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Kh-66/Kh-23 *Grom*
(NATO reporting name: AS-7 'Kerry')
Kh-66/Kh-23 Grom; (NATO reporting name: AS-7 'Kerry')
	; AS-7 'Kerry'
Type	Tactical air-to-surface missile
Place of origin	Soviet Union
Service history
In service	Kh-66 :20 June 1968; Kh-23 :1973; Kh-23M :1974
Used by	FSU, Warsaw Pact, Iraq, India
Production history
Designer	Yurii N. Korolyov
Manufacturer	Zvezda-Strela
Specifications
Weight	A921 :287 kg (633 lb)
Length	A921 :3.525 m (11 ft 7 in)
Diameter	27.5 cm (10.8 in)
Warhead weight	111 kg (245 lb)
Engine	Solid fuel rocket;
Wingspan	78.5 cm (2 ft 6.9 in)
Operational; range	2–10 km (1.1–5.4 nmi)
Speed	2,160–2,700 km/h (1,340–1,680 mph)
Guidance; system	Kh-66 :Beam-riding; Kh-23 :Radio command-guidance; Grom-B :TV guidance
Launch; platform	Mig-21PFM, MiG-23, MiG-27,; Su-17M3/20/22/22M3/M4,

K-5M (AA-1 'Alkali') air-to-air missile, ancestor of the Kh-66

The Zvezda Kh-66 and Kh-23 Grom (Russian: Х-23 Гром 'Thunder'; NATO:AS-7 'Kerry') are a family of early Soviet tactical air-to-surface missiles with a range of 10 km. They were intended for use against small ground or naval targets. The Kh-66 was effectively a heavy-warhead, beam-riding version of the K-8 (AA-3 'Anab') air-to-air missile rushed into service in Vietnam in 1968. The Kh-23 was an improved Kh-66 with command-guidance, similar to the AGM-12 Bullpup.

[edit] Development

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 Bisnovat R-40 (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 licenced 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.

[edit] Design

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.

[edit] Operational history

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

[edit] Variants

Serbian GROM-B missile, based on Kh-23

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 under licence^[3]
Grom (Grom 02) - Serbian 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-Tehnicki Institut in the mid-late 1990s; uses seeker based on that of AGM-65B Maverick^[6]