R-27K (SS-NX-13)
The R-27K (SS-NX-13) modification featured a nose cone with a terminal guidance system. This missile, designated 4K18, was designed to attack both coastal radio control installations and moving targets [eg, American aircraft carriers] at sea. The R-27K missile was tested in 1974 on board the converted "K-102" 629 Golf submarine.
The R-27K was the first ballistic missile in the world with self-guidance for sea mobile targets. The systems and assemblies of the two-stage R-27K missile are almost completely unified for the first-stage engine, the rocket-launch system, the manufacturing technology and other components of the R-27 missile. In the sketch design of the R-27K missile, a variant was adopted with a passive reception of the radar signal emitted by the enemy's shipboard connection and with a ballistic correction of the trajectory by. The engine of the second stage of the R-27K missile provided not only flight along the traditional trajectory, but also self-targeting the mobile target with a two-fold correction of the trajectory in the extra-atmospheric flight section.
Soviet attack ["shock"] systems designed to destroy Western surface ships were based on cruise missiles of various types. Such weapons had long proved themselves on the good side and enjoys well-deserved popularity. Nevertheless, in the past several attempts were made to develop an anti-ship complex based on a ballistic missile. Most of these projects did not lead to the rearmament of the armed forces, but it allowed gaining important experience. The first Soviet anti-ship ballistic missile was the R-27K.
In April 1962, the USSR Council of Ministers decided to begin the development of a new medium-range ballistic missile intended for use by submarines. The project of the missile complex received the conventional designation D-5, the missile itself - R-27. The developer of the project was the Miass SKB-385 (now the State Rocket Center) led by Makeyev. The work on the D-5 / R-27 project led to the fact that in 1968 a new missile system was adopted for the submarines.
Also in 1962, a proposal was made to develop a modification of the R-27 missile, designed to destroy moving surface targets at ranges up to 900 km. An anti-ship missile called the R-27K or 4K18 was to be based on the units of the R-27, but had a different purpose. In connection with the need to defeat small-sized moving targets, an anti-ship missile was to receive a set of new equipment, including homing systems.
Calculations showed that existing detection systems can determine the location of surface targets with an accuracy of 25-30 km. At the same time during the pre-launch preparation of the missile, the target could move 100-150 km from a previously defined point. Thus, an anti-ship ballistic missile must have been equipped with homing systems to independently determine the current location of the target.
Already in 1962 the general architecture of the new product was proposed, which allowed to solve the task. It was proposed to rework the existing missile and make it two-stage. The task of the first stage in this case was the initial acceleration and the withdrawal of the rocket to the required ballistic trajectory, and the second stage was to find and hit the target. In addition, the draft version of the first version suggested ways to solve the main tasks of searching for targets and aiming at them.
It was proposed to use the second stage in the form of a streamlined unit with a radio-transparent head and a passive side-scan radar system. With the help of a folding cross-shaped side-scan antenna, it was proposed to search for signals from the ship's radio-electronic systems, and final guidance would be made using a passive radar-tracking system. It was also proposed to use rather complex control equipment with gyroscopic instruments, etc.
Early work on the R-27K project led to the formation of a range of basic tasks that needed to be solved to create a rocket. First of all, it was determined that the second stage of the missile with guidance systems turns out to be too large. It can occupy up to 40% of the overall dimensions of the entire rocket, which would make it necessary to reduce the dimensions of the first stage and reduce the volumes of its tanks. In this case, the flight range was much lower than required. In addition, the guidance systems of the second stage needed a heat-resistant fairing, capable of transmitting radio signals. Required materials with such characteristics at that time were absent, and their creation required time and additional studies.
Probably it was the lack of ready-made developments for the manufacture of a radome fairing that led to the fact that in 1963 SKB-385 developed two versions of the R-27K missile with different variants of guidance systems. Both projects used a unified first stage, based on the units of the basic R-27. The stage received a shortened body with tanks for fuel and oxidizer, and also had to be equipped with a liquid engine, unified with P-27. On top of the first stage was to be installed the second, having its own control systems, engine, etc.
