The
            tandem two-seat VS-336 was designed to improve the R-4
            Hoverfly's performance and first flew in 1943.  Accepted into
            U.S. Army Air Force service as the R-5 Dragonfly and as the HO2S
            in the U.S. Navy.
            The "D" model changed the landing gear
            to a nosewheel configuration.  A civil four-seat version--the S-51--first
            flew in 1946 and was purchased by the U.S. Air Force as the H-5
            and U.S. Navy as the HO3S.
            This helicopter saw extensive action in Korea rescuing
            United Nations pilots shot down behind enemy lines.