| RK-55 Relief|
(NATO reporting name: SSC-X-4 'Slingshot')
S-10 Granat (SS-N-21 'Sampson')
|Type||surface/sub-launched nuclear cruise missile|
|Place of origin||Soviet Union|
|In service||since 1984|
|Used by||Soviet Union / Russia|
|Designer||L. V. Lyulev, Novator NPP Temp, Raduga|
|Manufacturer||Novator, NPP Temp, Raduga MKB, KhAZ (Kharkiv), others?|
|Mass||1,700 kg (3,750 lb)|
|Length||809 cm (26 ft 7 in)|
|Diameter||51 cm (20.1 in)|
|Blast yield||Nuclear 200kt |
|Engine||Solid-propellant rocket booster + R-95-300 or 36MT-37 turbofan|
|Wingspan||310 cm (122.0 in)|
|3,000 km (1,600 nmi)|
|Speed||720 km/h (447.4 mph)|
|Sprut inertial guidance plus TERCOM|
|Akula-class submarine, Sierra II, Victor III, Yankee Notch, Yasen-class submarine, TEL|
The Novator RK-55 Relief (Russian: РК-55 Рельеф 'Relief'; NATO: SSC-X-4 'Slingshot'; GRAU: 3K12) is a Russian land-based and the submarine-launched cruise missile with a nuclear warhead developed in the Soviet Union. 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. 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 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.
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. In 1971 Raduga began working on the air-launched Kh-55, which first flew in 1976. That same year, RK-55 first flew. 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. It is a two-stage design, which goes supersonic during its final approach to the target.
The S-10 is launched through 533 mm torpedo tubes.
Fewer than 100 SS-N-21s had been deployed by the end of 1988. The new Akula-class submarine, launched in September 1986, was the first class to receive the new missile. It was later fitted to the Sierra I/II class and eight Victor III's and the new Yasen-class submarines.
The four Grusha-class (Yankee Notch) submarines deployed in 1988 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  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.
The ground-launched variant was subject to the Intermediate-Range Nuclear Forces Treaty signed in December 1987 and had been tested. Six launchers with 84 missiles was deployed at the Missile/Launcher Storage in Jelgava (Latvian Soviet Socialist Republic) and had been destroyed by November 1990.
In early 2017, US officials and analyst Jeffrey Lewis asserted that Russia was violating the INF through the deployment of the 9M728 (SS-CX-7) and 9M729 (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 were deployed as of 14 February 2017 in violation of the treaty. Each battalion consists of 4 launchers, each launcher supplied with six nuclear-tipped cruise missiles. One battalion is allegedly located at Kapustin Yar near Volgograd; the other's location is unknown at this time. The German newspaper FAZ argued in February 2019 that in addition to two known locations where missiles and battalions are stationed – at a launch pad at Kapoustin Iar, in southern Russia, and Yekaterinburg – there would be two other places equipped with these missiles: Mozdok in North Ossetia and Shuya near Moscow. Each of the four battalions would have four-wheeled launchers, each carrying four missiles, adds the German media. This adds to 64 SSC-8 missiles in Russia's possession, which can be armed with conventional or nuclear warheads. This type of missile has a range of 2,350 kilometers. With a conventional warhead of 500 kilograms, the range is 2,000 kilometers.
- 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 and SSC-7 'Screwdriver' ground launched, assessed range 480–5,500 km (300–3,420 mi), nuclear capable (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.
- North Korea
- People's Republic of China
- South Korea Hyunmoo-3 cruise missile
- Ukraine Korshun (Luch Artem - KhAZ - Vizar ZhMZ - Yuzhnoe Pivdenmash) with MS400 (Ivchenko Progres Motor Sich) engine.
- 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.
Notes and references
- SIPRI (1989) p16
- Norris, Cochran; et al. (1989), SIPRI Yearbook 1989: World Armaments and Disarmament (PDF), p. 21, archived from the original (PDF) on 2008-12-09, retrieved 2009-02-04
- "SS-N-21 "Sampson" (RK-55)". Missile Threat. Retrieved 9 April 2019.
- "Kh-55 (AS-15 'Kent'/Kh-555/RKV-500/Kh-65)", Jane's Strategic Weapon Systems, 2009-09-09, archived from the original on February 4, 2009, retrieved 2009-02-04
- "RK-55 Granat (SS-N-21 'Sampson'/3M10)", Jane's Strategic Weapon Systems, 2008-09-10, retrieved 2009-02-04[dead link]
- "Kh-55/RKV-500A, Kh-55SM/RKV-500B, Kh-555 and Kh-65SE (AS-15 'Kent')", Jane's Air-Launched Weapons, 2008-08-01, archived from the original on June 4, 2009, retrieved 2009-02-06
- "RK-55 (SSC-X-4 'Slingshot' and 3K10 Granat)", Jane's Strategic Weapon Systems, 2008-09-12, archived from the original on 2012-09-03, retrieved 2009-02-04
- "SS-N-21 'Sampson' (P-1000 3M70 Vulkan/3K10 Granat)", Jane's Naval Weapon Systems, 2009-01-08, archived from the original on September 15, 2008, retrieved 2009-02-04
- Thomson, David B. (July 1999), A Guide to the Nuclear Arms Control Treaties LA-UR-99-3173 (PDF), Los Alamos National Laboratory, p. 131
- Thomson (1999) p 127
- Gordon, Michael R. (February 14, 2017). "Russia Deploys Missile, Violating Treaty and Challenging Trump". The New York Times. Retrieved 2018-10-22.
- "INF TREATY". www.bits.de. December 8, 1987. Retrieved 2018-10-22.
- Majumdar, Dave (2017-02-14). "Russia's Dangerous Nuclear Forces are Back". The National Interest. Retrieved 2018-10-22.
- Pike, John. "9M729 - SSC-X-8". www.globalsecurity.org. Retrieved 2018-10-22.
- Burns, Robert. "Official: Russia Has Deployed Missile in Violation of Treaty". Military.com. Retrieved 2018-10-22.
- "U.S. Accuses Russia of Deploying Cruise Missile in Threat to NATO". Newsweek. March 8, 2017. Retrieved 10 March 2017.
- "Russia Test Fires SSC X-8 Cruise Missile". defenseworld.net. September 28, 2015. Retrieved 10 March 2017.
- Pike, John. "9M729 - SSC-X-8". www.globalsecurity.org. Retrieved 2018-10-22.
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