The simple, effective infrared-homing Sidewinder is the most widely used air-to-air missile outside of the old Soviet Union with more than 110,000 having been produced. Development of the missile began in 1949 at the Naval Weapons Center at China Lake and the AIM-9 made its first flight on 11th September 1953. The Sidewinder is used by a variety of Western fixed-wing combat aircraft and helicopters, and has been adopted for surface-to-air use as the Chaparral missile.
The AIM-9J had an expanded target-engagement cone which enabled it to be launched at any spot in the rear half of a target aircraft rather than merely at its exhaust. Compared with the Vietnam-era AIM-9G, it had a more powerful motor and an improved warhead.
The AIM-9J introduced the Sidewinder Expanded Acquisition Mode (SEAM), which slaved the seeker of the missile to the radar when in ‘dogfight’ mode, and enabled the AIM-9J seeker head to be uncaged, slewed toward a specific target by the aircraft radar, and made to track that particular target only. The AIM-9H introduced improvements such as solid-state electronics, off-boresight acquisition and launch capability, even faster tracking (20 deg/sec), and double-delta foreplanes.
The ‘third generation’ AIM-9L introduced in 1979 was ‘all-aspect’, and no longer limited to engaging an enemy aircraft from the rear. The argon-cooled indium-antimony (InSb) seeker head was more sensitive and able to pick up heat from the friction off the leading edges of an aircraft’s wing and was able to distinguish between aircraft and decoy flares. The AIM-9L also uses a higher-impulse rocket motor, a more powerful warhead, and a proximity fuse rigged to blow outward toward the target in order to ensure better probability of a kill.
The AIM-9M introduced in 1982 had better capability to distinguish between aircraft and decoy flares, and has a low-smoke rocket motor so that it is less likely to be seen by its prey. The number of vacuum tubes was reduced to two. The missile cost approximately $100,000 each during 1988, the last year the Navy procured them. The service then believed it had a sufficient stock of Sidewinders to meet its immediate needs until its projected replacement, the AlM-132 Advanced Short Range Air-to-Air Missile (ASRAAM), entered production in the early 1990s. Frequent delays in ASRAAM led the Navy to join Air Force in procuring AIM-9Ms beginning in 1993. Even further delays in ASRAAM definition led to the AIM-9X development program to provide an improved Sidewinder for the 21st Century.
AIM-9s scored most of the air-to-air kills made during Vietnam, and by the Israeli Air Force in the 1967 and 1973 wars in the Middle East.
The AIM-9L is 9.4 feet long, has a wingspan of 25 inches and a diameter of 5 inches. A single solid-fuel Mk 17 or Mk 36 (depending on type) rocket motor provides a maximum speed of over Mach 2. The missile has four tail fins on the rear, with a rolleron’ at the tip of each fin. These rollerons are spun at high speed by the slipstream in order to provide roll stability. The missile is steered by four canard fins mounted in the forward part of the missile just behind the infrared seeker head. The Sidewinder missile has a launch weight of about 186 pounds, and a maximum effective range of approximately 11 miles. The blast- fragmentation warhead weighs 21 pounds.