Moscow's Air-Defense Network, Part 1: Foundations in Fear
Worried about US strategic bombers over the Red capital, Stalin initiates the world's largest air-defense network
by Michal Fiszer
Nov. 29, 2004
edefenseonline.com
In December 1954, on Premier Nikita Khrushchev's order, the 1st Special Purpose Army of the Soviet National Air Defense Forces was established. At its outset, the army was short of equipment and people who knew what they were doing. The army's primary asset, the S-25 surface-to-air missile (SAM) system, was only just being deployed. Its personnel were in training or otherwise engaged in construction of the units' facilities. The army was so secret that even the USSR's minister of defense did not know the details of its creation.
A depiction of a Type 215 missile of the S-25 air-defense system taking off. The task of developing the airframe of the missile that would be used in Moscow's air-defense system was assigned to Semion Lavochkin, the famous aircraft designer and director of the OKB-301 design bureau and its attending factory in Khimki, near Moscow. Igor Szablewski
On June 15, 1955, the 1st Special Purpose Army (SPA) was attached to the Moscow Air Defense District. Construction of its facilities had been mostly completed by that time. Final training and acceptance of the S-25 air-defense system took another year, so it was not until June 8, 1956, that the army was declared combat ready. The 1st Special Purpose Army remained operational until 1994, when the last of its S-25 systems was withdrawn from service. Since that time, Moscow has been defended by four air-defense brigades, each fielding eight S-300PT and six S-300PM battalions. Soon these units will be replaced by about 20 S-400 battalions.
For five decades, Moscow has been the most heavily defended city on Earth – against air attack, at least. The details of Moscow's air-defense network reveal as much about its creators' will and power as it does about their fears and weaknesses
Concentric Rings
From the very beginning of the Cold War, the danger of enemy air raids against the Soviet Union was treated very seriously. Already in 1948, air-defense forces were detached from other services and formed into an independent branch of the armed forces. In 1954 their status was raised to that of an independent service, fully equal to the army, navy, and air force.
In the late 1940s, when work on the first Soviet missiles exceeded the limits of German WWII achievements, Joseph Stalin became interested in surface-to-air missile systems as a way of increasing the combat effectiveness of air defenses in the nuclear era. At this time, the Soviets started three guided SAM programs, all of which were based on German concepts. Research-Scientific Institute (NII) No. 88, located in Podlipki, near Moscow, was the primary Soviet missile-development center in the early Cold War years and carried out all three early SAM programs. NII No. 88 included the Special Design Bureau (SKB) with a number of divisions handling a variety of ballistic and air-defense missile projects. The SAM efforts were the R-101 missile, a copy of the German Wasserfall; the R-103 missile, a copy of the German Rheintochter; and the R-105 missile, a copy of the German Schmetterling. None of these programs produced a successful missile, mainly due to problems with guidance and control systems.
In the early years of failure, a very important organization arose that, over the course of a half-century, would evolve into what is now the Almaz consortium, one of the most prolific missile-development groups in the world. The nascent organization was Special Design Bureau No. 1 (SB-1). In 1947 Sergei Beria, a son of Lavrentiy Beria, the powerful minister of the interior (MVD), graduated from Leningrad's Red Army Communications Academy. His graduating thesis was on a guidance and control system for an anti-ship missile. The lead professor on the project was Pavel Kuksenko, an experienced academic teacher. When Minister Beria, who reported directly to Stalin, learned about the work his son was involved in, he ordered the effort be made into a funded development program, and SB-1 was established for this purpose in September 1947 in Sokol, on Moscow's outskirts. Here also was the NII-20 radar institute led by Mikhail Sliosberg and Electrical Factory No. 465. Professor Kuksenko was transferred from the Red Army Communications Academy to become the chief of SB-1, while Sergei Beria was appointed his deputy. Soon, SB-1 received some talented specialists, mainly from NII-20.
Here is an illustration of the original S-25 layout around Moscow. Continuous lines are the internal (22 regiments) and external (34 regiments) rings. The small circles represent Air Defense Regiments. The shadowed triangles in the upper right show engagement sectors. The dashed circles are the fire ranges of internal- and external-ring regiments.
Almaz
By 1950 Stalin had became very concerned about the lack of progress in the development of SAM systems. Nevertheless, at his insistence, the Soviet Council of Ministers issued an August 9, 1950, decision about establishing the Moscow Air Defense system based on guided missiles. A few days later, Dmitri Ustinov, minister of armaments, issued a decision that SB-1 would be reorganized as KB-1, with Kuksenko and Sergei Beria released from administrative duties to pursue design work. The new KB-1 was quickly reinforced with various specialists taken from other institutions on Minister Beria's order. Some highly qualified and valuable specialists were taken from TsNII-108, a radar-research institute, among them the famous Aleksandr Raspletin, who became a deputy chief designer. A division of "Lager No. 1" (Gulag) with imprisoned German and Soviet specialists was also attached to KB-1. To supervise this part of the organization, Col. Grigori Kutepov of the Internal Security Forces was appointed the deputy director of KB-1, but he, in fact, reported directly to Minister Beria.
The newly created KB-1 was responsible for overall system integration, as well as development of the control and guidance of the SAM missile, which would come to be called the Berkut. A common story has it that "Berkut" stands for names of Sergei Beria and Kuksenko, but according to more reliable information it came from the names of their supervisors: Minister Beria and Col. Kutepov.
At the same time, the task of developing the airframe of the Berkut missile was assigned to Semion Lavochkin, the famous aircraft designer and director of the OKB-301 design bureau and its attending factory in Khimki, near Moscow. The liquid rocket engine for the missile was entrusted to NII-88 under the teams led by Aleksey Isayev and Dominic Sevruk. Lavochkin decided on a single-stage missile, because the system was to be deployed around Moscow, a densely urbanized area. Factories, research centers, design bureaus, military depots, and various other government facilities and compounds dominated Moscow's environs. In the case of any live firings, a launch booster would be dropped a few seconds after the missile took off and would fall down somewhere, jeopardizing any of these valuable assets.
