Radar – The Soviet Union WWII Part II

In 1938 the first Soviet Pulsed Radar station was tested. In the end of 1939 the development and the test the RUS-2 were concluded. With It aircraft could be located up to 120 kms with a maximum height up to 7 kms.”Redoubt” = mobile station.

When the Luftwaffe opened the Great Patriotic War by destroying a substantial fraction of Stalin’s air force, it was unhindered by Soviet radar. There was only one kind of radar in use when the conflict began: RUS-2, the pulse-type air-warning equipment working on 4 m. That statement discounts completely the few units of the radio screen, RUS-1, the production version of Oshchepkov’s Rapid of 1934, for which the war found no use; yet despite its complete failure during the Finnish War of 1939-1940, 13 RUS-1 sets were manufactured in 1941. RUS-2 proved of value as an air-warning set but suffered from the need to have transmitter and receiver separated by about a kilometer, the antennas of which had to move synchronously. There were six sets in existence when war broke out, but they had no effect on events. The Scientific Research Institute of the Radio Industry (SRI) had devised how to use a common antenna before the war began and had incorporated it into the modification, RUS-2S, but production had not yet begun. 

The radar groups in Leningrad (LFTI, NII-9) and Kharkov (UFTI) soon found their principal problem was evacuation to the east, both of development laboratories and production plants, a process that removed five months of any useful activity. The death in March 1940 of Professor M A Bonch-Bruyevich, who had taken over the leadership of NII-9 after the purges added to the turmoil with which that group had had to deal. The production of only 53 RUS-2S sets during 1942 tells the story more eloquently with numbers than is possible with words. 

The Soviet dismissal of radar at the beginning of the war was not reflected in their other attitudes concerning AA defense. Large cities had hundreds of guns, although their accuracy was poor [4]; the fighter squadrons were based at all-weather fields, much superior to the usual Soviet bases. Moscow was the best defended city in the world and, despite its proximity to the ground fighting, did not suffer serious damage from bombing. Besieged Leningrad suffered in every possible way, but it too put up a very strong air defense. Not surprisingly, the first effective Soviet use of radar was in augmenting the defenses of Moscow and Leningrad. 

An experimental station at Toksovo near Leningrad, used before the war by the Physico-technical Institute (LIPT), assumed immediate tactical functions and was manned by members of its technical staff. Its equipment was RUS-2 but with more power for greater range. Transmitter and receiver were mounted on separate 20 m steel towers; antenna movement allowed a 270° sector of observation. Operation was turned over to military personnel once they had been trained. 

The Research Institute of the Red Army (NIIIS KA), which had overall responsibility for radar, built in the first months of the war a large station for the Moscow air defense, which also used the RUS-2 principle. Specifications differ enough from those of other air-warning sets to be of interest: pulse duration 5060 µs, which allowed a receiver pass-band of only 40 kHz and a repetition rate 50 Hz. It mimicked CH in more than pulse rate, for it too used special demountable vacuum-pumped transmitter tubes; they were designated type IG-8 and made by the Svetlana tube plant. 

Leningrad received numerous air attacks, generally by formations of about 100 aircraft. In 1942 there were 38 such bombings, all of which were stoutly resisted. Radar’s performance opened the eyes of theretofore uninterested military leaders, as 20 000 targets were picked up that year. Attacking squadrons showed up on oscilloscope screens in plenty of time to alarm the city and scramble fighters. On a small scale the air defense of Leningrad was similar to the Battle of Britain, and by the end of 1942 the radar men did not have to beg for attention even though they had to beg for production. RUS-2 and RUS-2S gained reputations as simple, reliable pieces of equipment if only they could have given height information.

The poor showing of early Soviet gun-laying radars did not eliminate this type from the minds of designers, and NII-9 organized an experimental battalion-sized AA unit in October 1941, employed in the defense of Moscow while trying out its new equipment. Initially the battalion had four 75 mm, six 105 mm (German guns obtained during the time of the non-aggression pact) and six 37 mm automatic guns. A team of engineers headed by M L Sliozberg worked directly with the unit. They introduced some experimental sets, Sleep, B-2 and B-3 that worked on 15 cm using cavity magnetrons. The possession of the cavity magnetron, viewed in Britain and America as the ultimate microwave transmitter and the basis for uncounted radar successes in the coming years, seemed to hold no advantages for the Soviets. They were unable to produce a transmitter or local oscillator with sufficiently stable frequency to allow the construction of a heterodyne receiver, which was presumably attempted without a crystaldiode mixer. These gun-laying sets were failures and soon disappeared from the experimental battalion’s gun positions. 

