|Bell Model 209 "Huey Cobra"|
In 1965 the US Army finalised its requirement for the world's first armed battlefield helicopter, the Bell AH-1 Cobra, often called the HueyCobra.
The idea had arisen before Vietnam, but the Cobra arrived on the scene just when it was needed in the Southeast Asia conflict. The AH-1 featured a streamlined, narrow-width fuselage that accommodated a two-man crew in tandem seats with the pilot above and behind the co-pilot/gunner.
The US Army progressively improved this fine helicopter. The engine power, performance and armament had all been enhanced by 1972 when the AH-1 proved especially valuable during the North Vietnamese offensive. Already successful using guns and rockets for direct support of ground troops, the Cobras were pitched against Communist PT-76 light tanks.
The early design was so effective that improved versions of the AH-1 Cobra were ordered for the Army and the US Marine Corps. Beginning in the 1970s, twin-engined versions replaced 'first generation' HueyCobras. These newer combat helicopters still remain with some units.
R.Jackson "Helicopters. Military, Civilian, and Rescue Rotorcraft", 2005
In March 1965, Bell initiated company-funded development of the proven Model 204 (UH-1B/-1C Iroquois) to produce an armed helicopter suitable for close-support/attack roles. Intended to provide the US Army with an interim AAFSS (advanced aerial fire support system) helicopter, it combined a new narrow, low-profile, tandem-seat fuselage with the rotor/transmission system/powerplant of the UH-1C. First flown in prototype form on 7 September 1965, the new Bell Model 209 was evaluated by the US Army from December of that year, with orders for two pre-production and 110 production aircraft following during April 1966. Designated AH-1G, and named HueyCobra, the type was first delivered to the US Army in June 1967, and within two months the type was being used operationally in Vietnam. US Marine Corps interest in this helicopter resulted in 38 AH-1Gs being supplied from the US Army production line in 1969, pending initial deliveries of 49 of the AH-1J SeaCobra variant ordered by the US Marine Corps in May 1968. Examples generally similar to the US Army's AH-1G have been supplied to the Spanish navy (eight, designated Z.14) and Israel (six).
The HueyCobra has small stub-wings that serve the dual purpose of offloading the rotor in flight, and of carrying armament that, in the case of the AH-1G, can include folding-fin rockets or Minigun pods. Additionally, this version mounts beneath the nose an M-28 turret that can house two Miniguns, or two 40mm grenade-launchers, or one of each. Armour protection is provided for the crew in the form of Noroc side panels and seats, with other vital areas of the helicopter protected by panels of the same material.
JAH-1G HueyCobra: one armament research aircraft which has been flown with the Hellfire air-launched missile, and multi-barrel cannon
TH-1G HueyCobra: designation of dual-control trainer conversions from AH-1G
AH-1J SeaCobra: initial US Marine Corps version powered by a twin-turboshaft T400-CP-400 powerplant; this power unit incorporates two turbine engines, flat-rated to 820kW for continuous running, but with a take-off or emergency rating of 932kW; total of 69 delivered to USMC by early 1975, and 202 similar aircraft supplied to the Imperial Iranian Army Aviation from 1974
AH-1Q HueyCobra: designation of 93 AH-1Gs converted to launch TOW anti-tank missiles
AH-1R HueyCobra: version similar to AH-1G with a more powerful T53-L-703 turboshaft engine
AH-1S HueyCobra: overall designation under which existing US Army AH-1 aircraft were updated to have TOW capability and incorporated other improvements, and of new production aircraft to the same or higher standard; current designations include Modified AH-1S, which covers 197 AH-1Gs and the 93 AH-1Qs with upgraded gearbox, transmission, improved rotor, T53-L-703 engine, and TOW-capability; 100 generally similar Production AH-1S, being new production aircraft with advanced avionics, instrumentation, and systems; 98 Up-Gun AH-1S, generally as the Production AH-1S but with an improved turret and weapon management systems; and the Modernised AH-1S of which 126 new production aircraft have been ordered incorporating the improvements embodied in the other AH-1S aircraft, plus advanced nav/com, avionics, and protection systems. These are now known as AH-1F to avoid confusion with other variants AH-1T
