Bell AH-1 Cobra
The Bell AH-1 Cobra is a single-engined attack helicopter developed and manufactured by the American rotorcraft manufacturer Bell Helicopter. A member of the prolific Huey family, the AH-1 is also referred to as the HueyCobra or Snake.
The AH-1 was rapidly developed as an interim gunship in response to the United States Army's needs in the Vietnam War. It used the same engine, transmission and rotor system as the Bell UH-1 Iroquois, which had already proven itself to be a capable platform during the conflict, but paired it with a redesigned narrow fuselage among other features. The original AH-1, being a dedicated attack helicopter, came equipped with stub wings for various weapons, a chin-mounted gun turret, and an armored tandem cockpit, from which it was operated by a pilot and gunner. Its design was shaped to fulfill a need for a dedicated armed escort for transport helicopters, giving the latter greater survivability in contested environments. On 7 September 1965, the Model 209 prototype performed its maiden flight; after rapidly gaining the support of various senior officials, quantity production of the type proceeded rapidly with little revision.
During June 1967, the first examples of the AH-1 entered service with the US Army and were promptly deployed to the Vietnam theater. It commonly provided fire support to friendly ground forces, escorted transport helicopters, and flew in "hunter killer" teams by pairing with Hughes OH-6A Cayuse scout helicopters. In the Vietnam War alone, the Cobra fleet cumulatively chalked up in excess of one million operational hours; roughly 300 AH-1s were also lost in combat. In addition to the US Army, various other branches of the US military also opted to acquire the type, particularly the United States Marine Corps. Furthermore, numerous export sales were completed with several overseas countries, including Israel, Japan, and Turkey.
For several decades, the AH-1 formed the core of the US Army's attack helicopter fleet, seeing combat in Vietnam, Grenada, Panama, and the Gulf War. In US Army service, the Cobra was progressively replaced by the newer and more capable Boeing AH-64 Apache during the 1990s, with the final examples being withdrawn during 2001. The Israeli Air Force operated the Cobra most prolifically along its land border with Lebanon, using its fleet intensively during the 1982 Lebanon War. Turkish AH-1s have seen regular combat with Kurdish insurgents near Turkey's southern borders. Upgraded versions of the Cobra have been developed, such as the twin-engined AH-1 SeaCobra/SuperCobra and the experimental Bell 309 KingCobra. Furthermore, surplus AH-1 helicopters have been repurposed for other uses, including civilian ones; numerous examples have been converted to perform aerial firefighting operations.
Development
Background
Closely related to the development of the Bell AH-1 is the story of the Bell UH-1 Iroquois transport helicopter—an 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.The massive expansion of American military presence in Vietnam opened a new era of war from the air. The linchpin of US Army tactics was the helicopters, and the protection of those helicopters became a vital role. It became clear that unarmed troop helicopters were vulnerable against ground fire from Viet Cong and North Vietnamese troops, particularly as they approached landing zones to disembark or embark troops. Without friendly support from artillery or ground forces, the only way to pacify a landing zone was from the air, preferably with an aircraft 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. However, these makeshift gunships came with considerable tradeoffs, particularly being barely able to keep up with the troop transports they were intended to protect.
While some officials within the Pentagon, particularly those within the US Army, had recognized the potential value of purpose-built armed rotary aircraft as early as 1962 and were keen to see such a vehicle developed promptly, the issue was complicated in part due to inter-service politics. The United States Air Force largely held the opinion that most forms of US military aircraft should be operated only by their service, and that the US Army would be intruding into their domain by developing a complex armed aerial combatant, and ought to be largely restricted to transport aircraft. Meanwhile, some Army officials were concerned that the USAF did not take the close air support mission as seriously as it ought to, and that response times of 30 minutes or more for fixed-wing aircraft would be unacceptable.
Iroquois Warrior, Sioux Scout and AAFSS
Bell had been investigating helicopter gunships since the late 1950s, paying particular attention to the Algerian War, in which French forces mounted weapons on helicopters to fight the growing insurgency. The company created a mockup of its D-255 helicopter gunship concept, named "Iroquois Warrior". The Iroquois Warrior was planned to be a purpose-built attack aircraft based on 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.In June 1962, Bell displayed the mockup to US Army officials, hoping to solicit funding for further development; rival manufacturers issued protests to this approach, alleging that it was an attempt by Bell to circumvent the competitive process. Nevertheless, the Army was interested and awarded Bell a proof-of-concept contract in December 1962. Bell modified a Model 47 into the 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 that it was undersized, underpowered, and generally not suited for practical operations.
The Army's solution to the shortcomings of the Sioux Scout was to launch the Advanced Aerial Fire Support System competition. This called for a heavily armed helicopter capable of at least. A total of seven companies, including Bell, opted to respond to the requirement. It was out of the AAFSS program that the Lockheed AH-56 Cheyenne emerged, a heavy attack helicopter with high speed capability. During testing, it proved to be too sophisticated and costly, and was ultimately canceled in 1972 after ten years of development. In its place, the Advanced Attack Helicopter program was launched. Under this initiative, the Army sought a conventional attack helicopter with a greater level of survivability.
Model 209
Despite the Army's preference for the AAFSS program—for which Bell Helicopter was not selected to compete—the company persisted with their own idea of a smaller and lighter gunship, noting that Lockheed had little experience in developing rotorcraft and correctly predicted that it would encounter considerable difficulties. Bell employee Mike Folse played a key role in developing this new gunship, which he intentionally based around the existing UH-1 on the rationale that, while the Army could not purchase a completely original helicopter without a formal design competition, the service was able to procure a modification of an aircraft that was already in its inventory without invoking such hurdles. This initiative quickly caught the approval of Bell's senior management team.In January 1965, Bell elected to invest $1 million to proceed with the concept's detailed design. Mating the proven transmission, the "540" rotor system of the UH-1C augmented by a Stability Control Augmentation System, and the T53 turboshaft engine of the UH-1 with the design philosophy of the Sioux Scout, Bell produced the Model 209. It largely resembled the "Iroquois Warrior" mockup, particularly in its cockpit and tail boom; in broad visual terms, there was relatively little shared between the proposed design and the UH-1. Despite appearance, much of the Model 209's major elements, such as the tail rotor and much of the dynamic systems, were identical. Roughly 80 percent of its components already had existing Huey part numbers.
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 project's go-ahead and slightly under budget. This first flight was witnessed by around 20 US Army officials, the service having had no awareness of the project's existence prior to this, and rapidly drew the government's attention. One early test flight was met with a reportedly enthusiastic visit by US secretary of defense Robert McNamara. Bell claimed at this phase of the project that production units could be ready for service within one year.
As the Vietnam War proceeded, pressure accumulated 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 US Army needed an interim gunship for Vietnam and it approached five separate companies with its request 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.
During April 1966, Bell's submission emerged victorious in an evaluation against the other rival helicopters. The US Army promptly signed the first production contract, ordering an initial batch of 110 aircraft. By the end of the year, rapid follow-on orders had increased this to 500 Cobras. 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. An additional use for the demonstrator was participating in marketing initiatives. It was also modified to match the 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.