Military Knowledge: AH-64 Apache Attack Helicopter

History:
In the Advanced Attack Helicopter (AAH) program, the United States Department of Defense wanted a helicopter with more firepower, performance and range than the AH1-Cobra, and the new helicopter should also be able to fly at a very low altitude (nap-of-the-earth). -NoE) as well. So the Apache helicopter was developed to replace the AH-1 Cobra helicopter.

Proposals were submitted by Bell, Boeing Vertol/Grumman team, Hughes, Lockheed, and Sikorsky. In July 1973, the U.S. Department of Defense selected finalists Bell and Hughes Aircraft’s Toolco Aircraft Division (later Hughes Helicopters).

Each company built prototype helicopters and went through a flight test program. Hughes’ Model 77/YAH-64A prototype first flew on 30 September 1975, while Bell’s Model 409/YAH-63A prototype first flew on 1 October 1975. After evaluating the test results, the Army selected Hughes’ YAH-64A over Bell’s YAH-63A in 1976. Reasons for selecting the YAH-64A included its more damage tolerant four-blade main rotor and the instability of the YAH-63’s tricycle landing gear arrangement.

The AH-64A then entered phase 2 of the AAH program under which three pre-production AH-64s would be built, additionally, the two YAH-64A flight prototypes and the ground test unit were upgraded to the same standard. Weapons and sensor systems were integrated and tested during this time, including the laser-guided AGM-114 Hellfire missile. Development of the Hellfire missile had begun in 1974, originally known by the name of Helicopter Launched, Fire and Forget Missile (‘Hellfire’ being a shortened acronym), for the purpose of arming helicopter platforms with an effective anti-tank missile.

In 1981, three pre-production AH-64As were handed over to the U.S. Army for Operational Test II. The Army testing was successful, but afterward it was decided to upgrade to the more powerful T700-GE-701 version of engine, rated at 1,690 shp (1,260 kW). The AH-64 was named the Apache in late 1981, following the tradition of naming Army helicopters after Native American tribes. It was approved for full-scale production in 1982. In 1983, the first production helicopter was rolled out at Hughes Helicopter’s facility at Mesa, Arizona.

Hughes Helicopters was purchased by McDonnell Douglas for $470 million in 1984. The helicopter unit later became part of The Boeing Company with the merger of Boeing and McDonnell Douglas in August 1997. Today, MD Helicopters, a subsidiary of Boeing, is responsible for the production of AH-64 Apache helicopters.

Since 1984, some aerospace companies such as AgustaWestland have produced a number of parts for the Apache. Teledyne Ryan Aeronautical was the manufacturer of the Apache fuselage, which was handed over to Korea Aerospace Industries in 2004. This change in fuselage manufacturer led to a long legal dispute between Teledyne Ryan and Boeing.

Design:
The AH-64 Apache has a four-blade main rotor and a four-blade tail rotor. The crew sits in tandem, with the pilot sitting behind and above the co-pilot/gunner. Both crew members are capable of flying the aircraft and performing methods of weapon engagements independently.

The AH-64 is powered by two General Electric T700 turboshaft engines with high-mounted exhausts on either side of the fuselage. Various models of engines have been used on the Apache; those in British service use engines from Rolls-Royce. In 2004, General Electric Aviation began producing more powerful T700-GE-701D engines, rated at 2,000 shp (1,500 kW) for AH-64Ds.

The crew compartment and rotor blades are designed to sustain a hit from 23 mm (0.91 in) rounds. The airframe includes some 2,500 lb (1,100 kg) of protection and has a self-sealing fuel system to protect against ballistic projectiles. This compartment also incorporates a transparent blast shield between the pilot and gunner seats so that at least one crew member can survive in the event of a direct hit, but the canopy and windows are otherwise unrated against ballistic threats.

The aircraft was designed to meet the crashworthiness requirements of MIL-STD-1290, which specifies minimum requirement for crash impact energy attenuation to minimize crew injuries and fatalities. This was achieved through incorporation of increased structural strength, crashworthy landing gear, seats and fuel system.

On a standard day, when temperatures are 59 °F (15 °C), the AH-64 has a vertical rate of climb of 1,775 feet per minute (541 m/min), and a service ceiling of 21,000 feet (6,400 m). However, on a hot day, when temperatures are 70 °F (21 °C), its vertical rate of climb is reduced to 1,595 fpm (486 m/min), and service ceiling is reduced to 19,400 feet (5,900 m) due to less dense air.

One of the revolutionary features of the Apache was its helmet mounted display, the Integrated Helmet and Display Sighting System (IHADSS); among its capabilities, either the pilot or gunner can slave the helicopter’s 30 mm automatic M230 Chain Gun to their helmet, making the gun track head movements to point where they look.