The variant of the early project "A", developed in 1963, meant flight control by ballistic and aerodynamic methods. After dropping the first stage, the rocket, with the aid of a side-scan antenna, was to receive the signals of the target ship and determine its positions. Then a ballistic correction of the course was made, for which short-term starts of the second-stage engine were used. With the help of one or two inclusions of the engine (the fuel supply was limited), the second stage was to reach the required trajectory.
After passing the upper part of the ballistic trajectory, the rocket should include a passive radar homing head, find the target and fly to it. For control in the atmosphere, it was proposed to use aerodynamic rudders. This variant of two-stage ballistic-aerodynamic guidance made it possible to provide the highest accuracy of hit and gave the possibility of using a less powerful warhead.
Variant "B" proposed the use of only ballistic correction of the course. The missile was to find the target using a side-scan antenna, calculate the required trajectory and take it. After the return to the atmosphere, correction of the course was not envisaged. Ballistic guidance reduced accuracy and required a more powerful warhead ["combat unit"]. At the same time, such a guidance system was simple and did not need to reduce the dimensions of the first stage beyond the permissible limits, allowing to reach the required launch range.
After analyzing the two preliminary projects, it was decided to abandon the two-stage guidance. The implementation of ballistic and aerodynamic correction of the course was connected with a lot of problems and could not be fully implemented. For this reason, the project "A" was abandoned, continuing the development of option "B". Locating the target was to use a passive side-scan radar system.
NII-592 was involved in the development of the guidance system for the 4K18 product. The finished control system was based on a semiconductor element base and had to solve the task of finding the target with the subsequent calculation of the flight path. General features of the work were determined in accordance with the preliminary draft. At the same time, some new solutions were proposed. To search for targets, it was proposed to use a passive radar with a cross receiving antenna. During transportation and at the initial part of the flight, the antenna should be located in the cylindrical compartment of the second stage. After entering the path correction section, the rocket had to advance and unfold the antenna to find the target signals.
Having found the target and calculating the optimal trajectory for its defeat, the second stage of the rocket had to correct its course with the help of the existing engine. A fuel reserve allowed to turn on the engine twice. After correcting the course and braking, the second stage was to move to the descending section of the trajectory and follow the target.
The finished design of the R-27K missile meant the construction of a two-stage product based on the R-27 rocket aggregates. The anti-ship missile had a length of about 9 m and a diameter of 1.5 m. The launch weight was 13.25 m. The rocket of the new modification differed in its characteristic appearance. It received a head part of a complex shape formed by several conical and cylindrical surfaces. The complex head fairing had a long length in comparison with the units of the basic missile R-27.
The reduced length first stage with a reduced supply of fuel and oxidizer was equipped with a liquid engine 4D10, developed in OKB-2. As part of the engine there was a sustainer ["march"] engine with a thrust of 23 tons and a steering system of two separate chambers with a total thrust of 3 tons. The engine consumed fuel in the form of asymmetric dimethylhydrazine and nitrogen tetraoxide as an oxidizer. An interesting feature of the power plant of the R-27 and R-27K missiles was the placement of the engine. For the first time in domestic and foreign practice, to save space, the engine was placed inside the fuel tank.
The 4K18 missile could be launched using a standard shaft installation of the D-5 complex, designed for submarines of several projects. Before the launch, the tube ["mine"] had to be flooded, and in addition, it was necessary to pressurize the tanks to compensate for the pressure. When exiting the launcher, the missile was to be in the so-called "gas bell", which allowed reducing the impact of surrounding water. After the rise to the surface, the rocket continued its flight to the target with the help of the available guidance systems.
Reduction of the first stage and the volume of fuel tanks led to a significant reduction in flight range in comparison with the base rocket. The R-27 could destroy ground targets at a range of up to 2500 km, while the anti-ship R-27K was able to attack objects at only 900 km.
The defeat of the target was proposed to be carried out using a one-piece special combat unit with a yield of 650 kilotons. Such a nuclear warhead made it possible to compensate for the insufficient accuracy of aiming at the target and to ensure effective defeat of enemy surface ships.
