| AIM-120 AMRAAM | |
|---|---|
| Type | Medium-range, active radar homing air-to-air missile |
| Place of origin | United States |
| Service history | |
| In service | September 1991 |
| Production history | |
| Manufacturer | Hughes/Raytheon |
| Unit cost | $300-$400,000 for 120C variants, $700,000 for 120D (estimated) |
| Variants | AIM-120A, AIM-120B, AIM-120C, AIM-120C-4/5/6/7, AIM-120D |
| Specifications | |
| Weight | 335 pounds (152 kg) |
| Length | 12 feet (3.7 m) |
| Diameter | 7 inches (180 mm) |
| | |
| Warhead | High explosive blast-fragmentation AIM-120A/B: 50 pounds (23 kg) WDU-33/B blast-fragmentation AIM-120C-5: 40 pounds (18 kg) WDU-41/B blast-fragmentation |
| Detonation mechanism | Active RADAR Target Detection Device (TDD) Quadrant Target Detection Device (QTDD) in AIM-120C-6 – Lots 13 and up.[3] |
| | |
| Engine | High-performance directed rocket motor |
| Wingspan | 20.7 inches (530 mm) (AIM-120A/B) |
| Operational range | AIM-120A 48 kilometres (30 mi) |
| Speed | Mach 4 |
| Guidance system | INS, active radar |
| Launch platform | Aircraft:
Surface launched:
|
There are currently three variants of AMRAAM, all in service with the United States Air Force, USN, and the United States Marine Corps. The AIM-120A is no longer in production and shares the enlarged wings and fins with the successor AIM-120B. The AIM-120C has smaller "clipped" aerosurfaces to enable internal carriage on the USAF F-22 Raptor. AIM-120B deliveries began in 1994, and AIM-120C deliveries began in 1996.
The AIM-120C has been steadily upgraded since it was introduced. The AIM-120C-6 contained an improved fuse (Target Detection Device) compared to its predecessor. The AIM-120C-7 development began in 1998 and included improvements in homing and greater range (actual amount of improvement unspecified). It was successfully tested in 2003 and is currently being produced for both domestic and foreign customers. It helped the U.S. Navy replace the F-14 Tomcats with F/A-18E/F Super Hornets – the loss of the F-14's long-range AIM-54 Phoenix missiles (already retired) can be partially offset with a longer-range AMRAAM, but note that the AMRAAM does not have the long range capability of the Phoenix missile.
The AIM-120D is an upgraded version of the AMRAAM with improvements in almost all areas, including 50% greater range (than the already-extended range AIM-120C-7) and better guidance over its entire flight envelope yielding an improved kill probability (PK). Raytheon recently began testing the D model; on August 5, 2008, the company reported that an AIM-120D launched from an F/A-18F Super Hornet passed within lethal distance of a QF-4 target drone at the White Sands Missile Range.
There are also plans for Raytheon to develop a ramjet-powered derivative of the AMRAAM, the Future Medium Range Air-Air Missile (FMRAAM). It is not known whether the FMRAAM will be produced since the target market, the British Ministry of Defence, has chosen the Meteor missile over the FMRAAM for a BVR missile for the Eurofighter Typhoon aircraft.
Raytheon is also working with the Missile Defense Agency to develop the Network Centric Airborne Defense Element (NCADE), an anti-ballistic missile derived from the AIM-120. This weapon will be equipped with a Ramjet engine and an IR seeker derived from the Sidewinder missile. In place of a proximity-fused warhead, the NCADE will use a kinetic energy hit-to-kill vehicle based on the one used in the Navy's RIM-161 Standard Missile 3.
AIM-120 AMRAAM will continue to serve in the arsenal of the USAF, the U.S. Navy, and the U.S. Marine Corps until at least 2020 when the Joint Dual Role Air Dominance Missile (JDRADM) would potentially enter service. The -120A and -120B models are currently nearing the end of their service life while the -120D variant has just entered full production.
Interception course stage
AIM-120 AMRAAM uses two-stage guidance when fired at long range. The aircraft passes data to the missile just before launch, giving it information about the location of the target aircraft from the launch point and its direction and speed. The missile uses this information to fly on an interception course to the target using its built in inertial navigation system (INS). This information is generally obtained using the launching aircraft's radar, although it could come from an infrared search and tracking system (IRST), from a data link from another fighter aircraft, or from an AWACS aircraft.
If the firing aircraft or surrogate continues to track the target, periodic updates are sent to the missile telling it of any changes in the target's direction and speed, allowing it to adjust its course so that it is able to close to self-homing distance while keeping the target aircraft in the basket (the radar seeker's field of view) in which it will be able to find it.
Not all AIM-120 AMRAAM users have elected to purchase the mid-course update option, which limits AMRAAM's effectiveness in some scenarios. The RAF initially opted not to use mid-course update for its Tornado F3 force, only to discover that without it, testing proved the AMRAAM was less effective in BVR engagements than the older semi-active radar homing BAE Skyflash weapon—the AIM-120's own radar is necessarily of limited range and power compared to that of the launch aircraft.
Terminal stage and impact
Once the missile closes to self-homing distance, it turns on its active radar seeker and searches for the target aircraft. If the target is in or near the expected location, the missile will find it and guide itself to the target from this point. At the point where an AMRAAM switches to autonomous self-guidance, the NATO brevity code "Pitbull" would be called out on the radio, just as "Fox Three" would be called out upon launch.
If the missile is fired at short range (typically visual range), it can use its active seeker just after launch, making the missile truly "fire and forget". The NATO brevity code "Maddog" is used in this situation.