It was decided that air-defense missiles would be deployed in two rings around Moscow, the inner ring about 45-50 km from the city center and the outer ring about 90-100 km from the city center. The SAM units on each ring were to be deployed 15-20 km apart so that no gap would be left between their zones of engagement. This translated into 22 units on the internal ring and 34 on the external one, for a total of 56 SAM units. These units were organized into four sectors: Northern, Western, Eastern, and Southern. The Northern and Western sectors would deploy nine units on the external ring and six on the internal. The Eastern and Southern sectors would deploy eight units on the external ring and five units on the internal. There were to be central main and alternate operations centers of the 1st Special Purpose Army (SPA), functioning as Moscow's air-defense command posts. Every also sector got its own command post, which was manned by a corps HQ.
The basic SAM unit was to be formed as a SAM regiment, with 56 regiments in total. The 1st SPA received its own radar network. Eight long-range radar posts were constructed: four forward posts, called RUDs, deployed one per corps; and four on the closer ring, called RUBs, also one per corps. Each corps' main operation center was deployed at the RUD with the alternate at the RUB. A powerful A-100 radar set was deployed at each post with a range of 250-300 km and 360-degree coverage. NII-20 developed the A-100 especially for the Berkut system. The long-range sets provided targeting information for the B-200 fire-control radar sets deployed with each Berkut regiment. Each B-200 covered a 60-degree arc.
In November 1951, Soviet planners decided the Moscow air-defense system would be supplemented by an airborne element that would operate on the approaches to the ground-based elements. At the time, it was not clear that typical gun-armed fighters would be suitable for the role. Therefore, the airborne element would be built around the G-300 air-to-air missile, which was to be a smaller version of the S-25's V-300 surface-to-air missile. The missile's carrier aircraft would be the G-310, based on the Tu-4 piston-engine bomber (an exact copy of US Boeing B-29, made from damaged aircraft that diverted to the Soviet Union after bombing Japanese targets in Manchuria and were interned). The G-310 was also to be equipped with a fire-control radar, developed by NII-17 under Viktor V. Tikhomirov, in the nose and a guidance-command transmitter. The air-interception element also consisted of a radar-equipped D-500 Taifun command-and-control aircraft, also based on the Tu-4.
The G-300 missile, known at Lavochkin's OKB-301 as "missile 210," was 8.3-m long and 0.5-m in diameter and weighed 3 tons. Four of the missiles were to be carried by a single G-310 interceptor. In late 1951, the missile project was slightly modified into the 211 version by omitting the solid-propellant boosters, which had proved to be superfluous. In May-June 1952, the G-310 made 10 flights with 211 missile mock-ups, but the program was then terminated.
The D-500 Taifun had four antennas and four radar sets for observing the front, rear, upper, and lower hemispheres. The radar was also developed by NII-17 and had a range of 80-100 km. This aircraft also made some test flights before program cancellation. It was later used as a testbed for developing airborne-radar observation techniques that were ultimately used in the Tu-126 Moss airborne warning and control aircraft.
The programs based on the G-300 had been canceled because it became evident that airborne air defense could be accomplished by conventional fighter-interceptors armed with smaller missiles. Lavochkin proposed building such an aircraft: a supersonic fighter with a delta wing and a radar in the nose. The fighter, designated "205," was to be armed with "typical" air-to-air missiles of the K-15 family (275, 278, and 280 missiles), also developed by OKB-301. The "250" fighter is another story, but it can be said here that it never went beyond the prototype stage.
A Very Unique Radar
The B-200 was one of the strangest radar systems ever built. Probably no other radar in the world worked in a similar way. The B-200 was a very complicated 3D, multifunction unit with all functions – search, track, and fire control – accomplished on the same mode of operations. The radar had two antennas, one each for azimuth and elevation. Both antennas were similar and were formed by two triangular plates about two meters apart arranged in a six-pointed "Star of David." Instead of narrow pencil beams, the radar antennas created wide, flat beams. The two antenna complexes were deployed side by side: the elevation-scanning antenna was upright, while the azimuth-scanning antenna was angled at 30 degrees above the horizontal.
The B-200 volume-search, tracking, and fire-control radar for Moscow's air-defense system was one of the strangest radar systems ever built. The radar had two antennas, one each for azimuth (shown here angled upward) and elevation (standing vertical). Both antennas were similar and were formed by two triangular plates about two meters apart, arranged in a six-pointed "Star of David." The B-200 was capable of tracking up to 20 targets while scanning for up to 100 total targets in the same mode, all in an analog era of vacuum tubes and servo-mechanical "computers." Igor Szablewski
In operation, a given antenna formed six beams, each 30-degrees wide and less than 1-degree thick, in a fan shape that emerged from between the triangular plates and perpendicular to their flat planes. Each "pairing" of plate edges and points produced a 30-degree beam to the left or to the right of center, inclined toward the flat plate edge. The alternating pairings enabled 60-degree coverage. When a given beam reached the appropriate orientation, high power was switched to its emitter. After the powered-up beam traversed its useful 30 degrees left or right of center, the high power was switched to the next emitter in sequence. And so on: left 30 degrees, right 30 degrees, left 30 degrees, etc.
The elevation antenna was set up like a mill's water wheel, with the paired triangular plates rotating about a horizontal axis. Since every beam was 30-degrees wide, it was not possible to measure the azimuth of the target. The elevation antenna provided only information about whether a target was in the left or right half of the scanned sector. But the target's elevation was measured relatively accurately. The antenna rotated quickly, so information was updated frequently – an important condition for firm target track.
One could ask why the antenna was projecting six beams in the same direction instead of using only one beam mechanically scanning a 60-degree sector in a more conventional back-and-forth motion. The problem was that designers wanted to get a high scan rate, and the antenna assembly weighed a few tons. If such an antenna were forced to make oscillating movements, a constant antenna speed would be unattainable. The antenna would first accelerate from one extreme position to the desired speed and then would be decelerating to stop at the other extreme, only to accelerate on the way back. This very non-linear movement had to be mimicked exactly by the reference line on the radar's screen. Otherwise, errors in measurement would be created from differences between the real antenna position and the position of the screen's reference. In the B-200's accepted solution, the antenna was rotating in one direction at a constant speed and synchronized with the screen's reference, which was also the measured data used for fire control, since this was simple and accurate.
