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P-3 Pegmatite-3 / DUMBO

Many sources report the Soviet RUS-2 radar was code-named DUMBO. But RUS-2 was a highly mobile ground radar developed early in the World War II period. The complete equipment consisted of two trucks or one truck and a trailer. One vehicle contained the radar equipment and its operators, the other housed the generators. In addition to its high degree of mobility and aptness for concealment, the RUS-2 was a very simple form of radar and already obsolete by Anglo-American standards during the 1945–1950 period. The primary disadvantages of the RUS-2 were its inaccuracy in measurement of range and bearing, its lack of height-finding capability, and its poor range against low-flying aircraft.

P-3 was the first Soviet radar unit to the determination of 3 coordinates, built at the end of the Great Patriotic War. The work on the order was entrusted to the Moscow Research Institute-20, an organization established in 1921 as a Special Technical Bureau and engaged in special-purpose military inventions.

The resolution of the State Defense Committee of March 20, 1943, in addition to the radio range finder for the MZA, provided for the development of a new early-warning radar at the Research Institute of the Radio Industry. The need for such development was dictated by the following reasons:

  1. Stations RUS-2 and RUS-2s were created for VNOS service. But the experience of the war showed that they carried the service of early warning, both as an air defense fighter aviation guidance station, and in some cases as a target designation station FOR.
  2. As a guidance station and target designation RUS-2 and RUS-2s did not fully meet the requirements for the accuracy of determining the coordinates and areas of coverage.
  3. The experience of design and production accumulated during the years of war allowed to increase the operational reliability and simplify the maintenance of the station.

The tactical and technical requirements for this station were developed by NIIIS KA and approved by the command of the air defense forces. The requirements for a new radar were developed by the army and approved by the Kremlin. (Requirements: detection of aircraft not less than 130 km, reaction time not more than 25 seconds. Range in azimuth 360 degrees, range in elevation 4-18 degrees. Accuracy in azimuth max 650 m. Accuracy in range not more than 700 m .) The constructors were the design office engineers at plant No. 197 known as the plant of Vladimir Ilich Lenin in Moscow. (The radiolocation department of the plant, was transferred to Nizhny Novgorod and there functioned as the Institute of Radio Engineering - NNIIRT). Work on the radar lasted from the beginning of 1946, and for production and arming the P-3 radar came in 1947.

In May 1943, the research institute began to develop, and soon created the "Biryuza" radar. This system had a number of flaws, and on its basis a more advanced radar P-3 was created. The first tests of the station were carried out in August 1944. In 1945, the RLS was adopted by the Red Army. M. S. Ryazansky, Yu. K. Adel, I. N. Antonov, P. M. Belov, S. Ya. Boguslavsky, R. S. Budinov, S. P. Volman, A. R. Volpert, S. P. Zavorotishchev, L. V. Leonov, S. P. Piksotov, P. V. Podgornov, B. P. Terentyev, A. I. Uzkov, L. V. Shulgin, V. F. Shumskikh. In 1947, it was commissioned and the production of the radar version on vehicles, called the P-3a, began.

The research institutes successfully completed the development and from July 20 to August 15, 1944, the P-3 station passed factory tests near Moscow, which confirmed that the radar complies with the specified customer requirements. GAU, without waiting for the final refinement of the station and its field tests, made a proposal to VKS on the production of an experimental batch of the radar station in the same year. The State Defense Committee accepted the proposals and ordered the scientific research institute to release 14 sets of P-3 station in the fourth quarter of 1944. The ground tests of the P-3 station, carried out at the NIZAP GAU (test engineer G. T. Opryshko) in January-February 1945, confirmed the positive conclusions of factory tests near Moscow and showed good results. Later, the technology was transferred to the Gorky Plant imeni V.I.Lenin for serial production of the product, which was later used in the Korean War.

The radar station was called “Pegmantit 3” - or abbreviated for P 3. There were two modifications: a mobile (P-3M) and a fixed site (P-3A) version. The mobile version was built in containers on two trucks. The transmitter and and the receiving system were put in a separate container. The display still was an A-scope.

The stationary version P-3A and mobile P-3M were produced (In the set there were two cars). The radar has a separate transmit and receive antenna. The receiver's antenna consists of two antennas placed one above the other. The phase difference between the top and bottom of the Yagi antenna was used to calculate the angle of inclination, which can then be used to determine the target height of the detected object.

