AH-64D Longbow Apache



AH-64A Apahce AH-64D Longbow1 AH-64D Longbow2
Left: An AH-64A Apache. Center and Right: The AH-64D Longbow Apache. (Boeing Photos)


AH-64D Longbow Apache Specifications
Power Plant 2 x General Electric 1,940shp (1,446kW) T700-GE-701C truboshafts
Fuel Capacity 2,442 lbs (1,108kg) max internal; 5,980 lbs (2,712kg) max external
Perfomance (4,000ft/1,219m, 35°C/95°F) Max level speed 143kts; cruise speed 133kts; vert. rate of climb 1,025ft/min (5.2m/sec)
Weights Empty 11,800 lbs (5,352kg); Mission Gross 16,491 lbs (7,480kg); Max T-O 22,283 lbs (10,107kg)
Dimensions Fuselage length 50ft 9in (15.47m); With rotor turning 58ft 2in (17.73m); Main rotor diameter 48ft (14.63m); Tail rotor diameter 9ft 2in (2.79m); height over tailfin 10ft 10in (3.55m); Height over tail rotor 13ft 1in (4.30m); Overall 16ft 3in (4.95m)
Accomodation 2: Pilot and Co-Pilot/Gunner (CP/G) in 2 armored crashworthy seats
Armament 1 x M230E1 Chain Cannon with 1,200 rds; Up to 16 x Hellfire ATGMs; or up to 76 FFARs, or a combination of both; Up to 4 x AIM-92 Air to Air Stinger missiles

January 17, 1991

On the morning of first day of the Gulf War, a group of 8 AH-64A Apaches from the 101st Airborne Division, flying at 100 kts and 50 feet, slipped into Iraq ninety minutes ahead of the massive Coalition airstrike that was to follow. The Apaches had been led by USAF MH-53J Pave Lows to a point within about 12km of an Iraqi air defense radar site. This site and all its associated buildings and equipment had to be destroyed quickly to open a gap in the Iraqi air defense net, through which some of the more than seven hundred Allied aircraft will fly through, to strike over 500 strategic and tactical targets throughout Iraq. The Iraqi radars stayed in a search mode the whole time the Apaches were there, indicating they never saw it coming. At precisely ten seconds before 0238 hrs local time, all 8 Apaches launched their Hellfire missiles at the targets. Each helicopter's Primary target is his wingman's Secondary target. 4 1/2 minutes later the last building is destroyed, and soon after that the first Coalition aircraft flew overhead. In total, the Apaches were inside Iraqi airpsace for about 30 minutes.

During the course of the war, in which the AH-64 flew nearly 10,000 Close Air-Support (CAS) missions, the Apache destroyed:


Apaches also assisted in the capture of 4,764 Iraqis. In many cases, the Iraqis surrendered upon sight of the AH-64. However during the war and Operation Desert Shield which preceeded it, the heat and fine sand of the desert environment caused maintenance nightmares for the aircraft designed to fight World War III in Europe. The conditions would knock out air-conditioning system and cause problems with optics and engines. The environmental conditions kept about 1/3 of the 288 Apaches in the Gulf out of service, with each AH-64A requiring on average about 5 hours of maintenance for every hour of flight in Desert Storm.

The Apache was born out of the failure of the AH-56 Cheyenne. The demise of the Cheyenne led the US Army to launch the Advanced Attack Helicopter (AAH) competition. Hughes Aircraft's entry was the YAH-64 which first flew on 30 September 1975. Called the Hughes Model 77, it was competing against Bell Textron's YAH-63. The YAH-64 was selected as the winner of the competition by the Army in December 1976, and was named the Apache in 1981. By 1982 the AH-64 was ready for production, and deliveries began on 26 January 1984. The first Apache unit, the 3rd Squadron, 6th Cavalry Regiment, achieved Initial Operational Capability in July 1986. The 811th and final Apache was delivered in December 1994. The Apache first saw combat when 11 AH-64A's participated in Operation Just Cause in Panama in December 1989.

