2K11 anti-aircraft missile system Krug

The Decree of the Central Committee of the CPSU and the USSR CM of February 15, 1958 "On the creation of a prototype air defense system" Krug "were defined the main characteristics of the air defense system, cooperation of the leading executors in the means of the complex and the timing of work, determining the output of joint (state) tests in the III quarter of 1961. The air defense missile system was designed to intercept targets flying at speeds up to 600 m / s at altitudes from 3000 m to 25 000 m at a range of 45 km. The probability of hitting a target such as an IL-28 front bomber at altitudes up to 20 km of one SAM system was to be 0.8, with the ability to maneuver the target with an overload to four units. A target with an effective scattering surface (EPR) corresponding to the MiG-15 fighter should have been detected at a range of 115 km.

The head organization to develop an anti-aircraft missile system "Krug" (2K11) was determined by the Research Institute-20 of the State Committee for Defense Technology (GKOT), the chief designer - VP Efremov. Guidance Station 1C32 of the complex "Krug" was developed at the same research institute chief designer I.M.Driz.

The chassis for the launcher and guidance station was developed by Uralmashzavod specialists in two modifications based on the self-propelled artillery unit SU-100P. The weight of the pointing station chassis was 21 tons, the station equipment installed in it weighed 7 tons. The weight of the launcher chassis was 19 tons, payload - up to 10 tons. The calculated maximum speed was 60 km/h.

It was provided for the installation of gas turbine power supply units with 40 hp for the launcher and 80 hp for the guidance station.

On the chassis of the guidance station there was a thermal insulating sticker and provided for the installation of turbo-cooling unit for cooling equipment and air condensation in the operator's office.

Soundproofing materials were used in the compartment for calculating the launcher.

Due to the fact that the self-propelled unit SU-100P was not in production and in order to unify the Krug chassis with the mass medium tank, it was planned to carry out research and development works on the use of the tracked chassis with units and units borrowed from the T-55 tank for the launcher and guidance station.

The chassis to accommodate the detection and target designation station was developed by the Malyshev Plant specialists on the basis of the heavy artillery tractor AT-T. Chassis weight was 22 tons, payload - 14 tons. The maximum speed was 45 km/h. Power of the engine was 520 hp.

A special cabin for radar equipment and two gas turbine units of the power plant with 120 hp each was mounted on the chassis. (one unit is the backup).

The KS-40 (3M8) rocket with a direct-flow engine was to be created by the team of OKB-8 of the Sverdlovsk SNKh headed by L.V.Lyuliev.

The initial plans provided for the delivery of telemetry missiles to the testing range in the first quarter of 1959, missile guidance stations - by June, and target detection stations - in the III quarter of the same year. In fact, only November 26, 1959 took place the first of 10 run tests of the mock-up rocket with a natural starting engines, which revealed the first troubles - flutter, the destruction of the rocket at the separation of the launchers. Flight development of the flight engine 4 launches of missiles without control equipment began in June 1960. From August, and not having achieved the stable operation of the engine, began to implement program launches of missiles equipped with autopilot, but without radio control equipment. By June of the following year, 32 such launches had been carried out. Of these, the first 16 missiles were equipped with a simplified autopilot, which does not provide steerable control and a turbo-pump unit without a fuel control device. Of the 26 launches made by the end of 1960, six missiles were destroyed in flight, seven - did not turn on the marching engine and only 12 firing was relatively successful.

Given the large number of failures in the testing of ZM8 missiles by decision of the State Committee on Aviation Technology on August 25, 1961 was established a special expert commission to develop measures to improve the missile. Most of the accidents were related to combustion chamber burns, failures in the work of on-board equipment of the CRB, insufficient strength of some structural elements. A month later, on the recommendations of the commission it was decided to change the design of combustion stabilizers, eliminate the flow breakaway zones and increase the heat resistance of the combustion chamber of the marshal engine.

On the other hand, there was also an encouraging result - the analysis of capabilities of the missile guidance station and the ZSD guidance dynamics showed the possibility of ensuring acceptable accuracy when using only the radio command control system. Moreover, in the absence of CNS, strict limitations on the angle of attack were removed, which increased the maneuverability of the missile.