An approximate definition of the azimuth was made in the usual way - by the maximum amplitude of the signal from the antenna aimed at the aircraft. In the mode of accurate determination of the azimuth due to the action of the antenna switch and the interconnection of both parts of the azimuth antenna in protvvazhase on the screen of the marker when the system was oriented at the target, two pulses of equal amplitude, spaced apart on the scale; when the target left or right about the axis of the antenna, one pulse increased, and the other decreased.

To determine the flight altitude of the aircraft, a system was used consisting of two “wave channel” antennas installed at different heights from the ground surface (7 and 11 m). Each of these antennas through its feeder was connected to the station's equipment through a special goniometer. The resulting directivity characteristic of both antennas in the vertical plane depended on the position of the goniometer slider.

The elevation angle of the target was determined by the loss of signals at the time of moving the goniometer slider (zero radiation and reception). The distance and the found elevation of the place were used to determine the altitude of the target using a nomogram. The control of the directivity pattern of antennas in the vertical plane made it possible not only to determine the flight altitude, but also to eliminate the dead observation zones within fairly wide limits. The simultaneous use of the goniometer during transmission and reception made it possible to double the peleigational feeling of the station.

If the display is an A-scope only, this radar cannot rotate quickly. It has to be assumed that the turn was manually carried out (like a direction findig equipment by radio-monitoring). Otherwise the given accuracy in azimuth isn't concurring with the poor antenna gain of a single pair of Yagi-antennae to be expected.

The elevation angle was determined with a so-called “Goniometer” in older Russian VHF radars (e.g. the “Knife Rest” series). For this the radar unit has got two antennae (or groups) one above the other. The phase difference between the antennae is the measure of the targets elevation angle. The Goniometer produces a standing wave of the received RF impulses on two slip rings fed by the two Yagi- antennae. Two simultaneously moving measuring contacts on the slip rings measures the voltage difference between the slip rings. This voltage difference gets the value zero in a certain position. The mechanical angle of this position corresponds to the elevation angle of the target. With a nomograph the elevation angle could be converted to a height value in connection with the measured range.

The Dumbo radar was first reported in 1946 and represented an improvement over the RUS-2 (1943) in range and accuracy. Although not mobile the set was easily transportable. This set was also easily concealable and was often erected in wooded areas with only aerials clear of the tree tops. Dumbo proved to be the primary post–World War II early warning radar. However, this system was quickly followed by a family of radars characterized by metric frequency, the use of Yagi antenna, goniometric techniques and nearly identical transmitters.

The first B-29 Ferret represented a significant technological advance over previous jury-rigged aircraft. Officially designated “B-29 No. 812,” and nicknamed Sitting Duck by its crew, the B-29 Ferret probed the Siberian coast for signs of Soviet radar. From 11 June to 21 August 1947, the Sitting Duck flew nine reconnaissance sorties, first along the northern coast of Siberia and then along the southern edge. Before the Ferret flights, the Air Force had no information on Soviet radars in this area. After the B-29 Ferret exploration, the crew uncovered a chain of scattered Soviet RUS-2 early warning radars along the southern periphery of the Soviet Far East and the absence of Soviet radars along the USSR’s Arctic coast.

USAFE utilized the B-17 Ferrets as the nucleus of an ongoing ELINT program. Designated the 7499th Squadron, the Ferrets flew roughly three missions a week along the borders of Soviet-occupied Germany and Austria and over the Baltic Sea. These initial electronic reconnaissance sorties proved useful in assessing Soviet radar capabilities along the East-West frontier. They determined that the Soviets employed a small number of 70 MHz early warning radars of Russian manufacture, nicknamed “Dumbo,” with a range limited to 100 miles. Only operating between six and 12 sets at a time, the Soviets periodically shifted locations to mask their limited capability.

For the final 18 months of the Korean War, growing Communist radar defenses threatened USAF strategic air operations in Korea. The total number and sophistication of the Soviet radar net increased significantly. By December 1951, 13 RUS II (or “Dumbo”) radars operated in the Sinuiju to Sariwon, Korea, area alone.

The P-3 radar quickly got old and was replaced with the more handy P-8 radar.

TypeRadar station
country USSR
Start of production1944
Frequency VHF–Band
Frequency range75 MHz
Pulse duration12µs
pulse repetition time (PRT) --
pulse repetition frequency (PRF) --
pulsewidth (t) --
receive time --
dead time --
peak power 55 kW - 80-100kW
average power --
instrumented range 120-160 km
range resolution 2.5 km
azimuth determination1.3°-4°
range determination 850m-1.5 km
height determination 1.5
beamwidth 24°
hits per scan --
antenna rotation --
P-3A Radar

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Page last modified: 22-07-2019 18:27:15 ZULU