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The AH-1 was the backbone of the United States Army's attack helicopter fleet, but has been replaced by the AH-64 Apache in Army service.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. 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.

The Bell AH-1 SuperCobra is a twin-engine attack helicopter based on the United States Army's AH-1 Cobra. The twin Cobra family includes the AH-1J SeaCobra, the AH-1T Improved SeaCobra, and the AH-1W SuperCobra. The AH-1W is the primary attack helicopter of the United States Marine Corps, but it will be replaced in service by the Bell AH-1Z Viper upgrade.

Variants

Single-engine 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 (1,000 kW) Avco Lycoming T53-13 turboshaft. JAH-1G HueyCobra One helicopter for armament testing including Hellfire missiles and multi-barrel cannon. TH-1G HueyCobra Two-seat dual-control trainer. Z.14 HueyCobra The Spanish Navy purchased eight new-build AH-1Gs, designating the type the "Z-14". These were equipped with the M35 20 mm cannon system, and were used to support coastal patrol boats. Four of these were lost in accidents. The remaining helicopters were retired in 1985 with three sent back to the US, and one kept in storage in Spain. YAH-1Q Eight AH-1Gs with XM26 Telescopic Sight Unit (TSU) and two M56 TOW 4-pack launchers. 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. YAH-1S AH-1Q upgrade and TOW system. AH-1S The baseline AH-1S is an AH-1Q upgraded with a 1,800 shp (1,300 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.) 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. 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. 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. AH-1E aircraft included the M147 Rocket Management Subsystem (RMS) to fire 2.75-inch (70 mm) rockets. 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. Model 249 Experimental demonstrator version fitted with a four-bladed rotor system, an uprated engine and experimental equipment, including Hellfire missiles.

AH-1F Cobra Photo: Robert Deering 7/16/2014 American Helicopter Museum Brandywine Airport (OQN) West Chester, Pennsylvania   AH-1J Sea Cobra Photo: Robert Deering 4/18/2015 National Museum of Naval Aviation NAS Pensacola (NPA) Pensacola, Florida   AH-1J Sea Cobra Photo: Robert Deering 6/13/2017 USS Intrepid Museum (CV-11) New York City, New York   AH-1S Cobra Photo: Robert Deering 6/27/2015 USS Lexington Museum (CV-16) Corpus Christi, Texas   AH-1W Super Cobra Photo: Robert Deering 10/12/2008 Alliance Airport (AFW) Fort Worth, Texas

Twin-engine AH-1J SeaCobra Original twin engine version. AH-1J International Export version of the AH-1J SeaCobra. AH-1T Improved SeaCobra Improved version with extended tailboom and fuselage and an upgraded transmission and engines. AH-1W SuperCobra ("Whiskey Cobra"), day/night version with more powerful engines and advanced weapons capability. AH-1(4B)W Viper "Four-Bladed Whiskey" test version with a 4-bladed bearingless composite main rotor based on Bell 680 rotor. A prototype was converted from AH-1T 161022. AH-1Z Viper A new variant nicknamed "Zulu Cobra", and developed in conjunction with the UH-1Y Venom for the H-1 upgrade program. The variant includes an upgraded 4-blade main rotor and adds the Night Targeting System (NTS). Model 309 King Cobra Experimental all-weather version based on the AH-1G single-engine and AH-1J twin-engine designs.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.

Design and development

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 one of the most numerous helicopter types built. 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.

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.

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.

Iroquois Warrior, Sioux Scout and AAFSS

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.

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.

Army's solution to the shortcomings of the Sioux Scout was to launch the Advanced Aerial Fire Support System (AAFSS) competition. The AAFSS requirement gave birth to the Lockheed AH-56 Cheyenne, a heavy attack helicopter with high speed capability. It proved to be too sophisticated, and was canceled after 10 years of development in 1972. The Army sought greater survivability in a conventional attack helicopter.

Model 209

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.  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.  Bell's Model 209 largely resembled the "Iroquois Warrior" mockup.

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. 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.

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.  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.

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.

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. 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.

 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.  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.

The U.S. Marine Corps was very interested in the AH-1G Cobra, but it preferred a twin-engine version for improved safety in over-water operations, and also wanted a more potent turret-mounted weapon. At first, the Department of Defense had balked at providing the Marines with a twin-engine version of the Cobra, in the belief that commonality with Army AH-1Gs outweighed the advantages of a different engine fit. However, the Marines won out and awarded Bell a contract for 49 twin-engine AH-1J SeaCobras in May 1968. As an interim measure, the U.S. Army passed on 38 AH-1Gs to the Marines in 1969. The AH-1J also received a more powerful gun turret. It featured a three barrel 20 mm XM197 cannon that was based on the six barrel M61 Vulcan cannon.

The Marine Corps requested greater load carrying capability in high temperatures for the Cobra in the 1970s. Bell used systems from its Model 309 to develop the AH-1T. This version had a lengthened tailboom and fuselage with an upgraded transmission and engines from the 309. Bell designed the AH-1T to be more reliable and easier to maintain in the field. The version was given full TOW missile capability with targeting system and other sensors. An advanced version, known as the AH-1T+ with more powerful T700-GE-700 engines and advanced avionics was proposed to Iran in the late 1970s, but the overthrow of the Shah of Iran resulted in the sale being canceled.

In the early 1980s, the U.S. Marine Corps sought a new navalized helicopter, but it was denied funding to buy the AH-64 Apache by Congress in 1981. The Marines in turn pursued a more powerful version of the AH-1T. Other changes included modified fire control systems to carry and fire AIM-9 Sidewinder and AGM-114 Hellfire missiles. The new version was funded by Congress and received the AH-1W designation.  Deliveries of AH-1W SuperCobras totaled 179 new-built helicopters plus 43 upgrades of AH-1Ts.

The AH-1T+ demonstrator and AH-1W prototype was later tested with a new experimental composite four blade main rotor system. The new system offered better performance, reduced noise and improved battle damage tolerance. Lacking a USMC contract, Bell developed this new design into the AH-1Z with its own funds. By 1996, the Marines were again not allowed to order the AH-64.  Developing a marine version of the Apache would have been expensive and it was likely that the Marine Corps would be its only customer.  They instead signed a contract for upgrading 180 AH-1Ws into AH-1Zs.

The AH-1Z Viper features several design changes. The AH-1Z's two redesigned wing stubs are longer with each adding a wing-tip station for a missile such as the AIM-9 Sidewinder. Each wing has two other stations for 70 mm (2.75 in) Hydra rocket pods, or AGM-114 Hellfire quad missile launcher. The Longbow radar can be mounted on a wing tip station.

Operational history

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.

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.  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. Out of nearly 1,110 AH-1s delivered from 1967 to 1973 approximately 300 were lost to combat and accidents during the war. The U.S. Marine Corps used AH-1G Cobras in Vietnam for a short time before acquiring twin-engine AH-1J Cobras.

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.

USMC Cobras provided escort in the Persian Gulf in the late 1980s while the Iran–Iraq War was ongoing. The Cobras sank three Iranian patrol boats while losing one AH-1T to Iranian anti-aircraft fire.  USMC Cobras from the USS Saipan (LHA-2) flew "top cover" during an evacuation of American and other foreign nationals from Liberia in 1990.

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.

Army and Marine 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. USMC Cobras were used in U.S. military interventions in the former Yugoslavia in the 1990s, and assisted in the rescue of USAF Captain Scott O'Grady, after his F-16 was shot down by a SAM in June 1995.

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. 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. 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.

Specifications