Therefore, the decision of the military-industrial complex of January 12, 1963 approved the proposal of the General Rocket and Artillery Directorate (GRAU) and industry to conduct joint flight tests (SLI) in two stages - first only with the radio command system, then with the SOS. Thus, the process of abandonment of the combined guidance system with semi-active SLN on the missile in favor of the already mastered in the SAMs S-25, S-75 and S-125 purely radio command systems. However, testing of the 3M8 missile was still very difficult. Prior to the start of joint tests during the factory tests until April 1963 there were 26 launches. Most of them were made on so-called electronic targets, two - on parachute targets, four - on reconstructed IL-28. In the process of joint testing from January to May 1963 eight launches were made, three of them ended in failure. There were no successful rocket launches at angles of more than 46°, while it was required to provide the possibility of launching at angles up to 60°. Of the 25 launches made from February to August 1963, only seven were successful - it was possible to shoot down targets - IL-28. By the beginning of the next year there were two more launches, both successful. However, none of the shots were fired at relatively small MiG-17 targets or at targets flying at altitudes below 3000 m. The marching engine did not operate steadily at low altitudes. Auto oscillations occurred in the control loop, resulting in unacceptable misses when the target was overflying. There were no representative data on the functioning of the radio detonator and the combat unit for real targets.

One of the most difficult elements to work out was the inlet diffuser of the RVD rocket and the fuel pump with nozzles. Suffice it to say that about tens of thousands of nozzles had to be "burned out" before the optimal shape could be found. And this is only for this type of engine, and if its geometric dimensions changed, everything would have to be repeated again. This is one of the reasons why RVRP is not currently widely used - they are unique in their specific design. Each step during development was given with difficulty and was solved literally from scratch. From the beginning of controlled flights, the fight against the signal damping of the on-board radio transponder in the engine exhaust torch began. It turned out that the combustion products of ordinary kerosene - very well shield the antenna of the respondent. I had to take it out to the tail fin console. In total, in the course of joint tests from February 1963 to June 1964, 41 SAM launches were made, including 24 missiles in combat configuration. Four cases of wing flutter required the introduction of anti-flutter balancers, three "poor" disruption of the combustion process - finalization of the fuel regulator, six explosions of isopropyl nitrate - improvement of the fuel system, two failures of the radio-fuse - finalization of its scheme. However, at the final stage the tests were mostly successful and the State Commission chaired by A.G.Burykin recommended the complex for adoption into service.

Resolution of the CPSU Central Committee and the USSR CM, adopted on October 26, 1964 - "On the adoption of a mobile anti-aircraft guided missile system "Krug" with ZUR 3M8" defined the main characteristics of the complex. Most of the requirements for the main characteristics set forth by the 1958 decree were met. The exception was the range of flight altitudes of the targets to be hit - 3000-23500 m - which did not reach 1500 m in terms of the required maximum altitude reach. The Decree of October 26, 1964 also determined the cooperation of the main enterprises - manufacturers of the complex elements. Series production of 1C12 detection stations was carried out at Lianozovsky electromechanical plant of MPS, 1C32 missile guidance stations - at Mari MPS. The 2P24 launchers and missiles were produced at the Sverdlovsk MPP. M.I.Kalinin Sverdlovsk Machine Building Plant MAP. Nearby, at the Sverdlovsk Plant of Electric Automation there was a serial production of K-1 "Crab" control complex.

Along with the adoption of the complex in service to the industry were assigned work on its further improvement, which was carried out in several stages. First of all, taking into account the experience of the war in Vietnam, modifications were made to reduce the "dead zone". In 1967, the Krug-A SAM system was adopted, for which the lower boundary of the kill zone was reduced from 3000 to 250 m, and the close boundary was approached from 11 to 9 km. After modifications of the missile in 1971 it was adopted for service of the Krug-M missile defense system. The further boundary of the kill zone of the complex was removed from 45 to 50 km, the upper boundary was raised from 23,500 to 24,500 meters. In 1974 the Krug-M1 was adopted for service, for which the lower boundary was lowered from 250 to 150 m, the shorter boundary was reduced from 11 to 6-7 km. It became possible to engage targets on the catch-up courses at a range of up to 20 km.

The complex was highly effective in the fight against aircraft and the conditions of maneuverable combat operations. The Krug SAM system in various modifications was exported to the countries of the former Warsaw Pact. In Russia, the complex was removed from armament, it was replaced by a universal anti-aircraft missile system S-300V.

In the west, the system received the designation SA-4 "GANEF".