Sikorsky S‑51 / R‑5 / H‑5
in US Air Force

The Sikorsky H-5 was the first helicopter widely used by the Air Force, and the first to carry out combat rescues during the Korean War. Initially called the R-5, the first helicopter in this series made its maiden flight August 18, 1943. In March 1944 the US Army Air Forces ordered 26 YR-5As for service testing and in February 1945 the first of them was delivered. In 1948, when the Air Force overhauled its system for naming aircraft it replaced the R for rotorcraft category with H for helicopter. By 1952, the H-5 was being phased out of the Air Force inventory.