The US Army's AAH (Advanced Attack Helicopter) programme is the biggest Western programme of its kind: it calls for an aircraft capable of operating day and night in all weathers, which can be based with front line troops if necessary. Of the two contestants, the Bell YAH-63 and the Hughes YAH-64, the latter was the first to become airborne; it flew in September 1975, and two prototypes of each helicopter were delivered to the Army for comparative trials in May 1976. When these were completed in December of that year, the Hughes aircraft was chosen and three more were built, complete with electronics and armament.

The AH-64 is an aggressive-looking helicopter seating two in tandem, with a semi-monocoque fuselage of narrow cross-section. The copilot/gunner sits in the rear seat, which is raised and has good all-round visibility. The two 1690shp General Electric T700-GE-701 turbines are mounted on either side of the fuselage, behind the rotor transmission, in two separate nacelles. The four-blade metal rotor is of the articulated type with the blades angled at 60°/120° in relation to each other to reduce noise levels. The tail unit, which was modified during the aircraft's second development phase, includes an all-moving tail plane positioned slightly above the tail boom and a vertical fin to replace the earlier T-tail of the prototype. The tailwheel landing gear is fixed.

Apart from the technical/dynamic and structural characteristics of this large helicopter, what is really impressive is its armament and the complexity of the electronic equipment. The highly-sophisticated avionics include TADS (Target Acquisition and Designation Sight) associated with a night vision system using passive FLIR (Forward-Looking Infra-red), low light level TV, a laser rangefinder and target designator for use with Hellfire missiles, all associated with a computerized fire control system. The armament includes a 30mm XM-230E1 automatic cannon firing 750 rounds, and 16 Hellfire antitank missiles or seventy-six 2.75 inch rockets beneath the stub wings. All the most vulnerable parts are protected by armour against shots of up to 23mm caliber.

The US Army plans to acquire 536 of these Hughes helicopters. The first production AH-64A was rolled out in September 1983 and deliveries to Army units begin in 1984.

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

The AH-64 Apache originated as Hughes Helicopters' entry in the Army's 1973-1976 Advanced Attack Helicopter (AAH) competition, which was initiated following the forced cancellation of the AH-56 Cheyenne programme. The new AAH design was intended by the Army to be a less sophisticated and less costly aircraft than the Cheyenne, while retaining the latter's ability to undertake day, night and adverse weather anti-armor operations beyond the capabilities of the AH-1 Cobra. Preliminary AAH design proposals were submitted by Bell, Sikorsky, Boeing-Vertol and Lockheed, in addition to Hughes, and in June 1973 both Bell and Hughes were awarded contracts for the production of two prototype aircraft. Bell's Model 409 was subsequently designated the YAH-63, while Hughes' Model 77 became the YAH-64.

In accordance with the Army's AAH specifications both the YAH-63 and YAH-64 were powered by twin General Electric T700 turboshaft engines, were capable of carrying up to sixteen Hellfire or TOW missiles, and carried externally-mounted 30mm cannon for use against troops, soft-skinned vehicles, and other aircraft. Not surprisingly, given their common required attributes, the aircraft were very similar in general appearance. Each had a long slender fuselage with two-seat tandem cockpit forward, mid-mounted stub wings, engine pods on either side of the upper fuselage just below the rotor mast, and a high 'T'-tail. The YAH-64 differed from its competitor, however, in having a four-bladed, fully articulated main rotor, a four-bladed tail rotor with angled blades intended to reduce the aircraft's noise signature, and its co-pilot/gunner seated forward of, rather than behind, the pilot. The Hughes craft also carried its single-barrelled 30mm gun mounted under the lower fuselage rather than below the nose, and was equipped with semi-retractable twin main landing gear and a fixed tail wheel in place of the YAH-63's tricycle arrangement.

