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Bell AH-1 Cobra

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The Bell AH-1 Cobra (company designation: Model 209) is a two-bladed, single engine attack helicopter manufactured by Bell Helicopter. It shares a common engine, transmission and rotor system with the older UH-1 Iroquois. The AH-1 is also referred to as the HueyCobra or Snake.

The AH-1 was the backbone of the United States Army's attack helicopter fleet, but has been replaced by the AH-64 Apache in Army service. Upgraded versions continue to fly with the militaries of several other nations. The AH-1 twin engine versions remain in service with United States Marine Corps (USMC) as the service's primary attack helicopter. Surplus AH-1 helicopters have been converted for fighting forest fires. The United States Forest Service refers to their program as the Firewatch Cobra. Garlick Helicopters also converts surplus AH-1s for forest firefighting under the name, FireSnake.[1]

Development[]

Background[]

Closely related with the development of the Bell AH-1 is the story of the Bell UH-1 Iroquois—predecessor of the modern helicopter, icon of the Vietnam War and still one of the most numerous helicopter types in service today. The UH-1 made the theory of air cavalry practical, as the new tactics called for US forces to be highly mobile across a wide area. Unlike before, they would not stand and fight long battles, and they would not stay and hold positions. Instead, the plan was that the troops carried by fleets of UH-1 "Hueys" would range across the country, to fight the enemy at times and places of their own choice.[2]

It soon became clear that the unarmed troop helicopters were vulnerable against ground fire from Việt Cộng and North Vietnamese troops, particularly as they came down to drop their troops in a landing zone. Without friendly support from artillery or ground forces, the only way to pacify a landing zone was from the air, preferably with a machine that could closely escort the transport helicopters, and loiter over the landing zone as the battle progressed. By 1962 a small number of armed UH-1As were used as escorts, armed with multiple machine guns and rocket mounts.[3]

The massive expansion of American military presence in Vietnam opened a new era of war from the air. The linchpin of US Army tactics were the helicopters, and the protection of those helicopters became a vital role.[4]

Iroquois Warrior and Sioux Scout[]

Bell 207

Bell Model 207 Sioux Scout

Main article: Bell 207 Sioux Scout

Bell had been investigating helicopter gunships since the late 1950s, and had created a mockup of its D-255 helicopter gunship concept, named "Iroquois Warrior". In June 1962, Bell displayed the mockup to Army officials, hoping to solicit funding for further development. The Iroquois Warrior was planned to be a purpose-built attack aircraft based on the UH-1B components with a new, slender airframe and a two-seat, tandem cockpit. It featured a grenade launcher in a ball turret on the nose, a 20 mm belly-mounted gun pod, and stub wings for mounting rockets or SS.10 anti-tank missiles.[5]

The Army was interested and awarded Bell a proof of concept contract in December 1962. Bell modified a Model 47 into the sleek Model 207 Sioux Scout which first flew in July 1963. The Sioux Scout had all the key features of a modern attack helicopter: a tandem cockpit, stub wings for weapons, and a chin-mounted gun turret. After evaluating the Sioux Scout in early 1964, the Army was impressed, but also felt the Sioux Scout was undersized, underpowered, and generally not suited for practical use.[6]

AAFSS[]

Army's solution to the shortcomings of the Sioux Scout was to launch the Advanced Aerial Fire Support System (AAFSS) competition.[6] The AAFSS requirement would give birth to the Lockheed AH-56 Cheyenne–a heavy battlefield helicopter that would prove to be over-ambitious, over-complex and over-budget, before being canceled 10 years later in 1972.[6] The Cheyenne program developed future technology and demonstrated some impressive performance, but was never made to work as a functional gunship. It served to underline an important rule of the combat helicopter–survival would be ensured only by the right mix of speed, agility and weapons.

