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S-50 Helicopter S-50 full scale wood mockup 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 US 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. S-50 full scale mockup rear view 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.

S-50 tail landing skid with rubber doughnut shock absorber 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 S50 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 Main Rotor Blade engineering sketch S-50 Mockup of mechanical parts including flight controls. S-50 mockup including flight controls installation General Arrangement Drawing S-50 3-view drawing General

Characteristics and Performance S-50 PERFORMANCE Standard Day, Sea Level Maximum speed (Vne) Range Absolute ceiling Rate of Climb WEIGHTS Maximum takeoff gross weight Weight empty Maximum fuel load Useful Load 103.4 kts 1915 km/hr 250 miles 402.3 km 16,000 ft 4,877 m 1,400 ft/min 7.1 m/s 1,450 lbs 657.1 kg 1,050 lbs 476.3kg 21 gal 79.5 ltr 400 lbs 181.4 kg GENERAL DATA Crew seating capacity Seating capacity 1 1 passenger POWERPLANT RATINGS Standard Day at Sea Level Franklin 6ACV-298 (150 hp@ 3200 rpm) 150 hp 110.3 kw 30’ 0” 7’ 0” 23’ 4” 40’ 3” 9’ 0” 9.1 m 2.1 m 7.1 m 12.3 m 2.7 m AIRCRAFT DIMENSIONS Main rotor diameter (blade tip circle) Tail rotor diameter (blade tip circle) Fuselage length Length over-all (including rotors) Main landing gear tread Prepared by Vinny Devine October 2013