R-14 / SS-5 SKEAN
The R-14/SS-5 was a single-stage, storable liquid-propellant, intermediate range ballistic missile. The design of the R-14 missile drew heavily on the previously developed R-12 missile. As with the R-12, the Skean missile was a single stage missile with integral fuel tanks, though the Skean was larger and had twice the maximum range of the R-12. According to Western estimates it was capable of delivering a 3,500 lb reentry vehicle containing a nuclear weapon to a maximum operational range of 2,200 nm, and using an inertial guidance system with was assessed as having a CEP of approximately 0.5 nm.
The medium-range missile R-14 became a landmark for the industry. Almost at the same dimensions as the R-12, and using a single stage, the range was nearly doubled, reaching 4,500 km. The main difference between the R-14 was for the first time in the Soviet missile design use of high-boiling fuel components - oxidizer and fuel. Prior to this, the rockets were loaded with liquefied gases, conditionally speaking, oxygen and hydrogen, which are capable of being in the liquid phase at extremely low temperatures. For this, powerful cryogenic installations were required at the launch sites. For high-boiling components, that is, boiling at a high positive temperature, such a problem does not exist.
As a fuel in P-14, an asymmetric dimethylhydrazine (heptyl) was chosen, evaporating at +60 degrees, an oxidizer is a nitrogen oxidizer AK-27I, which has a boiling point equal to +22 degrees. At the same time, AK-27I can actually be in a liquid state and at a higher temperature, since it is contained in tanks under increased pressure. An important advantage of high-boiling components was their high specific impulse, not much lower than that of the "classical" oxygen-hydrogen pair.
Yangel's plans met serious bureaucratic resistance because of the need to create industrial production of a new type of fuel. It was also necessary to design engines of a different type. Against Yangel's design ideas, SP Korolyov, who worked only with liquefied components, actively spoke. However, Yangel managed to break the confrontation.
In comparison to the R-12 the increase of the propellant volume was reached through an increase of the diameter of fuel tanks. Fabrication of tanks with aluminum panels processed by a method of chemical contouring was used for the first time. The propulsion system of the R-14 consists of two identical blocks, each with a two-chamber combustion engine, a turbopump unit, gas generator and automatic control system, as well as a four chambered control motor. The use of hypergolic [self igniting] asymmetrical dimethylhydrazine allowed an increased specific impulse. For the first time a gas generator [instead of hydrogen peroxide] was used to power the main propellant components. The flight control still relied on jet vanes. Unlike the previous single-stage rockets, the R-14 used an efficient system of draining the propellant tanks to reduce required propellant mass.
The R-14 marked the first use of a gyro-stabilized platform as part of the autonomous inertial guidance system, allowing fewer instrumental errors and improving accuracy. The R-14 also mounted three solid-propellant retrorockets to prevent accidental collision of the booster with the nose cone after separation. Despite of its substantial longer range, the R-14 demonstrated the same accuracy as the R-12, though given its heavier payload its nose cone was blunted.
The development of the R-14 was authorized in July 1958. The authorization provided for the construction of a missile with an approximate range of 4,000 km, surpassing the R-12 by 2,000 km. The designer was M.K. Yangel of KB Yuzhnoye (OKB-586). The preliminary design was completed in December 1958. Flight tests of the R-14 began in July 1960 [Western sources suggest a first flight in June 1960] and were finished between December 1960 and February 1961. On 24 April 1961 deployment of the R-14 missile began. According to Western intelligence the initial operational capability with the Mod 1 reentry vehicle and soft sites was achieved in late 1961.
In May 1960 the development of the R-14U missile for silo and surface launchers began. The first flight test of the silo-launched R-14U was carried out on 12 January 1962, the surface-launched version was first tested on 11 February 1962. Both were subsequently introduced into the Strategic Missile Forces. The first regiment of surface-based R-14s was put on alert on 01 January 1962. According to Western intelligence an initial operational capability with hard sites was achieved in early 1963, and the initial operational capability with the Mod 2 reentry vehicle was achieved in mid-1963.
The SS-5 was deployed at both soft and hard launch sites. Soft-site reaction time during normal readiness condition is one to three hours. Hard-site reaction time in the normal readiness condition is five to fifteen minutes. Allowable hold time (reaction time equals three to five minutes) was many hours for soft sites and many days for hard sites. Maximum operational launcher deployment was reached in 1964. Between 1965 and 1969 the deployment of the R-14 and R-14U reached its peak with 97 launchers. Some phase-out of soft sites began in 1969 and some phase-out of hard sites began in 1971. In the period between 1978 and 1983 they were replaced by SS-20 Pioneer missiles, and in 1984 they were totally withdrawn from service.
The Intermediate-Range and Shorter-Range Nuclear Forces [INF] Treaty was signed in December 1987 and entered into force on 01 June 1988. The fundamental purpose of the INF Treaty was to eliminate and ban US and former USSR (FSU) ground-launched ballistic and cruise missiles, as well as associated support equipment, with ranges between 500 and 5500 kilometers. SS-4 and SS-5 missiles and components were eliminated at Lesnaya. Beginning in 1988 the six remaining non-deployed missiles were dismantled in compliance with the INF Treaty. The sixth and final SS-5 missile was eliminated at the Lesnaya Missile Elimination Facility in August 1989.
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