aircraft missiles ALARM (Air-Launched Antiradar Missile) with a passive radar homing head is designed to destroy radar control systems of enemy air defenses, including radar MANPADS medium and long range.
anti-radar missiles (PRR) ALARM was created companies Matra BAe Dynamics and Texas Instruments in accordance with the requirements of 1228 N Royal Air Force to replace obsolete missiles AS.37 Martel and AGM-45 Shrike similar purpose. Research was conducted from 1977 to 1980. Contract for the development was signed in June 1983, the first launch of the new missile took place in late 1988, the missile tests were at the landfill China Lake (USA) from 1988 to 1990. ALARM PRR was put into service in 1991. Originally planned purchases of missiles for the Royal Air Force was 750 pieces. PRR ALARM included in the armament of fighter-bombers, Tornado, fighters Harrier, Hawk stormtroopers and attack helicopters Lynx.
Rocket ALARM, is based on the normal aerodynamic scheme, with four small destabilizers in front of the body (see diagram). The missile body is functionally divided into several compartments, including: passive radar homing (PRGSN), control unit ("flying mission"), an inertial control system, proximity fuze with slam-actuator warhead marching solid rocket motor , steering and parachute compartments (see layout scheme).
PRGSN firm Marconi Defence Systems, has a fixed four-way helical broadband antenna. According to the developer PRGSN has high selectivity and resistance to countermeasures. GOS radome is made of a new synthetic material that provides minimal signal attenuation and distortion compared with ceramic fairing.
A characteristic feature of the RDP
ALARM is its ability to use the so-called. loitering mode, in which the missile with the engine off slowly reduced under the canopy, searching radar target. PRGSN missile has a high sensitivity and provides guidance on the radio emission corresponding to the side-lobe of the radar antenna. , Modern radars have very narrow main beam and low intensity side-lobe that given the rotation of antenna devices in a horizontal plane gives, in terms of PRGSN missiles pronounced pulsating nature of the radiation. On the final trajectory , PRR ALARM for all modes of application is almost vertical, which allows for missile guidance relatively constant radiation field vertical lobe of the radar antenna and reduces the target pointing error due to multipath signals from local objects. If the target stops radiation, the PRR is held on a course using the onboard inertial control system.
Inertial missile control is based on strapdown measurement module, which provides a measurement of angular and linear movement along three axes. Prior to launching rocket inertial control system PRR continuously receives information from the navigation system of the aircraft- carrier.
The structure of the control unit includes a digital processor Zilog Z8002, providing processing signals from PRGSN and inertial platform, the task of target identification and formation of management teams. Processor allows rapid reprogramming - characteristics enemy radar and priority objectives can administered immediately before departure. Software written in CORAL. Control unit provides target identification by comparison with typical radar pulse sequences from the database and depending on the type of target sets the height of warhead detonation above ground level. Such an algorithm is designed specifically for the functioning of defeat Radar detection of low-flying targets, antenna posts which are raised above ground level with a special tower. Typically, the height is set at undermining array radar control or cabin.
Warhead PRR ALARM - high-explosive/fragmentation/incendiary, developed by MBB. Warhead equipped ready heavy shrapnel of tungsten and is designed specifically to defeat the antenna arrays, electronic components and calculations radar. Proximity fuse Thorn EMI is based on solid-state laser and provides a predetermined height warhead detonation.
Solid boosters dual-mode with the possibility of re-inclusion, providing the ability to use rocket bombardment mode, developed by Bayern-Chemie. The engine is located in the central compartment of the missile is armed Low Smoke Zero composite propellant charge and provides traction on the starting and marching mode 10:1. Engine nozzle is connected to the combustion chamber gazovodom, laid on the axis of the rocket in two tail compartment.
In the steering compartment in the annular space between the casing and gazovodom missiles are four independent elektroservoprivoda providing aerodynamic rudder deflection. In the tail section of the rocket placed the parachute system, consisting of the brake and the main dome. After braking rockets and opening the main parachute mode loitering system provides vertical descent rocket and space spiral scan using PRGSN.
