First of three prototypes. 50 production models, HSL-1, were built.
2400 hp P&W R-2800
Production models had a cowl over the forward gear box and control surfaces on the tail. Advertised at the time as being the most powerful helicopter in the Navy. This was the only twin tandem rotor helicopter build by Bell. One source said the noise level was so high it interfered with sonar work.
