K-13 (AA-2 Atoll) Russian Short-Range Infrared Homing Air-to-Air Missile

The Vympel K-13 (NATO reporting name: AA-2 "Atoll") is a short-range, infrared homing air-to-air missile developed by the Soviet Union. It is similar in appearance and function to the American AIM-9 Sidewinder from which it was reverse-engineered. Although it since has been replaced by more modern missiles in frontline service, it saw widespread service in many nations. The Sidewinder was quickly reverse engineered as the K-13 (also called R-3 or Object 300) and entered limited service only two years later in 1960. This was followed by the improved K-13A (R-3S, Object 310), which entered service in 1962. The R-3S was the first version to enter widespread production, in spite of a very long seeker settling time on the order of 22 seconds, as opposed to 11 seconds for the original version. The R-3S was seen by the West in 1961 and given the NATO reporting name AA-2A 'Atoll'. Minimum engagement range for the R-3S is about one kilometre. All K-13 variants are physically similar to Sidewinder, sharing the 5 inch (127 mm) diameter. Subsequent examination of AA-2 missiles captured by NATO forces showed that parts from an AIM-9 could be interfaced with parts from an AA-2 and either combination would still work.