AH-64D Longbow

The AH-64D Longbow Apache is a remanufactured and upgraded version of the AH-64A Apache attack helicopter. The primary modifications to the Apache are the addition of a millimeter-wave Fire Control Radar (FCR) target acquisition system, the fire-and-forget Longbow Hellfire air-to-ground missile, updated T700-GE-701C engines, and a fully-integrated cockpit. In addition, the aircraft receives improved survivability, communications, and navigation capabilities. Most existing capabilities of the AH-64A Apache are retained.

The AH-64D has been fielded in two configurations. The full-up AH-64D includes all of the improvements listed above. In addition, a version of the AH-64D [formerly designated the AH-64C] without the FCR was also to be fielded. This version would not receive the new Radar Frequency Interferometer (RFI) or the improved engines, but would receive the other Longbow modifications. The AH-64D without FCR is capable of launching the Longbow Hellfire missile. Boeing delivered the first remanufactured Longbow Apache in March 1997. A total of 501 AH-64A Apaches were to be upgraded to the AH-64D configuration, 227 of which will be equipped with the FCR.

Transportability requirements were initially identified in the ORD and further defined in the AH-64D System Specification. Both configurations of the AH-64D, including any removed items and appropriate PGSE, were required to be capable of being transported aboard C-141B, C-5A, or C-17 aircraft. The aircraft would also be capable of being transported and hangar stored below decks in the landing platform helicopter (LPH) type carrier, Fast SeaLift ships, Roll-on/Roll-off, LASH, SEABEE ships, and Military SeaLift Command (MSC) dry cargo ships. Additionally, the aircraft had to be transportable by military M270A1 trailer and commercial "Air-Ride" trailer or equivalent. For aerial recovery, the AH-64D with MMA would be externally transportable by CH-47D aircraft using the Unit Maintenance Aerial Recovery Kit. Two AH-64D plus one FCR aircraft would be transportable by C-141, six AH-64Ds (with a minimum of three FCR mission kits) are transportable by C-5, and three AH-64Ds and three FCR mission kits are transportable by C-17.

The AH-64D Longbow Apache (LBA) provides increased data transfer capabilities such as SPOTREPs, SITREPs, battle damage reports, target handover, and real-time images of the battlefield with use of the IDM. The IDM is a tri-service device that offers backward capability to the OH-58D airborne target hand-over system (ATHS) and tactical fire (TACFIRE). With TACFIRE integration, the Longbow can send target information to the entire TACFIRE net for immediate suppression. Besides target handover, the IDM provides the capability to send fragmentary orders (FRAGOs), enemy/friendly location updates, graphic updates and changes, and any other pertinent information from the commander to the Longbow Apache company/team, or from LBA to commander, while en route to or in the battle position. This timely exchange of information reduces the time of manually plotting information and increases operational tempo, allowing the commander to shape the battlefield. The data transfer module (DTM), mounted in the Longbow Apache, is used to quickly upload the mission data and initialize aircraft systems for the mission. Data can be loaded into all aircraft or loaded into the first aircraft and transmitted via the IDM to all other aircraft in the mission. When the mission is complete, the DTM retains all mission data debriefing information to carry back to the AMPS for the debrief. In addition, the DTM provides the maintenance section with data for troubleshooting, reducing maintenance downtime.

The Longbow FCR significantly improves the adverse weather fighting abilities of the AH-64D helicopter, provides a true fire-and-forget capability and increases target acquisition efficiency and effectiveness, thus increasing battlefield effectiveness and survivability. The aircraft is able to detect and classify more than 128 targets, prioritize the 16 most dangerous targets, transmit the information to other aircraft and initiate a precision attack, all this in fewer than 30 seconds.

With the addition of a new and highly sophisticated FCR, more commonly called the Longbow FCR, the AH-64D has became one of the most advanced aerial fighting vehicles in the world. The FCR provides the Apache with the ability to detect, classify and prioritize stationary and moving targets both on the ground and in the air. With state of the art fire control, digital communications, automatic target classification and many other up to date features, the AH-64D Longbow Apache will dominate the battlefield for years to come.