The azimuth antenna worked in a more complicated way. To work exactly on the same principle as the elevation antenna, it should be placed horizontally with a vertical axis of rotation. In this case, any time one of the six beams would be scanning the 60-degree azimuth sector from left to right, clockwise. But in such an arrangement, three of the beams would be scanning 30 degrees above ground level while the other three would be directed 30 degrees below. So the B-200's azimuth antenna was angled 30 degrees above the ground. This arrangement caused measurement errors. Below this surface, the measured azimuth was larger than reality, and the error was the greatest at the outer edges of the sector, with zero error in the middle. Above the surface of the antenna plates, the situation was the opposite: the target's real azimuth was higher than measured. The measurement error was easily corrected, as will be described later.
Both elevation and azimuth antennas were synchronized to make sure that adequate angle and distance measurement referred to the same target. Up to 20 targets could be tracked by quick horizontal and vertical sector scanning, with azimuth/distance/altitude data output updated every rapid scan cycle while at the same time up to 100 other targets could be detected. Other contemporary systems typically provided continuous narrowbeam tracking of a single target. In the B-200 radar, an analog processor projected an "artificial" track between updates, giving the track data also in a continuous way to the fire-control processor. In this complicated way, a solution was achieved in the analog and vacuum-tube era. It is only in our digital, solid-state technology era that three-dimensional, multifunction radars have achieved such track-while-scan performance.
Here is a close up of a B-200 antenna at the Russian Federation Air Force Museum in Monino. It is important to note that the unit has been incorrectly assembled for the display. The two triangular plates should form a "Star of David" configuration and should not be matching as shown here. Properly configured, the plates spin together in synch so that the beams emitted from the central unit would be directed 30 degrees either to the left or the right, providing a coverage arc of 60 degrees.
Jerzy Gruszczynski
The complicated B-200 radar was fully developed by Soviet specialists, led by Kuksenko, Beria, and Raspletin. However, German specialists also worked on parallel solutions. In the 1940s and 1950s, it was a rule that the projects prepared by German specialists forced to work in the Soviet Union were not to be fielded but only monitored for some useful technical solutions. German specialists were very rarely informed about the details of a whole program and were never provided with information about technologies or materials that were available to Soviet industry. Therefore, their projects, with a few exceptions in the field of aviation, could not be realized practically, even in the form of an experimental prototype. This was also the case in B-200 development. However, Sergei Beria did not hesitate to seek advice from captive German engineers on particular matters. At least two serious problems were solved successfully with the Germans' help.
One was related to the transmission of guidance commands to the missiles. Initially, the commands were to be sent in sequence to up to 20 missiles on the same frequency by the same powerful emitter. Every package of guidance commands was to be sent together with simple code to be recognized by a particular missile. The whole system was very complicated, and there was no provision for increasing the number of missiles attacking the same target. The Germans proposed using 20 separate transmitters working on separate frequencies. Before a missile launch, the missile's onboard receiver would automatically be set on a chosen frequency, and then all guidance commands could be transmitted at the same time. Also, the fire-control processors were divided into 20 units, each responsible for tracking a single target and guiding the missile, working in four groups of five.
Every group was attended by two operators: one responsible for automatic track supervision and the other for preparation and launch of a missile while monitoring other targets approaching the engagement zone. From one position, the two operators supervised five engagement channels, thus five tracked targets and missiles, as well as other parameters related to them. It was deemed that five engagements was the maximum for a given team. Each operator had two screens: one showing the azimuth (horizontally) and distance (vertically) and the other showing elevation (horizontally) and distance (vertically). In addition, each group had three specialists responsible for manual track mode should the automatic track fail for any reason, one each for tracking azimuth, elevation, and distance of a single target and missile. So in the case of manual-mode operations, only one target in a given section could be tracked and engaged at a time instead of five. Thus, together with a shift commander, this organization required 21 operators for a single B-200 radar, not counting technical personnel.
The other problem also involved missile control during the engagement cycle. The problem was that the processor's software algorithm for preparing guidance commands was too complicated, and the processor worked too slowly, resulting in "outdated" commands. German specialists noticed that much of the computational delay occurred when the system processed geographical-reference grids for the target and missile track. These were calculated from azimuth/elevation and distance information. The Germans proposed using angle and distance as the base reference system, which eliminated the need to recalculate them. Laboratory tests showed that the Germans were right, and the problem was solved. Such an approach also eliminated the need for correction of the measurement error in azimuth, which was mentioned earlier, since the error referred equally to the target's position and missile's position. In the other words, the missile could be accurately directed to the target-interception point because the azimuth error of the missile and target differed from the real azimuth by the same value.
The huge technical phase of the project was completed in the autumn of 1951. It was decided to build an experimental example of the radar that was not quite a prototype but something that in the contemporary Western world would be called a "technology demonstrator." Such a demonstrator was constructed in Kratkovo (presently Zhukovsky), at the edge of LII's (Flight Research Institute) airfield. The airfield hosted a large number of flights of the most modern types of aircraft in the Soviet inventory and so offered the unique opportunity to test the experimental B-200 radar against all of those targets, deemed as being the future of military aviation.
A 217 or 217M missile and the improperly displayed B-200 radar antenna at the Monino Air Force Museum near Moscow. Powerful A-100 radar sets provided targeting information for the B-200 fire-control radar sets deployed with each S-25 regiment. The basic SAM unit was to be formed as a SAM regiment, with 56 regiments in total. Each regimental fire-control center had four teams of operators, each responsible for managing up to five targets and missile attacks.
Jerzy Gruszczynski
The experimental radar's components were built mostly by KB-1's facilities. Other factories built only a few elements. The largest and most important elements ordered externally were the antennas, which were produced by No. 701 State Factory in Podolsk. The experimental radar was not a complete B-200: for example, only some of the tracking/guidance channels were operational. For initial tests, a lot of specially developed simulation and test equipment was used. About 400 meters from the radar a 40-meter-high tower was raised that supported a missile's receiver and transponder. Both were connected to simulation equipment, working in a circuit. The receiver passed guidance commands to an analog, vacuum-tube, mechanical-servomechanism-based "computer," which calculated the expected position of the missile and sent data to the radar via cable. The radar tracked the transponder on the tower, but in some tests, the transponder input was replaced by missile-position data provided by the "computer," which calculated expected virtual missile position on the basis of guidance commands sent by the radar. In this way, the track and guidance sequence could be checked without actually launching any missiles, which were not available at this time. This is one of the early examples of computer modeling and simulation.