The Apache is the most expensive and complex weapons system operated by the US Army. It is essentially a flying Main Battle Tank. The nose of the aircraft has 2 sensors, the TADS and the PNVS. The AN/ASQ-170 TADS (Target Acquisition and Display System) is the drum-shaped sensor on the lower nose. The TADS has a FLIR (Forward-Looking Infra Red), 2 optical cameras, and a Laser Range-Finder/Detector (LRF/D). The starboard half of the TADS is dedicated to night sighting systems, and the port side is specilised for daytime operation. The TADS can turn 120° in either direction horizontally, and +30° up and -60° down. The FLIR has a field of view of +/-40° horizontally and +/-30° vertically. The AAQ-11 Mk-III PNVS (Pilot's Night Vision Sensor) is the sensor on the upper nose over the TADS. The PNVS contains a FLIR which can be swivelled up to 90° either way horizontally, and +20° up or -45° down. The FLIR can move at a maximum rate of 120° per second in the horizontal plane, and 93° per second in the vertical plane.

The PNVS is slaved to the Pilot, and the TADS is slaved to the Co-Pilot/Gunner (CP/G) via the Honeywell Integrated Helmet and Display Sighting System (IHADSS). In this system, each crewmember's helmet has a monocule placed in front of the right eye. At the base of the monocle is a 1" x 1" TV screen which projects FLIR imagery, superimposed with critical data such as altitude, airspeed and heading. Before taking off the crew places the monocle directly in front of the eye, and looks forward to a borsight reticle on the control panel, and once they are centered on it, the crewmember flips a switch in the cockpit and the computer saves the head position, moving the TADS or PNVS turrets along with the crewman's head movements. TADS imagery is displayed on the CP/G's eyepiece, and can also be viewed by the pilot in the back seat via a display on his control panel. During normal daytime flight the TADS and PNVS are typically swivelled back, to reduce the exposure of the lenses to particles or debris in the air. However, the TADS and PNVS FLIRs operate in the 8 to 12 Micron range, and as such can sometimes be blinded by rain or particle-infused smoke. This prompted some Apache crews to use image intensifying or I2 night vision goggles along with the FLIRs.

In 1988 the Army gave McDonnel Douglas a contract to launch an Apache Multi Stage Improvement Program. An AH-64B proposal, which was to modify 254 AH-64As to incorporate improvements over the AH-64A such as GPS, Sincgars radios, target handover capability, and improved rotor blades was cancelled in 1992. AH-64C was a designation for a upgrade of AH-64As to what is now called the AH-64D, minus the Longbow fire control radar. The C designation was abandonned in 1993, with all the uprgraded Apaches, including those without the radar, to be called the AH-64D.

Thus the Longbow radar was born. In the early 1980s the US Army launched the Helicopter Adverse Weather Target Aqcuisition and Designation System (HAWTADS), which led to the Helicopter Adverse Weather Fire Control and Aqcuisition Radar (HAWCFAR). This comptetition was won by Martin Marietta and Westinghouse in 1985, when they formed a joint venture, the Airborne Adverse Weather Weapons System (AAWWS), today called the Longbow. The first pre-production fire-control radar was delivered in June 1993, and installed on the second AH-64D prototype (89-0228) which flew with the radar on 20 August 1993. The Longbow fire-control radar itself, first tested in June 1986, is a mushroom shpaed dome mounted on top of the rotor mast, and is 52 in (132cm) in diameter, and 30 in (76cm) in height. The radar antenna weighs 250 lb (113 kg). It costs the Apache about 4 to 5 Kts of airspeed. The Longbow Radar is a Milimeter Wave (MMW) radar and operates in the Ka-Band area of around 35GHz. This frequency allows the radar to be small, as well as penetrate through ground clutter and be able to see through trees or camouflage netting. During the development phase, switching to a electro-formed radar antenna eliminated 10 parts from the system and reduced costs by 63%. Using a composite baseplate instead of a more conventional metal one saved 20 lbs (9kg). The Longbow's low-probability-of-intercept radar can detect moving targets out to 8km away, and stationary targets out to 6km away. The radar scans a 360° sector for air targets, and scans in 270° or 90° sectors for ground targets. The radar can detect, classify and display 256 targets on a Tactical Situation Display (TSD) in the cockpit. Longbow gives each target a Track ID #, a time/postion fix, and a speed and heading fix. The TSD displays the targets as:

