(Showcased structural dimension values pertain to the Sikorsky R-4 production model)
2,094 lb (950 kg)
2,646 lb (1,200 kg)
(Showcased weight values pertain to the Sikorsky R-4 production model)
1 x Warner R-550 piston engine developing 200 horsepower.
(Showcased powerplant information pertains to the Sikorsky R-4 production model)
75 mph (120 kph; 65 kts)
7,874 feet (2,400 m; 1.49 miles)
(Showcased performance values pertain to the Sikorsky R-4 production model; Compare this aircraft entry against any other in our database)
(Showcased armament details pertain to the Sikorsky R-4 production model)
XR-4 - Single Prototype Model; fitted with R-500-3 series engine of 165 horsepower.
YR-4A - Developmental model with R-550-1 engine of 180 horsepower; larger-diameter rotor for improved lift; 3 examples completed.
YR-4B - Development model for formal US Army evaluations; 27 examples produced.
R-4B - Production Designation of R-4 series; fitted with R-550-3 series engines of 200 horsepower; 100 examples produced.
XR-4C - Prototype model with R-550-1 engine of 180 horsepower; revised rotor.
HNS-1 - US Navy designation of three YR-4B and twenty-two R-4B models.
"Hoverfly I" - British military designation of R-4 production model; 52 examples delivered.
S-54 - R-4B test platform with observer's position added.
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.
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