US Army Air Forces/Vought-Sikorsky XR-5
The Sikorsky S-48 — US Army Air Forces (USAAF) designation XR-5 — was a significant improvement to the successful R-4 helicopter. The XR-5 was designed to meet a USAAF requirement (signed on Dec. 21, 1942) for a larger, more capable observation helicopter for the USAAF and the UK.
The first flight of the XR-5 occurred on Aug. 18, 1943. On Jan. 9, 1944, an XR-5 set an unofficial speed record of 115 mph (100 kt) over a 13 mile (21 km) course; on Jan. 10, 1944, an XR-5 set an unofficial altitude record of 21,200 ft (6,461,8 m).
The XR-5 had a 2-place tandem cockpit with the observer in the forward position and the pilot aft. It had a fuselage length of 41.6 ft (12.5 m) and an over-all height of 13.1 ft (4 m). The 3-bladed fully articulated main rotor had a diameter of 48 ft (14.6 m). The R-5A had an empty weight of 3,780 lb (1,714.6 kg) and a maximum takeoff gross weight of 4,900 lb (2,222.6 kg).
The XR-5 was powered by a 450 hp (335 kw) Pratt & Whitney Wasp Jr. R985-AN-5 radial engine, giving the helicopter a rate of climb of 2,000 ft/min (10.1 m/s), a maximum speed of 107 kt (198 km/hr), a service ceiling of 14,800 ft (4,511 m) and a range of 275 miles (442.6 km).
Five XR-5 models were manufactured from August 1944 to November 1944; 26 YR-5A models were manufactured from November 1944 to July 1945 and 14 R-5A and 20 R-5D models were manufactured from July 1945 to October 1946. The R-5D helicopter was equipped with a rescue hoist and an auxiliary fuel tank and was the first helicopter assigned to the USAAF Air Rescue Service.
The model was eventually used by the US Navy and Coast Guard (with the designations HO2S and HO3S), and by the US Post Office Department. The civilian version, under the designation S-51, was the first helicopter to be operated commercially, commencing in 1946. In December 1946, Sikorsky signed an agreement with Westland Aircraft to produce the aircraft under license in Britain as the Westland-Sikorsky WS-51 Dragonfly. By the time production ceased in 1951, more than 300 examples of all types of the H-5 had been built.
Description: Paul Fardink
Photo credit: NASM
Go back to the photo for last month or view the photo for next month
2021 History Calendar Index