For the initial target designation, it was proposed to use existing and prospective systems for detecting surface objects. During the development of the R-27K project, the "Success" system was based on reconnaissance aircraft. In the future, it was planned to put into operation the "Legend" system with the radar reconnaissance spacecraft. The appearance of the latter allowed the use of 4K18 missiles with maximum efficiency.
The main task of SKB-385 was the development of the basic project R-27. Because of this, the draft anti-ship weapon was created with a significant lag. As a result of this lag, the D-5 missile complex with the R-27 missile was adopted in 1968, and the 4K18 missile tests began only in 1970. One of the reasons for this lag was the difficulties with the development of certain elements of an anti-ship missile.
In December 1970, the first test launch of the R-27K rocket took place at the Kapustin Yar test site. In these tests, a stationary ground stand was used. During the next few months, 20 launches were carried out. 16 starts counted, while the rest failed. Shortly thereafter, several launch launches were carried out using a submerged platform ["booth"]. During such inspections, the input of the product from the submarine launcher in the underwater position was processed.
Since the mid-1960s the issue of choosing a submarine-carrier for new anti-ship ballistic missiles was being decided. Complex D-5 with a R-27K missile was proposed to be used with several types of submarines. Nevertheless, only projects 667A, 687 and 705B advanced further than preliminary works. Such submarines were to carry from 4 to 16 missiles of a new type. In the future, when developing all projects, certain problems arose. Thus, the 667A projected series of nuclear submarines had to participate only in strategic nuclear forces, and their use as carriers of 4K18 was considered inexpedient and unacceptable from the point of view of the combat ["impact"] potential. Projects 687 and 705B, in turn, faced numerous technical problems. As a result, three projects were never implemented.
By the beginning of the 1970s, the issue of the carrier of new missiles was not solved, but trials with submarine launches were nearing completion. Because of this, it was decided to involve one of the existing submarines in the tests. As a pilot vessel for testing new types of missiles, a diesel-electric submarine K-102 of project 629 was chosen. It was proposed to convert it into a new project 605, which proposed the installation of four launching mines and a number of other equipment. In particular, the navigation complex and target designation system were updated.
On December 9, 1972, the K-102 submarine first launched the R-27K missile. Over approximately a year of testing, 11 missiles were used, which were used to attack various targets. Of particular interest is the last launch, which took place on November 3, 1973. This time, two 4K18 missiles were launched on the target in the form of a barge with a radar station. One of the missiles successfully hit the target and hit it with a direct hit. The second went into the area of the target with an acceptable deviation. It is noteworthy that by the time the missiles were launched, uncertainty in the position of the target was 75 km. Despite this, the passive homing system detected the target and destroyed it. In general, the tests were a success. 10 launches out of 11 were considered successful.
September 2, 1975, after the completion of all design and test work, a decree was issued on the closure of the P-27K project. Such weapons were of some interest to the fleet, but there were a number of characteristic shortcomings that hampered its operation. Thus, the nuclear warhead made it difficult to deploy submarines with missiles of a new type in the light of the new SALT-2 treaty. Passive radar targeting system provided insufficient accuracy of guidance, and counteraction to it was quite simple. To disrupt the attack the enemy's ships were just enough to just turn off the radar for a while. Finally, by the mid-1970s, significant advances had been made in the field of cruise anti-ship missiles.
A number of reasons made the new project R-27K useless and unpromising. Because of this, all work on the new missile was stopped and it was not adopted. As a result, the navy did not receive new unusual weapons and continued to use existing systems of a more familiar form. At the same time, however, the K-102 boat with the D-5 complex remained in trial operation until the early eighties.
The first domestic project of an anti-ship ballistic missile ended with a successful solution of all the tasks assigned, but it was not brought to service in the troops. The reason for this was some of the project's problems, including the fundamentally unavoidable ones. Later Soviet specialists made another attempt to create such weapons. A new anti-ship ballistic missile was to be a P-33 type product, based on the design of the R-29 missile.
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