Developed in 1949, there are two versions, both of which have several designations.  Powered the the P&W R-1340-57 powerplant, designations include: 

  • HO4S-1 & 2 under the U.S. Navy
  • HO4S-2G under the U.S. Coast Guard
  • HRS-2 & under the U.S. Marine Corps
  • H-19A under the U.S. Air Force

There is also the H-19B (HRS-3) version, powered by the Wright R-1300-3 engine.


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: 4.07 m 13.4 ft
Overall Length: 18.99 m 62.3 ft
Overall Width: 16.15 m 53.0 ft
Airframe Dimensions
Airframe Length: 12.85 m 42.2 ft
Airframe Width: 3.53 m 11.6 ft
Airframe Height:  
Landing Gear Dimensions
Landing Gear Base: 3.16 m 10.4 ft
Landing Gear Track: 2.64 m 8.7 ft
Cabin Dimensions
Cabin Internal Height:  
Cabin Internal Length:  
Cabin Internal Width:  

Weights and Performance

Data on aircraft weight and flight characteristics

Cruise Speed: 85 mph (136.794 km/h)

Max Gross Weight (ground): 3,266 kg 7,200 lb
Max Gross Weight (airborne):  
Max Take-off Weight: 3,266 kg 7,200 lb
Empty Weight: 2,175 kg 4,795 lb
Useful Load: 1,091 kg 2,405 lb
Empty Weight Fraction: 0.666
Climb Performance
Max Rate of Climb: 4 m/s 700 fpm
Hover Performance
Hover Ceiling IGE:  
Hover Ceiling OGE:  
Max Level Flight Speed:  
Never Exceed Speed:  
Service Ceiling: 3,200 m 10,500 ft
Range and Endurance
Max Range: 652 km 352 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: P&W R-1340-57 reciprocating
Manufacturer: Pratt & Whitney
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: 16.15 m 53.00 ft
Direction of Rotation: Counterclockwise
Hub Type:
Main Rotor Blade Characteristics
Blade Construction:
Blade Chord:  
Blade Tip Geometry: Conventional
Blade Twist:  
Number of Blades: 3
Main Rotor Derived Characteristics
Disc Area: 204.96 m² 2206.3 ft²
Disc Loading: 15.93 kg/m² 3.264 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
Diameter: 2.64 m 8.66 ft
Configuration: Pusher
Direction of Rotation: Top blade aft
Tail Rotor Blade Characteristics
Number of Blades: 2
Blade Construction:  
Blade Chord:  
Blade Twist:  
Tail Rotor Derived Characteristics
Disc Area: 5.47 m² 58.9 ft²
Tail Rotor Blade Derived Characteristics
Tip Speed:  
Blade Area (per blade):  

Related VFS Resources

Resources related to the S-55/HO4S-1/HO4S-2/HRS-2/HRS-3 , provided by the Vertical Flight Society.
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Related Public Resources

Resources related to the S-55/HO4S-1/HO4S-2/HRS-2/HRS-3 , provided by public sources across the internet.