Model 209[]

Bell 209

Bell 209 prototype of the AH-1 Cobra series, with skids retracted (FAA no. N209J)

At the same time, despite the Army's preference for the AAFSS–for which Bell Helicopter was not selected to compete–Bell stuck with their own idea of a smaller and lighter gunship.[6] In January 1965 Bell invested $1 million to proceed with a new design. Mating the proven transmission, the "540" rotor system of the UH-1C augmented by a Stability Control Augmentation System (SCAS), and the T53 turboshaft engine of the UH-1 with the design philosophy of the Sioux Scout, Bell produced the Model 209.[6] Bell's Model 209 largely resembled the "Iroquois Warrior" mockup.[7]

In Vietnam, events were also advancing in favor of the Model 209. Attacks on US forces were increasing, and by the end of June 1965 there were already 50,000 US ground troops in Vietnam.[6] 1965 was also the deadline for AAFSS selection, but the program would become stuck in technical difficulties and political bickering. The U.S. Army needed an interim gunship for Vietnam and it asked five companies to provide a quick solution. Submissions came in for armed variants of the Boeing-Vertol ACH-47A, Kaman HH-2C Tomahawk, Piasecki 16H Pathfinder, Sikorsky S-61, and the Bell 209.[6]

On 3 September 1965 Bell rolled out its Model 209 prototype, and four days later it made its maiden flight, only eight months after the go-ahead. In April 1966, the model won an evaluation against the other rival helicopters. Then the Army signed the first production contract for 110 aircraft.[6] Bell added Cobra to the UH-1's Huey nickname to produce its HueyCobra name for the 209. The Army applied the Cobra name to its AH-1G designation for the helicopter.[8]

The Bell 209 demonstrator was used for the next six years to test weapons and fit of equipment. It had been modified to the match AH-1 production standard by the early 1970s. The demonstrator was retired to the Patton Museum at Fort Knox, Kentucky and converted to approximately its original appearance.[7]

Into production[]

The Bell 209 design was modified for production. The retractable skids were replaced by simpler fixed skids. A new wide-blade rotor was featured. For production, a plexiglass canopy replaced the 209's armored glass canopy which was heavy enough to harm performance.[7] Other changes were incorporated after entering service. The main one of these was moving the tail rotor from the helicopter's left side to the right for improved effectiveness of the rotor.[9]

The U.S. Marine Corps was interested in the Cobra and ordered an improved twin-engined version in 1968 under the designation AH-1J. This would lead to more twin-engine variants.[10] In 1972, the Army sought improved anti-armor capability. Under the Improved Cobra Armament Program (ICAP), trials of eight AH-1s fitted with TOW missiles were conducted in October 1973. After passing qualification tests the following year, Bell was contracted with upgrading 101 AH-1Gs to the TOW-capable AH-1Q configuration.[11] Following AH-1Q operational tests, a more powerful T53 engine and transmission were added from 1976 resulting in the AH-1S version. The AH-1S was upgraded in three steps, culminating with the AH-1F.[6][12]

United States[]

By June 1967, the first AH-1G HueyCobras had been delivered. Originally designated as UH-1H, the "A" for attack designation was soon adopted and when the improved UH-1D became the UH-1H, the HueyCobra became the AH-1G. The AH-1 was initially considered a variant of the H-1 line, resulting in the G series letter.[13]

AH-1 Cobras were in use by the Army during the Tet offensive in 1968 and through the end of the Vietnam War. Huey Cobras provided fire support for ground forces, escorted transport helicopters and other roles, including aerial rocket artillery (ARA) battalions in the two Airmobile divisions. They also formed "hunter killer" teams by pairing with OH-6A scout helicopters. A team featured one OH-6 flying slow and low to find enemy forces. If the OH-6 drew fire, the Cobra could strike at the then revealed enemy.[7] Bell built 1,116 AH-1Gs for the US Army between 1967 and 1973, and the Cobras chalked up over a million operational hours in Vietnam.[6] Out of nearly 1,110 AH-1s delivered from 1967 to 1973 approximately 300 were lost to combat and accidents during the war.[7][14] The U.S. Marine Corps used AH-1G Cobras in Vietnam for a short time before acquiring twin-engine AH-1J Cobras.[13]

AH-1 Cobras were deployed for Operation Urgent Fury, the invasion of Grenada in 1983, flying close-support and helicopter escort missions. Army Cobras participated in Operation Just Cause, the US invasion of Panama in 1989.[7]

During Operations Desert Shield and Desert Storm in the Gulf War (1990–91), the Cobras and SuperCobras deployed in a support role. The USMC deployed 91 AH-1W SuperCobras and the US Army 140 AH-1 Cobras; these were operated from forward, dispersed desert bases. Three AH-1s were lost in accidents during fighting and afterward. Cobras destroyed many Iraqi armored vehicles and various targets in the fighting.[7]

