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AH-64 Apache
Type	Attack helicopter
Manufacturer	Hughes, McDonnell Douglas, Boeing IDS
Maiden flight	30 September 1975
Status	Active service
Primary users	United States Army Israel Air Force Royal Netherlands Air Force Japan Ground Self-Defense Force
Produced	1984-present
Number built	1,048[1]
Unit cost	US$18 million (1996)[1]
Variants	Westland WAH-64 Apache

Main article: AH-64 Apache

--existing parts are olive colored

The AH-64 Apache is an American all-weather day-night military attack helicopter and is the United States Army's principal attack helicopter, and is the successor to the AH-1 Cobra. The AH-64 is a twin-engined helicopter with four-bladed main and tail rotors. It has a crew of two which sit in tandem in an armored crew compartment with the pilot sitting behind and above the copilot-gunner. The main fixed armament is a 30 mm M230 chain gun, it is also able to carry a mixture of AGM-114 Hellfire and Hydra 70 rockets on four hard points mounted on its stub-wing pylons.

Designed by Hughes Helicopters (as the Hughes Model 77) in response to the Army's Advanced Attack Helicopter Program. McDonnell Douglas purchased Hughes Helicopters and continued the development of the AH-64 resulting in the AH-64D Apache Longbow which is currently produced by Boeing Integrated Defense Systems.

United States Army operated Apaches have been in action in Panama, Gulf War (destroying 500 tanks^[2]), Afghanistan, and Iraq.

Contents 1 Development 1.1 The first predecessor 1.2 AAFSS 1.3 The competitors 1.4 After Vietnam 1.5 The AAH requirement 1.6 Preproduction 2 Design 3 References

[edit] Development

[edit] The first predecessor

In December 1962, the Bell company self funded a helicopter development as "flying gunboat" for the American Armed Forces at early stages of Vietnam war. This new design was aimed to give fire support to ground forces being based on Model 47. The result was the "Model 207 Sioux Scouts" that made his maiden flight in July 1963. ^[3]

The Sioux Scout had since then all characteristics that would have become then attack helicopters typical, like pilot and gunner tandem disposition, stub-wing pylons and a chin installed gun turret. U.S. Army officials evaluated the Sioux Scout in 1964 and despite they had been impressed from the project, they discarded the proposal as it was considered too under-dimensioned, not enough protected and evaluated of little practical utility. ^[3]

[edit] AAFSS

The U.S. Army issued a specification for an "Advanced Aerial Fire Support System" (AAFSS) in August 1964.^[3] The AAFSS requirements led to the development of another predecessor of the Apache; the Lockheed AH-56 Cheyenne. An engineering development contract was signed by the Army and Lockheed in March 1966 and a production contract for 375 aircraft followed the next year.^[4]

The aircraft first flew on 21 September 1967, but the project suffered a setback on 12 March 1969, when the rotor hit the fuselage of a prototype and killed the pilot. The Cheyenne proved to be too complex and ambitious for its time, resulting in budget overruns and program delays due to excessive technical difficulties. The program was eventually cancelled in 1972. ^[3]

[edit] The competitors

Despite being excluded from AAFSS, the Bell company ran over of own initiative, a million dollars self-funded project from January 1965, aimed for going further in attack helicopters development, continuing with his own concept to use a light helicopter as a base for designing ground fire support platforms ^[3] They started from UH-1 Iroquois also known as "Huey", main rotor and reliable transmission, combined with a low aerodynamic drag fuselage (width 91 cm) powered by well experimented turboshaft T53. The project resultant took the name of "Bell Model 209". Fast and manageable, but not sufficiently protected, it was coldly welcomed and wrongly considered without enough growth potential.

1965 was also a deadline for a definitive decision on the AAFSS programme and due to development troubles of Cheyenne, the U.S.Army adopted an "interim" solution to urgently deploy in Vietnam. It was asked to five manufacturers to present urgent proposals and responses were Boeing-Vertol CH-47 Chinook, Kaman UH-2, Piasecki 16H, Sikorsky S-61, and the Bell 209.^[3]

In April 1966, the "Model 209" won and the U.S. Army awarded a first production contract for 110 helicopters denominated "AH-1G HueyCobra". ^[3]. Bell built 1.116 AH-1Gs between 1967 and 1973 and the whole fleet did over a million combat flying hours during the Vietnam war. ^[3]

[edit] After Vietnam

American withdrawal from the Asian Southeast war theatre (ended in 1975) and the consequent cuts to military budgets, led US Army to present again the attack helicopter operational requirement, focusing this time on anti-tank warfare in the European theatre of operations, against the Warsaw Pact forces. The doctrine of deployment for this theatre was completely different from Vietnam anti-guerrilla and primarily tailored on a contrast scenario to that time supposed Soviet divisions attacking waves.^[5]

First generation helicopter launched anti tank missiles have been experimented on French Aérospatiale Alouette III for use during Algeria war, ending in poor results. ^[6]

Second generation anti tank missiles, were faster and compact, thanks to foldable fins, and more accurate using semiautomatic guidance, like BGM-71 TOW. These weapons could be loaded four each in the case of the UH-1 Iroquois, eight each with Cobras, but it become clear the need for more fire power in European theatres. New avionics technologies were available too in optics vision systems, nighttime light intensifiers, and thermal images sensors and their use became highly desirable for giving an effective all-weather, full day/night capability.

