330-PS-3339:   US Navy’s Anti-Submarine Helicopter Makes Initial Flight:, March 4, 1951.  The Navy’s first helicopter designed for anti-submarine XMSL-1.   Built by the Bell Aircraft Corporation, the helicopter is twice as heavy as helicopters now used in the Navy.   A high rotor tip speed makes it possible for the helicopter to reach high speeds.   (4/28/2015).
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