Army Cobras provided support for the US humanitarian intervention during Operation Restore Hope in Somalia in 1993. They were also employed during the US invasion of Haiti in 1994. US Cobras were also used in operations later in the 1990s.[7]

The US Army phased out the AH-1 during the 1990s and retired the AH-1 from active service in March 1999, offering them to NATO allies.[6][15] The Army retired the AH-1 from reserves in September 2001. The retired AH-1s have been passed to other nations and to the USDA Forest Service.[6] The AH-1 continues to be in service with the US military, by the US Marine Corps, which operate the twin-engine AH-1W SuperCobra and AH-1Z Viper.

Variants[]

Single-engine[]

AH-1S Cobra

Japan Ground Self-Defense Force AH-1S

Usfs-ah1-N107Z-bar complex fire

U.S. Forest Service Bell 209 on the Bar Complex Fire in California

Bell 209
Original AH-1G prototype with retractable skid landing gear. This model number is also used by the FAA for the civilian registration of former U.S. Army AH-1s used in firefighting service.
AH-1G HueyCobra
Initial 1966 production model gunship for the US Army, with one 1,400 shp (Bad rounding hereScript error: No such module "Math". kW) Avco Lycoming T53-13 turboshaft.
JAH-1G HueyCobra
One helicopter for armament testing including Hellfire missiles and multi-barrel cannon.[16]
TH-1G HueyCobra
Two-seat dual-control trainer.[16]
Z.14 HueyCobra
Spanish Navy designation of the AH-1G.[16]
YAH-1Q
Eight AH-1Gs with XM26 Telescopic Sight Unit (TSU) and two M56 TOW 4-pack launchers.[7]
AH-1Q HueyCobra
Equipped with the M65 TOW/Cobra missile subsystem, M65 Telescopic Sight Unit (TSU), and M73 Reflex sight. All future versions will be equipped with the TSU and be equipped to fire the TOW missile subsystem.
YAH-1R
AH-1G powered by a T53-L-703 engine without TOW system.[7]
YAH-1S
AH-1Q upgrade and TOW system.[7]
AH-1S
The baseline AH-1S is an AH-1Q upgraded with a 1,800 shp (Bad rounding hereScript error: No such module "Math". kW) T53-L-703 turboshaft engine. The AH-1S is also referred to as the "Improved AH-1S", "AH-1S Modified", or "AH-1S(MOD)" prior to 1988. (Prior to 1988, all upgraded aircraft were referred to as variants of the AH-1S.)[7]
AH-1P
100 production aircraft with composite rotors, flat plate glass cockpit, and improved cockpit layout for nap-of-earth (NOE) flight. The AH-1P is also referred to as the "Production AH-1S", or "AH-1S(PROD)" prior to 1988. These improvements are considered Step 1 of the AH-1S upgrade program.[7]
AH-1E
98 production aircraft with the Enhanced Cobra Armament System (ECAS) featuring the M97A1 armament subsystem with a three-barreled M197 20 mm cannon. The AH-1E is also referred to as the "Upgunned AH-1S", or "AH-1S(ECAS)" prior to 1988. These improvements are considered Step 2 of the AH-1S upgrade program.[7] AH-1E aircraft included the M147 Rocket Management Subsystem (RMS) to fire 2.75-inch (Bad rounding hereScript error: No such module "Math". mm) rockets.[17]
AH-1F
143 production aircraft and 387 converted AH-1G Cobras. The AH-1F incorporates all Step 1 and 2 upgrades to the AH-1S. It also featured Step 3 upgrades: a head-up display, a laser rangefinder, an infrared jammer mounted above the engine exhaust, and an infrared suppressing engine exhaust system, and the M143 Air Data Subsystem (ADS). The AH-1F is also referred to as the "Modernized AH-1S", "AH-1S Modernized Cobra", or "AH-1S(MC)" prior to 1988.[18]
QAH-1S
A target drone conversion of the AH-1S by Bell-Bristol Aerospace under a joint US and Canadian development program started in 1994. Honeywell further modified the QAH-1S into the Hokum-X by installing systems and hardware to allow it to simulate the Russian Kamov Ka-50 attack helicopter. Three Hokum-Xs were completed from 1998-2001.[19][20]
Model 249
Experimental demonstrator version fitted with a four-bladed rotor system, an uprated engine and experimental equipment, including Hellfire missiles.[21]
Bell 309 KingCobra
Experimental all-weather version based on the AH-1G single-engine and AH-1J twin-engine designs.[22] Two Bell 309s were produced; the first was powered by a PW&C T400-CP-400 Twin-Pac engine set and the second was powered by a Lycoming T-55-L-7C engine.[23]

