Construction of two lead submarines, project 629 (the second component of the weapon system) was going on simultaneously in Severodvinsk and Komsomolsk-on-Amur. They were commissioned in 1957, and two years later the naval flag was raised on five more of the same boats. All of them were equipped with the D-1 missile system. Their subsequent re-equipment for the D-2 complex was carried out by shipyards. In total, excluding the submarine of project 629B, the fleet received 22 submarines of project 629 - the last two entered service in the Pacific Ocean in 1962.
The testing of the weapons system consisted of ground experimental testing (NEO) of elements, systems of onboard and integrated automated control systems (KAFU) and ballistic missile assemblies and other components of the rocket complex: flight design tests of the rocket at the range using fixed and swinging stands with the same tasks that were also during similar tests of the RK D-1 (out of 19 missile launches, 15 were successful); joint tests with the Project 629 underwater launch vehicle (11 out of 13 missile launches were successful).
During August-September 1960, in the Kola Bay, on a special stand reproducing the missile compartment of the project 629 submarine, 6 explosion resistance tests were carried out, making it possible to check the safety of the missile system during the explosions of depth charges at various distances from the hull of the carrier boat. Based on their results, it was decided to refuel with an oxidizer on the shore. Refueling was still carried out on the submarine from its tanks. The "Project 629 Submarine - RKD-2" system was adopted by the Soviet fleet in 1960 and was in service until 1972.
This system provided for the possibility of launching SLBMs from a submerged position at a distance of at least 1100 km. The initial creation of the missile complex was planned to be entrusted to the design bureau M. K. Yangel, the future academician and creator of a whole range of intercontinental ballistic missiles (ICBMs), including the RS-20 heavy ICBM that caused the greatest concern among the Americans (according to the US classification SS-18, NATO - "Satan"). However, by mutual agreement of M. K. Yangel and V. P. Makeev, who were united by the unity of views and approaches, decided to entrust the design team of V. P. Makeeva (hereinafter - KBM).
In the spring of 1960, the preliminary design of the missile system was completed, reviewed and approved. V. L. was appointed the lead designer for D-4 at KBM. Kleiman, his deputies O. E. Lukyanov and N. A. Karganyan, supervision of the development from the Research Institute of the Navy was conducted by Captain 2nd Rank B. A. Khachaturov and Lieutenant Commander S. Z. Eremeev. This principle of operation was retained at all subsequent stages of the creation of the missile complex - the officers of the fleet were, in fact, full members of the design team, taking part in the search, development and implementation of the decisions made.
Particular attention was paid to ground-based experimental development (NEO) of elements, systems and assemblies of SLBM R-21 and other parts of the complex. Each design and circuit solution was verified by full-scale tests in bench conditions. Thus, dozens of firing bench tests (OSI) of the rocket engine were carried out, including simulating the action of backpressure during the launch of a liquid-propellant rocket engine in the mine of a submarine, using specially created plugs that were mounted in the nozzles of the combustion chambers.
To test the propulsion system (DU) of the rocket as a whole, the OSI DU was carried out, and by the beginning of the last three OSI there were already results of "throw" (about them - below) tests of R-21 SLBM mock-ups from the floating submersible stand (SS) at the South Range of the Navy … This made it possible to compare the results of full-scale and bench tests, evaluate the correctness of the calculation method and make the necessary adjustments. The result of this work was firing tests of the R-21 bench SLBM with the use of the onboard missile control system.
Structurally, the R-21 submarine ballistic missile was a single-stage ballistic missile based on liquid propellants (12.4 tons of oxidizer, 3.8 tons of fuel). The body of the rocket is all-welded, made of steel EI-811, it combined the sequentially located instrument compartment (OBO), the oxidizer tank, the fuel tank and the tail compartment of the rocket into a single whole.
The rocket engine, created in the design bureau A. M. Isaeva, was a four-chamber, also made according to an open scheme. It had automatic control of thrust and ratio of oxidizer and fuel consumption. LRE combustion chambers were also the governing bodies of SLBMs. The designers shifted the axes of their swing by an angle of 60 ° relative to the stabilization planes, which provided the most rational relationship between the values of the control moments in pitch, yaw and roll.
