Note: This aircraft never actually flew with the X-wing rotor. It is included to complete the historical record of this project.

It flew without the rotor to test the aircraft in an emergency configuration if the rotor had been deliberately severed from the aircraft.  A "stopped rotor" system allowed the 4-blade main rotor to be stopped midflight and still generate lift as "wings".  To achieve this, the blades were composed of carbon fiber containing a torsion box with flexible ducts along the edges of either side.  Compressed air was released to deform the ducts along the trailing edges as needed; when in the fixed-wing configuration, the blades on the lefthand side change their effected sides to create new trailing edges suitable for the position [FLIGHT INTERNATIONAL, 22 February 1986, page 18].   The X-Wing has no tail rotor; instead, the exhaust from the T58 engines was to be directed through a nozzle to counter the main rotors generated torque.

Source: "Hybrid Helicopters: Compounding the Quest for Speed", Robb, Raymond L., Vertiflite, Summer 2006.  Published by AHS International. Page 51


Data on design, manufacture and status

Design authority: Sikorsky Aircraft Corp.

Primary manufacturer: Sikorsky Aircraft Corp.

Parent type: Sikorsky S-72 RSRA

Aircraft status: Status unknown


Primary flight and mechanical characteristics

VTOL type: Helicopter

Compound type: Lift and Thrust

Lift configuration: Single main rotor

Dedicated control device: Tail rotor

Dedicated propulsion devices: 2

Crew required: 2-3

Crew seating: Side-by-side

Landing gear: Wheels (some retractable)

Layout and Dimensions

Data on aircraft size

Overall Dimensions
Overall Height: 3.15 m 10.3 ft
Overall Length: 19.00 m 62.3 ft
Overall Width: 15.24 m 50.0 ft
Airframe Dimensions
Airframe Length: 18.64 m 61.2 ft
Airframe Width:  
Airframe Height: 5.49 m 18.0 ft
Landing Gear Dimensions
Landing Gear Base: 6.35 m 20.8 ft
Landing Gear Track: 3.20 m 10.5 ft
Cabin Dimensions
Cabin Internal Height:  
Cabin Internal Length:  
Cabin Internal Width:  

Weights and Performance

Data on aircraft weight and flight characteristics

Design (theoretical) Performance

Max Gross Weight (ground): 10,886 kg 24,000 lb
Max Gross Weight (airborne):  
Max Take-off Weight: 10,886 kg 24,000 lb
Empty Weight:  
Useful Load:  
Empty Weight Fraction:  
Climb Performance
Max Rate of Climb:  
Hover Performance
Hover Ceiling IGE:  
Hover Ceiling OGE:  
Max Level Flight Speed: 833 km/h 450 kts
Never Exceed Speed:  
Service Ceiling:  
Range and Endurance
Max Range:  
Max Endurance:  

Engine Details

Aircraft powerplant (lift and/or propulsion)

Provided powerplant data is for uninstalled, sea level, static operations.

Number of engines: 2
Designation: GE TF34-GE-400A turbine
Manufacturer: GE Aviation
Normal Ratings
Max continuous:  
Take-off / rated:  
OEI Ratings
OEI contingency:  
OEI continuous:  
OEI 30-second:  
OEI intermediate:  

Primary Lift Device

Data on primary lift devices such as main rotors

Main Rotor Characteristics
Diameter: 15.24 m 50.00 ft
Direction of Rotation: Counterclockwise
Hub Type:
Main Rotor Blade Characteristics
Blade Construction:
Blade Chord: 1.033 m 3.39 ft
Blade Tip Geometry: Arced
Blade Twist:  
Number of Blades: 4
Main Rotor Derived Characteristics
Disc Area: 182.41 m² 1963.6 ft²
Disc Loading: 59.68 kg/m² 12.223 lb/ft²
Solidity: 0.1727
Main Rotor Blade Derived Characteristics
Blade area per blade: 7.87 m² 84.8 ft²
Tip Speed:  

Primary Control Device

Data on primary control devices such as tail rotors

Tail Rotor Characteristics
Configuration: Unknown
Direction of Rotation: Unknown
Tail Rotor Blade Characteristics
Number of Blades:  
Blade Construction: N/A
Blade Chord:  
Blade Twist:  
Tail Rotor Derived Characteristics
Disc Area:  
Tail Rotor Blade Derived Characteristics
Tip Speed:  
Blade Area (per blade):  

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