RK-55

In the late 1960s, the "Ekho" study conducted by the GosNIIAS institute concluded that it would be more effective to deploy many 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. ==Design==

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

Fewer than 100 RK-55s had been deployed by the end of 1988. The new was the first class to receive the new missile. It was later fitted on the Sierra I/II and Victor III classes and the new s. Four s deployed in 1988 are of a design of particular note, replacing the missile compartment 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 s. It has been suggested that S-10's could in future be fitted to converted s, or to surface ships, but these have not been confirmed. ==Variants==

• RK-55 (SSC-X-4 'Slingshot') – ground-based version • S-10 (SS-N-21 'Sampson') – submarine-launched version • 9M728 and 9M729 (SSC-7 and SSC-8 'Screwdriver') – ground-based version, assessed range , nuclear capable 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. ==Operators==

• Former • • • Derivatives • • • • • • Korshun (Luch Artem - KhAZ - Vizar ZhMZ - Yuzhnoe Pivdenmash) with MS400 (Ivchenko Progres Motor Sich) engine. ==Similar weapons==

• 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. • 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 ==See also==