Sikorsky H-5 (R-5, S-51, HO2S-1, HO3S-1)
Built by Sikorsky Aircraft Corporation. Known as the R-5 until 1948. Developed from the Sikorsky R-4. Used by the United States Army Air Force (USAAF) and later the United States Air Force (USAF). Also used by the United States Navy, United States Marine Corps and United States Coast Guard designations for this helicopter. Served in the United States Coast Guard (USCG) with the designations HO2S and HO3S.
During the Korean War, the H-5 / SO3S-1 was used in Korean to rescue United Nations pilots from behind enemy lines and to evacuate wounded personnel.
The US Marine Corps created the unit HMX-1, an operational test and development squadron formed on December 1, 1947. Their mission was to develop uses for the helicopter by the Marines. During an amphibious operation with forces from nearby Camp Lejeune five HO3S-1 helicopters transported 66 troops from ship to shore avoiding the dangers of a beach landing. After the start of the Korean War, the pilots and maintenance personnel of HMX-1 were assigned to VMO-6 which deployed to Korea with four HO3S-1 helicopters. In Korea they were used by the Marines as an Observation/Liaison role plus search and rescue (SAR) missions. By the end of 1950, twenty-three air crewmen were rescued from behind enemy lines by VMO-6 helicopters.
Westland-Sikorsky WS-51 Dragonfly
During December 1946, an agreement was signed between the Westland Aircraft and Sikorsky to produce a British version of the H-5 known as the S-51 or WS-51.
A total of roughly 300 were built until production ceased in 1951.
Sikorsky Product History - S-51/HO3S-1/H-5F, G, H Helicopter