The Sikorsky S-50 helicopter was a 1943 company funded design study for a small single engine helicopter based on the S-49 (XR-6) helicopter. The S-50 design gross weight was 1,450 lbs. vs. 2,590 lbs for the XR-6 helicopter, a 56 reduction in weight. It was unofficially marketed to the U.S. Army Air Corps. as a single pilot observation helicopter. The S-50 helicopter program never progressed beyond the full scale mockup stage. The Sikorsky S-50 original design strategy was to use the S-49 dynamic components with the 38 foot main rotor diameter reduced to 32 foot by shortening the S-49 main rotor blades. Weight calculations dictated that a new lighter weight hub and lighter weight blades would be required to meet the design goals. The main rotor blades were constructed with metal spars, plywood ribs, and plywood pockets with the entire blade covered with 2 layers of fabric. A NACA 0012 airfoil was used. The main rotor blades were constructed with metal spars, plywood ribs, and plywood pockets with the entire blade covered with 2 layers of fabric. A NACA 0012 airfoil was used. A Franklin 6ACV-298, 150 hp, 6 cylinder horizontally opposed engine was to be installed vertically under the center section of the helicopter with a cooling fan/flywheel above.