The TSD can display the footprint of the radar in scales of 1:50,000, 1:100,000, 1:250,000, 1:500,000 (this scale covers roughly 1,390 sq. miles / 3,600 km2). The Longbow's greatest asset is the ability to share information with other elements of the attack force. It does this via a Symetrics Industries Improved Data Modem (IDM) which can recieve and transmit data with other compatible aircraft and ground units via 4 radio channels at 16KB/s. Any Apache can designate fire zones and hand off targets to other elements of the Force to avoid wasting the valuable Hellfire missiles. The Longbow Apache can sneak into the target area, hiding behind terrain features and trees, then pop up for a few seconds, scan the battlefield, then pop back down behind cover again so the crew can make a more detailed evaluation of the data. This is a big advantage over the AH-64A which had to expose nearly the entire aircraft to employ its TADS/PNVS to look at the battlefield.

The two crewmen sit in tandem, restrained by a 5-point harness system, with the CP/G in the front, and the Pilot behind and above the CP/G. The crew sits in Kevlar-reinforced seats which can wisthstand and 42-ft/s crash. The cockpit, flooring and bulkead divider are reinforced with Boron armor to withstand 23mm AAA fire. The canopy is composed of flat plates except for the side windows which are curved slightly to reduce vibration caused by the rotors. The windows can withstand 12.7mm AAA fire. Between the 2 cockpits is a clear acrylic blast divider which is designed to reduce the likelyhood of both crewmembers being killed if one of the cokpits is compromized by enemy fire. Also, the crew is shielded from gorund fire by the 2 chine areas on the lower front sides of the cockpit. The interior of the cokpit has been revolutionized since the older AH-64A. In the A-model there were some 1,250 switches, while in the D this has been reduced to around 200. This is because the AH-64D now has a "glass" cockpit in which the majority of switches and analog dials and gauges have been replaced with Multifunction Displays (MFDs). In fact, the Longbow upgrades integrate electronics to such a degree over the AH-64A that around 400 lbs (180kg) of black boxes have been eliminated, along with about 35% of the wiring from the A.

For self-defense measures in the EW environment, the AH-64 carries an ALQ-136 radar jammer its reciever mounted on top of the fuselage between cockpit and the rotor mast. Its transmitter is located on the port side of the fuselage between the TADS and PNVS turrets. The AH-64D also carries the AN/ALQ-144 "Disco Ball" (so named because of its resemblance to its namesake). The AN/ALQ-144 is electrically powered and serves as an Infrared Countermeasures (IRCM) decvice. The 0.5kg control unit controls the 12.7kg transmitter unit which consists of a cylindrical block (most likely cemaric) which is heated by a long-life graphite source. The transmitter transmits modulated Infrared energy in an omnidirectional fashion to confuse the seeker heads of enemy IR-guided missiles. It has a 360° coverage zone, and has a 480h MTBF (Mean-Time Before Failure) rate and uses a 28V DC, 1200-2000W power supply.

