USSR / Russia
In our country, work on the installation of radars on combat aircraft began in the pre-war period. However, the realization of the need for radar patrol aircraft did not come immediately, and the first stations were intended exclusively for searching for enemy bombers at night. In the first half of 1941, a prototype of the first Russian airborne radar, named "Gneiss-1", was created at the Research Institute of the Radio Industry. This 10 kW station operating in the 200 MHz frequency range was still very imperfect. Since the weight of the radar equipment was approaching 500 kg, its installation on a single-engine fighter was excluded. It was decided to install a radar with external antennas of the "wave channel" type on twin-engine Pe-2 and Pe-3 aircraft.
The device for displaying radar information ("circular marker"), which made it possible to determine the distance to the target and its position, and the operator, who had the controls of the radar station, was placed in the navigator's cockpit. The hardware part took the place of the gunner-radio operator. In the summer of 1942, state tests of an improved version of the "Gneiss-2" took place on the Pe-2 aircraft. Although the station refused every 5-6 flights, its tests were considered successful.
Radar equipment set "Gneiss-2"
A bomber-type target with a flight altitude of not less than 2000 meters could be detected in a sector of about 110 ° at a distance of 300-3500 m with an accuracy of ± 5 ° in angular coordinates. Military tests of the Pe-2 with a radar took place in the winter of 1943 in the 2nd Guards Air Defense Corps near Leningrad, after which serial production of the station began. During the war, the industry produced 320 sets of Gneiss-2 radar equipment. A number of sources say that heavy fighters with radars were used near Stalingrad against German transport aviation, which was supplying the surrounded German troops, but, unfortunately, the results of the combat work of fighters equipped with radars could not be found.
Pe-2 with radar "Gneiss-2"
In 1943, an improved version of the "Gneiss-2M" was created, on which, in addition to improving reliability, it became possible to detect surface targets. In addition to domestically produced aircraft, American Douglas A-20G Boston, supplied under Lend-Lease, were equipped with radars. Compared to Petlyakov's machines, the Bostons had better flight performance, and at the end of 1943 two regiments of long-range fighters were formed on the A-20G.
A-20G
Aircraft with Gneiss-2 radars were also used during the war in mine-torpedo aviation regiments to detect enemy ships at night. These were both Bostons and Russian Il-4T torpedo bombers. On Ila, the transmitting antenna was mounted in place of the ShKAS bow machine gun, external receiving antennas were placed along the sides of the fuselage. The radar operator sat in the place of the radio operator, due to which the defensive capabilities of the Il-4T with the radar were significantly reduced. In addition, with a low detection range, the station, which did not work very reliably, required qualified maintenance and tuning. All this largely depreciated the ability to search for targets at night, and therefore the Ilov crews perceived the new technology without enthusiasm.
The creation of a full-fledged airborne radar patrol complex in the USSR began in the mid-50s, when the USSR air defense forces needed to push back the detection line of enemy bombers, thus ensuring timely notification and target designation for air defense systems and interceptors. This primarily concerned the northern regions of the European part of the USSR. At the same time, in the Soviet Union, unlike the US Barrier Force, long-range radar patrol aircraft were never considered the main means of detecting air targets.
The first Soviet AWACS aircraft was supposed to be created on the basis of the Tu-4 long-range bomber, but things did not progress beyond the projects. Subsequently, the long-range Tu-95 bomber, which was put into service in 1956, began to be considered as the base platform. However, after analyzing the options for aviation radar equipment, which the Soviet radio-electronic industry could quickly create, this was abandoned. The fuselage of the bomber was too narrow to accommodate a bulky radar complex on vacuum devices, communications equipment, work and rest areas for operators. In this case, the USSR simply did not have a suitable aviation platform for powerful radars designed according to terrestrial standards.