The arrival of British GL mark IIs produced much more interest than the experimental microwave sets. It was not much of a gun-laying set, to be sure, but it was a robust, reliable and well-engineered piece that found use for searchlights, fighter direction and even air warning. The British technicians who had been sent to instruct the Russians, and who had been led to believe that radar was unknown to the recipients, encountered personnel who mastered the equipment rapidly despite a significant language barrier. Sliozberg’s people soon made a copy of it, called SON-2. It proved the favorite Soviet radar, but British imports of GL mark II (generally called SON-2) overwhelmed native production, which produced only 124 during the entire war. 

Later Britain sent 44 microwave GL mark IIIs and America sent 25 SCR-268s, 15 SCR-545s and 49 of the superb SCR-584. A copy of GL mark III appeared as Neptune, and the 584 was copied after the war as SON-4. 

In the summer and fall of 1941 Stalin’s gigantic army and air force suffered a defeat coupled with losses of men and material of magnitude unparalleled in history, but as Hitler’s forces stood before Moscow, everything changed in an almost miraculous manner: (1) Japan was suddenly found to be completely occupied with America and Britain, thereby freeing many fresh Siberian divisions to board trains headed west; (2) the Russian people, who may have been originally indifferent to the downfall of the communist state, had come to realize that the war was against them, not just Stalin; (3) Hitler had also conveniently declared war on the United States, which was to prove a serious distraction for the Nazi state; (4) a Wehrmacht without winter clothing or equipment had been assailed by a winter as deadly as the enemy. In January 1942 Germany found herself in total war, a discomfort theretofore left to her adversaries. Only then did German total mobilization begin. 

During the intoxicating summer of 1941 radar had been, if anything, even less important to the Germans than the Russians. The new weapon, so important in the west, was ignored in the east. The Luftwaffe dominated the air and found little need for equipment in short supply and required for the defense of the Reich against Bomber Command. There had been use of Freya sets before the surprise attack of 22 June to ensure that no Soviet observation planes discovered the large assembly of forces, but few of the clumsy Freyas followed the Blitzkrieg. 

The Soviet air force had to make its recovery in the face of German air superiority, but its slow progress called for correspondingly increased vigilance by the Luftwaffe. A measure of Russian progress can be found in the extent of German radar deployment. As Leningrad became besieged, the air struggle there became more advanced, and Luftwaffe Signals set up Freyas on the islands of Hiiumaa and Saaremann, located to the west of Estonia, to protect German shipping from air raids. A Freya unit covering the south approaches of Leningrad found movement of the set in the terrible winter retreat of January 1942 so difficult that it had to be destroyed. 

In 1941 radar was closely associated with strategic bombing, and its use with and against tactical ground forces lay a few years in the future. The steady growth of Soviet power came from factories beyond the range of German bombers, and the railway network continued to distribute supplies and troops, hindered but not brought to collapse by air raids. The four-engine bomber that General Walter Wever had favored to attack these resources was absent and not going to appear. 

An early German use of radar came from an unexpected quarter-partisan warfare. When it became clear that Germany was the enemy of all those Soviet peoples that did not have some ethnic status that made them acceptable to the Nazis, partisan groups began to make no small amount of trouble behind the German lines. Made up of soldiers cut off but not taken prisoner and civilians escaping and fighting SS terror, these groups were organized and maintained by the Soviet command. Night flying served as the means of bringing vital supplies and officers to these units and the carrying out of information and wounded. Soon an elaborate air transport was established at night. Combating these infiltrating flights proved difficult, in great part because of the primitive Russian equipment used. The most important aircraft was a biplane, paradoxically designated the U-2. Flying slow and low and necessarily observing strict radio silence it was difficult to detect. Radar was obviously called for, and it came as railway radar trains, but an effective counter to the U-2 was never found. 

