Background

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.

Configuration Features

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.

To save weight the traditional oleo strut tail landing gear was replaced by a tail landing skid with 3 rubber doughnuts to absorb landing loads.

Main Rotor Assembly

A 3 bladed fully articulated main rotor head was planned for the S-50 helicopter with a 32 foot rotor diameter which was later reduced to 30 foot to save weight.

Tail Rotor Assembly

A 3 bladed 8’ 4’ diameter tail rotor (later reduced to 7 foot) with laminated wood blades was planned for the S-50 helicopter.

Engine

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.

Main Rotor Blades

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.

S-50 Mockup of Mechanical Parts Including Flight Controls.

General Arrangement Drawing