The YAH-64 prototypes (serials 73-22248 and -22249) both flew for the first time in the fall of 1975, and both were handed over to the Army for evaluation against the YAH-63 in May 1976. The following December Hughes was named winner of the AAH competition and was subsequently awarded an Army contract for a 'Phase Two' engineering development programme. Modifications introduced during this period included the replacement of the T'-tail by an enlarged vertical stabilizer and a low-mounted, movable tailplane, the adoption of a flat-plate canopy, the installation of infrared signature-suppressing engine exhausts, and full-length fuselage side fairings. These changes were incorporated into three additional prototypes, which were also fitted with various avionics and fire-control systems. The sensor suite finally adopted for use on production aircraft includes the Target Acquisition and Designation System (TADS) incorporating television, laser, infrared and optical components, the Pilot's Night Vision System (PNVS), and the Integrated Helmet and Display Sight System (IHADSS).

In January 1984 Hughes Helicopters was acquired by McDonnell-Douglas Aircraft, and soon thereafter the restructured McDonnell-Douglas Helicopter Company (MDHC) delivered to the Army the first of a projected 675 production AH-64A Apaches. By mid-1986 Apache production at the MDHC facility in Mesa, Arizona, was running at approximately twelve machines a month, and the 300th aircraft was delivered on 7 December 1987. In September 1985 MDHC and the Army began defining the configuration of an advanced AH-64B with an 2000km self-deployment range, improved flight controls, a simplified cockpit, more powerful engines, and improved sensors.

The Apache underwent its long-anticipated baptism of fire during the 1989 US invasion of Panama. Twelve AH-64s provided fire support during the operation, using Hellfire missiles and 30mm cannon fire. Three of the aircraft were hit by enemy fire, but were quickly repaired and returned to service. The Army subsequently judged the Apache's overall combat performance in Panama to be 'outstanding,' an evaluation supported by most knowledgeable defense and industry observers.

S.Harding "U.S.Army Aircraft since 1947", 1990

Original Hughes Model 77 entered for US Army Advanced Attack Helicopter (AAH) competition; first flights of two development prototype YAH-64s 30 September and 22 November 1975; selected by US Army December 1976; named Apache late 1981.

Deliveries started 26 January 1984; 800th delivered July 1993; 867 by December 1994, at which time US Army had ordered 821 (excluding prototypes) with export contracts totalling 104 AH-64As; latter total increased to 213 by July 1995. Self-deployment capability shown by 14th Apache with four 871 litre external tanks, which flew 1,891km Mesa - Santa Barbara - Mesa - Tucson - Mesa with 45 minutes fuel remaining on 4 April 1985; initial operating capability achieved by 3rd Squadron, 6th Cavalry Regiment, July 1986; 33 of 35 planned AH-64A battalions, including seven National Guard and two Army Reserve, combat-ready by July 1994; first combat use (11 AH-64As) in operation Just Cause, Panama, December 1989; used extensively (288) during January/February 1991 Gulf War against Iraq, including first air strike of conflict. First AH-64As issued to Army National Guard in 1987; fourth ArNG unit (1-211 AvRgt in Utah) established 1990; first overseas regiment 2/6 Cavalry Regiment, Illesheim, Germany, September 1987; eighth in Europe (3-4 AvRgt at Finthen) equipped 1990; battalion consists of 18 AH-64As and 13 Bell OH-58 Kiowas; more than 160 AH-64As based in Germany at peak strength, but force now reduced. Deployed to South Korea March 1994, with 17th Aviation Brigade (5-501st AVN) at Camp Eagle.

An 11 month programme to integrate air-to-air Stinger began October 1987; four missiles mounted in pairs on wingtips; five firings early 1989; air-to-air development programme included firing two AIM-9 Sidewinders in hover and at 80 kt (148 km/h; 92 mph) at White Sands, New Mexico, November 1987; laser ranging and tracking tests on Bell UH-1 and LTV A-7 flown in 1989; M230 Chain Gun being improved for air-to-air use; Matra Mistral captive carry tests completed. New missile control system by Base 10 Defense of Trenton, New Jersey, used for two more Stinger firings during 1990; Sidearm anti-radiation missile from AH-64A hit RF emitter on armoured vehicle at US Naval Weapons Center 25 April 1988.

