K-5 (AA-1 Alkali) Russian Short-Range Air-to-Air Missile

The Kaliningrad K-5 (NATO reporting name AA-1 Alkali), also known as RS-1U or product ShM, was an early Soviet air-to-air missile. The development of the K-5 began in 1951. The first test firings were in 1953. It was tested (but not operationally carried) by the Yakovlev Yak-25. The weapon entered service as the Grushin/Tomashevich (Russian: Грушин/Томашевич) RS-2U (also known as the R-5MS or K-5MS) in 1957. The initial version was matched to the RP-2U (Izumrud-2) radar used on the MiG-17PFU, MiG-19PM. An improved variant, K-5M or RS-2US in PVO service, entered production in 1959, matched to the RP-9/RP-9U (Sapfir) radar of the Sukhoi Su-9. The People's Republic of China developed a copy under the designation PL-1, for use by their J-6B fighters. The difficulties associated with beam-riding guidance, particularly in a single-seat fighter aircraft, were substantial, making the 'Alkali' primarily a short-range anti-bomber missile. Around 1967 the K-5 was replaced by the K-55 (R-55 in service), which replaced the beam-riding seeker with the semi-active radar homing or infrared seekers of the K-13 (AA-2 'Atoll'). The weapon was 7.8 kg (17 lb) heavier than the K-5, but had a smaller 9.1 kg (20 lb) warhead. The K-55 remained in service through about 1977, probably being retired with the last of the Sukhoi Su-9 interceptors.