The Bell AH-1 SuperCobra is a twin-engine attack helicopter based on the US 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 backbone of the United States Marine Corps's attack helicopter fleet, but will be replaced in service by the Bell AH-1Z Viper upgrade.
Design and development
The AH-1 Cobra was developed in the mid-1960s as an interim gunship for the U.S. Army for use in Vietnam. The Cobra shared the proven transmission, rotor system, and the T53 turboshaft engine of the UH-1 "Huey". By June 1967, the first AH-1G HueyCobras had been delivered. Bell built 1,116 AH-1Gs for the U.S. Army between 1967 and 1973, and the Cobras chalked up over a million operational hours in Vietnam.
The U.S. Marine Corps was very interested in the AH-1G Cobra, but 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 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.
Crew: 2: pilot, co-pilot/gunner (CPG)
Length: 53 ft 5 in (16.3 m) (with both rotors turning)
Rotor diameter: 43 ft 11 in (13.4 m)
Height: 13 ft 5 in (4.1 m)
Empty weight: 6,610 lb (2,998 kg)
Max. takeoff weight: 10,000 lb (4,540 kg)
Powerplant: 1 × Pratt & Whitney Canada T400-CP-400 (PT6T-3 Twin-Pac) turboshaft, 1,800 shp (1,342 kW)
Total engine output: 1,530 shp (1,125 kW) limited by helicopter drivetrain
Rotor systems: 2 blades on main rotor, 2 blades on tail rotor
Fuselage length: 45 ft 9 in (13.5 m)
Stub wing span: 10 ft 9 in (3.28 m)
Never exceed speed: 180 knots (207 mph, 333 km/h)
Maximum speed: 180 knots (207 mph, 333 km/h)
Range: 311 nmi (358 mi, 576 km)
Service ceiling: 10,500 ft (3,215 m)
Rate of climb: 1,090 ft/min (5.54 m/s)
20 mm (0.787 in) M197 3-barreled gatling cannon in the M97 turret (750 rounds ammo capacity)
2.75 in (70 mm) Mk 40 or Hydra 70 rockets - 14 rockets mounted in a variety of launchers
5 in (127 mm) Zuni rockets - 8 rockets in two 4-round LAU-10D/A launchers
AIM-9 Sidewinder anti-aircraft missiles - 1 mounted on each hardpoint