Boeing awarded four year, US$15.9 million contract on 27 May 1998 to design, manufacture and flight test new centre fuselage section incorporating advanced composites materials. In a separate development, a modified AH-64D Apache Longbow prototype made initial flight with Rotorcraft Pilot's Associate (RPA) advanced cockpit management system featuring updated controls and displays, including Boeing-developed four-axis, full authority, advanced digital flight control system. On 27 May 1999, Boeing and Canada's Derlan Aerospace signed an agreement to develop components for a revolutionary new transmission which will have significantly reduced operating support and acquisition costs, weigh less and transfer more power from the engines to the rotor system.

VERSIONS

AH-64A: Production for US Army and export. All to be upgraded to AH-64D; last in 2010. Retrofit from 1993 with SINCGARS secure radios and GPS; first installed in Apaches of 5-501 Aviation Regiment on deployment to Camp Eagle, South Korea.

Detailed description refers to AH-64A except where indicated

AH-64B: Cancelled in 1992. Was planned near-term upgrade of 254 AH-64As with improvements derived from operating experience in 1990-91 Gulf War, including GPS, SINCGARS radios, target handover capability, better navigation, and improved reliability including new rotor blades.

AH-64C: Previous designation for upgrade of AH-64As to near AH-64D standard, apart from omission of Longbow radar and retention of -701 engines; provisions for optional fitment of both. Designation abandoned late 1993; all Apaches to become AH-64D, including those not fitted with radar.

GAH-64A: At least 17 AH-64As grounded for technical instruction.

JAH-64A: Seven AH-64As for special testing, of which one reverted to standard.

CURRENT VERSIONS

AH-64D Apache Longbow: Current improvement programme based on Westinghouse mast-mounted Longbow millimetre-wave radar and Lockheed Martin Hellfire with RF seeker; includes more powerful GE T700-GE-701C engines, larger generators for 70 kVA peak loads, Plessey AN/ASN-157 Doppler navigation, MIL-STD-1553B databus allied to dual 1750A processors, and a vapour cycle cooling system for avionics;

NAH-64D: New-built AH-64Ds for Royal Netherlands Air Force, without Longbow radar.

WAH-64D: Assembled by Westland; British Army version with Longbow radar and two Rolls-Royce/Turbomeca RTM322 turboshafts.

CUSTOMERS: US Army 827, (including six prototypes) of which last delivered 30 April 1996. Confirmed export deliveries totalled 116 by mid-1998. Total of 97 of orders for 213 aircraft still to be delivered. UK announced order for 67, July 1995. Netherlands signed contract on 24 May 1995 for 30 Apaches for 1998 service; radar not required; US Army has supplied 10 AH-64As on lease basis for period 1996-99; all delivered 13 November 1996. Boeing has identified a further export potential for the AH-64D of 725 units.

COSTS: New US$18 million. Longbow radar costs US$2 million (1990) without supporting modifications compared with US$9.96 million flyaway cost of AH-64A. Longbow R&D contract (for four prototypes) US$194.6 million. Programme cost (807 aircraft at 1991 values) US$1,169 million. Latest Egyptian request costed at US$318 million for 12 Apaches plus four spare Hellfire launchers, 34 70mm rocket launchers, six spare T700 engines, one spare TADS/PNVS system and miscellaneous spares.

DESIGN FEATURES: AH-64 is required to continue flying for 30 minutes after being hit by 12.7mm bullets coming from anywhere in the lower hemisphere plus 20°; also survives 23mm hits in many parts; Target Acquisition and Designation System (TADS) and Pilot Night Vision System (PNVS) sensors mounted in nose; low-airspeed sensor above main rotor hub; avionics in lateral containers; chin-mounted Chain Gun fed from ammunition bay in centre-fuselage; four weapon pylons on stub wings (six when air-to-air capability is installed); engines widely separated, with integral particle separators and built-in exhaust cooling fittings; four-blade main rotor with lifting aerofoil blade section and swept tips; blades can be folded or easily removed; tail rotor consists of two teetering two-blade units crossed at 55° to reduce noise; airframe meets full crash-survival specifications. Two AH-64s will fit in C-141, six in C-5 and three in C-17A.

