The Bell Company’s HSL was one of the world’s first helicopters developed specifically for the antisubmarine role. Although the Germans employed helicopters from ships to search for submarines during World War II, it was an ad hoc effort using available aircraft, as were the few subsequent U.S. and British navy trials in this field.
Bell won the Navy competition to develop a helicopter specifically for antisubmarine warfare (ASW) in June 1950. The HSL was produced in relatively large numbers for its time—three XHSL-1 prototypes and 50 HSL-1 production helicopters, completed from 1953 to 1956. The U.S. Navy had ordered more, and the Royal Navy had contracted for 18, but problems with the helicopter in the ASW role led to U.S. cutbacks and cancellation of the British order.
The HSL was a tandem-rotor helicopter designed to carry dipping sonar and to attack submerged submarines with acoustic homing torpedoes and surfaced submarines with the AUM-N-2 Petrel missile (actually a modified Mk 21 aerial torpedo). With a gross weight of 26,500 pounds, it was the largest helicopter ordered in quantity up to that time, requiring a 1,900-horsepower engine.
In the “hunter” mode, the HSL had a crew of three or four and was fitted with the AN/SQS-4A dipping sonar. In the “killer” role, the two-man crew had two Mk 43 homing torpedoes. The helicopter was fitted for night and instrument flight.
The first prototype flew on 3 March 1953, and HSL deliveries to Helicopter Utility Squadron 1 began in January 1957. However, flight trials revealed that the helicopter’s noise was too high for efficient sonar use, while the aircraft’s large size and manually folded rotor blades made it too awkward for shipboard operation.
The HSL’s value in the ASW role was questionable, but the Navy made good use of the helicopter. In 1954, it began testing the HSL in the mine countermeasures role, demonstrating the helicopter’s ability to pull a 310-ton barge at 18 knots. An HSL also pulled the floating derrick YSD-51 in another towing demonstration. Six of the helicopters were modified for minesweeping and were employed in that development role until 1960. Another HSL fuselage was stripped and suspended under a Sikorsky S-60 Skycrane in 1960 to test the feasibility of the larger aircraft for mine countermeasures. And another HSL was evaluated by the Army in 1956 for possible use as a troop carrier.
Despite its relatively large production run and evaluation in several roles beyond the original antisubmarine configuration, the HSL was not successful. Many subsequent Bell helicopters set the standard for effective military “whirlybirds.”