In December 1954, Premier Khrushchev ordered the establishment of the 1st Special Purpose Army of the Soviet National Air Defense Forces. The army's primary asset, the S-25 surface-to-air missile (SAM) system and its V-300 missile (shown here), was only just being deployed. The 1st Special Purpose Army remained operational until 1994, when the last of its S-25 systems was withdrawn from service. Since that time, Moscow has been defended by four air-defense brigades, each fielding eight S-300PT and six S-300PM battalions. These units will soon be replaced by about 20 S-400 battalions.
Almaz
In the spring of 1952, the B-200's design was refined to the point where a decision was made to proceed with a so-called "test radar," which today would be called a "full-scale development" example. At this stage, it was decided to prepare the selected Soviet factories for series production of the system components and involve them in construction of the test radar. State Factory No. 304 in Kuntsevo, near Moscow, would be the main contractor and would be responsible for final assembly of the radar. Since June 1945, the former ammunition factory had been involved in the production of the SON-series of anti-aircraft-artillery (AAA) fire-control radar and the PUAZO AAA electro-mechanical fire calculator. Presently, the factory is known as AOOT Moscow Radio-Technical Factory. During its history, the factory has produced fire-control radar sets for the S-75 (SA-2), S-125 (SA-3), S-200 (SA-5), and S-300 (SA-10) systems, and presently is producing radar sets for export S-300PMU and for Russian S-400 systems.
Missile Development
The Soviet Council of Ministers entrusted the development of a missile for the Berkut system to OKB-301 at Khimki, near Moscow, in August 1950. By March 1951, an initial design of the V-300 missile was presented for approval, which was quickly granted. At the same time, the first live engine trials were conducted on a test stand in Zagorsk. This was Isayev's SO8.2 engine that used pressurized air to push fuel and oxidizer into the gas chamber of the engine (VAD system) and generated 8,000 kg of thrust.
The first V-300 missiles, called "article 205," were delivered to the Kapustin Yar shooting range in early June 1951. The first unguided launch with a stabilized autopilot took place on June 27. However, the first launches were not successful. The missiles went out of control and crashed prematurely. During one launch, a fallen missile damaged the barracks where the engineers and technicians were living, but fortunately they were empty at the time. The problem was soon located: there was an error in the electrical scheme of the autopilot. The error was actually discovered by two old German engineers working at KB-1. Normally, German engineers were not allowed to be so close to the Soviet's most secret works, but KB-1 had "special" status. After the correction was implemented, the subsequent launches were mostly successful. Through the end of September 1951, a total of 30 launches were conducted.
Work on the missile accelerated in September 1951. It was concluded that more guidance and control specialists were needed at Lavochkin's OKB-301, so 14 guidance-system specialists, led by Georgiy Babakin, were transferred from NII-88. At the same time, Petr Grushin became Lavochkin's deputy.
The second phase of missile tests started in March 1952. The missiles were equipped with the SO9.29A engine delivering 9,000 kg of thrust, developed by A. Isayev at Lavochkin's request. During these tests, trials of the command-control system were also conducted. No real target was involved, though. The goal was simply to guide a missile into a certain point in space. Missiles in flight were tracked by SON-4 AAA fire-control radar. The next part of these trials was conducted with the use of the test example of the B-200 radar. Attempts were undertaken to track launched missiles, but five attempts all failed. The radar initiated contact with the missiles' transponders and tracked them while they climbed vertically, but every time the missiles started to turn towards the targets, the track was lost. The transponders were carefully checked, but all of them were fully functioning. The radar was also tracking all other targets – just not the transponder-equipped missiles after they turned! Nobody could figure out the nature of the phenomena.
As it turned out, the problem was simple. The missile was disappearing in a cloud of ions created by the rocket engine's flames. Increasing the transponder's power output solved the matter as far as the test series was concerned. Ultimately, tuning changes to the transponder frequency cured the problem for practical use. During the second phase of missile and radar tests, completed in September 1952, 31 launches were conducted. More than half of these were successful. Still, a lot of work remained ahead for the design teams.
The last phase of the factory-testing program was the most complex and the longest part of the Berkut system trials. In this phase, all of the system elements were being tested together, with live firing and missile control by the B-200 radar system. Test shots were made against virtual targets generated artificially on the screen by a special simulator, against radar reflectors dropped on parachutes, and against unmanned radio-controlled target drones converted from Tu-4 bombers. Altogether, 123 launches were carried out from Oct. 18, 1952, through September 1953.
At that time, there were no specialized drones available and the aforementioned aircraft targets were only provisionally equipped with a radio receiver that controlled the bomber's standard autopilot. The autopilot could stabilize barometric altitude and magnetic heading. The control aircraft could change a target's heading and the altitude by radio, but the "drone" had to take off as a manned aircraft. The pilots of Tu-4 targets performed manual take-off and flew to the designated test zone together with the controller aircraft. When all was ready, the crew engaged the autopilot and ejected. The ejection seats were not standard equipment on the Tu-4 but were mounted for the test series because the crew had to stabilize speed above 500 kmph before leaving the aircraft. This was too fast for a safe bailout from the standard hatches. It should be pointed out that early ejection seats used explosives – like artillery shells – and were neither as safe nor as reliable as modern rocket-powered ejection seats. Crews for these manned drones were offered substantial financial rewards to undertake the risk and the shock attending these sorties, but there were few crewmembers who withstood more than two or three ejections.
The first radio-controlled Tu-4 was shot down by the Berkut system on April 26, 1953. The aircraft fell relatively close to all of the people present on the spot, among them designers, engineers, technicians, and government representatives. Many of these people rushed toward the crash site, where the wreck of the aircraft was still burning. When the crowd reached the wreck, there was suddenly a loud explosion that threw everybody to the ground. Luckily nobody was seriously injured, but approaching downed aircraft in the future was strictly forbidden.
Through the end of September 1953, a total of five Tu-4 radio-controlled aircraft were shot down by the Berkut system, which would receive the designation S-25. Many parachute target reflectors were "hit" as well. Among the 123 fired missiles, there were also 13 of the first series-production missiles produced by No. 82 State Factory in Tushino, near Moscow. Everybody expected a decision accepting the system into service. However, that did not happen just yet.