Main transmission, by Litton Precision Gear Division, can operate for 1 hour without oil; tail rotor drive, by Aircraft Gear Corporation, has grease lubricated gearboxes with Bendix driveshafts and couplings; gearboxes and shafts can operate for 1 hour after ballistic damage; main rotor shaft runs within airframe-mounted sleeve, relieving transmission of flight loads and allowing removal of transmission without disturbing rotor; AH-64A has flown aerobatic manoeuvres and is capable of flying at 0.5 g.

FLYING CONTROLS: Fully powered controls with stabilisation and automatic flight control system; automatic hover hold; tailplane incidence automatically adjusted by Hamilton Standard control to streamline with downwash during hover and to hold best fuselage attitude during climb, cruise, descent and transition.

STRUCTURE: Main rotor blades (by Tool Research and Engineering Corporation, Composite Structures Division) tolerant to 23mm cannon shells, have five U-sections forming spars and skins bonded with structural glass fibre tubes, laminated stainless steel skin and composites rear section; blades attached to hub by stack of laminated steel straps with elastomeric bearings. Teledyne Ryan produces all fuselages, wings, tail, engine cowlings, canopies and avionics containers.

LANDING GEAR: Menasco trailing arm type, with single mainwheels and fully castoring, self-centring and lockable tailwheel. Mainwheel tyres size 8.50-10, tailwheel tyre size 5.00-4. Hydraulic brakes on main units. Main gear is non-retractable, but legs fold rearward to reduce overall height for storage and transportation. Energy absorbing main and tail gears are designed for normal descent rates of up to 3.05m/s and heavy landings at up to 12.8m/s. Take-offs and landings can be made at structural design gross weight on terrain slopes of up to 12° (head-on) and 10° (side-on).

POWER PLANT: Two 1,265kW General Electric T700-GE-701 turboshafts, derated for normal operations to provide reserve power for combat emergencies, and with automatic OEI rating of 1,285kW; -701C engines from 604th (89-0192) AH-64A onward (1990) giving 1,409kW maximum continuous and 1,447kW OEI. Engines mounted one on each side of fuselage, above wings, with key components armour-protected. Upper cowlings let down to serve as maintenance platforms. Two crash-resistant fuel cells in fuselage, combined capacity 1,421 litres. Modifications ordered September 1993 for carriage of four 871 litre (230 US gallons; 192 Imp gallons) Brunswick Corporation external tanks on 437 Apaches. Total internal and external fuel 4,910 litres (1,295 US gallons; 1,078 Imp gallons). New, crashworthy, ballistically self-sealing internal fuel tank entered evaluation phase in fourth quarter of 1997; tank holds 492 litres (130 US gallons; 108 Imp gallons) and is interchangeable with ammunition storage magazine. 'Black Hole' IR suppression system protects aircraft from heat-seeking missiles: this eliminates an engine bay cooling fan, by operating from engine exhaust gas through ejector nozzles to lower the gas plume and metal temperatures.

ACCOMMODATION: Crew of two in tandem: Co-Pilot/Gunner (CPG) in front, pilot behind on 48 cm (19 in) elevated seat. Crew seats, by Simula Inc, are of lightweight Kevlar. Teledyne Ryan canopy, with PPG transparencies and transparent acrylic blast barrier between cockpits, is designed to provide optimum field of view. Crew stations are protected by Ceradyne Inc lightweight boron armour shields in cockpit floor and sides, and between cockpits, offering protection against 12.7mm armour-piercing rounds. Sierracin electric heating of windscreen. Seats and structure designed to give crew a 95% chance of surviving ground impacts of up to 12.8m/s.

