| Helicopter, Transport 1944-1962 |
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| Helicopter, Utility pre-1949 |
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| Helicopter, Utility 1950-1962 |
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Lists relating to aviation |
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