Worried about US strategic bombers over the Red capital, Stalin initiates the world's largest air-defense network
by Michal Fiszer
Nov. 29, 2004
edefenseonline.com
In December 1954, on Premier Nikita Khrushchev's order, the 1st Special Purpose Army of the Soviet National Air Defense Forces was established. At its outset, the army was short of equipment and people who knew what they were doing. The army's primary asset, the S-25 surface-to-air missile (SAM) system, was only just being deployed. Its personnel were in training or otherwise engaged in construction of the units' facilities. The army was so secret that even the USSR's minister of defense did not know the details of its creation.
A depiction of a Type 215 missile of the S-25 air-defense system taking off. The task of developing the airframe of the missile that would be used in Moscow's air-defense system was assigned to Semion Lavochkin, the famous aircraft designer and director of the OKB-301 design bureau and its attending factory in Khimki, near Moscow. Igor Szablewski
On June 15, 1955, the 1st Special Purpose Army (SPA) was attached to the Moscow Air Defense District. Construction of its facilities had been mostly completed by that time. Final training and acceptance of the S-25 air-defense system took another year, so it was not until June 8, 1956, that the army was declared combat ready. The 1st Special Purpose Army remained operational until 1994, when the last of its S-25 systems was withdrawn from service. Since that time, Moscow has been defended by four air-defense brigades, each fielding eight S-300PT and six S-300PM battalions. Soon these units will be replaced by about 20 S-400 battalions.
For five decades, Moscow has been the most heavily defended city on Earth – against air attack, at least. The details of Moscow's air-defense network reveal as much about its creators' will and power as it does about their fears and weaknesses
Concentric Rings
From the very beginning of the Cold War, the danger of enemy air raids against the Soviet Union was treated very seriously. Already in 1948, air-defense forces were detached from other services and formed into an independent branch of the armed forces. In 1954 their status was raised to that of an independent service, fully equal to the army, navy, and air force.
In the late 1940s, when work on the first Soviet missiles exceeded the limits of German WWII achievements, Joseph Stalin became interested in surface-to-air missile systems as a way of increasing the combat effectiveness of air defenses in the nuclear era. At this time, the Soviets started three guided SAM programs, all of which were based on German concepts. Research-Scientific Institute (NII) No. 88, located in Podlipki, near Moscow, was the primary Soviet missile-development center in the early Cold War years and carried out all three early SAM programs. NII No. 88 included the Special Design Bureau (SKB) with a number of divisions handling a variety of ballistic and air-defense missile projects. The SAM efforts were the R-101 missile, a copy of the German Wasserfall; the R-103 missile, a copy of the German Rheintochter; and the R-105 missile, a copy of the German Schmetterling. None of these programs produced a successful missile, mainly due to problems with guidance and control systems.
In the early years of failure, a very important organization arose that, over the course of a half-century, would evolve into what is now the Almaz consortium, one of the most prolific missile-development groups in the world. The nascent organization was Special Design Bureau No. 1 (SB-1). In 1947 Sergei Beria, a son of Lavrentiy Beria, the powerful minister of the interior (MVD), graduated from Leningrad's Red Army Communications Academy. His graduating thesis was on a guidance and control system for an anti-ship missile. The lead professor on the project was Pavel Kuksenko, an experienced academic teacher. When Minister Beria, who reported directly to Stalin, learned about the work his son was involved in, he ordered the effort be made into a funded development program, and SB-1 was established for this purpose in September 1947 in Sokol, on Moscow's outskirts. Here also was the NII-20 radar institute led by Mikhail Sliosberg and Electrical Factory No. 465. Professor Kuksenko was transferred from the Red Army Communications Academy to become the chief of SB-1, while Sergei Beria was appointed his deputy. Soon, SB-1 received some talented specialists, mainly from NII-20.
Here is an illustration of the original S-25 layout around Moscow. Continuous lines are the internal (22 regiments) and external (34 regiments) rings. The small circles represent Air Defense Regiments. The shadowed triangles in the upper right show engagement sectors. The dashed circles are the fire ranges of internal- and external-ring regiments.
Almaz
By 1950 Stalin had became very concerned about the lack of progress in the development of SAM systems. Nevertheless, at his insistence, the Soviet Council of Ministers issued an August 9, 1950, decision about establishing the Moscow Air Defense system based on guided missiles. A few days later, Dmitri Ustinov, minister of armaments, issued a decision that SB-1 would be reorganized as KB-1, with Kuksenko and Sergei Beria released from administrative duties to pursue design work. The new KB-1 was quickly reinforced with various specialists taken from other institutions on Minister Beria's order. Some highly qualified and valuable specialists were taken from TsNII-108, a radar-research institute, among them the famous Aleksandr Raspletin, who became a deputy chief designer. A division of "Lager No. 1" (Gulag) with imprisoned German and Soviet specialists was also attached to KB-1. To supervise this part of the organization, Col. Grigori Kutepov of the Internal Security Forces was appointed the deputy director of KB-1, but he, in fact, reported directly to Minister Beria.
The newly created KB-1 was responsible for overall system integration, as well as development of the control and guidance of the SAM missile, which would come to be called the Berkut. A common story has it that "Berkut" stands for names of Sergei Beria and Kuksenko, but according to more reliable information it came from the names of their supervisors: Minister Beria and Col. Kutepov.
At the same time, the task of developing the airframe of the Berkut missile was assigned to Semion Lavochkin, the famous aircraft designer and director of the OKB-301 design bureau and its attending factory in Khimki, near Moscow. The liquid rocket engine for the missile was entrusted to NII-88 under the teams led by Aleksey Isayev and Dominic Sevruk. Lavochkin decided on a single-stage missile, because the system was to be deployed around Moscow, a densely urbanized area. Factories, research centers, design bureaus, military depots, and various other government facilities and compounds dominated Moscow's environs. In the case of any live firings, a launch booster would be dropped a few seconds after the missile took off and would fall down somewhere, jeopardizing any of these valuable assets.