The M230E1 can be alternatively fixed to a locked forward firing position, or controlled via the Target Acquisition and Designation System (TADS). On more modern AH-64s, the TADS/PNVS has been replaced by Lockheed Martin’s Arrowhead (MTADS) targeting system.

U.S. Army engagement training is performed under the Aerial Weapons Scoring System Integration with Longbow Apache Tactical Engagement Simulation System (AWSS-LBA TESS), using live 30 mm and rocket ammunition as well as simulated Hellfire missiles. The Smart Onboard Data Interface Module (SMODIM) transmits Apache data to an AWSS ground station for gunnery evaluation.

The AH-64’s standard of performance for aerial gunnery is to achieve at least 1 hit for every 30 shots fired at a wheeled vehicle at a range of 800–1,200 m (870–1,310 yd). British Apache pilot with IHADSS The AH-64 was designed to perform in front-line environments, and to operate at night or day and during adverse weather conditions.

Various sensors and onboard avionics allows the Apache to perform in these conditions; such systems include the Target Acquisition and Designation System, Pilot Night Vision System (TADS/PNVS), passive infrared countermeasures, GPS, and the IHADSS.

Additional avionics and sensor improvements includes an extended-range radar capable of detecting small ships in littoral environments, software adaptions to handle maritime targets, and adding Link 16 data-links for better communications with friendly assets.

Variants:

AH-64A:
The AH-64A is the original production attack helicopter. The crew sit in tandem in an armored compartment. It is powered by two GE T700 turboshaft engines. The A-model was equipped with the −701 engine version until 1990 when the engines were switched to the more powerful −701C version.
U.S. Army AH-64As are being converted to AH-64Ds. The service’s last AH-64A was taken out of service in July 2012 before conversion at Boeing’s facility in Mesa, Arizona. On 25 September 2012, Boeing received a $136.8M contract to remanufacture the last 16 AH-64As into the AH-64D Block II version and this was planned to be completed by December 2013.

AH-64B:
In 1991, after Operation Desert Storm, the AH-64B was a proposed upgrade to 254 AH-64As. The upgrade would have included new rotor blades, a Global Positioning System (GPS), improved navigation systems and new radios. U.S. Congress approved $82M to begin the Apache B upgrade. The B program was canceled in 1992. The radio, navigation, and GPS modifications were later installed on most AH-64As via other upgrades.

AH-64C:
Additional funding from Congress in late 1991 resulted in a program to upgrade AH-64As to an AH-64B+ version. More funding changed the plan to upgrade to AH-64C, which would include all of the changes to be included in the AH-64D except for mast-mounted radar and newer −700C engine versions. However, the C designation was dropped after 1993. With AH-64As receiving the newer engine from 1990, the only difference between the AH-64C and the AH-64D was the radar, which could be moved from one aircraft to another; thus the decision was made to simply designate both versions as AH-64D.

AH-64D Apache Longbow:
The AH-64D Apache Longbow is equipped with a glass cockpit and advanced sensors, the most noticeable of which being the AN/APG-78 Longbow millimeter-wave fire-control radar (FCR) target acquisition system and the Radar Frequency Interferometer (RFI), housed in a dome located above the main rotor.

The radome’s raised position enables target detection while the helicopter is behind obstacles (e.g. terrain, trees or buildings). The AN/APG-78 is capable of simultaneously tracking up to 128 targets and engaging up to 16 at once; an attack can be initiated within 30 seconds. A radio modem integrated with the sensor suite allows data to be shared with ground units and other Apaches, allowing them to fire on targets detected by a single helicopter.

The aircraft is powered by a pair of uprated T700-GE-701C engines. The forward fuselage was expanded to accommodate new systems to improve survivability, navigation, and ‘tactical internet’ communications capabilities. In February 2003, the first Block II Apache was delivered to the U.S. Army, featuring digital communications upgrades. The Japanese Apache AH-64DJP variant is based on the AH-64D; it can be equipped with the AIM-92 Stinger air-to-air missiles for self-defense.

AH-64E:
Formerly known as AH-64D Block III, in 2012, it was redesignated as AH-64E Guardian. It has improved digital connectivity, the Joint Tactical Information Distribution System, more powerful T700-GE-701D engines with upgraded face gear transmission to handle more power, capability to control unmanned aerial vehicles (UAVs), full IFR capability, and improved landing gear. New composite rotor blades, which completed testing in 2004, increase cruise speed, climb rate, and payload capacity. Deliveries began in November 2011. Full-rate production was approved on 24 October 2012, 634 AH-64Ds will be upgraded into AH-64Es.