SYSTEMS: AiResearch totally integrated pneumatic system includes a shaft-driven compressor, air turbine starters, pneumatic valves, temperature control unit and environmental control unit. Parker Bertea dual-hydraulic systems, operating at 207 bars, with actuators ballistically tolerant to 12.7mm direct hits. Redundant flight control system for both rotors. In the event of a flying control system failure, the system activates Honeywell secondary fly-by-wire control. Bendix electrical power system, with two 35kVA fully redundant engine-driven AC generators, two 300A transformer-rectifiers and URDC standby DC battery. AlliedSignal GTP 36-55(H) 93kW APU (36-155(BH) in AH-64D) for engine starting and maintenance checking. DASA (TST) electric blade de-icing.

AVIONICS: Comms: AN/ARC-164 UHF, AN/ARC-186 UHF/VHF; retrofit of SINCGARS secure radio from 1993; KY-28/58/TSEC crypto secure voice, C-8157 secure voice control; AN/APX-100 IFF unit with KIT-1A secure encoding; Tempest C-10414 intercom.
Radar: Optional Lockheed Martin/Northrop Grumman AN/APG-78 Longbow mast-mounted 360° radar, presenting up to 256 targets on tactical situation display; detects air targets in air-to-ground mode; air-to-air mode for flying targets only.
Flight: Plessey Electronic Systems AN/ASN-137 lightweight Doppler navigation system (upgrade to AN/ASN-157 on AH-64D), Litton LR-80 (AN/ASN-143) strapdown AHRS, AN/ARN-89B ADF, GPS retrofit from 1993, Honeywell Digital Automatic Stabilisation Equipment (DASE), Astronautics Corporation HSI, Pacer Systems omnidirectional, low-airspeed air data system, remote magnetic indicator, BITE fault detection and location. Doppler system, with AHRS, permits nap of the earth navigation and provides data for storing target locations. Marconi air data system, comprising two omnidirectional Airspeed And Direction Sensors (AADSs) mounted on engine cowlings and a High Integration Air Data Computer (HIADC) installed in avionics bay.
Instrumentation: Honeywell all-raster symbology generator processes TV data from IR and other sensors, superimposes symbology, and distributes the combination to CRT and helmet-mounted displays; Honeywell AN/APN-209 radar altimeter video display unit, AH-64D with 'Manprint' (manpower integration) cockpit instrumentation including Litton Canada upfront display and two Bendix/King 15 x 15cm monochrome CRT displays. AH-64A's 1,200 cockpit switches reduced to approximately 200 on AH-64D.
Mission: Lockheed Martin Orlando Aerospace target acquisition and designation sight and AN/AAQ-11 pilot's night vision sensor (TADS/PNVS) comprises two independently functioning, fully integrated systems mounted on nose.
     Contract for new sensor system, known as Arrowhead, awarded to Team Apache Systems (TAS) to give helicopters greater night vision and targeting capabilities.
     TADS consists of a rotating turret (±120° in azimuth, ±30/-60° in elevation) housing sensor subsystems, optical relay tube in the CPG's cockpit, three electronic units in the avionics bay, and cockpit-mounted controls and displays; used principally for target search, detection and laser designation, with CPG as primary operator (can also provide back-up night vision to pilot in event of PNVS failure). Once acquired by TADS, targets can be tracked manually or automatically for autonomous attack with gun, rockets or Hellfire missiles. TADS daylight sensor consists of TV camera with narrow and wide angle fields of view (0°50' and 4° 0'); narrow and wide angle direct view optics (4° and 18°); laser spot tracker; and International Laser Systems laser rangefinder/designator. Night sensor, in starboard half of turret, incorporates FLIR sight with narrow, medium and wide angle fields of view (3° 6', 10° 6' and 50°).
     PNVS consists of FLIR sensor (30 x 40° field of view) in rotating turret (±90° in azimuth, +20/-45° in elevation) mounted above TADS; electronic unit in the avionics bay; and pilot's display and controls; provides pilot with thermal imaging for nap of the earth flight to, from and within battle area at night or in adverse daytime weather, at altitudes low enough to avoid detection. PNVS imagery displayed on monocle in front of one of pilot's eyes; flight information including airspeed, altitude and heading is superimposed on this imagery to simplify piloting. Monocle is part of Honeywell integrated helmet and display sighting system (HADSS) worn by both crew members. Retrofit of Rockwell Collins Automatic Target Handover System in AH-64A; transmits 1,200 bits/s. AH-64D to have Symetrics Industries improved data modem for transmission of target data (and eventually real-time imagery) between helicopters, tactical jet, Joint-STARS airborne command posts, HQs and ground units at 16,000 bits/s, plus radio frequency interferometer beneath radome for identification of hostile transmitters.
Self-defence: Aircraft survivability equipment (ASE) consists of Aerospace Avionics AN/APR-39 passive RWR, Sanders AN/ALQ-144 IR jammer, AN/AVR-2 laser warning receiver, AN/ALQ-136 radar jammer and chaff dispensers, and Lockheed Martin AN/APR-48A radar frequency interferometer. Sanders AN/ALQ-212 Advanced Threat Infra-Red Countermeasures (ATIRCM) system and ITT Industries AN/ALQ-211 Suite of Integrated RF Countermeasures (SIRFC) system currently under development. ATIRCM combines next-generation directable IRCM system with Sanders AN/AAR-57 Common Missile Warning System (CMWS); SIRFC currently at EMD stage, with contractor tests on Apache Longbow prototype undertaken in 1999, followed by operational test and evaluation from early 2000 and production decision in mid-2000.