It was decided that air-defense missiles would be deployed in two rings around Moscow, the inner ring about 45-50 km from the city center and the outer ring about 90-100 km from the city center. The SAM units on each ring were to be deployed 15-20 km apart so that no gap would be left between their zones of engagement. This translated into 22 units on the internal ring and 34 on the external one, for a total of 56 SAM units. These units were organized into four sectors: Northern, Western, Eastern, and Southern. The Northern and Western sectors would deploy nine units on the external ring and six on the internal. The Eastern and Southern sectors would deploy eight units on the external ring and five units on the internal. There were to be central main and alternate operations centers of the 1st Special Purpose Army (SPA), functioning as Moscow's air-defense command posts. Every also sector got its own command post, which was manned by a corps HQ.
The basic SAM unit was to be formed as a SAM regiment, with 56 regiments in total. The 1st SPA received its own radar network. Eight long-range radar posts were constructed: four forward posts, called RUDs, deployed one per corps; and four on the closer ring, called RUBs, also one per corps. Each corps' main operation center was deployed at the RUD with the alternate at the RUB. A powerful A-100 radar set was deployed at each post with a range of 250-300 km and 360-degree coverage. NII-20 developed the A-100 especially for the Berkut system. The long-range sets provided targeting information for the B-200 fire-control radar sets deployed with each Berkut regiment. Each B-200 covered a 60-degree arc.
In November 1951, Soviet planners decided the Moscow air-defense system would be supplemented by an airborne element that would operate on the approaches to the ground-based elements. At the time, it was not clear that typical gun-armed fighters would be suitable for the role. Therefore, the airborne element would be built around the G-300 air-to-air missile, which was to be a smaller version of the S-25's V-300 surface-to-air missile. The missile's carrier aircraft would be the G-310, based on the Tu-4 piston-engine bomber (an exact copy of US Boeing B-29, made from damaged aircraft that diverted to the Soviet Union after bombing Japanese targets in Manchuria and were interned). The G-310 was also to be equipped with a fire-control radar, developed by NII-17 under Viktor V. Tikhomirov, in the nose and a guidance-command transmitter. The air-interception element also consisted of a radar-equipped D-500 Taifun command-and-control aircraft, also based on the Tu-4.
The G-300 missile, known at Lavochkin's OKB-301 as "missile 210," was 8.3-m long and 0.5-m in diameter and weighed 3 tons. Four of the missiles were to be carried by a single G-310 interceptor. In late 1951, the missile project was slightly modified into the 211 version by omitting the solid-propellant boosters, which had proved to be superfluous. In May-June 1952, the G-310 made 10 flights with 211 missile mock-ups, but the program was then terminated.
The D-500 Taifun had four antennas and four radar sets for observing the front, rear, upper, and lower hemispheres. The radar was also developed by NII-17 and had a range of 80-100 km. This aircraft also made some test flights before program cancellation. It was later used as a testbed for developing airborne-radar observation techniques that were ultimately used in the Tu-126 Moss airborne warning and control aircraft.
The programs based on the G-300 had been canceled because it became evident that airborne air defense could be accomplished by conventional fighter-interceptors armed with smaller missiles. Lavochkin proposed building such an aircraft: a supersonic fighter with a delta wing and a radar in the nose. The fighter, designated "205," was to be armed with "typical" air-to-air missiles of the K-15 family (275, 278, and 280 missiles), also developed by OKB-301. The "250" fighter is another story, but it can be said here that it never went beyond the prototype stage.
A Very Unique Radar
The B-200 was one of the strangest radar systems ever built. Probably no other radar in the world worked in a similar way. The B-200 was a very complicated 3D, multifunction unit with all functions – search, track, and fire control – accomplished on the same mode of operations. The radar had two antennas, one each for azimuth and elevation. Both antennas were similar and were formed by two triangular plates about two meters apart arranged in a six-pointed "Star of David." Instead of narrow pencil beams, the radar antennas created wide, flat beams. The two antenna complexes were deployed side by side: the elevation-scanning antenna was upright, while the azimuth-scanning antenna was angled at 30 degrees above the horizontal.
The B-200 volume-search, tracking, and fire-control radar for Moscow's air-defense system was one of the strangest radar systems ever built. The radar had two antennas, one each for azimuth (shown here angled upward) and elevation (standing vertical). Both antennas were similar and were formed by two triangular plates about two meters apart, arranged in a six-pointed "Star of David." The B-200 was capable of tracking up to 20 targets while scanning for up to 100 total targets in the same mode, all in an analog era of vacuum tubes and servo-mechanical "computers." Igor Szablewski
In operation, a given antenna formed six beams, each 30-degrees wide and less than 1-degree thick, in a fan shape that emerged from between the triangular plates and perpendicular to their flat planes. Each "pairing" of plate edges and points produced a 30-degree beam to the left or to the right of center, inclined toward the flat plate edge. The alternating pairings enabled 60-degree coverage. When a given beam reached the appropriate orientation, high power was switched to its emitter. After the powered-up beam traversed its useful 30 degrees left or right of center, the high power was switched to the next emitter in sequence. And so on: left 30 degrees, right 30 degrees, left 30 degrees, etc.
The elevation antenna was set up like a mill's water wheel, with the paired triangular plates rotating about a horizontal axis. Since every beam was 30-degrees wide, it was not possible to measure the azimuth of the target. The elevation antenna provided only information about whether a target was in the left or right half of the scanned sector. But the target's elevation was measured relatively accurately. The antenna rotated quickly, so information was updated frequently – an important condition for firm target track.
One could ask why the antenna was projecting six beams in the same direction instead of using only one beam mechanically scanning a 60-degree sector in a more conventional back-and-forth motion. The problem was that designers wanted to get a high scan rate, and the antenna assembly weighed a few tons. If such an antenna were forced to make oscillating movements, a constant antenna speed would be unattainable. The antenna would first accelerate from one extreme position to the desired speed and then would be decelerating to stop at the other extreme, only to accelerate on the way back. This very non-linear movement had to be mimicked exactly by the reference line on the radar's screen. Otherwise, errors in measurement would be created from differences between the real antenna position and the position of the screen's reference. In the B-200's accepted solution, the antenna was rotating in one direction at a constant speed and synchronized with the screen's reference, which was also the measured data used for fire control, since this was simple and accurate.
