Lockheed research into compound rigid rotor helicopters began in the early 1960s using the XH-51. In 1966, Lockheed's design for an operational attack helicopter, the AH-56 Cheyenne, won the contract to build the US Army's Advanced Aerial Fire Support System (AAFSS). The Cheyenne had a 3,435 shp General Electric T64-GE-16 turboshaft engine that powered a rigid 50 ft four-bladed rotor, as well as a 10 ft three-bladed pusher propeller and a four-bladed anti-torque rotor on the tail. In horizontal flight, almost the entire engine output is used to drive the propeller. The AH-56 weighed 12,000 lb empty, had a 55 ft long fuselage and a 27 ft wingspan. Maximum vertical take-off weight was 22,000 lb, but a short take-off could be made at 28,000 lb.

First flight was on 21 September 1967. A maximum speed of 277 mph was reached. The third of ten prototypes crashed on 12 March 1969 when the rotor impacted the front and rear fuselage, killing the pilot. The AH-56 was highly agile and a very capable weapon system, but development was halted in 1972, due to defense cutbacks. A production order of 375 AH-56s had been approved in 1968, but canceled the next year, also as a result of budget cuts.

Source: AHS V/STOL Wheel

Overview

Data on design, manufacture and status

Design authority: Lockheed Aircraft Corporation

Primary manufacturer: Lockheed Aircraft Corporation

Parent type: Lockheed AH-56 Cheyenne

Aircraft status: No longer flying

Configuration

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: 1

Crew required: 2

Crew seating: Tandem

Landing gear: Wheels (all retractable)

Layout and Dimensions

Data on aircraft size

Overall Dimensions
Overall Height: 4.14 m 13.6 ft
Overall Length: 18.44 m 60.5 ft
Overall Width: 15.62 m 51.2 ft
Airframe Dimensions
Airframe Length: 16.63 m 54.5 ft
Airframe Width: 8.14 m 26.7 ft
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: 388 km/h

Weights
Max Gross Weight (ground): 7,707 kg 16,991 lb
Max Gross Weight (airborne):  
Max Take-off Weight: 7,707 kg 16,991 lb
Empty Weight: 5,315 kg 11,718 lb
Useful Load: 2,392 kg 5,273 lb
Empty Weight Fraction: 0.690
Climb Performance
Max Rate of Climb: 17 m/s 3,419 fpm
Hover Performance
Hover Ceiling IGE:  
Hover Ceiling OGE: 3,230 m 10,597 ft
Limitations
Max Level Flight Speed: 407 km/h 220 kts
Never Exceed Speed:  
Service Ceiling: 7,620 m 25,000 ft
Range and Endurance
Max Range: 1,408 km 760 nm
Max Endurance:  

Engine Details

Aircraft powerplant (lift and/or propulsion)

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

Powerplant
Number of engines: 1
Designation: GE T64-GE-16 turbine
Manufacturer: GE Aviation
Normal Ratings
Max continuous:  
Take-off / rated:  
Intermediate:  
Maximum:  
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: 15.39 m 50.50 ft
RPM: 246.0 rpm 246.0 rpm
Direction of Rotation: Counterclockwise
Hub Type: 'Rigid rotor' with only articulation in pitch
Main Rotor Blade Characteristics
Blade Construction:
Blade Chord:  
Blade Tip Geometry:
Blade Twist:  
Number of Blades: 4
Main Rotor Derived Characteristics
Disc Area: 186.07 m² 2002.9 ft²
Disc Loading: 41.42 kg/m² 8.483 lb/ft²
Solidity:  
Main Rotor Blade Derived Characteristics
Blade area per blade:  
Tip Speed: 198.26 m/s 650.4 fps

Primary Control Device

Data on primary control devices such as tail rotors

Tail Rotor Characteristics
Diameter: 3.05 m 10.00 ft
Configuration: Unknown
Direction of Rotation: Unknown
RPM:  
Tail Rotor Blade Characteristics
Number of Blades: 4
Blade Construction:  
Blade Chord:  
Blade Twist:  
Tail Rotor Derived Characteristics
Disc Area: 7.30 m² 78.5 ft²
Solidity:  
Tail Rotor Blade Derived Characteristics
Tip Speed:  
Blade Area (per blade):  

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