The AH-64D Apache Longbow increases combat effectiveness over the AH-64A by providing a more flexible digital electronics architecture and integrating computer-based on-board Built-In Test Equipment (BITE), Automatic Test Equipment (ATE), and hard copy operator or Interactive Electronic Technical Manual (IETM) troubleshooting/maintenance manuals that will easily accommodate changes resulting from system growth. In addition, upgrades to electrical power and cooling systems and the expansion of the forward avionics bays to accommodate the installation of the FCR, and provide for future growth. Navigation system accuracy is improved through integration of a miniaturized integrated Embedded Global Positioning System (GPS)/Inertial Navigation Unit (INU) (EGI), and an improved DOPPLER Velocity Rate Sensor (DVRS).

The fully integrated AH-64D without Longbow Mission Kit incorporates greater ordnance capability and flexibility than the AH-64A by utilizing the family of Semi-Active Laser (SAL) missiles (including the HELLFIRE II) and Longbow HELLFIRE RF Missile. The AH-64D without Longbow Mission Kit can operate in harmony with the FCR-equipped AH-64D and can accept a target hand over and fire the Longbow missile with minimum exposure to hostile forces.

The AN/APG-78 FCR is a multi-mode Millimeter Wave (MMW) sensor integrated on the Apache Longbow with the antenna and transmitter located above the aircraft main rotor head. It enhances Longbow system capabilities by providing rapid automatic detection, classification, and prioritization of multiple ground and air targets. The radar provides this capability in adverse weather and under battlefield obscurants. The FCR has four modes: (1) the Air Targeting Mode (ATM) which detects, classifies, and prioritizes fixed and rotary wing threats; (2) the Ground Targeting Mode (GTM) which detects, classifies, and prioritizes ground and air targets; (3) the Terrain Profiling Mode (TPM) which provides obstacle detection and adverse weather pilotage aids to the Longbow crew; (4) and the Built in Test (BIT) Mode which monitors radar performance in flight and isolates electronic failures before and during maintenance.

The Longbow RF missile and the Longbow HELLFIRE Launcher (LBHL) are referred to as the Longbow Hellfire Modular Missile System (LBHMMS). The system incorporates a fire-and-forget missile that accepts primary and/or secondary targeting information from the FCR and single targeting information from TADS or another aircraft to acquire and engage targets. Similar to the FCR, the RF missile provides the capability to engage threats in adverse weather and through battlefield obscurants. Two acquisition modes, lock-on-before-launch (LOBL) and lock-on-after-launch (LOAL), allow engagement of ground and rotary wing threats at extended ranges. In the LOBL mode, the missile will acquire and track moving or short range stationary targets prior to leaving the launch platform. In the LOAL mode, the missile will acquire long range stationary targets shortly after leaving the launch platform.

The Longbow HELLFIRE missile is a radar-guided version of the laser-guided HELLFIRE anti-tank, air-to-ground missile. The Army manages the Longbow HELLFIRE missile as a separate program. The Longbow HELLFIRE features an active millimeter wave seeker and a dual tandem warhead designed to defeat reactive armor. Either the FCR or the Target Acquisition and Designation Sight can provide target location data to the missile prior to launch. The Longbow HELLFIRE can engage moving or stationary vehicles. The missile has been upgraded through the Home-on-Jam/Anti-Jam (HOJ/AJ) and Counter-Active Protection System (CAPS) programs. The HOJ/AJ upgrade is a software revision that changes the guidance logic to improve effectiveness against self-screening and standoff jammers. The CAPS upgrade includes hardware and software to provide active counter-countermeasures for the missile.

The combination of the integrated FCR, LBHMMS and the Apache aircraft enhances battlefield awareness by providing coverage of the battle area at extended ranges, by reducing operational dependence on weather and battlefield conditions, and by rapid display of detected targets. It further improves the Longbow system's war fighting capability and survivability by providing rapid multi-target detection and engagement ability, navigational aids, and a fire-and-forget weapon delivery system.