Improved SeaCobra: generally improved version of the AH-1J, incorporating an uprated T400-WV-402 powerplant, the dynamic system of the Bell Model 214, and the fuselage lengthened by 1.09m; 57 built, and equipped for operation with TOW missiles
AH-1W SuperCobra: new USMC version with two GE T700-GE-700 engines, producing 1260kW each. Better protection and avionics are incorporated. Conversion applied to AH-1T aircraft
Model 249: company designation of a Modernised AH-1S which was equipped and tested with an advanced four-blade main rotor as developed for the Bell Model 412
D.Donald "The Complete Encyclopedia of World Aircraft", 1997
In 1962, Bell mated the dynamic components of the Huey to a new streamlined two-seat fuselage to create the D-255 Iroquois Warrior. This aircraft with its tandem two-seat cockpit was conceived as a dedicated high speed helicopter gunship with a very narrow head-on profile and provision for a wide range of externally-mounted weapons. It sparked off the Army AAFSS design competition which Bell failed to win, but Bell then decided to build a simpler and smaller aircraft. They built the experimental Model 207 Sioux Scout and this formed the basis for the Model 209 which first flew in September 1965.
The Model 209 was evaluated by the Army and ordered into production as an interim machine to meet the urgent needs in Vietnam. The initial AH-1G Cobra led to a series of "Hueycobra" variants, not only for the Army but also for use by the U.S. Marines and the Navy. Cobras were sold to many foreign air arms including Iran, Pakistan, South Korea, Israel, Spain, Thailand and Turkey. Inevitably, the users of Cobras found reasons for needing to upgrade them and obtain improved performance and this led firstly to the AH-1J which traded the single Lycoming T53 turboshaft for a Pratt & Whitney PT6T-3 TwinPac engine. In turn, this was upgraded to a more powerful variant in the AH-1T - and eventually the AH-1W was substantially redesigned to take a pair of 3250shp General Electric T700 engines in which guise it was named "SuperCobra".
R.Simpson "Airlife's Helicopter and Rotorcraft", 1998
Bell Helicopter Textron initiated the Model 209 in March 1965 as a company-funded development of the UH-1B/C Iroquois intended specifically for armed helicopter missions. The original design combined the basic transmission and rotor system and (in its standard form) the power plant of the UH-1C with a new, streamlined fuselage designed for maximum speed, armament load and crew efficiency. Relatively small, its low silhouette and narrow profile make it easy to conceal with small camouflage nets or to move under cover of trees. Tandem seating provides the best possible field of view for the crew of two.
The Model 209 prototype made its first flight 7 September 1965, and the US Army's intention to order the aircraft was announced 11 March 1966, the initial model being known as the AH-1G HueyCobra. Total orders for all versions of the HueyCobra and SeaCobra exceeded 1,400.
AH-1E: Formerly Enhanced Cobra Armament System or Up-gun AH-1S; with AH-1P improvements plus universal 20mm gun turret (invariably fitted with long-barrel 20mm cannon); improved wing stores management system for 70mm rockets; automatic compensation for off-axis gun firing; 10 kVA alternator for increased power. A total of 98 new build aircraft delivered 1978-79. All remaining upgraded.
AH-1F: Fully upgraded TOW version, previously designated Modernised AH-1S; 149 manufactured for US Army in 1979-86, including 50 transferred to Army National Guard; also 378 AH-1Gs converted to full AH-1F standard between November 1979 and June 1982, including 41 TAH-1F trainers; improvements of AH-1P and AH-1E added, plus new fire-control system having laser range-finder and tracker, ballistics computer, low-airspeed sensor probe, Kaiser pilot's head-up display, Doppler navigation system, IFF transponder, infra-red jammer above engine, hot metal and plume infra-red suppressor, closed-circuit refuelling, new secure voice communications, Kaman composite rotor blades.