In this regard, specially for use on an AWACS aircraft on the basis of the P-30 radar, by 1960, an aviation all-round radar "Liana" with acceptable weight and size characteristics was created. According to the data declared by the developers, the radar with a horizontal rotating antenna could, depending on the height and size, detect air targets at ranges from 100 to 350 km and large surface targets at ranges of up to 400 km. The station was originally created as part of the aviation complex. Primary data processing was carried out on an onboard computer. The transmission of the received radar information was to be carried out in encrypted form by telecode equipment, to ground control points located at a distance of up to 2000 km. The avionics also included an electronic reconnaissance station capable of detecting an operating radar at a distance of up to 600 km.
The design of the radome of the radar antenna of the Tu-126 aircraft
In turn, the specialists of the Tupolev design bureau decided to design a radar system based on the recently created passenger Tu-114, which was a development of the Tu-95 bomber. Unlike its "ancestor", the Tu-114 had a larger diameter and volume of the pressurized cabin. At the same time, it was possible to solve the problems: placement of equipment, provision of cooling of individual units, the possibility of inspection and repair of equipment. On board there was space for two shifts of operators and technicians, places of rest and eating. Compared to the passenger car, the internal space of the AWACS aircraft has undergone a rearrangement and was divided into a larger number of compartments. The number of windows has been significantly reduced. Instead of the usual one, they used special lead glass, which was dictated by the need to implement measures to protect against high-frequency radiation. In the event of an emergency, the crew could leave the aircraft through a special hatch in the floor of the first compartment, as well as through the niche of the front landing gear support in the extended position, which was not provided for on the passenger airliner. The engines remained the same - 4 turboprop NK-12M.
Great difficulties arose with the placement of the disk-shaped radar antenna, rotating at a speed of 10 rpm, on a pylon with a height of 2.6 meters. For this, a unique bearing with a diameter of 1200 mm had to be created. In order to compensate for the disturbances introduced by the antenna with a diameter of 11 meters, an additional keel-ridge of a large area was fixed under the aft fuselage.
Tu-126
The first flight of the experimental Tu-126 took place on January 23, 1962. In November 1963, without waiting for the test results, the aircraft was launched into series. The official adoption of the Tu-126 AWACS took place in April 1965. In the same year, the Air Force began to receive production vehicles.
In total, taking into account the prototype, nine Tu-126s were built until 1967. Serial aircraft, in addition to the in-flight refueling equipment, differed from the first copy in the composition of the communication equipment and the automatic ejection of the dipole reflectors. On the last three aircraft, the REP SPS-100 "Reseda" station was installed in the elongated tail section. To determine the location of the aircraft by the sun, the star-solar orientator BTs-63 was used. The optical heads of this device were located in a fairing, which protruded as a small hump above the first compartment.
An aircraft with a maximum takeoff weight of 171,000 kg could stay in the air without refueling for 11 hours. The duration of the flight with one refueling increased to 18 hours. At an altitude of 9000 meters, the maximum speed was 790 km / h. Cruising speed - 650-700 km / h. The service ceiling is 10,700 meters. The aircraft crew was divided into flight and radio engineering groups. The flight group consisted of two pilots, two navigators, a radio operator and a flight engineer. The second group consisted of a targeting officer, four operators and a radio equipment repair specialist. During long flights, the crews were duplicated and worked in shifts. In total, 24 people could be on board.
The information received was transmitted via closed telecode communication to radio centers near Arkhangelsk and in Severomorsk, and then to the central command post of the USSR air defense. By radio, it was possible to simultaneously transmit the coordinates of 14 air targets. At the design stage, it was planned to pair the data transmission equipment with the automatic target designation system of Tu-128 long-range interceptors. However, it was not possible to bring the equipment to a working condition, and guidance was carried out only in manual mode - 10 fighters for 10 targets.
The working conditions of the flight and radio technical staff on the Tu-126 were very difficult. High-frequency radiation had a detrimental effect on the health of the crew. Due to the strong noise, the operability of the operators dropped after 3-4 hours. People were forced to stay for a long time in a "metal box" with poor thermal and sound insulation under the influence of strong electromagnetic fields. When flying in high latitudes, the crew put on special rubberized marine life suits that protected them from hypothermia in icy water.
