AIM-120 AMRAAM

Clockwise from top left: Go Get 'im, Fido! An AIM-120A AMRAAM
is launched from a USAF F-16C. (U.S. Air Force photo); The Future Medium-Range Air-to-Air Missile (FMRAAM), the proposed multi-national developpment of the AIM-120 AMRAAM (BAe pic); A pair of AIM-120s are loaded onto an F/A-18C; The FMRAAAM (now BVRAAM) (Hughes Missiles photo); An F-18C loaded with 10 AIM-120As. (Hughes Missiles photo)

AIM-120A AMRAAM Specifications

Length:	143.9in (366cm)
Body diameter:	7in (17.78cm)
Front Finspan:	20.7in (52.58cm)
Rear Finspan:	25in (63.5cm)
Launch Weight:	335lbs (150.75kg)
Maximum Range:	46mi (74km)
Flight Speed:	Mach 4
Warhead:	50.6lb (23kg) ABF
Propulsion:	Hercules solid fuel, single-grain ducted rocket
Guidance:	Inertial (mid-phase), active monopulse radar (terminal phase)
Operational Service entry:	September 1991
Unit cost:	$386,000 U.S.

BACKGROUND

Thus was born the requirement in 1975 for a new missile to be called the AIM-120 AMRAAM, which would be free of SARH limitations. The joint USN/USAF requirement also stated that the AMRAAM be able to engage targets at ranges of 3 to 40+ miles. The AIM-120 completed the conceptual pahse in 1979. In 1981 five contractors had competed, and this number had been reduced to 2: Hughes and Raytheon, which were awarded full-scale developpment contracts. Since Hughes and Raytheon were incorporating extremely advanced technology into the AMRAAM, there were severe developpment probelems, promptin gin 1985 a review, which extended the development phase by two years, and delayed the initial production date from 1986 to 1989. Even further evaluation probelms delayed the actual service enty date to 1991. To date, around 800 AMRAAMs have been fired in testing, and 3 have been fired in combat.

The AMRAAM, its hundreds of thousands of lines of computer codes now free of "bugs", is known to pilots as the Slammer, for its incredble performance and reliablity. Unlike the AIM-7, when the Slammer is fired at long range, the missile flies using an inertial navigation system, which senses pitch, yaw, and roll through a series of mechanical gyros, toward the vicinity of the target. During this pahse of the flight, there is the option of updating the Slammer in-flight with the launch aircraft's fire-control radar. The missile and aircraft communicate using a 2-way datalink, the antennae for which are mounted near the rear of the AIM-120. Another option is for the launch aircraft o leave the area immediatly. When the AMRAAM closes to the target's location, the missile activates its own Hughes monopulse radar, and locks onto the target. As it does this, the AMRAAM interrogates the target with its IFF (Identification Friend or Foe) system to reduce the possibilty of "friendly fire" occurences. The AIM-120's 50.6lb (23kg) annular blast-fragmentation (ABF) warhead is detonated by either impact or laser proximity fuses. For closer-range engagements, the AIM-120 utilises its own radar as soon as it leaves its launch rail and proceeds unaided to the target. These engagement capabilities give the Slammer a true "fire-and-forget" or "launch-and-leave" capabilty.

The AMRAAM is capable against targets flying almost any flight profile, from terrain-hugging to high-altitude. The AIM-120's extreme maneoverability is possible beacause maneovering is done by the aft fins (as opposed to the forward fins on the AIM-7), which designers have found give better maneovering properties in the critical terminal phase of the flight. This agility allows the Slammer to accomplish 30-G turns. The AMRAAM's effectiveness is best meaured through the "no-escape zone", which is a large teardrop-shaped area in front of the missile. Any target caught inside this zone at time of launch will have zero chance of outrunning or outturning the AIM-120, no matter how good the plane or its pilot is. The AIM-120 has a maximum head-on range of 46 miles, while this would be reduced to a maximum 12 mile tail-chase range.

The AIM-120 is also extremely adaptable. Its solid-state electronics are of modular design with the capabilty to be rapidly and easily upgraded should the need arise. Also, an mean-time before failure rate of 1,500 hours has been demonstrated on AIM-120's being carried on sorties in captive form. In fact, in November 1994, the AIM-120 passed the 200,000-hour captive carry mark, because of the high tempo of USAF operations monitering the No-Fly Zones over Iraq and Bosnia. The missile's modular electronic "black boxes" consist of the Microwave Associates monopulse radar mount, behind which is the Watkins-Johnson signal proccessor, behind which is the transmitter/reciever, digital autopilot, and battery. The AIM-120A's small size (143.9in) and launch weight (335lbs) allow the AMRAAM to be fitted to aircaft that couldn't accomodate the much larger and heavier AIM-7. Also, the AMRAAM can also be fitted to launchers previuosly only capable of supporting the AIM-9 Sidewinder (for example, it's common to find F-16C/D's with an AIM-120 on each wingtip rail and Sidewinders on the outbaord wing stations). On Navy F-14 and F/A-18 aircraft, the AMRAAM is mounted on LAU-127 launch rails which incorporate the mechanical and electrical interface.

The Slammer also has an astonishing record in both flight tests (once proper sofware was perfected) and in combat. For example, in one test over White Sands Missile Range in New Mexico, one F-15C Eagle ripple-fired four AIM-120A's at 4 QF-100 drones. The drones were performing evasive maneovers, releasing chaff, and were also equipped with jammers. All 4 AIM-120's hit the targets dead-on. This and other tests earned the nickname Slammer (One F-15 driver compared firing the AMRAAM at targets to being like clubbing baby seals), as well as other nicknames such as "The World War III Shot". Some people have even taken to calling the AMRAAM the "Go Get'em Fido" Missile. The Slammer has been fired in combat on 3 occasions. On the first, which took place on 27 December 1992, an F-16C patrolling the No-Fly Zone over Iraq destroyed an Iraqi MiG-25 Foxbat head-on at medium range. Later on 17 January 1993 another F-16C shot down an Iraqi MiG-23 at closer range, at the limit of the AMRAAM's no-escape zone. The third kill in AMRAAM history took place over Bosnia when a Serbian tactical fighter, flying in a terrain-hugging profile, was hit by a U.S. Slammer.

Future planned developments include replacing the 3 mechanical inertial gyros with laser gyros, and possibly the addition of a small GPS reciever to improve naviagational accuracy. The AMRAAM has been purchased by 14 countries and is compatible with the F-14, F-15, F-16, F/A-18, AV-8B, Sea Harrier, JA-39 Gripen, JA-37 Viggen, Tornado, and the forthcoming EF-2000. Another version of the AMRAAM is the AIM-120C, which will have smaller control surfaces. This is designed to permit increased numbers of the missile to be carried in the internal weapons bays of the F-22 Raptor. Norway also uses the AIM-120 in the surface-to-air role, where the missile is also quite capable. In this system, the Norweigan Advanced Surface-to-Air System (NASAMS), the AIM-120s used are identical to ones used in the air-to-air role, allowing systems commonality and reducing logistical constraints. A proposed multi-national improvement of the Slammer was known as the FMRAAM, or Future Medium Range Air-to-Air Missile. It was recently redisgnated the BVRAAM or Beyond-Visual-Rang Air-to-Air Missile. This is being jointly developped by several companies, including British Aerospace (BAe) and Hughes Missiles. The FMRAAM would incorporate ramjet engines to give it longer range, as well as a higher average speed.