air to air | Plane-Encyclopedia

United States (1956)
Air to Air Missile – Over 200,000 Built

The Sidewinder is a supersonic, heat seeking, air to air missile for use by fighter aircraft. The missile was originally developed for the U.S. Navy for fleet defense, but was subsequently adapted for wider usage by the U.S. Air Force. The AIM-9 achieved the first successful combat use of a guided air to air missile. It has become the most used missile by Western air forces, with it’s low cost and reliable track record. Its code word is “FOX-2,” which refers to the launch of an infrared guided missile. The Sidewinder is estimated to have 270 aircraft kills. An example of the current unit cost of one Sidewinder is $603,817 for one AIM-9X Block II (2015).

The AIM-9 Sidewinder is the world’s most successful short-range air-to-air missile, and will remain the U.S. military’s main “dogfight” AAM until at least 2055.

History

In the 1950s the United States Navy went about developing a short range air to air missile that could be used during combat. The missile was originally developed by the United States Navy at Naval Air Weapons Station China Lake, California. William B. McLean were experimenting with proximity fuzes sensitive to infrared heat. Being involved in R&D, it was not officially sanctioned for their office to develop weapons. As such their ‘intelligent’ fuze was kept under wraps and developed by volunteers using spare parts for several years, with the ultimate goal of building a heat seeking air to air missile. The final design featured a gyroscopic mirror spinning at around 4,000 RPMs behind a glass cover on the front of the missile. It utilized a lead-sulfide detector as it’s ‘eye’ which kept the assembly focused on the infrared source of the target. Issues with roll and target tracking were overcome with the invention of ‘rollerons’ which were wheels mounted to the tail fins of the missile to stabilize it in flight. The guidance section utilized circuits comprised of 14 tubes and 24 moving parts, a remarkable achievement in the 1950s.

After it became clear that its new technologies offered superior performance over the USAF’s own AIM-4 Falcon, the Air Force began using the Sidewinder on most of its combat aircraft.

The first kill from a Sidewinder missile was on September 24^th 1958, when F86 Sabers belonging to The Republic of China Air Force (ROCAF) ambushed a flight of MiGs belonging to the People’s Republic of China (PLAAF) during the Second Taiwan Strait Crisis .

During this conflict, one AIM-9B struck one of the PLAAFs MiG-17s without detonating, enabling the pilot to safely bring the aircraft back to base. The Soviets used this to reverse engineer their own copy of the Sidewinder, dubbed the Vympel K-13 or AA-2 Atoll (NATO).

AIM-9s were used extensively in Vietnam by the USAF and the US Navy. The two services combined scored 82 air to air victories out of 452 Sidewinders fired, resulting in a kill probability of 18%. Sidewinders of this period often flew up into the exhaust of their targets before detonating just aft of the wing.

Today though various upgrades and variants the AIM-9 is being used by most Western countries, with many more equipped with the Soviet copied K-13.

Sidewinder Operation

The missile’s primary components consist of an infrared guidance section with active optical target detection, a high explosive warhead, and rocket motor. The principles of the infrared guidance allow it to ‘home in’ on a target aircraft’s exhaust heat signature. The missile’s seeker must be cooled to extremely low temperatures to achieve effective operation. This operation makes the missile a ‘fire and forget,’ and relatively immune to electronic countermeasures.

Early versions of the missile had to be fired at the rear of the target to maintain an effective lock. The seventies saw the introduction of the AIM-9L which was capable of “all aspect” usage, meaning it could be fired at a target from all directions. This even meant that a target could be engaged head-on, a factor that has since significantly impacted aerial combat doctrines.

The Sidewinder is also capable of being equipped to rotary wing aircraft, such as the AH-1 SuperCobra. AIM-9Xs have also been successfully tested against ground targets and have proven useful against light ground targets.

Variants

AIM-9B – The first joint service production version of the Sidewinder, utilizing an uncooled detector with thermionic (i.e. vacuum tube circuits) and possessing a top speed of around 1.7 mach, making its combat debut in 1958.
AIM-9D – The first Navy version implemented numerous changes and upgrades. The seeker head was now cooled and the warhead size was more than doubled to 25 lbs. The 9D and all other subsequent models could achieve speeds of 2.5 mach or above. The 9D also achieved dozens of kills during Vietnam.
AIM-9E The first USAF version, utilizing a peltier electronic cooling device for its seeker head, meaning that the seeker could remain in continuous operation during flight. It also integrated a few solid state components into the guidance section. The canards were changed to a square tip double delta arrangement to improve angle of attack performance. Around 5,000 9Bs were rebuilt as 9Es. The 9E achieved six kills during the Vietnam period.
AIM-9G – The 9G was an upgrade of the 9D for the Navy, utilizing a Sidewinder Extended Acquisition Mode (SEAM) allowing the missile to be slaved to the onboard radar or helmet sight.
AIM-9H – This version was a further evolution of the 9G produced in the early 70s and seeing limited use during Vietnam. It retained the G’s optical system, but the electronics were upgraded to solid state. A thermal battery replaced the previous turbo alternator. It also had an increased tracking rate and stronger actuators. The 9Hs fired in Vietnam reportedly had the best kill rate of any missile of the period.
AIM-9J – The Juliet was developed from the 9E for use by the USAF in the early 70s, and saw changes to the forward canards, offering incremental improvements in maneuverability, speed, and range. 6,700 built and widely exported.
AIM-9L – The first ‘all-aspect’ Sidewinder. With the introduction of the Lima in 1976, the missile was once again a joint-service model, developed from the 9H and capable of hitting a target from any direction, including head on. Characterized by a now standard natural metal finish on the guidance control section, it first saw combat with 2 US Navy F-14 Tomcats shot down 2 Libyan Su-22 Fitters in the Gulf of Sidra in 1981. In the Falklands conflict it saw large scale use by the United Kingdom, achieving an 80% kill ratio as compared to the Vietnam era versions with around a 15% kill ratio.
AIM-9M – An evolution of the Lima with upgrades only to the guidance section, improving capabilities against infrared countermeasures and ‘background rejection.’ The Mike was first deployed in 1982. Subvariants of the Mike include versions for the Navy and Air Force and were the mainstay of the USAF and USN short range AA capability from the 80s to the introduction of the 9X.
AIM-9R – The 9R was a prototype project that began in the late 80s that aimed to introduce digital imaging and programmable software into the guidance section allowing for aiming of the vulnerable area of a target. The R was being developed by the Naval Weapons Center and had flown live fire trials until the early 90s when its funding was cut in the wake of the collapse of the Soviet Union.
AIM-9X – In the mid eighties the Soviet Union developed and deployed successful infrared countermeasures (IRCM) that reduced the effectiveness of existing Sidewinders. After various stalled efforts in the late 80s, the U.S. began working with Raytheon and Hughes on the 9X during the 90s. Upon introduction in 2003 the 9X ushered in Joint Helmet Mounted Cueing System (JHMCS) compatibility, allowing a pilot to lock on to a target simply by looking at it. This capability drastically increases combat effectiveness, along with “Lock-on After Launch” capability which allows for use in internal launch bays such as the F-35 and F-22.