R-36 / SS-9 SCARP
The R-36 (8K67) ballistic missile, known in the west as the SS-9 SCARP, was a a two-stage, tandem, storable liquid-propellant intercontinental ballistic missile. The missile used an all-inertial guidance system and according to Western estimates had a CEP of 0.4 to 0.5 nm.
The R-36 missile was derived from the experience gained during the development of the R-16 missile, and the first stage of the two missiles are very similar. The propulsion system of the first stage R-36 consisted of three open-cycle rocket engines with two combustion chambers and a four-chambered control engine. The second stage comprised a single engine with two combustion chambers. The oxidizer and fuel tanks of the second stage was the first Soviet ICBM to incorporated a common bulkhead, all propellant tanks were synchronously drained. Asymmetrical dimethylhydrazine and nitrogen tetroxide were used as propellants, and during flight gaseous combustion products were used to pressurize the fuel tanks. In order to increase accuracy the guidance system was originally planned to encompass a combination of an autonomous inertial system and radio-control. However, the deployed missile only disposed of an autonomous, inertial guidance/control system that provided the required accuracy.
The SS-9's combination of high accuracy and yield constituted a convincing threat for the American ICBMs for the first time. The SS-9 was viewed in the United States as specifically designed to attack American Minuteman ICBM Launch Control Centers (LCCs), which initially were the "Achilles heel" of the Minuteman system, as 100 LCCs controlled all 1,000 Minuteman missiles. However, by 1969, as a result of redundant internetting of Minuteman silos and a backup airborne launch control system, the LCCs no longer were the "achilles heel" of Minuteman, so building one SS-9 for each Minuteman silo required MIRVed systems.
R-36 refers to second generation ICBMs, the ancestor of Moscow's heavy-duty missiles. It was designed to defeat the most important strategic targets of the enemy, protected by anti-missile defense. The two-stage missile was designed according to the "tandem" scheme of high-strength aluminum alloys. The first stage provided for the acceleration of the rocket and consisted of the tail section, the propulsion system and fuel-fuel and oxidizer carriers. The fuel tanks were pressurized in flight by the combustion products of the main components and had a device for damping the oscillations.
The propulsion system consisted of a six-chamber march and four-chamber steering liquid rocket engines. Marching LPRE was assembled from three identical two-chamber blocks, mounted on a common frame. The supply of fuel components to the combustion chambers was provided by three turbo-pump units whose turbines were untwisted by the combustion products of the fuel in the gas generator. The total thrust of the engine at the ground was 274 tons. The steering LPRE had four rotary combustion chambers with one common turbo-pump unit. Cameras were installed in the "pockets" of the tail section.
The second stage provided acceleration to the speed corresponding to the specified range of fire. Its fuel tanks of the supporting structure had a combined bottom. The propulsion system located in the tail section consisted of a two-chamber march and four-chamber steering liquid rocket engines. Marching RD-219 for design in many ways was similar to the engine blocks of the first stage. The main difference was that the combustion chambers were designed for a large degree of gas expansion.
Steps were separated from each other and the head part by triggering discontinuous bolts. To prevent collisions, braking of the separated stage was provided due to the operation of brake powder engines.
For the P-36, a combined control system was developed. The autonomous inertial system provided control of the missile in the active part of the trajectory and included a stabilization automaton, a range automatic system, a SOS system providing simultaneous production of an oxidizer and fuel from tanks, a rocket turn system after launching to the designated target. The radio control system had to correct the movement of the rocket at the end of the active section of the trajectory. However, in the course of flight tests it became clear that the autonomous system provides a given accuracy of fire - a circular probable deviation (CWO) of about 1200 meters - and the radio system was abandoned. This made it possible to significantly reduce financial costs and simplify the operation of the missile complex.
The R-36 was equipped with a monoblock thermonuclear head of one of two types - light and heavy. To overcome the enemy's anti-missile defense, a reliable set of special means was installed on the rocket. In addition, there was a system of emergency destruction of the combat charge, which was triggered by the deviation of the parameters of motion in the active section of the trajectory in excess of permissible.
Four payload variants were tested and deployed.
- The Mod 1 featured a single reentry vehicle with a warhead with a yield estimated by Western intelligence at 12 to 18 MT [this light version carried a warhead with a yield of 5 MT according to Russian sources]. This variant was assesed by Western intelligence as being capable of capable of delivering a payload of 12,500 lb to a range of 5500 nm.
- The Mod 2 featured a single reentry vehicle with a warhead with a yield estimated by Western intelligence at 18 to 25 MT, although this heavy version carried a warhead with a yield of 10MT according to Russian sources. This variant was assesed by Western intelligence as being capable of capable of delivering a 13,500 lb reentry vehicle a maximum operational range of 5300 nm. The large yield, single warhead Mod 2 variant was the most extensively deployed.
- The Mod 3 was a fractional-orbit, depressed-ICBM variant which combines the SS-9 first and second stages with an upper stage.
- The Mod 4 variant was a three-warhead MRV which probably began as an attempt to achieve a true MIRV capability. The large throw-weight of the 8K67 missiles (up to 5.8 tons) made them suitable for carrying multiple warheads. The design for the R-36P missile carrying three warheads (8K67P) were conducted by the KB Yuzhnoye (OKB-586) in November 1967. The flight-design tests were started in August 1968. American intelligence remained divided over whether these warheads were independently targetable [MIRV], or merely flying parallel trajectories [MRV], and the issue assumed considerable importance in the context of the debate over the deployment of the American anti-missile program.
The development of the R-36 missile in its heavy, light and orbital version began after its approval by the Soviet government on 16 April 1962. The leading developer was KB Yuzhnoye (OKB-586). The flight-design tests of the ballistic missiles (8K67) began on 28 September 1963, though the first Mod 1 flight test was not detected by Western intelligence until 03 December 1963. The flight-design tests of the R-36 missile were conducted at the Baikonur cosmodrome. The tests of the 8K67 ballistic missiles lasted from 28 September 1963 though May 1966.
The missile was placed in a silo of 41.5 meters deep with a shaft diameter of 8.3 meters and a door-diameter of 4.64 meters. Unlike the silo of the R-16U missile, the launch platform was not rotary, and the missile was directed to its trajectory (azimuthal guidance) through an onboard command structure after it left the silo. The SS-9 was deployed in individual, dispersed silos hardened to withstand 500-psi overpressure from a 1-MT weapon. The reaction time in the normal readiness condition is three to five minutes, with an unlimited hold time in that condition.
According to Western estimates, the initial operational capability for the SS-9 system, with both the Mod 1 and Mod 2 single reentry vehicle variants was reached in early 1966. According to Russian sources, the first regiment equipped with R-36 missiles was placed on alert on 05 November 1966, deployment of the 8K67 ballistic missiles began on 21 July 1967, and on 26 October 1970 deployment of the multiple-warhead variant began. Between 1965 and 1973 a total of 268 launchers for the R-36 missiles were constructed. Their replacement by the MIRVed R-36P began in 1975. The R-36 ballistic missile was phased out in 1978. The missile was ready for launch during its whole period of service that was originally fixed at five years but subsequently extended to 7.5 years.
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