Changes in production lots 4 through 6 include a cognitive decision aiding system and new self-diagnostic abilities. The updated Longbow radar has an oversea capacity, potentially enabling naval strikes; an AESA radar is under consideration. It will have a L-3 Communications MUMT-X datalink in place of two older counterparts, communicating on C, D, L, and Ku frequency bands to transmit and receive data and video with all Army UAVs. Lots 5 and 6 will have Link 16 data-links. The AH-64E is to be fit for maritime use. The U.S. Army expressed interest in extended-range fuel tanks for greater endurance. As of April 2020, 500 AH-64Es have been delivered.

AH-64F:
In 2014, Boeing conceptualized an Apache upgrade prior to the introduction of the U.S. Army’s anticipated attack version of the Future Vertical Lift (FVL) aircraft, forecast to replace the Apache by 2040. The conceptual AH-64F would have greater speed via a new 3,000 shp turboshaft engine from the Improved Turbine Engine Program, retractable landing gear, stub wings to offload lift from the main rotor during cruise, and a tail rotor that can articulate 90 degrees to provide forward thrust. In October 2016, the Army revealed they would not pursue another Apache upgrade to focus on funding FVL; the Army will continue buying the Apache through the 2020s until Boeing’s production line ends in 2026, then FVL is slated to come online in 2030.
In 2014, Boeing conceptualized an Apache upgrade prior to the introduction of the U.S. Army’s anticipated attack version of the Future Vertical Lift (FVL) aircraft, forecast to replace the Apache by 2040. The conceptual AH-64F would have greater speed via a new 3,000 shp turboshaft engine from the Improved Turbine Engine Program, retractable landing gear, stub wings to offload lift from the main rotor during cruise, and a tail rotor that can articulate 90 degrees to provide forward thrust. In October 2016, the Army revealed they would not pursue another Apache upgrade to focus on funding FVL; the Army will continue buying the Apache through the 2020s until Boeing’s production line ends in 2026, then FVL is slated to come online in 2030.

Compound Apache:
In October 2018, Boeing began testing the AH-64E Block 2 Compound, a compound helicopter design which added a larger fixed wing and a pusher propeller to the Apache airframe to provide additional lift and thrust, respectively. In addition, the engine exhaust was redirected downwards. Collectively, the modifications were anticipated to improve speed to 185 kn (343 km/h; 213 mph), range to 460 nmi (850 km; 530 mi), payload to 5,900 lb (2,700 kg), and fuel economy. A 30% scale model completed wind tunnel testing in January 2019. The Compound Apache has been pitched as an interim replacement for the Apache before its replacement under the Future Vertical Lift program.

Sea Apache:
During the 1980s naval versions of the AH-64A for the United States Marine Corps and Navy were examined. Multiple concepts were studied with altered landing gear arrangements, improved avionics and weapons. The USMC conducted a two-week evaluation of the Apache in September 1981, including shipboard operation tests. Funding for a naval version was not provided; the USMC continued to use the AH-1.

The Canadian Forces Maritime Command also examined naval Apaches. In 2004, British Army AgustaWestland Apaches were deployed upon the Royal Navy’s HMS Ocean, a Landing Platform Helicopter, for suitability testing; there was U.S. interest in the trials. During the 2011 military intervention in Libya, the British Army extensively used Apaches from HMS Ocean. In 2013, US AH-64Ds were tested on several U.S. Navy ships.

Export Apaches:
Several models have been derived from the AH-64A, AH-64D and AH-64E for export. The British-built AgustaWestland Apache (assembled from kits purchased from Boeing) is based on the AH-64D Block I with several different systems, including more powerful engines, folding rotor blades, and other modifications for operation from Royal Navy vessels.

Specifications of AH-64E Guardian helicopter:
Role: Attack helicopter
In service: since 1986
Origin: USA
Manufacturer: Boeing Defense, Space & Security
Crew: 2
Length: 14.68 meters
Height: 4.72 meters
Rotor diameter: 14.63 meters
Engine: 2 General Electric T700-GE-701
Speed: 279 km/h
Ascent rate: 853 meters per minute
Weight: 6838 kg
Maximum take-off weight: 10432 kg
Combat range: 480 km
Maximum range: 1896 km
Flight ceiling: 6096 meters
Armament:
1× 30mm M230 Chain Gun with 1,200 rounds
4× hardpoints under the wings

More pictures of the Apache attack helicopter:

Infographics of Apache AH-64 attack helicopter in Arabic, Russian, Persian, Azeri and Kurdish:

Sources:
Boeing AH-64 Apache
AH-64 Apache – Boeing
ah64 apache attack helicopters