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Air-to-Air Missiles: AIM-9 SidewinderThe AIM-9 Sidewinder is a short-range, heat-seeking supersonic air-to-air missile used by the U.S. military on fighter aircraft and some helicopter gunships. Entering service with the U.S. Air Force in the 1950s, the Sidewinder operates over a range of 1 to 2 miles, typically during the day and in clear weather. Named for the tendency of the early version of the missile to zig and zag towards its target like the eponymous snake, the Sidewinder has been continuously improved and will likely remain in service well into the 21st century.
AIM-9 Sidewinder Air-to-Air Missile Development
Initial development of the Sidewinder started at the Naval Ordinance Test Station (NOTS) in Inyokern, CA, in 1946. William B. McLean undertook what he called the "Local Fuze Project 602" to develop a heat-homing rocket. In 1951 the project received official funding after review by Admiral William Parsons, Deputy Chief of the Bureau of Ordnance. The Sidewinder included new technological developments to make it simpler and more reliable than the Air Force AIM-4 Falcon. The Sidewinder used a forward-facing mirror that rotates around a shaft pointed out of the front of the missile, with a detector mounted in front of the mirror. This allowed the missile to efficiently track targets using infrared. A much better guidance algorithm was used in the Sidewinder. The algorithm relies on the change in position of a target since last sighting. This so-called "proportional pursuit" system is simple but effective, allowing the missile to lead rather than chase a target. The Sidewinder airframe includes control surfaces near its end. These surfaces have spinning disks on their outside called rollerons. Airflows over the disk during flight spins them to high speeds, providing the gyroscopic stabilization necessary for the forward-facing mirror and guidance algorithm to function effectively. The first prototype of the Sidewinder was tested successfully in September 1953 under the designation XAAM-N-7 (renamed AIM-9A). A production version started operational service with the U.S. Navy in 1956 under the designation AAM-N-7 (renamed AIM-9B). As a heat-seeking missile, the Sidewinder had to be fired from the rear aspect during combat. The U.S. Air Force adopted the Sidewinder for the F-4 Phantom per Department of Defense orders. The F-4D Phantom deployed in the Vietnam War performed poorly with the AIM-4 Falcon, and the Air Force decided to reconfigure the aircraft to carry the Sidewinder. The Sidewinder underwent upgrades and improvements throughout its service. Better seekers with various cooling systems and propulsion systems were used, and warheads were improved. The U.S. Navy AAM-N-7 Sidewinder 1B (renamed AIM-9C) used a semi-active radar homing seeker head created for the F-8 Crusader. Fewer than 1,000 of this variant were manufactured, and it is the only Sidewinder not to use infrared homing.
The Navy version of the Sidewinder evolved to include a forward canard design in the G and H variants for improved ACM performance. The H variant also was solid state, increasing reliability in an aircraft carrier environment. The Air Force developed the AIM-9E in 1967, with larger forward canards and a more aerodynamic infrared seeker with an improved motor. The Air Force brought out the AIM-9J in July 1972. This variant not only could handle launch at 7.5g, but also had solid-state components and better actuators to improve performance in a dogfight. During the 1960s, the Air Force and the Navy maintained separate versions of the Sidewinder. However, cost considerations led to the two services using the same variants starting with the AIM-9L. The AIM-9L represented the next major advance in the Sidewinder. Introduced in 1978, it was an all-aspect weapon, capable of being fired from any direction, including in head-on confrontations. This made the Sidewinder highly lethal, as most opposing air forces had yet to develop tactics to evade such an attack. The AIM-9M was an overall improved version of the Sidewinder, with better resilience against infrared countermeasures, a reduced-smoke rocket motor, and improved background discrimination capability. All these changes took place in the Guidance Control Section (GCS) of the missile. The AIM-9R is a Navy-developed variant of the Sidewinder, started in 1987. It used a Focal Plane Array (FPA) seeker with a charge-coupled device (CCD) detector and better off-boresight capability. Though effective, this technology was limited to daylight use. The Air Force did not like this limitation, and the AIM-9R was canceled when both services agreed to jointly develop the AIM-9X.
The AIM-9X was developed by Raytheon engineers and entered service in November 2003. The AIM-9X is a major step forward for the Sidewinder. It has an imaging infrared focal plane array (FPA) seeker with a reported 90° off-boresight capability. It works with helmet-mounted displays including the U.S. Joint Helmet Mounted Cueing System. This allows a pilot to target a Sidewinder by simply looking at a target. Reduced drag increases the AIM-9X speed and range. The missile also has an internal cooling system, eliminating the launch-rail cooling previously required. The Air Force deployed the AIM-9X on the F-15C, and the Navy on the F/A-18C. The Sidewinder has also been developed and used by other nations. Over 110,000 missiles have been produced. The AIM-9 has an estimated 270 kills to its credit. AIM-9 Sidewinder Operational History
The AIM-9 Sidewinder has been used on the vast majority of U.S. Navy and Air Force fighter aircraft since its introduction, as well as on the aircraft of dozens of other nations. The Sidewinder achieved its first successful air-to-air kill when a Taiwanese F-86F shot down Communist Chinese MiG-15s using AIM-9Bs provided by the U.S. Navy. Both the Navy and the Air Force used the Sidewinder extensively in Vietnam. The Air Force recorded 28 air-to-air kills using the AIM-9. The Navy also had success with the Sidewinder, in particular the AIM-9D and AIM-9G. A total of 82 kills are credited to the Sidewinder in Vietnam. In Operation Desert Storm in 1991, the AIM-9 Sidewinder was deployed on Navy and Air Force fighters. A total of 13 air-to-air kills achieved. The Sidewinder has also been used on UAVs, in particular the MQ-9 Reaper. In March 2010, Boeing won a contract to support the Sidewinder through 2055, suggesting that the Sidewinder will remain in service through the latter part of this century. Characteristics of the AIM-9 Sidewinder
Note: Characteristics change slightly depending on the AIM-9 variant. Recommended Books about Air-to-Air Weapons and the AIM-9 Sidewinder |
