Vertipedia - Bell AH-1S Cobra

Existing AH-1G and AH-1Q Cobras were converted to AH-1S aircraft under the Improved Cobra Agility and Maneuverability Program (ICAM) and used the more powerful T53-L-703 powerplant. Initial AH-1S Cobras (AH-1S Modified) retained the 7.62mm minigun chin turret and 8 TOW missile hardpoints of the AH-1Q. An interim version (the "up-gunned" or AH-1S Production) replaced the minigun with a single M197 three-barreled cannon. A flat-panel canopy was also fitted. The final, fully modified configuration (AH-1S Modernized) added a distinctive extended exhaust nozzle and AN/AAS-32 laser tracker on the forward end of the rotor pylon fairing. All variants were officially designated AH-1S in 1987.

Overview

Data on design, manufacture and status

Design authority: Bell Helicopter Textron, Inc.

Primary manufacturer: Bell Helicopter Textron, Inc.

Parent type: Bell Model 209/AH-1 Cobra

Aircraft status: Operational

Configuration

Primary flight and mechanical characteristics

VTOL type: Helicopter

Lift devices: 1 Single main rotor

Dedicated control device: 1 Tail rotor

Crew required: TBA in Tandem arrangement

Landing gear: Skids

Key Characteristics

Data on key physical features

Aircraft Details

Data on aircraft configuration, weights, flight performance and equipment

Layout and Dimensions

Weights and Performance

Engine Details

Primary Lift Device

Primary Control Device

Airframe width includes stub wings. While there is some variation among Cobra variants, most fuselage widths without stub wings are .914 m (3 ft).

Overall Dimensions
Overall Height:	4.10 m	13.5 ft
Overall Length:	16.14 m	53.0 ft
Overall Width:	13.41 m	44.0 ft

Airframe Dimensions
Airframe Length:	13.77 m	45.2 ft
Airframe Width:	3.15 m	10.3 ft
Airframe Height:	3.11 m	10.2 ft

Landing Gear Dimensions
Landing Gear Base:	3.27 m	10.7 ft
Landing Gear Track:	2.13 m	7.0 ft

Cabin Dimensions
Cabin Internal Height:
Cabin Internal Length:
Cabin Internal Width:

Weights
Max Gross Weight (ground):	4,536 kg	10,000 lb
Max Gross Weight (airborne):
Max Take-off Weight:	4,536 kg	10,000 lb
Empty Weight:	2,862 kg	6,310 lb

Climb Performance
Max Rate of Climb:	8 m/s	1,620 fpm

Hover Performance
Hover Ceiling IGE:	3,719 m	12,200 ft
Hover Ceiling OGE:

Limitations
Max Level Flight Speed:	237 km/h	128 kts
Never Exceed Speed:	315 km/h	170 kts
Service Ceiling:	3,780 m	12,400 ft

Range and Endurance
Max Range:	519 km	280 nm
Max Endurance:

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

Powerplant
Number of engines:	1
Designation:	Lycoming T53-L-703 turbine
Manufacturer:	Lycoming Engines

Normal Ratings
Max continuous:
Take-off / rated:
Intermediate:
Maximum:	1343 kW	1800 hp

OEI Ratings
OEI contingency:
OEI continuous:
OEI 30-second:
OEI intermediate:

B540 blade for two-bladed Cobra main rotors.

Main Rotor Characteristics
Diameter:	13.40 m	43.96 ft
RPM:	324.0 rpm	324.0 rpm
Direction of Rotation:	Counterclockwise
Hub Type:	Flex-beam, stiff-in-plane teetering hub

Main Rotor Blade Characteristics
Blade Construction:	Bonded aluminum spar and skin; nomex honeycomb core
Blade Chord:	0.686 m	2.25 ft
Blade Tip Geometry:	Square-edged tips
Blade Twist:	-0.175 rad	-10.000 deg
Number of Blades:	2

Main Rotor Derived Characteristics
Disc Area:	141.03 m²	1518.0 ft²
Disc Loading:	32.16 kg/m²	6.588 lb/ft²
Solidity:	0.0652

Main Rotor Blade Derived Characteristics
Blade area per blade:	4.59 m²	49.5 ft²
Tip Speed:	227.33 m/s	745.8 fps

Tail Rotor Characteristics
Diameter:	2.59 m	8.50 ft
Configuration:	Tractor
Direction of Rotation:	Top blade aft
RPM:	1654 rpm	1654 rpm

Tail Rotor Blade Characteristics
Number of Blades:	2
Blade Construction:	Bonded aluminum skin with abrasion strip
Blade Chord:	0.292 m	0.96 ft
Blade Twist:

Tail Rotor Derived Characteristics
Disc Area:	5.27 m²	56.7 ft²
Solidity:	0.1436

Tail Rotor Blade Derived Characteristics
Tip Speed:	224.37 m/s	736.1 fps
Blade Area (per blade):	0.378 m²	4.07 ft²

References

References and sources used

Bell AH-1 Cobra Variants

Peoples, Kenneth
Aerofax, Arlington TX, 1988 (page 38)
Book
Aerofax Datagraph 4

Operator's Manual, Army Model AH-1G Helicopter

U.S. Dept. of the Army
Technical Manual TM 55-1520-221-10, 1967 (page 53)
Report or Technical Manual

Production Validation Test - Government: Kaman K747 Improved Main Rotor Blade

Diekmann, Vernon L. et al
US Army Aviation Engineering Flight Activity, Edwards Air Force Base, October 1979 (page 17)
Report or Technical Manual
Defense Technical Information Center / USAAEFA Report No. 77-38. Contains specifications on K747 and B540 main rotor blades.