RK-55

The Grusha-class submarine carried up to forty S-10's in tubes behind the sail

The Novator RK-55 Relief (Russian: РК-55 Рельеф 'Relief'; NATO: SSC-X-4 'Slingshot'; GRAU: 3K12) is a Soviet land-based/submarine-launched cruise missile with a nuclear warhead. It was about to enter service in 1987, when such weapons were banned under the Intermediate-Range Nuclear Forces Treaty. A version launched from submarine torpedo tubes, the S-10 Granat (SS-N-21 'Sampson'; GRAU: 3K10), has apparently been converted to carry conventional warheads and continues in service to this day.^[3] The Russian Federation was reported to have deployed the derivative SS-CX-7/SS-CX-8 systems on February 14, 2017.

The RK-55 is very similar to the air-launched Kh-55 (AS-15 'Kent') but the Kh-55 has a drop-down turbofan engine^[4] and was designed by MKB Raduga. Both have formed the basis of post-Cold-War missiles, in particular the Sizzler which has a supersonic approach phase.^[5]

Development

In the late 1960s, the "Ekho" study conducted by the GosNIIAS institute concluded that it would be more effective to deploy lots of small, subsonic cruise missiles than the much more expensive supersonic missiles then in favour.^[6] In 1971 Raduga began working on the air-launched Kh-55, which first flew in 1976.^[4] That same year, RK-55 first flew.^[5] NPO Novator would work on the submarine- and ground-launched versions. In 1993 Novator exhibited the Sizzler series weapons, which appears to be based on the RK-55.^[5] It is a two-stage design, which goes supersonic during its final approach to the target.

Design

Six RK-55 missiles are carried on an eight-wheeled transporter-erector-launcher (TEL) based on the MAZ 543 launcher of the R-17 (SS-1 'Scud B').^[7]

The S-10 is launched through 533 mm torpedo tubes.

Operational history

Fewer than 100 SS-N-21s had been deployed by the end of 1988.^[2] The new Akula-class submarine, launched in September 1986, was the first class to receive the new missile.^[8] It was later fitted to the Sierra I/II class and eight Victor III's and the new Yasen-class submarines.^[8]

The four Grusha-class (Yankee Notch) submarines deployed in 1988^[2] is a design of particular note, replacing the missile compartment of a Yankee class SSBN with additional torpedo tubes for 35-40 land attack cruise missiles. They were probably nuclear-tipped S-10s during the Cold War, and then converted to use conventional warheads ^[8] after the START I treaty restricted sub-launched nuclear cruise missiles. The US Navy has done the same on a grander scale with the SSGN conversions of four Ohio-class submarines. It has been suggested that S-10's could in future be fitted to converted Delta class submarines, or to surface ships, but these have not been confirmed.^[5]

The ground-launched variant was subject to the Intermediate-Range Nuclear Forces Treaty signed in December 1987 and had been tested but not deployed by that time.^[9] 80 missiles had been destroyed by November 1990.^[10]

In early 2017, reports emerged that Russia was violating the INF through the deployment of the 9M728 (SS-CX-7) and 9M729^[11] (SS-CX-8) missiles as part of the Iskander missile system. These are widely reported as variants of the earlier SS-C-4. According to U.S officials, two missile battalions equipped in SSC-8 are deployed as of 14 Feb. 2017 in violation of the treaty.^[12][13][14] Each battalion consists of 4 launchers, each launcher supplied with six nuclear-tipped cruise missile. One battalion is located at Kapustin Yar near Volgograd, the others location is unknown at this time.^[12]

Variants

• RK-55 (GRAU-index 3K12)(SSC-X-4 'Slingshot') - ground-based version
• S-10 (GRAU-index 3K10)(SS-N-21 'Sampson') - submarine-launched version
• SSC-8, SSC-X-8 ground launched, assessed range 300–3400 miles, nuclear capable^[15][16] (maybe 9M728, 9M729, Kh-55 / Kh-555, Kh-101 / Kh-102 missiles)

Conventional unitary High Explosive (HE) warhead and submunition warhead versions of the RK-55 have probably been developed, to justify the continuing service of the submarines that carry them.^[5]

Operators

•  Russia

Former

•  Soviet Union
•  Belarus
•  Ukraine

Derivatives

•  India
•  Iran
•  North Korea
•  People's Republic of China
•  Pakistan
•  Republic of Korea Hyunmoo cruise missile .

Similar weapons

• Raduga Kh-55 - originally thought in the West to be an air-launched version of the RK-55, now has tactical versions such as the Kh-555 and the stealthy Kh-101.
• UGM-109 Tomahawk - the Capsule Launch System allows Tomahawks to be fired from torpedo tubes or dedicated submarine launch tubes
• Ground Launched Cruise Missile (BGM-109G Gryphon) - land-based Tomahawk with tactical nuclear warhead of 10-50 kt and 2000–2500 km range
• Pershing 1b and Pershing II RR - 740 km range ballistic missile also in testing at the time of the INF Treaty.

See also

Intermediate-range ballistic missile

Notes and references

External links

• CSIS Missile Threat - SS-N-21 (RK-55)
• Explosions calculator (use .2 megaton)