PRR ALARM (see diagram) using special rail aircraft launchers (AAP). Rocket leaves the rails with acceleration up to 4g. Team to unlock aerodynamic rudders fed through 0.5s after the disappearance of the rails.
missile can be launched on board a variety of media. The simplest interface APU interface provides only the command to start the engine and the RDP provides the possibility of placing missiles in various media. In this case, the training of the flight task and putting it into the control system is made rockets at the airport before departure.
other options for interfacing with the carrier board are carried out on the basis of the multiplex information exchange standard MIL STD 1553. Limited version, designated Active Interface, provides transmission aboard PRR ALARM data about the location and speed of the aircraft carrier in real time. Using Active Interface removes restrictions on media maneuvers before missile launch.
MIL STD 1553 interface capabilities besides Active Interface allows you to quickly reprogram the missile in flight to perform a new combat mission until the start-up, as well as testing and verification systems missiles with viewing the results on the multifunction display of the cockpit. < / p>
ALARM has three basic modes of operation, which, depending on the type of media can be programmed prior to departure or specified directly on the suspension during the flight.
direct attack method - a method tratsitsionny defeat radar when the rocket is launched on a pre-explored goals and moves along the optimal trajectory. Capturing goals PRGSN missiles on the suspension occurs on the target designation from the equipment or aircraft carrier on the trajectory. Maximum range with direct attacks ahead of the explored goal is about 93km. Directly in front of goal and rocket attacks performs hill top goal. When loss goals may divert to another radar missiles.
second mode - loitering. In the second method rocket is launched from the aircraft carrier, to fly at low altitude at a distance of 40 km from the target. The rocket is made when there is no direct line of sight of radar target. After starting the rocket climbs to 12km, and the engine is switched off and the parachute opens, through which the missile can patrol about two minutes. In the process of reducing RGSN rocket searches operating enemy radar. When capturing objectives RGSN parachute is shot and PRR, start the engine and dives at the target.
third mode - the combined application. In this mode, the missile is launched in a direct attack mode, the loss of contact with the target PRR climbs and enters loitering. This mode is used with large and medium altitudes and media optimal in the case of actions against mobile and maritime air defense systems.
known that one of the ways to counter the attacks of the RDP is to reduce the time of radar in air by full or periodic shutdown station. Length of the pause in the radar is determined by the transit time PRR final trajectory. Use RDP ALARM mode loitering, and the ability volley and alternately run multiple missiles can do a pause value unacceptably large for the normal functioning of the air defense system. This ensures removal of radar failure if not by its destruction, forced by her off.
Maximum range, km
maximum flight speed, m / s
tests and operation
Royal Air Force was first used in 1991 UR ALARM. During the war in the Persian Gulf, and these missiles have not consisted in service, and their tests to the outbreak of hostilities were not completed. The Royal Air Force in the Persian Gulf had nine fighter-bombers equipped Tornado GR.1 UR ALARM. Aircraft made sorties from Tabuk in Saudi Arabia. Loading planes usually was three missiles on ventral suspension. As a defensive means REP used hanging container Skyshadow one underwing pylons and hanging container with automatic chaff and IR-traps at the other pole. Launches RDP implemented at a range of 8 to 100 km, at altitudes from 800 to 6000 m in horizontal flight, followed by pitching. PRR carriers, usually located in the head group order of battle or in groups, designed to suppress air defenses. In total, the Royal Air Force carried out 24 missions on the suppression of the Iraqi air defenses to use ALARM and 52 sorties during which 121 rocket was released. Stocks missiles were exhausted by mid-February, after which the suppression of Iraqi air defense was assigned to the U.S. Air Force. Due to technical failure of the initial batch of missiles, several launches were unsuccessful. Thus, the UK has tested a new missile that according to Western military observers helped to accelerate the adoption of her adopted.
During the NATO aggression against Yugoslavia in 1999. reported on the use of six missiles ALARM. Information about the effectiveness of the missing.