Twin-engine[]

For all twin-engine variants, such as AH-1J, AH-1T, AH-1W, and AH-1Z, see Bell AH-1 SuperCobra.

Aircraft on display[]

  • The American Helicopter Museum & Education Center in West Chester, Pennsylvania has an AH-1G sn 68-15138 on display.[24]
  • Veterans Park in Kremmling, Colorado has an AH-1F on display.[25]

Specifications[]

AH-1G HueyCobra[]

AH-1G

Data from Modern Military Aircraft,[26] Verier,[27] Modern Fighting Aircraft[28]

General characteristics

  • Crew: 2: one pilot, one co-pilot/gunner (CPG)
  • Length: 53 ft (16.2 m) (with both rotors turning)
  • Rotor diameter: 44 ft (13.4 m)
  • Height: 13 ft 6 in (4.12 m)
  • Empty weight: 5,810 lb (2,630 kg)
  • Max. takeoff weight: 9,500 lb (4,310 kg)
  • Powerplant: 1 × Lycoming T53-L-13 turboshaft, 1,100 shp (820 kW)
  • Rotor system: 2 blades on main rotor, 2 blades on tail rotor
  • Fuselage length: 44 ft 5 in (13.5 m)
  • Stub wing span: 10 ft 4 in (3.15 m)

Performance

  • Never exceed speed: 190 knots (219 mph, 352 km/h)
  • Maximum speed: 149 knots (171 mph, 227 km/h)
  • Range: 310 nmi (357 mi, 574 km)
  • Service ceiling: 11,400 ft (3,475 m)
  • Rate of climb: 1,230 ft/min (6.25 m/s)

Armament

  • 2 × 7.62 mm (0.308 in) multi-barrel Miniguns, or 2 × M129 40 mm Grenade launchers, or one of each, in the M28 turret. (When one of each was mounted, the minigun was mounted on the right side of the turret, due to feeding problems.)
  • 2.75 in (70 mm) rockets - 7 rockets mounted in the M158 launcher or 19 rockets in the M200 launcher
  • M18 7.62 mm Minigun pod or XM35 armament subsystem with XM195 20 mm cannon

    • AH-1F "Modernized" Cobra[]

    Bell AH-1F SUPER COBRA

    Data from Verier,[27] Modern Fighting Aircraft[28]

    General characteristics

    • Crew: 2: one pilot, one co-pilot/gunner (CPG)
    • Length: 53 ft (16.1 m) (with both rotors turning)
    • Rotor diameter: 44 ft (13.6 m)
    • Height: 13 ft 6 in (4.12 m)
    • Empty weight: 6,600 lb (2,993 kg)
    • Max. takeoff weight: 10,000 lb (4,500 kg)
    • Powerplant: 1 × Lycoming T53-L-703 turboshaft, 1,800 shp (1,300 kW)
    • Rotor system: 2 blades on main rotor, 2 blades on tail rotor
    • Fuselage length: 44 ft 7 in (13.6 m)
    • Stub wing span: 10 ft 4 in (3.15 m)

    Performance

    • Never exceed speed: 170 knots (196 mph, 315 km/h)
    • Maximum speed: 149 knots (172 mph, 277 km/h)
    • Range: 274 nmi (315 mi, 510 km)
    • Service ceiling: 12,200 ft (3,720 m)
    • Rate of climb: 1,620 ft/min (8.2 m/s)

    Armament

  • General Dynamics 20 mm (0.787 in) M197 3-barreled gatling cannon
  • Hydra 70 2.75 in (70 mm) rockets - 7 rockets mounted in the M260 launcher or 19 rockets in the M261 launcher[29]
  • TOW Missiles - 4 or 8 missiles mounted in two-missile launchers on each hardpoint

