Sikorsky Product History

Sikorsky S-50

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 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.

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 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 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

Performance
Standard Day at Sea Level
Maximum Speed (Vne)
103.4 kts / 191.5 km/hr
Range
250 mi / 402.3 m
Absolute Ceiling
16,000 ft / 4,877 m
Rate of Climb
1,400 ft/min / 7.1 m/s
Weights
Maximum Takeoff Gross Weight
1,450 lbs / 657.1 kg
Weight Empty
1,050 lbs / 476.3kg
Maximum Fuel Load
21 gal / 79.5 ltr
Useful Load
400 lbs / 181.4 kg
General Data
Crew Seating Capacity
1
Seating Capacity
1 passenger
Powerplant Ratings
Standard Day at Sea Level
Franklin 6ACV-298 (150 hp@ 3200 rpm)
150 hp / 110.3 kw
Aircraft Dimensions
Main Rotor Diameter (Blade Tip Circle)
30’ 0” / 9.1 m
Tail rotor diameter (blade tip circle)
7’ 0” / 2.1 m
Fuselage Length
23’ 4” / 7.1 m
Length Overall (Including Rotors)
40’ 3” / 12.3 m
Main Landing Gear Tread
9’ 0” / 2.7 m

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