ARMAMENT: Boeing M230 Chain Gun 30mm automatic cannon, located between the mainwheel legs in an underfuselage mounting with Smiths Industries electronic controls. Normal rate of fire is 625 rds/min of HE or HEDP (High-Explosive Dual-Purpose) ammunition, which is interoperable with NATO Aden/DEFA 30mm ammunition. Maximum ammunition load is 1,200 rounds. New 'Sideloader' system demonstrated June 1994; cuts normal loading time of 20 minutes by up to half and reduces number of personnel required from two to one; under US Army consideration for fleetwide adoption. Gun mounting is designed to collapse into fuselage between pilots in the event of a crash landing. Four underwing hardpoints, with Aircraft Hydro-Forming pylons and ejector units, on which can be carried up to 16 Hellfire anti-tank missiles or up to 76 70mm FFAR (Folding Fin Aerial Rockets) in their launchers or a combination of Hellfires and FFAR. Planned modification adds two extra hardpoints for four Stinger, four Mistral or two Sidewinder (including Sidearm anti-radiation variant) missiles. Hellfire remote electronics by Rockwell; Bendix aerial rocket control system; multiplex (MUX) system units by Honeywell. Co-Pilot/Gunner (CPG) has primary responsibility for firing gun and missiles, but pilot can override his controls to fire gun or launch missiles.

Jane's Helicopter Markets and Systems

- An Apache battalion consists of 18 AH-64s and 13 OH-58 scout helicopters for target spotting and designation.

- AH-64s escorted MH-53J helicopters in the first mission of Desert Storm.

- More than 500 Iraqi tanks were destroyed by US Army Apaches.

- Apaches of the 101st Aviation Regiment fired the first Allied shots of the Gulf War against Iraqi radar installations.

- Leased US Army AH-64As were delivered to the Netherlands army in 1996.

- New developments have led to the advanced AH-64D Longbow Apache.

- The Apache is designed to survive hits from 23mm cannon, and the cockpit to withstand hitting the ground at 13m per second.

- The Apache uses a super-heated ceramic block to deceive heat-seeking missiles.

- Apache operators include Egypt, Greece, Israel, Saudi Arabia, the UAE and the USA.

- The Apache's 16 laser-guided Hellfire missiles can destroy a tank 20km away.

- The Apache uses digital technology to pinpoint targets for commanders, other helicopters, tanks and vehicles.

- The Apache's Chain Gun weighs 56kg and fires 625 rounds per minute.