iscover
The AIM-9L is a very late model of the famous Sidewinder family, which saw considerable use in the Vietnam War. The missile weighs in at 85 kg. has a cruise velocity of Mach 3 and carries an 11.4 kg fragmentation warhead. The weapon has an effective range of around 20 km and has been launched from a large number of aircraft including even USMC AH-1T SeaCobra attack helos. The launch aircraft in this instance is an F/A-18, here configured for the air superiority role, with two AIM-7 (semi-active radar) Sparrow and two AIM-9 Sidewinders. The USN would task this aircraft with TarCAP or MigCAP-it is very probable that the RAAF will adopt the same weapon configurations. Alternate configurations enable the carriage of 6x AIM-9 or 2x AIM-9/4x AIM-7, the latter mix is expected to become standard for USN Fleet Air Defence missions. The F/A-18s integrated cockpit fire control automatically conditions radar and HUD modes for the selected weapon and features a number of auto-lock-on modes, including an off-boresight mode allowing the pilot to lock on to a target in a tight turn.
Technology Explained
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Heat-Seeking Missile Guidance
Of all the air-to-air weaponry developed in the latter half of the 20th century, the air-to-air guided missile has probably had the greatest impact, affecting the design of weapon systems, airframes, and propulsion and often leading to a complete reassessment of combat tactics. Air-to-air missiles (AAMs) differ principally in guidance, the two broad groups being radar-guided and heat-seeking or infra-red (IR) missiles. Of the two categories, the second, by virtue of its simplicity and lower demands on launch aircraft complexity, has become the numerically superior, arming high-performance fighters like the F-15 or F-14 operated by frontline air forces, yet also equipping vintage 1950s fighters, defending Third World countries.
The initial deployment of heat-seeking missiles began in the late 1950s, with the USAF acquiring its first AIM-4 Falcons and AIM-9 Sidewinders, however, it was not until the Vietnam War that the AIM-9 saw widespread use. The weapon was not as successful as expected, and reliability was a particular problem, especially with the USN (repeated carrier launches and recoveries – quote “banging them on the deck after every flight”), but when the missile did work, it was effective, which may be confirmed by a number of NVAF pilots who had the unique experience of a ‘Winder entering the tailpipe of their sturdy Mikoyan, resulting in its subsequent bisection. Current versions of the AIM-9 are a vast improvement, though they are to be replaced by the end of this decade by the ASRAAM – solid state electronics allowing for higher reliability and enabling the guidance to be “smarter” in discriminating between targets and resisting jamming.
As their name implies, heat-seeking missiles home onto the hot areas of a target. The target will usually both reflect and emit infrared radiation, which propagates through the atmosphere, losing its identity due to a number of effects. This radiation is detected by the missile’s seeker head which, if the conditions are right, will then provide the guidance with the relative position of the target enabling the weapon to home in and destroy the target. In order to fully appreciate the problems involved in creating an effective weapon of this kind, we must examine the behaviour of infra-red radiation, the characteristics of an aircraft as a source of IR energy, the manner in which this energy travels through the atmosphere and finally, how the missile seeker processes it to gain information as to the target’s position.
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