Boeing AH-64 Apache gunship helicopter – AAH winner
Story of AH-64 Apache
The AH-64 Apache is the US Army’s principal gunship/antitank helicopter. It was the winner in the 1973-76 competition for an Advanced Attack Helicopter (AAH), beating out the Bell YAH-63 entry. The AH-64 is intended primarily for the antitank role, with an all-weather/nigh t operating capability. It is relatively fast and maneuverable, carries a large antiarmor weapons load, has reduced radar and Infrared (IR) signatures, is damage-resistant against most small and medium antiaircraft artillery, and is crashworthy.
Apache rotor system
The four-blade main rotor assembly consists of a hollow mast with an inertia-welded nickel-steel driveshaft. Each blade has five stainless-steel spars, steel leading edge, stainless-steel skin, and composite trailing edge. The blade design feature s a high-lift airfoil section and swept tips; the 20° sweep at the tips delays compressibility and improves the stability of both advancing and retreating blades.
The blades are linked to the hub arms with 22-ply-laminate strap packs. Two lead-lag dampers are fitted to each hub arm, and the flapping hinge is offset to 4% of blade radius to augment control power. The blades can be folded for transport by large cargo aircraft.
The antitorque rotor has two two-blade teetering rotors with a relatively low tip speed, which reduces tail rotor noise, and a 4,500-hour fatigue life. The titanium fork assembly carries one set of blades in elastomeric bearings above the plane of the other and at a 60°/120° angle. The tailplane had originally been mounted at the top of the tail. After tests, the broad, all-moving surface was relocated to near the base of the pylon. It adjusts automatically to provide a level attitude during Nap of the Earth (NOE) flight.
Flight Control
Primary flight control is by hydraulic actuation; a Sperry Fly-by-Wire (FEW) is provided as a backup. Stabilization is by the Sperry Digital Automatic Stabilization Equipment (DASE). Manufacturer McDonnell Douglas Helicopters claims that the AH-64 can move laterally and to the rear at speeds up to 45 knots (52 mph; 83 km/h). Maximum load factors are 3.5 g/—0.5 g; the positive load factor is reduced to 2.4 g with a 3,350-lb (1,520-kg) weapons load. The two turboshaft engines are shoulder-mounted on the fuselage behind the main rotor mast. Each engine is fitted with a “black hole” passive IR exhaust suppressor.
Design of AH-64
The fuselage of Apache is designed to be crashworthy in vertical crashes of up to 42-ft/ sec descent; the crew compartment is further protected by progressive deformation of the rest of the airframe, which absorbs additional energy. The entire airframe is designed to be invulnerable to 12.7-mm rounds. In addition, most vital components can sustain hits from 23-mm rounds and continue flying to a safe landing.
The pilot and copilot/gunner sit in tandem, Kevlar-armored seats surrounded by boron armor and under a heavily framed canopy. The canopy frame is designed to act as a roll cage, and the glazing between the crew members is impact-resistant; the glazing is not ballistically tolerant. The pilot is in the rear seat, which is 19 in (480 mm) above the copilot/gunner’s. The front seat has a full set of flight controls that are typically stowed under the front sight.
The landing gear is fixed with the main, trailing-arm struts below the pilot’s position and the tail gear extending beyond the tail rotor pylon. Detachable stub wings are fitted to the fuselage below the main rotor mast; each wing has two weapons pylons.
AH-64 Apache avionics and electronics
The core of the AH-64 Apache avionics fit is the Martin Marietta Target Acquisition and Designation Sight/Pilot’s Night Vision Sensor (TADS/PNVS) linked to the Honeywell Integrated Helmet and Display Sight System (IHADSS) worn by both crew members. The turrets for the TADS and PNVS systems are fitted in the nose of the Apache. The upper PNVS turret contains a Forward-Looking Infrared (FLIR) sensor directly linked to the IHADSS and traverses with the user’s head movements. Azimuth range is /-90 0; elevation is 20°/-45°.
The lower TADS turret is divided vertically; the left half has direct vision optics with two fields of view (4° and 18°) above a daylight TV with 0.9° and 4° fields of view. The right half has a FLIR sensor. TADS is also fitted with a laser spot tracker and laser designator. Azimuth coverage is /-120°, elevation is 30°/-60°. TADS imagery is relayed to the copilot/gunner through an optical relay “tube” that resembles a small console; it has both Head-Down and Head-Up Displays (HDD/HUD).
Armament and self-defense
The three principal weapons systems on the AH-64 Apache are the McDonnell Douglas Helicopters M230 30-mm Chain Gun, Rockwell AGM-114 Hellfire laser-guided antitank missiles, and Hydra 2.75-in (70mm) rocket pods. The Chain Gun is fitted in a turret below the cockpit; turret traverse is / —100°, elevation is 11°/—60°. Ammunition is fed from a 1,200-round pallet fitted under the main rotor assembly; operational experience has shown that a 380-round ammunition load is best. The stub pylons can carry up to 16 Hellfire missiles, although a load of eight is more typical. As an alternative load, up to four 19-rocket Hydra pods can be carried.
To improve its self-defense capabilities, the Apache was tested in November 1987 with Loral Aeroneutronic AIM-9 Sidewinder Air-to-Air Missiles (AAM) fitted on stub wingtip rails. The usual AAM fit, however, is the Air-to-Air Stinger (ATAS) adaptation of the General Dynamics FIM-92 Stinger shoulder-fire d surface-to-air missile. Shorts (UK) Starstreak and Matra Mistral air-to-air and AGM-122 Sidearm antiradar missiles are also compatible.
Development of AH-64
The Apache’s initial operational capability was in 1985. Its first flight was on September 30, 1975, and its first production rollout was in January 1984; the 500th production aircraft was rolled out on September 15, 1989. The first squadron of Apaches stationed in Europe arrived in August 1987 as part of REFORGER ’87. A total of 975 AH-64A Apaches had been planned for procurement through FY1992, equipping 27 attack helicopter battalions. With the defense draw-downs following the collapse of the Soviet Union, the figure was again reduced under former Defense Secretary Cheney.
Since its service entry in 1985, the AH-64 Apache has been the most advanced combat helicopter in service as well as plagued with reliability shortcoming s in several key areas. Several studies conducted by the General Accounting Office (GAO) found many faults with the Apache, both mechanical and with its electronics.
Several countries have purchased the Apache: Bahrain, Egypt, Greece, Israel, Kuwait, Saudi Arabia, and the United Arab Emirates.
Apache data and performance
Name: | Boeing AH-64 Apache |
Role: | Attack Helicopter |
First Flight: | 1975 | Introduction: | 1986 |
Primary User: | United States and Israel Air Force |
Service: | In service |
Crew: | 2 (pilot and gunner) |
Capacity: | 2 (crew) |
Length: | 17.73 m (58 ft) | Rotor Diameter: | 14.60 m (48 ft 5 in) |
Height: | 3.87 m (12 ft 6 in) | Weight: | 5,165 kg (11,400 lb) |
Loaded Weight: | 8,000 kg (17,700 lb) | Max. Weight: | 10,500 kg (23,050 lb) |
Powerplant: | 2 × General Electric T700-GE-701 | Power: | 1,300 kW (1,690 shp) |
Max. Speed: | 365 km/h (197 knots, 230 mph) | Range: | 476 km (257 nmi, 295 mi) |
Rate Of Climb: | 12.7 m/s (2,520 ft/min) |
Service Ceiling: | 6,100 m (20,000 ft) |
Number Built: | 1,200 |
Unit Cost: | 20.000.000 USD |
Video of AH-64 Apache
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