The azimuth antenna worked in a more complicated way. To work exactly on the same principle as the elevation antenna, it should be placed horizontally with a vertical axis of rotation. In this case, any time one of the six beams would be scanning the 60-degree azimuth sector from left to right, clockwise. But in such an arrangement, three of the beams would be scanning 30 degrees above ground level while the other three would be directed 30 degrees below. So the B-200's azimuth antenna was angled 30 degrees above the ground. This arrangement caused measurement errors. Below this surface, the measured azimuth was larger than reality, and the error was the greatest at the outer edges of the sector, with zero error in the middle. Above the surface of the antenna plates, the situation was the opposite: the target's real azimuth was higher than measured. The measurement error was easily corrected, as will be described later.
Both elevation and azimuth antennas were synchronized to make sure that adequate angle and distance measurement referred to the same target. Up to 20 targets could be tracked by quick horizontal and vertical sector scanning, with azimuth/distance/altitude data output updated every rapid scan cycle while at the same time up to 100 other targets could be detected. Other contemporary systems typically provided continuous narrowbeam tracking of a single target. In the B-200 radar, an analog processor projected an "artificial" track between updates, giving the track data also in a continuous way to the fire-control processor. In this complicated way, a solution was achieved in the analog and vacuum-tube era. It is only in our digital, solid-state technology era that three-dimensional, multifunction radars have achieved such track-while-scan performance.
Here is a close up of a B-200 antenna at the Russian Federation Air Force Museum in Monino. It is important to note that the unit has been incorrectly assembled for the display. The two triangular plates should form a "Star of David" configuration and should not be matching as shown here. Properly configured, the plates spin together in synch so that the beams emitted from the central unit would be directed 30 degrees either to the left or the right, providing a coverage arc of 60 degrees.
Jerzy Gruszczynski
The complicated B-200 radar was fully developed by Soviet specialists, led by Kuksenko, Beria, and Raspletin. However, German specialists also worked on parallel solutions. In the 1940s and 1950s, it was a rule that the projects prepared by German specialists forced to work in the Soviet Union were not to be fielded but only monitored for some useful technical solutions. German specialists were very rarely informed about the details of a whole program and were never provided with information about technologies or materials that were available to Soviet industry. Therefore, their projects, with a few exceptions in the field of aviation, could not be realized practically, even in the form of an experimental prototype. This was also the case in B-200 development. However, Sergei Beria did not hesitate to seek advice from captive German engineers on particular matters. At least two serious problems were solved successfully with the Germans' help.
One was related to the transmission of guidance commands to the missiles. Initially, the commands were to be sent in sequence to up to 20 missiles on the same frequency by the same powerful emitter. Every package of guidance commands was to be sent together with simple code to be recognized by a particular missile. The whole system was very complicated, and there was no provision for increasing the number of missiles attacking the same target. The Germans proposed using 20 separate transmitters working on separate frequencies. Before a missile launch, the missile's onboard receiver would automatically be set on a chosen frequency, and then all guidance commands could be transmitted at the same time. Also, the fire-control processors were divided into 20 units, each responsible for tracking a single target and guiding the missile, working in four groups of five.
Every group was attended by two operators: one responsible for automatic track supervision and the other for preparation and launch of a missile while monitoring other targets approaching the engagement zone. From one position, the two operators supervised five engagement channels, thus five tracked targets and missiles, as well as other parameters related to them. It was deemed that five engagements was the maximum for a given team. Each operator had two screens: one showing the azimuth (horizontally) and distance (vertically) and the other showing elevation (horizontally) and distance (vertically). In addition, each group had three specialists responsible for manual track mode should the automatic track fail for any reason, one each for tracking azimuth, elevation, and distance of a single target and missile. So in the case of manual-mode operations, only one target in a given section could be tracked and engaged at a time instead of five. Thus, together with a shift commander, this organization required 21 operators for a single B-200 radar, not counting technical personnel.
The other problem also involved missile control during the engagement cycle. The problem was that the processor's software algorithm for preparing guidance commands was too complicated, and the processor worked too slowly, resulting in "outdated" commands. German specialists noticed that much of the computational delay occurred when the system processed geographical-reference grids for the target and missile track. These were calculated from azimuth/elevation and distance information. The Germans proposed using angle and distance as the base reference system, which eliminated the need to recalculate them. Laboratory tests showed that the Germans were right, and the problem was solved. Such an approach also eliminated the need for correction of the measurement error in azimuth, which was mentioned earlier, since the error referred equally to the target's position and missile's position. In the other words, the missile could be accurately directed to the target-interception point because the azimuth error of the missile and target differed from the real azimuth by the same value.
The huge technical phase of the project was completed in the autumn of 1951. It was decided to build an experimental example of the radar that was not quite a prototype but something that in the contemporary Western world would be called a "technology demonstrator." Such a demonstrator was constructed in Kratkovo (presently Zhukovsky), at the edge of LII's (Flight Research Institute) airfield. The airfield hosted a large number of flights of the most modern types of aircraft in the Soviet inventory and so offered the unique opportunity to test the experimental B-200 radar against all of those targets, deemed as being the future of military aviation.
A 217 or 217M missile and the improperly displayed B-200 radar antenna at the Monino Air Force Museum near Moscow. Powerful A-100 radar sets provided targeting information for the B-200 fire-control radar sets deployed with each S-25 regiment. The basic SAM unit was to be formed as a SAM regiment, with 56 regiments in total. Each regimental fire-control center had four teams of operators, each responsible for managing up to five targets and missile attacks.
Jerzy Gruszczynski
The experimental radar's components were built mostly by KB-1's facilities. Other factories built only a few elements. The largest and most important elements ordered externally were the antennas, which were produced by No. 701 State Factory in Podolsk. The experimental radar was not a complete B-200: for example, only some of the tracking/guidance channels were operational. For initial tests, a lot of specially developed simulation and test equipment was used. About 400 meters from the radar a 40-meter-high tower was raised that supported a missile's receiver and transponder. Both were connected to simulation equipment, working in a circuit. The receiver passed guidance commands to an analog, vacuum-tube, mechanical-servomechanism-based "computer," which calculated the expected position of the missile and sent data to the radar via cable. The radar tracked the transponder on the tower, but in some tests, the transponder input was replaced by missile-position data provided by the "computer," which calculated expected virtual missile position on the basis of guidance commands sent by the radar. In this way, the track and guidance sequence could be checked without actually launching any missiles, which were not available at this time. This is one of the early examples of computer modeling and simulation.
