The R-11 Zemlya (Russian: Р-11 Земля, lit.'Earth'), GRAU index8A61 was a Soviettactical ballistic missile. It is also known by its NATO reporting name SS-1b Scud-A. It was the first of several similar Soviet missiles to be given the reporting name Scud. Variant R-11M was accepted into service, with GRAU index 9K51 (9К51).
Origin
The R-11 originated from a 1951 requirement for a ballistic missile with similar performance to the German V-2 rocket, but half its size. With the Wasserfall, an anti-aircraft version of the V-2, as a model, the R-11 was developed by engineer Victor Makeev, who was then working in OKB-1, headed by Sergey Korolyov. The two men agreed on the use of RG-1 as the fuel, but disagreed over which oxidizer to use, with Korolev favouring liquid oxygen, and Makeev advocating the use of a storable but toxic oxidizer. Makeev's version, that first flew on 18 April 1953, was fitted with an Isayev engine using RG-1 and nitric acid. On 13 December 1953, a production order was passed with SKB-385 in Zlatoust, a factory dedicated to producing long-range rockets. In June 1955, Makeev was appointed chief designer of the SKB-385 to oversee the programme and, in July, the R-11 was formally accepted into military service. The definitive R-11M, designed to carry a nuclear warhead, was accepted officially into service on 1 April 1958. The launch system received the GRAU index 9K51, the rocket itself 8K11, and the launcher was initially designated 2U218 but later changed to 8U218.
Systems specification
8U218 launcher (rocket without a warhead)8U218 with R-11 missile in firing position
Like the V-2, the R-11 relied on inertial guidance, and its flight was controlled by four graphite vanes in the engine exhaust, that were active only while the motor was burning. The R-11M had a maximum range of 270km (170mi), but when carrying a nuclear warhead, this was reduced to 170km (110mi), hence an alternative designation R-170. At maximum range, it was found to have an average range error of 1.19km (0.74mi) and an azimuth error of 660m (0.41mi). It was used as a mobile nuclear strike vector[clarification needed], giving the Soviet Army the ability to hit European targets from forward areas. To give the system sufficient mobility on the battlefield, the R-11 was mounted on a transporter erector launcher with a chassis derived from the ISU-152K, which was designated 8U218. The main payload was a nuclear warhead with an estimated yield of 10, 20 or 40 kilotons. There was also HE-Frag warhead 9N33 with 535kg (1,179lb) of explosive.
A naval variant, the R-11FM was first tested at Kapustin Yar in February 1955, and was first launched from a converted Project 611 (Zulu class) submarine in September of the same year. While the initial design was done by Korolev's OKB-1, the programme was transferred to Makeyev's SKB-385 in August 1955. It became operational in 1959 as the D-1 launch system, the world's first submarine-launched ballistic missile (SLBM), and was deployed onboard Project 611 and Project 629 (Golf Class) submarines, until its replacement by the R-13 in 1961 (SS-N-4) and the R-21 (SS-N-5) in 1963. During its service, 77 launches were conducted, of which 59 were successful. The success of the R-11FM established Makeev as the main designer of submarine-launched weapons for the Soviet Armed Forces, and the R-11FM served with the first generation SLBM submarine units of the Soviet Navy.
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