The addition of the Longbow FCR provides a second and completely independent target acquisition sensor which may be operated by either crew member or combined to provide a degree of multi-sensor synergy. When operated independently, the pilot could use the FCR to search for air targets in the ATM mode while the copilot/gunner (CPG) searches for ground targets using the Target Acquisition Designation Sight (TADS).

Using both TADS and the FCR together combines the unique advantage of each sight. The rapid search, detection, classification, and prioritization of targets by the Longbow FCR can then be quickly and positively identified by using the electro-optics of TADS. The center of view can be focused on the location of the highest priority target and the CPG, at the touch of a switch, can view either display. Alternately, the FCR centerline can be cued to the TADS so that a rapid and narrow search could be made of a suspected target area.

The RFI is an integral part of the Longbow FCR. It has sensitivity over an RF spectrum to detect threat emitters when a threat radar is in a search and acquisition mode and also when the threat emitter is "looking" directly at and tracking the Longbow system. The RF band has been extended over that which was developed for the OH-58D Kiowa Warrior at the low end of the RF spectrum to detect newly identified air defense threats. The RFI has a programmable threat emitter library to allow additional threat signatures to be stored and/or updated.

The Modernized TADS/PNVS program replaces six of the current LRUs with new ones. They are the PNVS, PNVS Shroud, NSA, BSM, TEU, TPS, and PEU. Also, slight modifications are being made to other components to address other maintenance drivers identified over the years. The DSA and Laser are not being modified. The modernization includes moving to a two-level maintenance concept for the new LRUs. The Line Replaceable Units (LRUs) were being designed to allow smaller Line Replaceable Modules (LRMs) to be fault isolated and replaced, rather than the entire LRU.

The basic configuration and outer look of the M-TADS/PNVS is almost be identical to the current system. The PNVS shroud looks different, because it now has two sensors, the new FLIR and an Image Intensification Sensor (basically a built-in 18mm NVG tube). The pilot is now be able to switch between the two sensors and to fly using the one best for the existing conditions. Complete provisions were included to eventually fuse the two images. The shroud is broken into two LRMs (shroud and window), making removal much simpler. The current W-10 harness is being replaced with a two-piece design. The new FLIR has a much better image quality than the current system. It has 4 pixels across and 480 pixels down (4x480), compared to the current common module 1x180 configuration. What this means is that the system has much better wire detection and marginal weather performance, at least 20/45 visual acuity, compared to the previous 20/80.

The boresighting module was replaced with a new module to eliminate the need for the out-front boresighting procedure. Boresighting would be accomplished automatically after initiation by the CPG. The entire boresighting procedure would take under 2 minutes to complete. The existing target tracker was being replaced with a new, more robust design. The new multi-target tracker system will be capable of tracking up to six targets. The NSA will still have the three fields of view: wide, medium, and narrow. In addition, there was to be a 2X zoom with no time limit. The system would incorporate extended range algorithms to provide even greater ID ranges. This would result in almost twice the range capability of the current system. The CPG pilotage mode (wide FOV FLIR) was expected to equal the existing PNVS pilotage performance.

Maintainers have three methods to fault isolate problems, including the aircraft Fault Detection/Location System (FD/LS). In addition, select LRUs have LCD displays on the front that display an error code indicating the faulty LRM. The TEU, for instance, is broken down into individual circuit cards that can be removed and replaced. A small LCD display on the front of the TEU will show the maintainer which card is faulty and needs to be replaced. Finally, the system has the capability to interface with the SPORT computer. Other maintainer-friendly changes are being made. Straps on the existing TEU and TPS, for instance, were replaced with real handles for easier handling.

The Army was also looking at replacing the IHADSS with an upgrade to take full advantage of the increased performance of the new system. The replacement for the ORT, TEDAC, would be included as part of the M-TADS/PNVS upgrade for aircraft that had not received it by the time fielding of the system had begun. The Army was also pursuing a digital TECA to be fielded in conjunction with the M-TADS/PNVS.

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