By Rob Russell
We have all seen them – mostly in the movies and fired from a wingtip in some war scene, but what is that thing that smokes and heads off into the yonder?
The RTX AIM-9 Sidewinder (Air Interception Missile No9) is a short-range air-to-air missile manufactured by Raytheon RTX. Entering service with the United States Navy in 1956 and the Air Force in 1964, the AIM-9 is one of the oldest, cheapest, and most successful air-to-air missiles The Sidewinder is the most widely used air-to-air missile in the West, with more than 110,000 missiles produced for the U.S. and 27 other nations, of which perhaps one per cent have been used in combat. It has been built under license by many European nations and other nations. The AIM-9 has an estimated 270 aircraft kills.
The AIM-9 was a product of the US Naval Weapons Centre at China Lake in the Mojave Desert. It features a lightweight, compact design with cruciform canards and tail fins. It uses a solid rocket motor for propulsion, similar to most conventional missiles, a continuous-rod fragmentation warhead, and an infrared seeker.
The seeker tracks a difference in temperatures detected and uses proportional guidance to achieve success. Older variants such as the AIM-9B, with uncooled seeker heads, could only track the high temperatures of engine exhaust, making them strictly rear aspect. Later variants, however, featured liquid nitrogen coolant bottles in the launchers, allowing the missile to track any part of the aircraft heated by air resistance due to high-speed flight, giving modern Sidewinders all-aspect capabilities.
The nose canards provide manoeuvrability for the AIM-9, with the latest version, the AIM 9X, using thrust vectoring to augment this. The hot gases generated were used to actuate the nose canards in older models, while newer variants use thermal batteries.
To minimize the amount of energy devoted to actuating control surfaces, the AIM-9 does not use active roll stabilization. Instead, it uses rollerons, small metal discs protruding out of the aft end of the tips of the tail fins which spin as the missile flies through the air, which help; and provide gyroscopic stabilization.
The AIM-9 uses a passive infrared proximity fuse to detonate its warhead near an enemy aircraft, scattering shrapnel that aims to damage the aircraft or nowadays drones or other unmanned aircraft, rendering it inoperable. The continuous rod warhead features rods welded together to form a cylindrical outer shell, with explosive filler inside. Upon detonation, the rods are scattered, ensuring that at least some portion of the shrapnel hits enemy aircraft.
Newer models of the AIM-9 sought to increase the range that the seeker head's gimbal can turn, allowing the missile to track aircraft at greater angles from its direct line of sight, or boresight. Models such as the AIM-9L, AIM-9M, and AIM-9X feature high off-boresight capabilities, meaning they are able to track targets at high seeker gimbal angles, or greater range from the missile head
The development of the Sidewinder missile began in 1946 at the Naval Ordnance Test Station (NOTS), Inyokern, California, now the Naval Air Weapons Station China Lake, as an in-house research project conceived by William B. McLean. McLean initially called his effort "Local Fuze Project 602" using laboratory funding, volunteer help and fuze funding to develop what they called a heat-homing rocket. The name Sidewinder was selected in 1950 and is derived from the common name of Crotalus cerastes, a rattlesnake, which uses infrared sensory organs to hunt warm-blooded prey.
It did not receive official funding until 1951 when the effort was mature enough to show to Admiral William "Deak" Parsons, the then Deputy Chief of the Bureau of Ordnance (BuOrd). It subsequently received designation as a program in 1952. Originally called the Sidewinder 1, the first live firing was on 3 September 1952. The missile intercepted a drone for the first time on 11 September 1953. The missile carried out 51 guided flights in 1954, and in 1955 production was authorized.
In 1954, the US Air Force carried out trials with the original AIM-9A and the improved AIM-9B at the Holloman Air Development Centre. The first operational use of the missile was by Grumman F9F-8 Cougars and FJ-3 Furies of the United States Navy in the middle of 1956
Nearly 100,000 of the first generation (AIM-9B/C/D/E) of the Sidewinder were produced with Raytheon and General Electric as major subcontractors
Continuous improvement and developments have seen the Sidewinder missile improve with age. The Air Intercept Missile (AIM)-9X Sidewinder is the latest of the Sidewinder family of short-range air-to-air missiles. It features a high off-bore sight focal-plane array seeker mounted on a highly manoeuvrable airframe with a greatly improved infrared counter-countermeasures feature.
The AIM-9X incorporates many AIM-9M legacy components (rocket motor, warhead and active optical target detector), but its performance far exceeds the legacy Sidewinder. Unlike previous AIM-9 models, the AIM-9X can even be used against targets on the ground, making it a true multi-role missile. The AIM-9X Block II is the most advanced short-range air-air missile in the U.S. inventory, capable of using its datalink, thrust vectoring manoeuvrability, and advanced imaging infrared seeker to hit targets behind the launching fighter. The missile provides fighter aircrew with the first shot, first kill opportunities that are essential for survival during air combat manoeuvring in the visual arena.
The AIM-9X delivers these opportunities, with unmatched offensive and defensive capabilities against threats, as well as supports air superiority in the Beyond Visual Range air-to-air battle. (the original AIM 9 missile, being a heat seaker essentially required the aircraft shooting it, to be able to see the target and position itself, so that the missile would lock on to the target). The AIM-9X Block II missile provides the Joint Force with fighter aircraft lethality and survivability necessary to counter threats identified in the Chief of Naval Operations Guidance and the National Defense Strategy.
The first combat use of the Sidewinder came on 24 September 1958 by the Republic of China (Taiwan) Air Force during the Second Taiwan Strait Crisis. At the time, ROCAF North American F-86 Sabres were routinely engaged in air battles with the People's Republic of China over the Taiwan Strait.
Other examples of where the missile was fired in anger include:
Vietnam War 1965–1973. The performance of the 454 Sidewinders launched during the war was not as satisfactory as hoped. Both the USN and USAF studied the performance of their aircrews, aircraft, weapons, training, and supporting infrastructure. A lack of understanding of the missile, lack of sufficient training amongst other factors, were the main reasons for the missile’s poor performance.
It has been reported that the 9B version, was used by the SAAF, to equip the Sabre and Mirage IIIs. It was known locally, as the V1.
1982 Falklands War. During the Falklands War, the United States Air Force provided the Royal Air Force with 200 units of the AIM-9L Sidewinder air-to-air missile for use on their Harrier jump jets. The first combat use of the AIM-9L Sidewinder by British forces occurred on 01 May 1982, when Sea Harriers of the 801 Naval Air Squadron shot down a Mirage III fighter jet of the Argentine Air Force. It is believed that the Argentinian pilots feared to missiles and the potential to destroy their aircraft, contributing to their downfall and eventual defeat.
2023 Israel–Hamas war. On 2 November 2023, Israeli Air Force claimed one of its F-35I had shot down an unidentified cruise missile, using an AIM-9X Sidewinder.
Despite many new missiles being developed and tested, the Sidewinder missile, and its modern derivatives remain the most successful air-launched missile, in service with over 45 Air Forces.
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