The Bell AH-1Z Viper is a twin-engine attack helicopter based on the AH-1W SuperCobra,
that was developed for the United States Marine Corps. The AH-1Z features a four-blade, bearingless,
composite main rotor system, uprated transmission, and a new target sighting system. The AH-1Z
is part of the H-1 upgrade program. It is also called "Zulu Cobra" in reference to its
variant letter.
Development Background
Aspects of the AH-1Z date back to the Bell 249 in 1979, which was basically an AH-1S
equipped with the four-blade main rotor system from the Bell 412. This helicopter demonstrated
Bell's Cobra II design at the Farnborough Airshow in 1980. The Cobra II was to be equipped
with Hellfire missiles, a new targeting system and improved engines. Later came the Cobra
2000 proposal which included General Electric T700 engines and a four-blade rotor. This
design drew interest from the US Marine Corps, but funding was not available. In 1993, Bell
proposed an AH-1W-based version for the UK's new attack helicopter program. The derivative
design, named CobraVenom, featured a modern digital cockpit and could carry TOWs, Hellfire
or Brimstone missiles. The CobraVenom design was altered in 1995 by changing to a four-blade
rotor system. The design lost to the AH-64D later that year however.
H-1 upgrade program In 1996, the USMC launched the H-1 upgrade
program by signing a contract with Bell Helicopter for upgrading 180 AH-1Ws into AH-1Zs and upgrading
100 UH-1Ns into UH-1Ys. The H-1 program created completely modernized attack and utility helicopters
with considerable design commonality to reduce operating costs. The AH-1Z and UH-1Y share
a common tail boom, engines, rotor system, drive train, avionics architecture, software,
controls and displays for over 84% identical components.
Bell participated in a joint Bell-Government integrated test team during the engineering
manufacturing development phase of the H-1 program. The AH-1Z program progressed slowly
from 1996 to 2003 largely as a research and development operation. The existing two-blade
semi-rigid, teetering rotor system is being replaced with a four-blade, hingeless, bearingless
rotor system. The four-blade configuration provides improvements in flight characteristics
including increased flight envelope, maximum speed, vertical rate-of-climb, payload and
reduced rotor vibration level. The AH-1Z first flew on 8 December 2000. Bell
delivered three prototype aircraft to the United States Navy's Naval Air Systems Command
at Naval Air Station Patuxent River in July 2002, for the flight test phase of the program.
Low-rate initial production began in October 2003, with deliveries to run through 2018.
In late 2006 NAVAIR awarded a contract to Meggitt Defense Systems to develop a new linkless
20 mm ammunition handling system to improve on the gun feed reliability of the existing
linked feed system. These systems are now being retrofitted into the AH-1W and AH-1Z
fleets with good results during combat in Afghanistan.
In February 2008, the U.S. Navy adjusted the contract so the last 40 AH-1Zs are built as
new airframes instead of the previously planned rebuild of AH-1Ws. In September 2008, the
Navy requested an additional 46 airframes for the Marine Corps, bringing the total number
ordered to 226. In 2010, the Marine Corps planned to order 189 AH-1Zs with 58 of them
being new airframes, with deliveries to continue until 2019. On 10 December 2010, the Department
of the Navy approved the AH-1Z for full-rate production.
Design
The AH-1Z incorporates new rotor technology with upgraded military avionics, weapons systems,
and electro-optical sensors in an integrated weapons platform. It has improved survivability
and can find targets at longer ranges and attack them with precision weapons.
The AH-1Z's new bearingless, hingeless rotor system has 75% fewer parts than that of four-bladed
articulated systems. The blades are made of composites, which have an increased ballistic
survivability, and there is a semiautomatic folding system for storage aboard amphibious
assault ships. Its 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 2.75-inch
Hydra 70 rocket pods, or AGM-114 Hellfire quad missile launchers. The Longbow radar
can also be mounted on a wing tip station.
The Z-model's integrated avionics system has been developed by Northrop Grumman. The system
includes two mission computers and an automatic flight control system. Each crew station has
two 8x6-inch multifunction liquid crystal displays and one 4.2x4.2-inch dual function
LCD display. The communications suite combines a US Navy RT-1824 integrated radio, UHF/VHF,
COMSEC and modem in a single unit. The navigation suite includes an embedded GPS inertial navigation
system, a digital map system and Meggitt's low-airspeed air data subsystem, which allows
weapons delivery when hovering. The crew are equipped with the Thales "Top
Owl" helmet-mounted sight and display system. The Top Owl has a 24-hour day/night capability
and a binocular display with a 40° field of view. Its visor projection provides forward
looking infrared or video imagery. The AH-1Z has survivability equipment including the
Hover Infrared Suppression System to cover engine exhausts, countermeasure dispensers,
radar warning, incoming/on-way missile warning and on-fuselage laser spot warning systems.