In December 1954, Premier Khrushchev ordered the establishment of the 1st Special Purpose Army of the Soviet National Air Defense Forces. The army's primary asset, the S-25 surface-to-air missile (SAM) system and its V-300 missile (shown here), was only just being deployed. The 1st Special Purpose Army remained operational until 1994, when the last of its S-25 systems was withdrawn from service. Since that time, Moscow has been defended by four air-defense brigades, each fielding eight S-300PT and six S-300PM battalions. These units will soon be replaced by about 20 S-400 battalions.
Almaz
In the spring of 1952, the B-200's design was refined to the point where a decision was made to proceed with a so-called "test radar," which today would be called a "full-scale development" example. At this stage, it was decided to prepare the selected Soviet factories for series production of the system components and involve them in construction of the test radar. State Factory No. 304 in Kuntsevo, near Moscow, would be the main contractor and would be responsible for final assembly of the radar. Since June 1945, the former ammunition factory had been involved in the production of the SON-series of anti-aircraft-artillery (AAA) fire-control radar and the PUAZO AAA electro-mechanical fire calculator. Presently, the factory is known as AOOT Moscow Radio-Technical Factory. During its history, the factory has produced fire-control radar sets for the S-75 (SA-2), S-125 (SA-3), S-200 (SA-5), and S-300 (SA-10) systems, and presently is producing radar sets for export S-300PMU and for Russian S-400 systems.
Missile Development
The Soviet Council of Ministers entrusted the development of a missile for the Berkut system to OKB-301 at Khimki, near Moscow, in August 1950. By March 1951, an initial design of the V-300 missile was presented for approval, which was quickly granted. At the same time, the first live engine trials were conducted on a test stand in Zagorsk. This was Isayev's SO8.2 engine that used pressurized air to push fuel and oxidizer into the gas chamber of the engine (VAD system) and generated 8,000 kg of thrust.
The first V-300 missiles, called "article 205," were delivered to the Kapustin Yar shooting range in early June 1951. The first unguided launch with a stabilized autopilot took place on June 27. However, the first launches were not successful. The missiles went out of control and crashed prematurely. During one launch, a fallen missile damaged the barracks where the engineers and technicians were living, but fortunately they were empty at the time. The problem was soon located: there was an error in the electrical scheme of the autopilot. The error was actually discovered by two old German engineers working at KB-1. Normally, German engineers were not allowed to be so close to the Soviet's most secret works, but KB-1 had "special" status. After the correction was implemented, the subsequent launches were mostly successful. Through the end of September 1951, a total of 30 launches were conducted.
Work on the missile accelerated in September 1951. It was concluded that more guidance and control specialists were needed at Lavochkin's OKB-301, so 14 guidance-system specialists, led by Georgiy Babakin, were transferred from NII-88. At the same time, Petr Grushin became Lavochkin's deputy.
The second phase of missile tests started in March 1952. The missiles were equipped with the SO9.29A engine delivering 9,000 kg of thrust, developed by A. Isayev at Lavochkin's request. During these tests, trials of the command-control system were also conducted. No real target was involved, though. The goal was simply to guide a missile into a certain point in space. Missiles in flight were tracked by SON-4 AAA fire-control radar. The next part of these trials was conducted with the use of the test example of the B-200 radar. Attempts were undertaken to track launched missiles, but five attempts all failed. The radar initiated contact with the missiles' transponders and tracked them while they climbed vertically, but every time the missiles started to turn towards the targets, the track was lost. The transponders were carefully checked, but all of them were fully functioning. The radar was also tracking all other targets – just not the transponder-equipped missiles after they turned! Nobody could figure out the nature of the phenomena.
As it turned out, the problem was simple. The missile was disappearing in a cloud of ions created by the rocket engine's flames. Increasing the transponder's power output solved the matter as far as the test series was concerned. Ultimately, tuning changes to the transponder frequency cured the problem for practical use. During the second phase of missile and radar tests, completed in September 1952, 31 launches were conducted. More than half of these were successful. Still, a lot of work remained ahead for the design teams.
The last phase of the factory-testing program was the most complex and the longest part of the Berkut system trials. In this phase, all of the system elements were being tested together, with live firing and missile control by the B-200 radar system. Test shots were made against virtual targets generated artificially on the screen by a special simulator, against radar reflectors dropped on parachutes, and against unmanned radio-controlled target drones converted from Tu-4 bombers. Altogether, 123 launches were carried out from Oct. 18, 1952, through September 1953.
At that time, there were no specialized drones available and the aforementioned aircraft targets were only provisionally equipped with a radio receiver that controlled the bomber's standard autopilot. The autopilot could stabilize barometric altitude and magnetic heading. The control aircraft could change a target's heading and the altitude by radio, but the "drone" had to take off as a manned aircraft. The pilots of Tu-4 targets performed manual take-off and flew to the designated test zone together with the controller aircraft. When all was ready, the crew engaged the autopilot and ejected. The ejection seats were not standard equipment on the Tu-4 but were mounted for the test series because the crew had to stabilize speed above 500 kmph before leaving the aircraft. This was too fast for a safe bailout from the standard hatches. It should be pointed out that early ejection seats used explosives – like artillery shells – and were neither as safe nor as reliable as modern rocket-powered ejection seats. Crews for these manned drones were offered substantial financial rewards to undertake the risk and the shock attending these sorties, but there were few crewmembers who withstood more than two or three ejections.
The first radio-controlled Tu-4 was shot down by the Berkut system on April 26, 1953. The aircraft fell relatively close to all of the people present on the spot, among them designers, engineers, technicians, and government representatives. Many of these people rushed toward the crash site, where the wreck of the aircraft was still burning. When the crowd reached the wreck, there was suddenly a loud explosion that threw everybody to the ground. Luckily nobody was seriously injured, but approaching downed aircraft in the future was strictly forbidden.
Through the end of September 1953, a total of five Tu-4 radio-controlled aircraft were shot down by the Berkut system, which would receive the designation S-25. Many parachute target reflectors were "hit" as well. Among the 123 fired missiles, there were also 13 of the first series-production missiles produced by No. 82 State Factory in Tushino, near Moscow. Everybody expected a decision accepting the system into service. However, that did not happen just yet.
