In 1967, a new UR-100 complex with an 8K84 intercontinental ballistic missile entered service with the strategic missile forces. Due to its simplicity and relative cheapness, such a rocket could be produced in large quantities. However, the simplification of the design and a number of other factors led to the fact that after a few years the UR-100 complex began to need to be replaced. This task was solved, and the MR UR-100 / 15P015 complex with the 15A15 missile was adopted by the Strategic Missile Forces, a characteristic feature of which was the widespread use of new technologies and design solutions.
In August 1970, a decree of the USSR Council of Ministers was issued, which determined the further development of the Strategic Missile Forces weapons. In connection with the gradual obsolescence of the UR-100 complex, it was required to modernize it, aimed at improving the main tactical and technical characteristics. It was decided to involve two organizations at once in the development of the modernization project - the Yuzhnoye Design Bureau (Dnepropetrovsk) and the Central Design Bureau of Mechanical Engineering (Reutov). It was believed that competition between the two bureaus would ensure the creation of an optimal project in all respects.
Monument rocket 15A15. Photo Arms-expo.ru
In accordance with the customer's requirements, it was necessary to develop a version of a deep modernization of the 8K84 light rocket, which is distinguished by increased characteristics while maintaining an acceptable cost and production complexity. The new product was supposed to use the existing mine launchers (silos) from the UR-100 complex. Flight design tests of the finished rocket were required to begin in 1973.
Both organizations started developing new projects. At the same time, the Yuzhnoye design bureau, headed by M. K. Yangel had some advantages. Shortly before the start of the development of a new project 15P015, it began to create a promising complex with a heavy missile - R-36M. A number of solutions for this missile could find application during the modernization of the UR-100. In addition, it was planned to study and implement new ideas. The combination of existing units, borrowed ideas and completely new solutions ultimately ensured the 15P015 project a victory in the competition.
In accordance with the main requirements of the customer, the updated MR UR-100 / 15P015 complex was supposed to use the existing launchers from the UR-100 system. Reconstruction of silos, command posts, etc. was not required. However, a project for the modernization of ground assets was developed, which was distinguished by increased combat stability and improved means of ensuring the microclimate. In particular, the new mine received thermal insulation and seals, as well as passive air dehumidifiers, so it did not need energy-consuming climate systems.
The missile of the 15P015 complex in a transport-launch container. Photo Fas.org
The main changes in the new project affected the design of the ICBM itself. The new product with the index 15A15 was a two-stage rocket with a detachable warhead. Liquid-propellant rocket engines (LRE) were retained at both stages. The warhead could be monoblock or include several individually guided warheads. From the point of view of the general architecture, the missile of the MR UR-100 complex resembled the ICBM from the UR-100 as much as possible, but differed in the set of components and solutions to various design problems.
The 15A15 rocket differed from its predecessor in increased dimensions. Its first stage had a cylindrical body with a diameter of 2, 25 m, the second - 2, 1 m. The steps were connected to each other by a conical transition compartment. The combat stage received a conical fairing. Due to the increase in size, the rocket did not fit into a silo of limited depth. This problem was solved with a special head fairing. Its front part was made in the form of a pair of half-shells. In the transport position, they lay on the sides of the fairing. After leaving the silo, the spring mechanisms folded them into a conical structure.
The cases of the steps were made in the form of wafer shells made of aluminum and magnesium alloys. This decision was taken from the P-36M project. The hulls also served as fuel tanks: an architecture with single containers separated by intermediate bottoms was used. The tanks contained the elements of the fuel system. In particular, new intake devices with destratifiers were used, which ensured the maximum extraction of fuel from the tank. The fuel system was fully ampulized for ease of use.
Product diagram 15A15. Figure Rbase.new-factoria.ru
The first stage of the rocket was equipped with a single-chamber sustainer engine 15D168 and a four-chamber control 15D167. The main engine was borrowed from the second stage of the R-36M rocket. To reduce the length of the rocket, the first stage received a concave bottom of a complex shape, in the niches of which there were propulsion units. The controlled 15D167 engine of an open circuit without afterburning was responsible for maneuvering, and also provided pressurization of the tanks with reducing gas. The thrust of the main engine on the ground was 117 tons, of the steering engine - 28 tons. The engines used a heptyl-amyl fuel pair (asymmetric dimethylhydrazine and dinitrogen tetroxide).
The smaller second stage also received a concave bottom bottom, on which the 15D169 engine was installed. There was no separate steering motor in the second stage. For roll control, gas engines were used with the selection of the working fluid from the turbopump unit. There were also means for changing the thrust vector in the form of a generator gas injection system into the supercritical part of the nozzle. The thrust of the second stage engine in the void is 14.5 tons.
The split warhead had its own power plant, built on the basis of the 15D171 solid-propellant engine. This product was also created on the basis of the R-36M rocket units, but differed in different dimensions and, accordingly, reduced characteristics.
The 15A15 rocket received an autonomous control system based on a central computer interfaced with other components. All instruments responsible for the control and guidance of the missile were installed in a common container in the warhead compartment. This made it possible to get rid of additional compartments, and in addition, to reduce the weight of the equipment, shorten the length of cables, etc. Finally, a unified control system was responsible for both the flight of the rocket and the breeding of warheads. The missile equipment made it possible to retarget to another object during prelaunch preparation. Also, the principle of automatic measurement of instrument errors was implemented with the subsequent introduction of corrections into the flight task.
Placement of the missile in silos. Figure Rbase.new-factoria.ru
The combat stage of the 15A15 rocket could carry different equipment. A variant with a monoblock warhead was proposed. In this case, a special warhead with a capacity of 3.4 Mt was used. A split warhead was also developed with four individual guidance blocks, carrying a charge of 400 kt each. In all cases, the warheads were protected from the damaging factors of a nuclear explosion.