After being put into service, the serial Tu-126s entered the 67th separate AWACS aviation squadron at the Siauliai airfield (in Lithuania). After the commissioning of long-range reconnaissance aircraft Tu-95RTs, the task of monitoring the sea water area from the crews of Tu-126 was removed. The main work of the crews was the detection and guidance of air targets and the conduct of electronic reconnaissance. The Tu-126 did not conduct constant round-the-clock combat duty in the air, although there were always aircraft prepared for departure.
Most often, radar and electronic reconnaissance was carried out in the waters of the Kara, Barents and Baltic Seas, in the vicinity of the islands of Gotland, Franz Josef Land, Bear and the Novaya Zemlya archipelago. Sometimes flights were carried out "around the corner" - along the northern and north-western coasts of Norway. Aircraft combat duty in the North was carried out in the interests of 10 separate air defense army of the USSR, and Severomorsk and Olenegorsk were often used as combat duty airfields. Sometimes Tu-126s cruised along the western borders of the USSR to the Black Sea. Also during the exercises, AWACS aircraft flew to the eastern part of the country. The patrols were carried out at an altitude of 7500-8000 meters. The usual duration of the raid was 8-9 hours.
There are cases when planes flew into the airspace of a number of Scandinavian countries and even Great Britain. They repeatedly met over the sea with American aircraft carrier strike groups.
The aircraft, which received the NATO designation "Moss" (eng. Moss), attracted keen interest. The ability to hang in the air for a long time, a fairing with an 11-meter rotating antenna, powerful high-frequency radiation from the radar and intense radio communication with ground control points testified that the Soviet Union managed to create a machine, which had no analogues in the West until 1977. In addition to the interest of Western intelligence services, foreign buyers of Soviet weapons were actively interested in the AWACS aircraft. So, according to American sources, Indian representatives came out with a proposal to lease the Tu-126 during the armed confrontation with Pakistan in 1971.
From the first half of the 70s, the crews of the Tu-126 had to carry out very risky missions. Since NATO aviation, in connection with the strengthening of the Soviet air defense, switched to low-altitude flights, AWACS aircraft dropped to an altitude of 600 meters. This had to be done in order to steadily see and track targets flying above the horizon. At the same time, the detection range and the time spent by the Tu-126 in the air were significantly reduced. Fortunately, for 20 years of service, not a single disaster happened, although there were prerequisites for this. So, in June 1981, due to incorrect actions of the pilots, the Tu-126 entered a dive and nearly crashed. The aircraft was leveled at an altitude of about 2000 meters. On their return, the crew tried to hide what had happened, but at the top of the middle part of the fuselage, due to overload, a corrugated-like permanent deformation of the skin was formed, and this aircraft no longer flew.
Operation of the Tu-126 continued until 1984. The first prototype took the longest flight until 1990. This machine, converted into a flying laboratory, was used to test the Shmel radar for the A-50 AWACS aircraft and a model of the radar fairing for the A-50M AWACS aircraft. Not a single Tu-126 has survived to this day, in the early 90s they were all mercilessly "disposed of".
The first prototype on which the Liana and Bumblebee radars were tested
When evaluating the combat effectiveness of the Tu-126, one should take into account that the operating conditions of the operators directly influenced the level of basic characteristics: accuracy, productivity, as well as the time required to "tie" the target track and its stable tracking. Target detection was carried out visually on the screens of indicators of a circular view, and the removal and correction of coordinates was carried out using rather primitive "joysticks". It is now at the disposal of operators of radar systems there is equipment for automatic target detection and determination of their coordinates, which makes it possible to provide both the required performance and accuracy, and then these tasks were solved mostly manually. The weak target selection system did not allow for detection against the background of the earth. At the same time, thanks to the use of a relatively long working wave, it was possible to see targets against the background of the sea at ranges of at least 100 km.
