Vertipedia - Bell 209 Firewatch Cobra

AKA Bell 209. Retired US Army AH-1Fs have been converted into US Forest Service Firewatch Cobras with infrared and low-light sensors for real-time fire monitoring, GIS mapping, real-time color video, geo-referenced infrared, and infrared downlink. In addition to intelligence gathering, they are also used as a platform for an Air Attack Group Supervisor (ATGS) or a Helicopter Coordinator (HLCO).

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: 2 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):
Max Gross Weight (airborne):
Max Take-off Weight:
Empty Weight:

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:

The Kaman K747 blade was designed to improve upon the B540's hover performance, maintainability and reliability, while also reducing ballistic vulnerability. Aircraft using the K747 blades used the same general hub as the B540, but added other improvements such as strengthened swash plates, scissors and other control system elements designed to account for the K747's higher loads.

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:	Multi-cell filament wound spar, Nomex core, fiberglass skin and Kevlar trailing edge
Blade Chord:	0.762 m	2.50 ft
Blade Tip Geometry:	Trapezoidal planform tip taper
Blade Twist:	-0.209 rad	-12.000 deg
Number of Blades:	2

Main Rotor Derived Characteristics
Disc Area:	141.03 m²	1518.0 ft²
Disc Loading:
Solidity:	0.0724

Main Rotor Blade Derived Characteristics
Blade area per blade:	5.11 m²	55.0 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

Cobra Gold: The US Army’s Smart Retirement Program

Defense Industry Daily staff
N/A, 2010, Nov 24
Website
Reference for the number of Firewatch Cobras operated by the US Forestry Service

Search at SciTech Connect (OSTI).

Public resources provided by select scholarly and academic sources

Search at European Rotorcraft Forum Document Repository.

Search at IOPScience.

Search at CiteSeerX.

Additional links

Search for at Google Scholar.

Search for at Bielefeld Academic Search Engine (BASE).

Search for at Semantic Scholar.

Search for at CORE (COnnecting REpositories).

Search for at JSTOR.

Images

Overview

Attribution

Number of engines:	1 Turbine
Max Level Flight Speed:	237 km/h	128 kts
Max Range:	519 km	280 nm
Max Endurance:

Bell 209 Firewatch Cobra

Bell 209 Firewatch Cobra

Overview

Configuration

Key Characteristics

Aircraft Details

References

Related VFS Resources

Forum Proceedings

Vertiflite articles

Web files from vtol.org

Webpages from vtol.org

Images from the VFS Gallery

Related Public Resources

Publicly-funded resources provided by the US Government

Public resources provided by select scholarly and academic sources

Additional links

Images

Overview

Main Rotor Diameter:	13.40 m	43.96 ft
Max Gross Weight (ground):