The rocket of a new type at the plant was to be placed in a transport and launch container with a diameter of about 2.5 m and a length of 20 m. This product was made of AMg6 alloy and had a cylindrical body with external ribs. Various devices and devices were placed on the outer surface of the TPK. In the space between the tail of the rocket and the bottom, there was a powder pressure accumulator for a mortar launch - this was one of the first cases of using such equipment on domestic missiles. The TPK missile complex 15P015 was unified as much as possible with existing products, which made it easier to work with it.
The transportation of the rocket at all stages, from the factory to loading into silos, did not require any new devices or samples of technology. The same applied to the refueling of missiles and the installation of combat equipment. All such work could be carried out using standard equipment and equipment of the Strategic Missile Forces without the use of any new samples.
Rocket 15A15 without warhead. Photo Fas.org
In the flight configuration, the 15A15 rocket had a length of 22.5 m with a maximum diameter of 2.25 m. The launch weight was 71.2 tons, of which 63.2 tons were propellants. Payload - 2100 kg. The minimum firing range was determined at 1000 km. The maximum range with the use of a monoblock warhead is 10,320 km; when using the split part - 10250 km. Warheads were deployed within an area 200x100 km in size. The circular probable deviation did not exceed 500 m.
The widespread use of proven solutions and elements made it possible to start flight design tests ahead of schedule. The first drop launches of the 15A15 rocket took place already in May 1971 at the 5th Research Test Site (Baikonur). On December 26, 1972, the first test launch was carried out as part of the LCI. The last of the test launches took place on December 14, 1974.
During the LCI, 40 test runs were performed. In more than 30 cases, the conditional target was located at the Kura test site, which made it possible to test the missile at maximum ranges. There was also one launch at the minimum range. During the tests, there were only 3 emergency launches, 2 more were recognized as partially successful. Thus, 35 launches ended in full success.
On December 30, 1975, the Council of Ministers issued a decree on the adoption of the new MR UR-100 / 15P015 missile system with an 15A15 intercontinental ballistic missile. By this time, the Yuzhmash plant had started preparing for the serial production of new components of the complex. Several other enterprises were involved in the release of missiles. In particular, the TPK of a new design was ordered to the Tyazhmash enterprise (Zhdanov).
The first stage of the rocket. Photo Fas.org
By the time it was officially adopted, the first regiment, armed with 15A15 missiles, had already managed to take up combat duty. The first MR UR-100 complexes served near the town of Bologoye. Until the end of the decade, a number of other Strategic Missile Forces formations that had previously used UR-100 complexes switched to new weapons. According to known data, as part of the replacement of outdated weapons, a total of 130 15A15 missiles were put on duty. The overall production of mass-produced items was apparently higher.
In 1976, shortly after the official adoption of the MR UR-100 into service, the Council of Ministers ordered a new modernization of this complex. According to the results of new work, in 1979, the deployment of the MR UR-100 UTTH / 15P016 complex with 15A16 missiles began. In connection with the launch of the production of new missiles, the release of the previous ones was stopped. 15A16 missiles became on duty instead of the existing 15A15 and gradually replaced them. The replacement process was completed in 1983, when the last ICBM of the MP UR-100 complex was removed from the mine.
During the operation of the 15P015 complex, 27 combat training launches of missiles were carried out against targets at domestic land ranges. Only two such starts ended in an accident and did not lead to the defeat of the designated target. Taking into account the launches at the test stage, a total of 67 missiles were used, and 60 coped with the assigned tasks. In general, the rockets have shown high reliability and have proven themselves well.
According to various sources, the 15A15 missiles, as they were replaced with new 15A16s, went to warehouses or were sent for disassembly. A certain number of such products remained in stock during the preparation of the Treaty on the Reduction of Offensive Arms (START-I). As part of this agreement, the Soviet ICBM received the designation RS-16A. Its improved version 15A16 was called RS-16B.
Scheme of objects of the 15P015 / MR UR-100 missile system deployed near Kostroma. Figure Fas.org
By the time START I was signed, the RS-16A / 15A15 missiles were not on duty. The missile silos contained less than fifty newer 15A16 / RS-16B. Shortly before that, a decision was made to decommission outdated samples of the UR-100 family, and the 15P015 complexes were to be decommissioned. By the mid-nineties, all remaining RS-16 missiles were disposed of or destroyed.
The 8K84 missiles of the UR-100 complex at one time showed themselves well and ensured the rapid rearmament of strategic missile forces: almost a thousand of such products were on duty at the same time. However, over time, this weapon began to need to be replaced, as a result of which an interesting project of deep modernization appeared. On the basis of 8K84 and using completely new solutions, the 15A15 rocket was created, which had improved characteristics.
However, the 15A15 ICBM of the 15P015 complex did not become widespread and could not completely replace the existing UR-100. Besides, she didn't serve too long. Already at the end of the seventies, the first 15A16s were put on duty, and after a few years 15A15s were removed from duty. However, this did not prevent some samples of this type from lying in warehouses before the appearance of the arms reduction treaty.
The full operation of the 15P015 complex with the 15A15 rocket lasted only a few years, after which they began to replace it with newer weapons. Nevertheless, it turned out to be a landmark development of the domestic defense industry and had a serious impact on the further development of the nuclear missile shield. In the design of the 15A15 and R-36M missiles, a number of fundamentally new solutions were used that fully justified themselves and found application in future projects. Thus, despite the short service and not the largest number, the 15P015 / MP UR-100 complex left its mark on the history of our Strategic Missile Forces.