    • See also[]

    • Bell UH-1 Iroquois
    • Bell AH-1 SuperCobra
    • Bwll AH-1Z Viper
    • Bell 309 KingCobra
    • Bell YAH-63
    • List of helicopters in the Vietnam War

    References[]

    Notes
    1. ↑ Stephens, Ernie. "Recycling helicopters from military service to public service." Rotor & Wing, November 2008. Retrieved on 12 October 2009.
    2. ↑ Wheeler 1987, pp. 62-64.
    3. ↑ Wheeler 1987, pp. 57-62, 64-65.
    4. ↑ Wheeler 1987, pp. 60-61.
    5. ↑ Verier 1990, pp. 12-17.
    6. ↑ 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 Donald and March 2004.
    7. ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 7.11 7.12 7.13 Bishop 2006.
    8. ↑ Verier 1990, pp. 30–31.
    9. ↑ Verier 1990, p. 44.
    10. ↑ Verier 1990, pp. 86-88.
    11. ↑ RD&A, Sect 135 - Army Historical Summary: FY74
    12. ↑ Verier 1990, pp. 57, 59-61.
    13. ↑ 13.0 13.1 Donald 2004, p. 166.
    14. ↑ Verier 1990, p. 35.
    15. ↑ Army retires Cobras from active force. U.S. Army, 31 March 1999.
    16. ↑ 16.0 16.1 16.2 Donald 1997, p. 112.
    17. ↑ McGowen, Stanley S. Helicopters: An Illustrated History of Their Impact, p. 159. Santa Barbara, Calif.: ABC-CLIO, 2005. ISBN 1-85109-468-7.
    18. ↑ Bishop 2006, p. 11.
    19. ↑ "Bristol Aerospace Hokum-X". Jane's Unmanned Aerial Vehicles and Targets, Jane's Information Group, 2006. (subscription article dated 14 December 2006)
    20. ↑ "Honeywell QAH-1S". Jane's Unmanned Aerial Vehicles and Targets, Jane's Information Group, 2006. (subscription article dated 3 February 2006)
    21. ↑ Verier 1990, pp. 72-76.
    22. ↑ Verier 1990, pp. 57.
    23. ↑ Richardson 1987, pp. 8–9.
    24. ↑ [1]
    25. ↑ [2]
    26. ↑ Gunston, Bill: The Illustrated Encyclopedia of the World's Modern Military Aircraft, p. 205. , New York, NY USA: Crescent Books, ca. 1978. ISBN 978-0-517-22477-9.
    27. ↑ 27.0 27.1 Verier 1990, p. 184.
    28. ↑ 28.0 28.1 Richardson 1987, p. Appendix.
    29. ↑ U.S. Army Helicopter Weapon Systems[dead link]
    Bibliography
    • Bishop, Chris. Huey Cobra Gunships. Osprey Publishing, 2006. ISBN 1-84176-984-3.
    • Donald, David. The Complete Encyclopedia of World Aircraft. Barnes & Nobel Books, 1997. ISBN 0-7607-0592-5.
    • Donald, David and March, Daniel (eds). Modern Battlefield Warplanes. AIRtime Publishing Inc, 2004. ISBN 1-880588-76-5.
    • Gunston, B. and Michael Spick. Modern Fighting Helicopters, pp. 104–05. New York: Crescent Books, 1986. ISBN 0-517-61349-2.
    • International Air Power Review, Volume 12. AIRtime Publishing, 2004. ISBN 1-880588-77-3.
    • Nolan, Keith W. Into Laos: Dewey Canyon II/Lam Son 719, Vietnam 1971. Presidio Press, 1986. ISBN 0-89141-247-6.
    • Richardson, Doug. Modern Fighting Aircraft, Volume 13, AH-1 Cobra. New York: Prentice Hall, 1987. ISBN 0-13-020751-9.
    • Verier, Mike. Bell AH-1 Cobra. Osprey Publishing, 1990. ISBN 0-85045-934-6.
    • Wheeler, Howard A. Attack Helicopters, A History of Rotary-Wing Combat Aircraft. The Nautical and Aviation Publishing Company, 1987. ISBN 0-933852-52-5.

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