Bell HSL

The Bell HSL, Bell Model 61, was an American anti-submarine warfare helicopter of the 1950s that Bell Helicopter built for the United States Navy, and the only tandem-rotor type Bell designed. The Navy chose the Model 61 in a June 1950 competition, and the prototype first flew on 3 March 1953. It carried a crew of two pilots and two sonar operators, a dipping sonar and two Mark 43 torpedoes, and used a single Pratt and Whitney R-2800 radial engine. Development problems made it obsolete before it entered service in 1957 and the Navy found it unsatisfactory, so the production contract was cancelled after only 50 had been built. A handful were used for airborne mine-sweeping development, and the last was struck off in early 1960.