AIM-9 Sidewinder

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.