The Lockheed Martin target sight system incorporates a third-generation FLIR sensor. The TSS provides
target sighting in day, night or adverse weather conditions. The system has various view modes
and can track with FLIR or by TV. The same system is also used on the UH-1Y Venom and
the KC-130J Harvest HAWK. Operational history
The AH-1Z completed sea-trial flight testing in May 2005. On 15 October 2005, the USMC,
through the Naval Air Systems Command, accepted delivery of the first AH-1Z production helicopter
to enter the fleet. The AH-1Z and UH-1Y completed their developmental testing in early 2006.
During the first quarter of 2006 the aircraft were transferred to the Operational Test Unit
at the NAS Patuxent River, where they began operational evaluation testing.
In February 2008, the AH-1Z and UH-1Y began the second and final portion of OPEVAL testing.
AH-1Z testing was stopped in 2008 due to issues with its targeting systems. The AH-1Z was
later declared combat-ready in September 2010. Foreign interest
On 21 September 2012, the U.S. Congress was notified of the possible purchase of 36 AH-1Z
Vipers by South Korea. The request included 84 engines, 288 AGM-114K3 Hellfire missiles,
72 AIM-9M-8 Sidewinder missiles, integrated missiles launchers, targeting systems, and
radar jammers. The order would be worth $2.6 billion. The Viper was competing against the
Boeing AH-64 Apache and the TAI/AgustaWestland T-129 for the order; a decision was expected
by the end of 2012. In April 2013, South Korea announced they had selected the AH-64E Apache.
Operators United States
United States Marine Corps Specifications
Data from Bell Specifications, The International Directory of Military Aircraft, 2002–2003,
Modern Battlefield Warplanes General characteristics
Crew: 2: pilot, co-pilot/gunner Capacity: 6,661 lb
Length: 58 ft 3 in Rotor diameter: 48 ft
Height: 14 ft 4 in Disc area: 1,808 ft²
Empty weight: 12,300 lb Useful load: 5,764 lb
Max. takeoff weight: 18,500 lb Powerplant: 2 × General Electric T700-GE-401C
turboshaft, 1,800 shp each Rotor systems: 4 blades on main rotor, 4 blades
on tail rotor Performance
Never exceed speed: 222 knots in a dive Cruise speed: 160 kn
Range: 370 nmi Combat radius: 125 nmi with 2,500 lb payload
Service ceiling: 20,000+ ft Rate of climb: 2,790 ft/min
Armament Guns: 1 x 20 mm M197 3-barreled Gatling cannon
in the A/A49E-7 turret Hardpoints: Up to 6 pylon stations on stub
wing Rockets: 2.75 in Hydra 70 or APKWS II rockets
– Mounted in LAU-68C/A or LAU-61D/A launchers Missiles:AIM-9 Sidewinder air-to-air missiles
– 1 mounted on each wing tip station AGM-114 Hellfire air-to-surface missiles – Up
to 16 missiles mounted in four 4-round M272 missile launchers, two on each wing
Avionics Lockheed Martin / Northrop Grumman AN/APG-78
Longbow fire control radar See also
U.S. Helicopter Armament Subsystems, AH-1 Related development
Bell AH-1 SuperCobra Bell YAH-63
Bell UH-1Y Venom Aircraft of comparable role, configuration
and era A129 InternationalAgustaWestland T-129
Boeing AH-64 Apache CAIC WZ-10
Eurocopter Tiger Harbin WZ-19
Mil Mi-28 HAL Light Combat Helicopter
Related lists List of attack aircraft
List of helicopters List of active military aircraft of the United
States References
External links AH-1Z page on Bell Helicopter Textron web
site AH-1Z Viper page on US Navy RDA site
AH-1Z page on GlobalSecurity.org Bell AH-1Z Super Cobra – Bell 449 on helis.com
"First Production H-1 Helicopters Rollout", Bell Helicopter, 27 September 2006
" AH-1Z Super Cobra Completes Envelope Expansion Testing", U.S. Navy, 9 January 2003.