The engine had a thrust at the surface of the earth equal to 40 tf, the specific thrust was 241.4 tf. An emergency shutdown of the liquid-propellant engine (AED) was envisaged, while ensuring reliable hermetic isolation of the fuel lines. The specifics of the underwater launch required the tightness of the SLBM compartments, pneumatic-hydraulic fittings, electrical connectors, cables, etc. This was provided by an all-welded single body structure, sealed cables that exited the compartments through special hermetic ducts, the cavities of which were inflated with air, and sealed joints of the warhead with the rocket body, using an inflated rubber tire.
The onboard missile control system is inertial. It was based on gyroscopic devices, which were located in the instrument compartment of the rocket: gyroverticant, gyrohorizon and gyrointegrator of longitudinal accelerations. All other devices and elements of the on-board control system were created mainly in the research institute, which was headed by N. A. Semikhatov, future academician and lead developer of control systems for all strategic naval missile systems. Military control over the creation of the SU in this research institute was carried out by Captain 2nd Rank V. V. Sinitsyn).
The communication of the on-board control system with the ship's test, as well as launching equipment, was carried out through two special sealed connectors by means of replaceable cables supplied from the manufacturer along with the rocket. During the prelaunch preparation, to ensure tightness, the cables were inflated with air with a nominal pressure of 6 kg / sq. cm.
Launched SLBM from a submerged mine submarine. During the prelaunch preparation, the gyro devices were guided, the firing range was set, the cables and tires were pressurized and, consecutively in two stages, the tanks were pressurized. After reaching the required pressure in the tanks, the submarine shaft was automatically filled, then the water pressure inside the shaft was equalized with the outboard pressure, and the shaft cover was opened.
Immediately before the launch, the rocket was transferred to onboard power (from the ampoule battery), in a given space of the rocket, by supplying compressed air, a "bell" was created. The "bell" was inflated in an automatic mode, which was controlled by appropriate sensors. It was needed to damp the gas-dynamic processes accompanying the launch, which made it possible to reduce to acceptable limits the power and thermal loads on the rocket that arise when launching from a "blind" mine not equipped with special gas vents.
The unstressed exit of SLBMs from the mine of a submarine, which was in motion in the presence of disturbances caused by sea waves and the course of the submarine, was ensured by using a drag-type directional scheme, which consisted of rigid guides mounted on the walls of the mine, and yokes mounted on the body of the rocket itself. The launch pad was locked with special pins during the start. To reduce aerodynamic drag, the yokes were dropped at the beginning of the air segment of the flight trajectory (15 s after the SLBM was detached from the launch pad). To improve static stability, during flight, the rocket was equipped with four stabilizers, polarized in the tail section.
The warhead of the rocket weighing 1179 kg was equipped with special ammunition. The warhead compartment was produced by excess air pressure in the instrument compartment of the rocket. Before this, the warhead was freed from rigid attachment to the rocket body with the help of four pyro-locks triggered by commands from the on-board control system.
The missile flight time to the target located at the maximum range did not exceed 11.5 minutes, the maximum height of the ballistic trajectory reached 370 km. In the case of firing at a minimum range of 400 km, the flight time was reduced to 7.2 minutes, and the maximum altitude was just over 130 km. Before the issuance of SLBMs to an underwater carrier, a complex of operations was carried out at the technical missile base (TRB) of the fleet, incl. pneumatic testing of systems, alignment, horizontal testing of the onboard control system, refueling with propellants and docking of the missile with the warhead. According to the classification adopted in the USA, the P-21 SLBM received the alphanumeric index SS-N-5, according to the NATO classification - the name "Serb".
The most important components of the D-4 missile complex were an integrated automated control system of KAFU, a launcher (PU), a complex of ground equipment (KNO) and an aiming system PP-114.
The basis of KAFU was, created in one of the research institutes of the Ministry of Industry and Trade, the automatic bearing and range formation (APD) "Stavropol-1" and the computing-decisive equipment of the "Izumrud" system, which guided the onboard gyro devices taking into account the input from the navigation complex (NK) "Sigma "information.