Later modifications have included C-Nite equipment fitted to 50 US Army AH-1Fs (reduced from planned 500), Air-To-Air Stinger (ATAS) and Cobra Fleet Life Extension (C-Flex), engine air filter, redesigned swashplate, M43 nuclear/biological/chemical mask, AN/AVR-2 laser warning and improved SCAS roll modifications. C-Nite FLIR for TOW sight delivered 1990 to US Army's Aviation Battalion in South Korea. C-Flex items already completed include Nite Fix lighting, AH-1G to AH-1S upgrade and K-Flex driveshaft; remaining C-Flex work includes rotor improvements, improved TOW test set and radio upgrade.
AH-1G HueyCobra: Original version for the US Army, powered by a single 1,044kW Avco Lycoming T53-L-13 turboshaft, derated to 820kW for T-O and maximum continuous rating. Development contract for two preproduction aircraft placed 4 April 1966, followed on 13 April by an initial order for 110 aircraft plus long-lead-time spares, deliveries of which began in June 1967. Total production, including small number of export units came to 1,127. All surviving aircraft converted to AH-1F standard.
AH-1J SeaCobra: Initial twin turboshaft version for US Marine Corps, powered by a 1,342kW Pratt & Whitney Canada T400-CP-400 coupled free-turbine turboshaft, a military version of the PT6T-3 Turbo Twin-Pac. Total of 69 delivered to US Marine Corps between mid-1970 and February 1975, the last two being converted later as prototypes for the AH-1T. A further 202 TOW-capable AH-1Js were supplied to the Imperial Iranian Army Aviation from 1974, the US Army acting as purchasing agent. All USMC SeaCobras withdrawn.
AH-1P: First batch of 100 new-production TOW Cobras (formerly called Production AH-1S), delivered 1977-78, two becoming AH-1F prototypes; improvements include flat-plate canopy, upturned exhaust, improved nap of the earth (NOE) instrument panel, continental US (CONUS) navigation equipment, radar altimeter, improved communication radios, uprated engine and transmission, push/pull anti-torque control and, from 67th aircraft onwards, Kaman composite rotor blades with tapered tips.
AH-1Q HueyCobra: Interim anti-armour version for US Army, converted from AH-1G to fire Hughes TOW anti-tank missiles. Total of 92 converted; subsequently upgraded to Mod AH-1S standard.
AH-1S: Formerly AH-1S(MOD); first ordered as TOW-capable version of AH-1G in 1975; programme included conversion of earlier AH-1Gs and three-stage production of new aircraft with various degrees of upgrading; all versions designated AH-1S until March 1987, when new-build AH-1s allotted dormant UH-1 Iroquois suffixes AH-1P, AH-1E and AH-1F. 92 AH-1Qs (early TOW-capable AH-1G) upgraded by 1979; 87 AH-1Qs upgraded in 1986-88 with Textron Lycoming T53-L-703 engines, Kaman rotor blades (see AH-1P) and TOW system, but retaining original curved canopies; total includes 15 in TH-1S Night Stalker configuration for training AH-64 crews to operate night vision system and Integrated Helmet and Display Sighting System (IHADSS).
AH-1T Improved SeaCobra: Improved version of twin-engined AH-1J for US Marine Corps. Last two AH-1Js modified as prototypes under a US Army Aviation Systems Command contract, with uprated components for significantly increased payload and performance. Incorporates features of AH-1J airframe, but embodies dynamic system of Bell Model 214, some technology developed for Bell Model 309 KingCobra, an upgraded power plant (1,469kW T400-WV-402) and transmission capable of transmitting the full rated engine power. Initial contract for 10 announced 23 June 1975; total of 57 built, of which 51 were subsequently modified to TOW configuration. First AH-1T flew 20 May 1976, and was delivered to US Marine Corps 15 October 1977. All have been converted to AH-1W SuperCobra standard.
