Sikorsky S-51 / R-5

Sikorsky Aircraft Corp. Bridgeport, CT

First Flight  February 16, 1946

Four seats

Restored by Keystone Helicopter Corporation

Acquisition Source: Peter Wright Donation

Sikorsky followed the production R‑4 with the bigger R‑5, first flown on 18 August 1943. Powered by a 450‑hp Wasp Junior radial, this was ordered as the R‑5A for the US Army and as the H02S‑1 for the US Navy, both being two‑seat tandem observation machines with twin front wheels and a stilted rear wheel at the root of the long tail boom. The 48‑ft rotor was a notable advance over the R‑4, and gross weight was 5000 lb., just twice as great. Instead of steel tube and fabric, the R‑5 was made chiefly of light‑alloy mono­coque. Eventually about 300 were delivered, plus 139 built in England as the Westland Dragonfly with modified airframe and Alvis Leonides engine.Small batches were sold for commercial purposes.

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 con­trols, while at least 20 modified R­-5As were later given new, 600 hp Wasp Junior engines and redesignated R‑5D. The USAAF ordered 4 XR‑5 prototypes in early 1943, shortly after the first flight of the R‑4. A fifth prototype was ordered later in the year. These were followed by 26 YR‑5A helicopters for service trials and a production order for 100 R‑5A aircraft, of which only 34 were completed.

The S‑51, the first commercial helicopter designed by Sikorsky. was a modification of the R‑5 designed as a four‑place aircraft. Using basically the same rotor system as the R‑5, it had a slightly en­larged four‑seat cabin. The primary configuration difference is the reversal of the landing gear ‑ the S‑51 having a nose gear instead of the tail gear of the R‑5. The, it first flew on 16 February 1946 and received CAA certification a month later. Deliveries began in August 1946. Helicopter Air Transport (HAT) purchased the first three S‑5ls at $48,500 each. During 1947, Los Angeles Airways initiated the world's first scheduled helicopter service with five S‑51s.

In 1947 the U.S.A.F. received eleven military S‑51s designated R‑5F; these were followed in 1948‑49 by thirty‑eight H‑5Gs with rescue hoists and maximum take‑off weight increased from 6,200 lb. (2,812 kg.) to 6,500 lb. (2,948 kg.) and seventeen similar H‑5Hs with amphibious wheel/pontoon landing gear.

Sikorsky production of the R‑5/S‑51 series ended in 1951 after some 300 aircraft were delivered to military and civilian customers. The US Air Force, Air Rescue Service outfitted the aircraft with an enclosed stretcher mounted externally on each side of cabin for medical evacuation during the Korean War. The Navy also used the aircraft for plane guard and general observation duties.Of the Navy procurement, the Coast Guard flew 2 H02S‑1G and 9 H03S‑1G helicopters from 1946‑1950. Nine of the H03S‑1 helicopters were used by the U.S. Marine Corps from 1948‑1955, the first helicopters to be flown by that service. Westland in Britain produced 133 of the S‑51 design under license for military and civil use. The RAF flew the helicopter as the Dragonfly in combat in Malaya from 1950‑1956.

Aircraft Specifications

Rotor Diameter: 
49 ft.
Fuselage Length: 
41 ft. 2 in.
Maximum Speed: 
103 mph
Cruise Speed: 
85 mph
Height: 
13 ft.
Empty Weight: 
4,050 lbs.
Gross Weight: 
5,500 lbs.
Engine: 
450 HP Pratt & Whitney R 985 AN5