Kh-23 Grom

Work on air-to-air missiles had started at the Kaliningrad Engineering Plant (then known as Plant #455, and later merged into Zvezda-Strela) in 1955.[1] This had resulted in the Kaliningrad K-5 (AA-1 'Alkali') family of beam-guided missiles, including the K-51 (RS-2-US) carried by the Su-9 'Fishpot'. OKB-4 Molniya (later Vympel NPO) under Matus Bisnovat would go on to produce missiles such as the AA-6 Acrid.[1] Meanwhile, in 1963 the RS-2-US was tested as an air-to-surface missile.[1] It was concluded that the small warhead and inaccurate guidance made such an application "pointless".[1]

However, in 1965 North Vietnam requested an air-to-surface missile from the Soviet government;[1] the AGM-12 Bullpup had entered service with the US Air Force before the start of the Vietnam War. In April 1965 OKB-134 (later NPO Vympel) started work on this missile under the project name Kh-23, but they had problems developing a guidance system that would work with existing aircraft.[3] As a result, Yurii N. Korolyov came up with his own proposals based on the earlier experiments with the RS-2-US. A design bureau to develop the RS-2-US for surface targets was set up under Korolyov by decree #100 of 12 March 1966 of the Ministry of the Aircraft Industry;[1] this bureau would become the Zvezda OKB in 1976.[4]

The resulting weapon used the body of a K-8 (AA-3 'Anab') K-5 guidance and propulsion systems but increased the warhead from 13 kg (29 lb) to 100 kg (220 lb).[5] This had the big advantage of allowing the new weapon to be fitted to any aircraft capable of firing the K-5.[3] Design began in 1966,[4] so the project was known as Kh-66 or Izdeliye 66 ('Article 66'). The Kh-66 was a beam-riding weapon that was tested on a MiG-21PFM[4] and entered production in 1968 for that aircraft. The Kh-66 was only an interim solution as it required the launch aircraft to dive towards the target to maintain lock on the target. Flight testing of the Kh-66 began in 1967[1] and it entered service on 20 June 1968.[1]

Meanwhile, Korolyov took over work on the Kh-23 project intended for carriage on the Soviet Union's new MiG-23.[3] The Kh-23 became a development of the Kh-66 design with an improved propellant and new Delta-R1M guidance system.[3] The main practical difference was that it was a line-of-sight radio-command weapon similar to the Bullpup, allowing it to be fired in level flight (unlike the Kh-66). The first ten were tested in early 1968,[3] but significant delays were caused by problems with unreliable guidance which was eventually traced to the smoke generator which interfered with the antenna.[3] Once the receiver had been moved to a tail extension,[3] the government tested the missile on the MiG-23 and MiG-23B between 20 March 1970 and 3 October 1973.[1] and it entered service in 1973.[2] A laser-guided version of the Kh-23, the Kh-25, became the basis for the AS-10 'Karen' family of missiles.[1] Technology from these was 'backported' to the Kh-23 to create the Kh-23M in 1974.[2]

The Kh-23 was later licensed for local production in both Romania and Yugoslavia.[3] In 1977 a dummy Kh-23 was fired from a Ka-252TB helicopter,[1] the prototype of the Kamov Ka-29TB 'Helix-B' assault transport.

The Kh-66 used the airframe of the Kaliningrad K-8 (AA-3 'Anab') air-to-air missile, with the nozzle split to make room for the antenna of the beam-riding guidance system of the Kaliningrad K-5 (AA-1 'Alkali').[3] It has cruciform control fins on the nose, and four clipped-tip delta-wings at the rear with elevators for control.

The Kh-66 entered production for the MiG-21 in 1968, and the Kh-23 was certified for the MiG-23 'Flogger' in 1973.

Sukhoi Su-17M3 with a Kh-23 missile

• Kh-66 - the original beam-riding missile based on the K-8
• Kh-23 (Izdeliye 68)[4] - First command-guidance version with improved propellant
• Kh-23M - improved Kh-23 with technology from the Kh-25 family[2]
• Kh-23L - Western name for a laser-guided version that in fact was the baseline Kh-25 (AS-10 'Karen')[4]
• A921 - Version made in Romania[3]
• Grom (Grom 02) - Yugoslav version that appeared in the 1980s.[6] This should not be confused with the Polish SAM
• Grom-B (Grom 2) - TV-guided version from Serbia's Vojno-Tehnički Institut in the mid-late 1990s; uses seeker based on that of the AGM-65B Maverick[6]

Map with former Kh-23 operators in red

•  North Korea
•  Syria[7]

• AGM-12 Bullpup
• AS-20 - French air-to-ground missile based on an early air-to-air missile

• Cooper, Tom (2018). MiG-23 Flogger in the Middle East, Mikoyan i Gurevich MiG-23 in Service in Algeria, Egypt, Iraq, Libya and Syria, 1973-2018. Warwick: Helion & Company Publishing. ISBN 978-1-912-390328.
• Gordon, Yefim (2004), Soviet/Russian Aircraft Weapons Since World War Two, Hinckley, England: Midland Publishing, ISBN 1-85780-188-1