DESIGN FEATURES: Kaman composite blades, fitted from 67th AH-1P onwards, tolerate hits by 23mm shells, have tungsten carbide bearing sleeves and outer 15% of blade is tapered in chord and thickness; tailboom strengthened against 23mm hits; airframe has infra-red suppressant paint finish.
POWER PLANT: One 1,342kW Textron Lycoming T53-L-703 turboshaft. Fuel capacity 980 litres. IR suppression nozzle on AH-1F.
ACCOMMODATION: Flat-plate canopy has seven planes of viewing surfaces, designed to minimise glint and reduce possibility of visual detection during nap of the earth (NOE) flying; it also provides increased headroom for pilot. Improved instrument layout and lighting, compatible with use of night vision goggles. Improved, independently operating window/door ballistic jettison system to facilitate crew escape in emergency.
SYSTEMS: 10kVA 400Hz AC alternator with emergency bus added to electrical system. Hydraulic system pressure 103.5 bars, maximum flow rate 22.7 litres/min. Open reservoir. Battery-driven Abex standby pump, for use in event of main hydraulic system failure, can be used for collective pitch control and for boresighting turret and TOW missile system. Improved environmental control and fire detection systems.
AVIONICS: Standard lightweight avionics equipment (SLAE) includes AN/ARC-114 FM, AN/ARC-164 UHF/AM voice com, and E-Systems (Memcor Division) AN/ARC-115 VHF/AM voice com (compatible with KY-58 single-channel secure voice system). Other avionics include AN/ASN-128 Doppler nav system in AH-1F; HSI; VSI; radar altimeter; push/pull anti-torque controls for tail rotor; co-pilot's standby magnetic compass. C-Flex upgrade includes introduction of Magnavox AN/ARC-164(V) UHF/AM, Collins AN/ARC-186 VHF/AM-FM, ITT AN/ARC-201 (SINCGARS) VHF/FM, and LaBarge AN/ARN-89B D/F.
ARMAMENT: M65 system with eight Hughes TOW missiles, disposed as two two-round clusters on each outboard underwing station. Inboard wing stations remain available for other stores. M28 (7.62/40mm) turret in earlier HueyCobras replaced by new electrically powered General Electric universal turret, designed to accommodate 20mm weapon and improve standoff capability, although only 20mm M197 three-barrel cannon (with 750 rounds) mounted in this turret. Rate of fire 675 rds/min. Turret position is controlled by pilot or co-pilot/gunner through helmet sights, or by co-pilot using M65 TOW missile system's telescopic sight unit. Field of fire up to 110° to each side of aircraft, 20.5° upward and 50° downward. Also equipped with Baldwin Electronics M138 wing stores management subsystem, providing means to select and fire, singly or in groups, any one of five types of external 70mm rocket store. These mounted in launchers each containing 7 or 19 tubes, additional to TOW missile capability.
In addition to these installations, first AH-1F introduced fire-control subsystem which includes Kaiser head-up display for pilot, Teledyne Systems digital fire-control computer for turreted weapon and underwing rockets, omnidirectional airspeed system to improve cannon and rocket accuracy, Hughes laser range-finder (accurate over 10,000m), and Rockwell AN/AAS-32 automatic airborne laser tracker. Other operational equipment includes Hughes LAAT stabilised sight, GEC Avionics M-143 air data subsystem, AlliedSignal AN/APX-100 solid-state IFF transponder, Sanders AN/ALQ-144 infra-red jammer (above engine), suppressor for infra-red signature from engine hot metal and exhaust plume, and AN/APR-39 radar warning receiver.
Jane's Helicopter Markets and Systems
Technical data for AH-1S
Engine: 1 x Avco Lycoming T53-K-703 turboshaft, rated at 1342kW, main rotor diameter: 13.41m, length with rotors turning: 16.18m, fuselage length: 13.59m, width: 0.99m, height: 4.09m, max take-off weight: 4535kg, loaded weight: 2993kg, max cruising speed with Tow misiles: 227km/h, max rate of climb: 8.22m/s, hovering ceiling, OGE: 3720m