[edit] The AAH requirement

In 1972, the Army conducted an evaluation between the Bell Model 309 KingCobra, the Lockheed Cheyenne and Sikorsky S-67 in a competitive fly-off, beginning in the spring of 1972 and was completed in July. In August the Army rejected all three and cancelled the AAFSS program.^[5] In the same year, the US Army issued a request for proposals (RFP) for a new program now named Advanced Attack Helicopter (AAH).^[2]

The Army specified that the AAH was to be powered by twin General Electric T700 turboshaft engines with 1,120 kW (1,500 SHP) each, the same powerplant fit specified for a new Army utility helicopter competition that would be won by the Sikorsky S-70 Black Hawk. The AAH would be armed with a 30 millimetres cannon and sixteen TOW anti-tank missiles. The missile armament specification was later modified to include an alternate load of 16 laser-guided AGM-114 Hellfire anti-tank missiles. Hellfire was then in development and promised greater range and lethality than TOW.^[5]

Proposals were submitted by five manufacturers: Bell, Boeing-Vertol (teamed with Grumman), Hughes, Lockheed, and Sikorsky.

Among the five contenders, in 1973 finalists were declared the Bell 409, a new Kingcobra variant who paved the way to following Supercobra and the Hughes Model 77. Hughes' Model 77/YAH-64 prototype first flew on September 30, 1975, while Bell's Model 409/YAH-63 prototype first flew the following day.^[2] After evaluating test results, the Army selected Hughes' YAH-64 over Bell's YAH-63 in December. The Army felt the YAH-63's two-blade rotor was more vulnerable to damage than the Apache's four-bladed rotor, and the service did not like the YAH-63's tricycle landing gear scheme, feeling it was less stable than the Apache's "taildragger" configuration. Some observers also suspected the Army did not want to divert Bell from AH-1 production.^[5].

[edit] Preproduction

The AH-64 then entered phase 2 of the AAH program. This called for building three preproduction AH-64s, and upgrading the two YAH-64 flight prototypes and the ground test unit up to the same standard.^[7] Weapons and sensor systems were integrated and tested during this time,^[2] including the new Hellfire missile.^[7]

In 1981, three pre-production AH-64s were handed over to the U.S. Army for Operational Test II. The Army testing was successful, but afterwards it was decided to upgrade to the T700-GE-701 version of engine, producing 1,690 shp (1,259 kW).^[2] In late 1981, the AH-64 was named the "Apache" keeping with the Army's traditional use of Native American tribal names for its helicopters. Hughes was approved for full-scale production in 1982.^[2] In 1983, the first production helicopter was rolled out at Hughes Helicopter's facility at Mesa, Arizona. In 1984, Hughes Helicopters was purchased by McDonnell Douglas for $500 million. Hughes later became part of The Boeing Company with the merger of Boeing and McDonnell Douglas in August 1997. The total cost of the AH-64D program is US$ 10.5 billion through April 2007.^[8]

[edit] Design

The AH-64 is powered by two General Electric T700 turboshaft engines with high-mounted exhausts on either side of the rotor shaft. The Apache has a four-blade main rotor and four-blade tail rotor. The crew sits in tandem, with the pilot sitting behind and above the copilot-gunner in an armored crew compartment. The crew compartment is armored against 23 mm gunfire.

The helicopter is armed with a 30 mm M230 chain gun that can be slaved to the gunner's helmet-mounted gunsight, fixed to a locked forward firing position, or controlled via the TADS (Target Acquisition and Designation System). The AH-64 carries a range of external stores on its stub-wing pylons, typically a mixture of AGM-114 Hellfire anti-tank missiles, Hydra 70 general-purpose unguided 70 mm (2.75 in) rockets, and AIM-92 Stinger anti-aircraft missiles for defense. In case of emergency the pylons also have mounting points for personnel transfer (mounting points are handles normally used by maintenance personnel).^[9]

The AH-64 is designed to endure front-line environments and to operate during the day or night and in adverse weather using avionics and electronics, such as the Target Acquisition and Designation System, Pilot Night Vision System (TADS/PNVS), passive infrared countermeasures, Global Positioning System (GPS), and the Integrated Helmet And Display Sight System (IHADSS).

[edit] References