Developed by 1942, the production aircraft were designated R-4B by the U.S. Army Air Force; HNS-1 by the U.S. Navy (which may be fitted with landing floats) and Hoverfly I by the Royal Navy.  The R-4B/HNS-1 was both the first helicopter to enter service with the U.S. military.


Data on design, manufacture and status


Primary flight and mechanical characteristics

VTOL type: Helicopter

Lift configuration: Single main rotor

Dedicated control device: Tail rotor

Crew required: 1-2

Crew seating: Side-by-side

Landing gear: Wheels (non-retractable)

Layout and Dimensions

Data on aircraft size

Overall Dimensions
Overall Height: 3.68 m 12.1 ft
Overall Length: 14.66 m 48.1 ft
Overall Width: 11.58 m 38.0 ft
Airframe Dimensions
Airframe Length:  
Airframe Width:  
Airframe Height:  
Landing Gear Dimensions
Landing Gear Base:  
Landing Gear Track:  
Cabin Dimensions
Cabin Internal Height:  
Cabin Internal Length:  
Cabin Internal Width:  

Weights and Performance

Data on aircraft weight and flight characteristics

Cruise Speed: 65 mph (104.607 km/h)

Max Gross Weight (ground): 1,152 kg 2,540 lb
Max Gross Weight (airborne):  
Max Take-off Weight: 1,152 kg 2,540 lb
Empty Weight: 916 kg 2,020 lb
Useful Load: 236 kg 520 lb
Empty Weight Fraction: 0.795
Climb Performance
Max Rate of Climb:  
Hover Performance
Hover Ceiling IGE:  
Hover Ceiling OGE:  
Max Level Flight Speed:  
Never Exceed Speed:  
Service Ceiling: 2,438 m 8,000 ft
Range and Endurance
Max Range: 322 km 174 nm
Max Endurance:  

Engine Details

Aircraft powerplant (lift and/or propulsion)

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

Number of engines: 1
Designation: Warner R-550-3 Super Scarab reciprocating
Manufacturer: Warner
Normal Ratings
Max continuous:  
Take-off / rated: 149 kW 200 hp
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: 11.58 m 38.00 ft
Direction of Rotation: Counterclockwise
Hub Type:
Main Rotor Blade Characteristics
Blade Construction:
Blade Chord:  
Blade Tip Geometry:
Blade Twist:  
Number of Blades: 3
Main Rotor Derived Characteristics
Disc Area: 105.36 m² 1134.2 ft²
Disc Loading: 10.93 kg/m² 2.240 lb/ft²
Main Rotor Blade Derived Characteristics
Blade area per blade:  
Tip Speed:  

Primary Control Device

Data on primary control devices such as tail rotors

Tail Rotor Characteristics
Configuration: Unknown
Direction of Rotation: Top blade aft
Tail Rotor Blade Characteristics
Number of Blades: 3
Blade Construction:  
Blade Chord:  
Blade Twist:  
Tail Rotor Derived Characteristics
Disc Area:  
Tail Rotor Blade Derived Characteristics
Tip Speed:  
Blade Area (per blade):  

Related VFS Resources

Resources related to the HNS-1 , provided by the Vertical Flight Society.
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Related Public Resources

Resources related to the HNS-1 , provided by public sources across the internet.