Russia’s notoriously muddy roads made movement by rail essential for heavy equipment a Freya required 28 horses for movement by typical road and radar trains were the obvious answer, first placed in service in October 1942. They were portable fighter control units that consisted of a Freya for early warning and two Würzburg giants, one to track the enemy and the other to track the interceptor so the controller could bring the two together. Some trains made good use of searchlights. It was the system called Himmelbett in the west. As the air situation deteriorated for the Luftwaffe, the radar trains became more numerous and more important. In 1943 a radar train in the Orel-Bryansk sector took credit for bringing down about 30 planes. 

 (The first radar trains may have been placed in service somewhat earlier in France during the summer of 1942. By that time the activities of the underground were beginning to be troublesome, and light aircraft transported agents and supplies between the continent and England. Finding the resistance personnel was more important than bringing down the airplanes, so railway-mounted equipment that could be moved to suspected places of operation in order to observe where they landed was an obvious answer. It is reported to have led to several arrests.) 

Growing Soviet air power began forcing the Luftwaffe to bomb at night, and their efforts had grown to such an extent that the Soviets began organizing night fighter units in late 1943. These units were not particularly effective because they lacked both airborne and ground radar capable of bringing about interception. 

The absence of strategic bombing in the east meant there was no centralized air defense, so radar use on both sides tended to take on local character and ingenuity. A German bomber group at Shitomir (near Kiev) used two Freyas for night bombing Russian concentrations at locations beyond artillery range. One Freya directed a bomber by radio so as to follow an arc of constant radius while the second controlled the release of bombs. The attacks were not only complete surprises but remarkably accurate.

By the time of the great tank-air battle at Kursk during 511 July 1943 the Soviet air force was something that had to be dealt with, and the Germans assigned five of the nine then existent radar trains to the sector. The Wehrmacht lost decisively. The wreckage of hundreds of aircraft and tanks littered the field, but one Freya was credited with saving Fliegerkorps VIII from complete destruction.

Any Soviet use of radar at Kursk has escaped mention in the sources available. Indeed, Soviet use of radar in general was hardly noticed by the Luftwaffe until 1944 and never reached the stage where countermeasures were employed. They seem to have thought all of the enemy’s radar was of British or American manufacture and been unaware that any of the Russian equipment was of indigenous manufacture. 

German radar found ever wider use on the Eastern Front as ever more equipment became available and the pressure of Soviet air power increased and not just Soviet. The oil fields of Rumania received a generous allotment of AA and fighter units and with them came Freyas and Würzburgs for Flak and fighter control. Their effectiveness is attested by the heavy losses of the American bombers that attacked Ploesti. The saving or at least preventing the capture of the extensive radar deployment in Rumania became a matter of serious concern when Russian forces secured that nation in August and September 1944. 

Such was radar in the east. Compared with the use in the west and at sea it was small indeed, being a mere perturbation on the cataclysmic battles that were fought there. Germany’s deployment was, until near the end, trivial when measured against the air defense system facing the Allies. Russia used it first only in defense of her two largest cities, to what effect it is difficult to say. In the east huge ground forces struggled with air power restricted to army support. It was not until the appearance of remarkably accurate 10 cm equipment, such as SCR-584, that radar showed real value for this kind of warfare. In the hands of ingenious officers the equipment could be of benefit, especially to local fighter squadrons, but these contributions were never decisive. The actions in the deserts of North Africa are apt illustrations of this. Given this tactical background it is difficult to fault the Soviet command for not giving radar a greater priority. Were it not for their demonstrated capacity for confused and self-destructive administration, one might be tempted to attribute wisdom to the Soviet leaders for the low priority given radar. But whether from wisdom or folly, there is little reason to fault the result. The critical industrial strengths required for the manufacture and operation of radar were put to better purpose in communication equipment vital to mobile ground warfare. 

The quality of Soviet radar development before and during the war must be evaluated by what was accomplished against what was attempted. Here is a bewildering confusion of competence at its highest and lowest. Soviet engineers invented the cavity magnetron, a device for which praise in Britain and America exceeds that for any comparable device. That not being enough they invented the klystron independently of the Varians and Hansen. But their attempts at putting them to use failed, owing to an inability to master the lesser arts of microwaves, and resulted in an especially bad gun-laying set that was never produced. The klystron does not seem to have entered a serious Soviet radar design. In meter-wave equipment the advantage of an early entrance was lost. Postwar design started from Allied and captured German sets.

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