The AIM-9 Sidewinder is a supersonic, heat-seeking, air-to-air missile carried by fighter aircraft. It has a high-explosive warhead and an active infrared guidance system. The Sidewinder was developed by the US Navy for fleet air defense and was adapted by the U.S. Air Force for fighter aircraft use. Early versions of the missile were extensively used in the Southeast Asian conflict. In September 1958 Chinese Nationalist F-86s fired the first Sidewinder air-to-air missiles to down 11 communist Chinese MiG-17s over the Formosa Straits. Until that time, aircraft defensive means where primarily limited to pilots and tail gunners firing small caliber ammunition in dog-fight situations.
The AIM-9 has a cylindrical body with a roll-stabilizing rear wing/rolleron assembly. Also, it has detachable, double-delta control surfaces behind the nose that improve the missile's maneuverability. Both rollerons and control surfaces are in a cross-like arrangement.
The missile's main components are an infrared homing guidance section, an active optical target detector, a high-explosive warhead, and a rocket motor.
The infrared guidance head enables the missile to home on target aircraft engine exhaust. An infrared unit costs less than other types of guidance systems, and can be used in day/night and electronic countermeasures conditions. The infrared seeker also permits the pilot to launch the missile, then leave the area or take evasive action while the missile guides itself to the target.
The development process has produced increased capabilities with each missile modification.
The AIM-9A, prototype of the Sidewinder, was first fired successfully in September 1953. The initial production version, designated AIM-9B, entered the Air Force inventory in 1956 and was effective only at close range. It could not engage targets close to the ground, nor did it have nighttime or head-on attack capability. These shortcomings were eliminated on subsequent versions.
The AIM-9G provided the capability to lock on and launch against a target offset from the axis of the launch aircraft.
The AIM-9H configuration replace vacuum tubes with solid-state modules and a thermal battery replaced the turbo-alternator. The AIM-9H was configured with a continuous-rod bundle warhead.
The AIM-9J, a conversion of the AIM-B and E models, has maneuvering capability for dogfighting, and greater speed and range, giving it greater enhanced aerial combat capability. Deliveries began in 1977 to equip the F-15 and other Sidewinder-compatible aircraft.
The AIM-9L added a more powerful solid-propellant rocket motor as well as tracking maneuvering ability. Improvements in heat sensor and control systems have provided the AIM-9L missile with an all-aspect attack capability and improved guidance characteristics. The L model was the first Sidewinder with the ability to attack from all angles, including head-on. An improved active optical fuze increased the missile's lethality and resistance to electronic countermeasures. A conical scan seeker increased seeker sensitivity and improved tracking stability. The AIM-9L is configured with an annular blast fragmentation warhead. Production and delivery of the AIM-9L began in 1976. The all aspect heatseeking Lima model of the established AIM-9 Sidewinder missile was one of the most significant air combat weapons of its time. The AIM-9L did not require a tail chase position to lock on to a tailpipe, and could lock on from any angle including 12 o'clock ie head-on. Soon after deployment the AIM-9L proved that existing air combat tactics were obsolete, since instantaneous turning performance became far more important than sustained turning performance. The ability to point the aircraft's nose at an opponent and quickly fire a missile became far more important than the ability to follow through multiple turning maneuvers to acquire a tail aspect gun/heatseeker firing position. While a tail aspect position did improve the AIM-9L kill probability by reducing the target's evasive maneuver options, the AIM-9L's all aspect performance was still superb, as learned the hard way by the Argentine and Syrian air forces in 1982.
The AIM-9M missile utilizes a guidance control section with counter-countermeasures and improved maintainability and producibility. The AIM-9M is configured with an annular blast fragmentation warhead.
The AIM-9P, an improved version of the J model, has greater engagement boundaries, enabling it to be launched farther from the target. The more maneuverable P model also incorporated improved solid-state electronics that increased reliability and maintainability. Deliveries began in 1978.
The AIM-9P-1 has an active optical target detector instead of the infrared influence fuze; the AIM-9P-2 added a reduced-smoke motor. The most recently developed version, the AIM-9P-3, combined both the active optical target detector and the reduced-smoke motor. It also has added mechanical strengthening to the warhead as well as the guidance and control section. The improved warhead uses new explosive material that is less sensitive to high temperature and has a longer shelf life.
The AIM-9M, currently the only operational variant, has the all-aspect capability of the L model, but provides all-around higher performance. The M model has improved defense against infrared countermeasures, enhanced background discrimination capability, and a reduced-smoke rocket motor. These modifications increase ability to locate and lock-on a target and decrease the missile's chances for detection. Deliveries of the M model began in 1983.
The AIM-9M-9 has expanded infrared counter measures detection circuitry.
The AIM-9X Sidewinder Air-to-Air missile program will develop a short range heat seeking weapon to be employed in both offensive and defensive counter-air operations. Offensively, the weapon will assure that US and combined air forces have the ability project the necessary power to insure dominant maneuver. In the defensive counter-air role, the missile system will provide a key capability for force protection. The multi-service Air Intercept Missile (AIM-9X Sidewinder) development will field a high off-boresight capable short range heat seeking missile to be employed on US Air Force and Navy/Marine Corps fighters. The missile will be used both for offensive and defensive counter-air operations as a short range, launch and leave air combat missile that uses infra red guidance. The AIM-9X will complement longer range radar guided missiles such as the Advanced Medium Range Air-to-Air Missile (AMRAAM). The AIM-9X system design approach incorporates a fifth-generation staring Focal Plane Array seeker for robust guidance performance, and Infrared Countermeasure resistance and jet vane control for extremely agile turning performance.
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