Already in the 70s, the military was not satisfied with the performance of processing and transmitting radar data and the impossibility of transmitting them directly to interceptors and air defense command posts. In the late 60s - mid 70s, in most of the characteristics of the Tu-126, the American AWACS aircraft ES-121 Warning Star were superior, with the exception of the equipment for transmitting data to ground points and interceptors. At the same time, the US Air Force and Navy operated about 20 times more than the EU-121.
Since the Tu-126 became the first AWACS aircraft with a disk-shaped rotating radar antenna, often from people who are poorly familiar with the history of the development of aviation technology, one can hear the opinion that the United States copied this scheme from a Soviet machine. In fact, the experienced WV-2E (EC-121L) with the AN / APS-82 radar took off in mid-1957, that is, more than 4 years earlier than the Tu-126 in the USSR. And although this aircraft was not serially built due to the lack of radar, the results obtained were later used to create the E-2 Hawkeye and E-3 Sentry. In the late 70s, after the appearance of the AWACS aircraft and the E-3A Sentry of the AWACS system, the Americans took the lead. The capabilities of the first E-3A to detect targets against the background of the underlying surface, as well as on the Tu-126, were far from required, and this problem was successfully solved only after a radical improvement of the AN / APY-1 radar and data processing computers.
For the Soviet aviation industry and the radio-electronic industry, the creation of an AWACS aircraft with the Liana radar system was an outstanding achievement. Despite a number of shortcomings, one cannot say that the first pancake came out lumpy, and the Tu-126, launched into mass production in the mid-60s, fully met the requirements. Although, of course, the aircraft equipment was not ideal, and then little attention was paid to ergonomics and living conditions in military aviation. It is not for nothing that the charter said about hardships and hardships.
Taking into account the fact that in the 60s and 70s, military aviation and electronics developed at a very high rate, the potential laid down during the creation made it possible to actively operate the Tu-126 for 20 years. But already in the early 70s it became clear that Liana was beginning to become obsolete. Just at this time, the combat aviation of a potential enemy, relying on the experience of local conflicts, switched to low-altitude flights. The main disadvantage of the radar was the inability to see targets against the background of the earth. Also, the equipment for automated data processing and transmission required improvement. It cannot be said that the Soviet top military leadership and designers did not understand the need to create new early warning radar systems based on modern aircraft platforms. Soon after the start of the serial construction of the Tu-126, the question arose about its modernization. Since 1965, a number of research organizations have been working on the creation of radars capable of stably observing air attack weapons against the background of the earth. Based on the research results, in 1969 NPO Vega began to develop a new radar complex "Shmel". New electronic countermeasures systems, a repeater and space communication equipment were to be combined with it.
Since the passenger Tu-114 was discontinued by that time, the anti-submarine Tu-142 was considered as a platform. However, calculations showed that it was impossible to accommodate all the required equipment and provide normal working conditions for a large crew in this vehicle.
In 1972, the passenger Tu-154 began to make regular flights, this machine in terms of internal volumes fully met the requirements. To cool the equipment in the AWACS aircraft version, a large air intake was provided in the upper part of the fuselage.
Estimated appearance of the AWACS aircraft based on the Tu-154B
However, a detailed study of the project showed that the flight range of the Tu-154B in this configuration would not exceed 4500 km, which the military considered insufficient, and work on this version of the early warning aircraft was stopped.
Since the "Bumblebee" could not be crossed with existing civilian or military vehicles, the Tupolev Design Bureau began work on the design of a fundamentally new Tu-156 aircraft with a long flight duration, specially designed for use as an air radar picket.
Aircraft model AWACS Tu-156
Externally, the aircraft with four D-30KP aircraft engines strongly resembled the E-3A Sentry. The design data was also very close to the American car. At a cruising speed of 750 km / h, the aircraft had to be in the air without refueling for more than 8 hours. The duration of the refueling flight was supposed to reach 12 hours. But this promising machine existed only on paper, it still had to be embodied in metal and tested. Even in Soviet times, when the pace of technology development was much higher, this required at least 5 years. In this connection, for the radar complex "Shmel" had to look for other options.