The engines have been upgraded. The 1,649shp (1,263kW) T700-GE-701 engines on the A have been replaced by the more powerful 1,900shp (1,417kW) -701C engines. The -701C was first introduced to the 604th AH-64A in 1990. The engines are mounted in twin pods on either side of the aircraft to isolate them from each other. The exhaust is passed through a Black Hole IR supressor, which directs the exhaust away from the aircraft, insulates the exhaust area, and mixes it with outside air to reduce the IR signature. The Longbow's 4-bladed main rotor is attached to the fuselage at 8 points. Each blade can move independantly of the others, thanks to new flexible elastometric bearings at the attachments. This freedom of movement allows the Longbow Apache to be extraodinarily maneoverable, able to take +3.5G or -2G forces with a roll rate of 100°/sec. The leading edge of the rotor blade is constructed of Titanium, with the trailing edge moade out of graphite compostie. The interior of the blade is a glass-fiber honeycomb supported over 5 tubular stainless-steel spars, allowing the isolation of battle damamge if the rotor is hit. The rotor's 4 blades produce a remarkeably quiet growling noise, instead of the more familiar whop-whop-whop associated with 2-bladed helicopters such as the UH-1. The tail rotor consitts of 2 blades mounted at 55 degrees to each other (to reduce noise), and the driveshaft (located on the top of the tail boom) to the tail rotor can function for one hour without oil.

The Longbow Apache's main armament is the Hellfire (HELicopter-Launched FIRE and forget) missile. This missile has a maximum range of 5,000 to 8,000m and a minimum range of 500m. The earlier versions of the Hellfire guide onto laser energy in the 1.06æm wavelength, and seeks out a specific pulsing pattern to only lock onto it's designated target and not follow another laser beam. The Longbow Hellfire or RF AGM-114L Hellfire uses its own active radar seeker so that the Longbow Apache won't have to stay in a hover while guiding the missile (the Hellfire takes approx 13 seconds to travel its maximum range of 8,000m). Instead, each Hellfire recieves target information from the Longbow radar, and stores the characteristics of the target's radar signature. The Hellfire flies its way to the target are, then turns on its millimeter-wave radar seeker until it finds the target matching the signature it downloaded from the launch aircraft. The first RF Hellfire was launched in June 1994 against a moving T-72 MBT at Eglin Range. The AH-64D had acquired and ID'd the tank from 2.3nm (4.2km) away, and the RF Hellfire hit its mark. The AGM-114K Hellfire II is semi-active laser-guided version that uses a dual warhead to defeat reactive armor. It uses a 100mm precursor warhead, fitted with a Molybdenum liner, that is designed to detonate the reactive armor and dissipate it effects before the main one is detonated. The main warhead uses a 178mm shaped charge warhead that uses a primary ignition charge different from previous models (due to the Maganvox electronic safety & control unit). The Hellfire was also designed to meet a US Army requirement that it hit targets +/-20° in the horizontal relationship the launch platform at distances up to 1,000m away. The Mach-1.4 Hellfire, which can pull 14 Gs, which means the Hellfire can be used against aircraft. However, the Longbow Apache's main antiaircraft weapon is the AIM-92 Air-to-Air Stinger missile. The Longbow can carry the AIM-92 in 2-round launchers which are carried on each tip of the Apache's stub wings.

The Longbow has the M230E1 Chain Cannon. The M230E1 is an improved version of the M230, incorporating several new accuracy features and a provision to change cannon burst lengths in-flight. The single-barreled, electrically-powered is 1.68m in length, weighs 57.5kg, has a rate of fire of 600-650 rounds per minute (0.2 sec spool-up time to max rate of fire), and a muzzle velocity of 805m/sec. The single barrel is slaved to the gunner's head movements. The M230E1 fires the 30mm M789 HEDP (High-Explosive Dual-Purpose) shell which contains a shaped charge incorporating 21.5g of explosive. The shell has an aluminum casing and can penetrate about 2" of armor, and fragments upon impact, lethal within a 10 ft radius to exposed personnel. The gun has a 1,200-round magazine capacity, and has an azimuth range of +/-220°, and an elevation range of +11° or -60°.

The Apache can also carry the Hydra-70 Folding-Fin Aerial Rocket (FFAR). This is a 2.75in/70mm unguided rocket that is carried in a 19-round alumimun pod. It uses a Mk-66 rocket motor and has 3 folding aluminum fins that pop out upon launch. The rocket (minus warhead) is 1.06m long, has a diameter of 70mm, a tailspan (deployed) of 186mm, and a 6.2kg launch weight. It can carry a variety of payloads, including:



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