The launcher, named SM-87-1, provided: storage of SLBMs in a submarine shaft with loading parameters, launching a rocket from a shaft filled with water, as well as the operability of a ballistic missile after exposure to storm conditions and explosions on the submarine at a specified radius; its fire and explosion safety after ruptures at the critical radius. The corrosion resistance of the launcher systems provided six-time prelaunch preparation of missiles, with complete flooding of the mines with seawater.
With the help of a complex of ground equipment, the necessary operations for the ground operation of SLBMs were carried out (transportation, loading onto a submarine, daily storage, preparatory work for issuance to an underwater carrier in a technical rocket base, refueling).
After the completion of the stage of ground-based experimental development in a volume that allows one to start working out an underwater launch (in the established jargon of missilemen - "throw" tests), tests of mock-ups of the R-21 rocket began, first from a floating submersible stand (SS), and then with a re-equipped Project 613 D-4 (one missile silo was mounted behind the wheelhouse enclosure) of the S-229 submarine. The mock-ups fully corresponded to the R-21 SLBM in terms of weight and size characteristics, external contours and places of docking with ship systems. They were filled with fuel components based on the engine operation for a given time.
The chief designer of the floating submersible stand and submarine of project 613 D-4 was an employee of the Central Design Bureau-designer of the submarine of project 629 Ya. E. Evgrafov. The work on the manufacture of the stand and the submarine was carried out by the Black Sea Shipyard.
"Throwing" tests were carried out from May 1960 to October 1961 at the Southern Range of the Navy (16 launches of mock-ups were carried out from the stand, 10 launches from a submarine), under the supervision of a commission under the leadership of Colonel M. F. Vasilyeva. Tests have confirmed that the R-21 SLBM is suitable for underwater launches from depths of up to 50 meters.
In the final period of these tests on R-21 missiles, two experiments were carried out to determine the safety of the missile at launch for a submarine. In the course of the first experiment, the jamming of SLBM yokes in the guides at the very beginning of the rocket movement in the shaft was simulated, in the second, the leakage of the oxidizer line in the tail of the rocket was simulated, which led to the mixing of the propellant components. The results of the experiments were successful. The dummies of the missiles came out of the mine without causing significant damage to the elements of the mine. In total, 28 mock-ups were used for the "throw" tests, which speaks of the extremely responsible approach of the developers and naval specialists to the solution of a fundamentally new task - the guaranteed development of an underwater launch of SLBMs. The way for the presentation of the D-4 missile system at the stage of joint tests was opened.
These tests were carried out from the submarine pr. 629B "K-142". The first launch of the SLBM was performed on February 24, 1962 (before that, a trial launch of the "throw" mock-up took place). In total, 28 launches were made during the tests, of which 27 were successful.
The completeness and thoroughness of ground and flight testing during operation paid off handsomely - even when the service life of the R-21 SLBM reached 18 years, unsuccessful launches of this missile were extremely rare. The D-4 complex was put into service in the late spring of 1963. They planned to re-equip Project 629 submarines (upgraded to Project 629A) and Project 658 submarines. By this time, our Navy included 22 Project 629 submarines, which had the D-2 missile system. In total, according to project 629A, from 1965 to 1972, 14 submarines were re-equipped (taking into account the submarine of project 629B, which also underwent re-equipment according to project 629A) submarines. The lead submarine in the Northern Fleet "K-88" joined our Navy in December 1966. In the course of its state tests, 2 launches of the R-21 SLBM were carried out with positive results. Note that during the conversion of these submarines according to Project 629A, along with the replacement of the ship systems of the missile complex itself, the Pluto navigation system was also replaced with the more advanced Sigma.
As for the submarines of the 658M project, all 8 boats of the 658 project, which entered service in the period from November 1960, were re-equipped. The refurbishment was completed in 1970.
In 1977-1979, this weapon system underwent modernization associated with the replacement of the warhead. The missile with the new warhead received the alphanumeric designation R-21M, and the entire complex - D-4M. The armament system "Project 658M (629A) submarine - RK D-4 (M)" was in the combat composition of the Navy until the end of the eighties. And new achievements awaited ahead. The development of the first naval missile weapon system of the second generation "Project 667A submarine - RK D-5" has already been set, design studies and work were carried out to create an SLBM with a firing range that seemed fantastic until recently.
