History domestic adjusted aviation bombs began shortly after the end of World War II. The materials on the German project FX-1400 Fritz-X fell into the hands of Soviet engineers. The analysis of the documentation dragged on and only in 1947, the Design Bureau No. 2 of the Ministry of Agricultural Engineering was instructed to develop its own ammunition of a similar type. The theme received the name "Crab" and the SNAB-3000 index, and D.V. Candlestick. The terms of reference provided for the creation of a guided ammunition of a caliber of 3000 kg with a thermal homing head. Based on the requirements, the general appearance of the new bomb was formed. The body of the ammunition had an elongated teardrop shape with a characteristic cut in the nose. The latter housed homing equipment. In the middle of the bomb, four wings were installed in an X-shaped pattern. The presence of the wings was due to the need for maneuvering in flight. Without additional planes, the aerodynamic rudders of the "Crab" simply could not provide the proper speed of trajectory correction. The leading edge of the wings had a sweep of 30 °. The span of each pair of wings is 2520 millimeters. On all wing consoles there were spoilers measuring 30x350 mm, which served to control the roll. On the narrowed tail of the bomb, the plumage was placed, consisting of two stabilizers and two keels. Unlike X-shaped wings, fins and fins were mounted horizontally and vertically, respectively. Spoilers were also used as elevators and rudders, but on the tail they had a smaller size: 30x173 mm. A warhead with 3000 kilograms of TNT was placed in the middle of the SNAB-1285 bomb. The AB-515 fuse was developed especially for the new guided ammunition. At the same time, it was possible to install two serial AB-139 instead of the standard fuse.
However, the greatest interest is not the design of the bomb, and the equipment installed in its nose. CKB-393 has developed two thermal guidance systems, designated 01-53 and 01-54. They were sensitive to each other. 01-53 sensors detected thermal radiation of at least 0,04 µW / cm2. The homing head 01-54, in turn, "saw" already 0,018 µW / cm2. Structurally, both of the GOS were similar: each of them had in its composition two sulfur-lead photocells, each of which, through its own lens, followed the eight-wide sector. One of the solar cells "made observation" in the horizontal plane, the other - in the vertical. A two-fold difference in sensitivity gave approximately the same difference in the range of target detection. Thus, the 01-53 seeker was able to detect a target of the CHP type at a distance of about 4,5 km. In 01-54, this figure was nine kilometers. However, a less sensitive head could be useful when attacking some industrial objects. Due to its relatively low performance, the 01-53 was not “blinded” by the equipment of steel mills, etc. enterprises where extremely high temperatures were used.
In 1951, two dozen Crab bombs were collected. Two specimens were immediately used for testing without homing heads. According to the results of these discharges, the rudder control system was improved. At this time, the KB-2, which worked on the bomb, was renamed GSONI-642. Minor improvements to the control system and the homing head continued almost until the end of 52, after which tests of bombs with the workers of the GOS began. Instead of a warhead at this stage ballast was used. On the range Vladimirovka was equipped with several training objectives. They consisted of large braziers with kerosene. The flame of such a “fire” successfully imitated a number of targets, primarily industrial facilities. During the test bombing, the Krabov carrier aircraft was a Tu-4, the payload of which allowed two bombs to be delivered to the target simultaneously. By the end of the tests in 1953, all valid bomb drops had ended successfully. All SNAB-3000 lay at a distance of no more than 70-75 meters from the aiming point. Uncontrollable bombs of similar caliber deviated almost 800 meters. The further second stage of factory testing ended even more successfully. 12 bombs without a warhead and three equipped with it, showed a slightly better result. In this case, the deviation of eight bombs was less than fifty meters.
At the stage of completion of the factory tests, the method of using the Crab was finally formed. On the approach to the goal, the bomber maintained an approximate course, as well as in the case of using unguided bombs. The SNAB-3000 was reset when the target hit the crosshair of the standard sight. Then the autopilot of the bomb took it into a dive at an angle 50 ° to the horizon. A few seconds after that, the homing head was switched on, according to the commands of which further bomb guidance was carried out. The type of guidance equipment affected the application restrictions. Due to the use of infrared radiation targets, "Crabs" could only be used at night in cloudless weather. Bombing with clouds was allowed, but for this to happen they had to be at a height of at least three kilometers.
At the beginning of 1955, the Tu-4 bomber was declared completely outdated and unsuitable for the delivery of the Krab bombs. New carrier chosen just created Tu-16. The carrying capacity of this aircraft at the price of the range allowed to double the number of bombs transported. Only here, in comparison with the Tu-4, the cruising speed caused certain concerns. In the spring of 55, four test drops of the Crab from the Tu-16 were made. All of them were unsuccessful. The new bomber flew higher and faster, which had a bad effect on the characteristics of the bomb. At speeds around M = 0,9, the SNAB-3000 lost its longitudinal stability, and the spoiler wheels ceased to have a significant effect on the trajectory. In the course of the next 32 flights, recommendations were made on the use of the new weapons. The maximum dumping height was limited to ten kilometers, and the maximum speed - to 835-840 km / h.
But even such restrictions almost did not produce a result: the accuracy characteristics dropped noticeably. State testing in September 1955 meant 18 bomb dropping. The first 12 "Crab" were dropped on a conventional goal, which had an average thermal "appearance", similar to the Krasnodar Oil Refinery. Four bombs fell at a distance of up to forty meters. The deviation of two more was twice as large. The rest of the bombing did not give results because of the failure of the equipment. The thermal target of low brightness (imitated Shchekinskaya CHP) remained intact. Only one bomb captured the target, but lay outside the circle with a radius of 80 meters, provided for by the terms of reference. Two more bombs did not capture an insufficiently bright target, and on the fourth there was a breakdown of the GOS. Finally, the brightest target, imitating the Azov Iron and Steel Works, was hit by both dropped bombs with a deviation of no more than 12 meters.
As a result of not very successful tests, a number of measures were taken. However, they didn’t lead to anything, and in August 1956 of the year, the SNAB-3000 project was closed down because of its futility. The main problem of the guided bomb "Crab" is considered the wrong choice of the type of guidance system. Infrared seeker has sufficient characteristics to destroy enemy equipment, but almost always such guidance systems are installed on missiles designed to destroy enemy aircraft. For air-to-surface munitions, infrared homing turned out to be disadvantageous, primarily because of the difficulty of detecting a particular object from thermal radiation.
"The Seagull" and "Condor"
A few years after the start of work on the "Crab" in the same State Research Institute-642 under the direction of A.D. Nadiradze began the creation of two other guided bombs, one of which eventually was even adopted. These were UB-2000F Chaika and UB-5000F Condor. Guided ammunition caliber 2000 and 5000 kilograms, respectively, should have a simpler targeting system than SNAB-3000. The customer demanded that a radio command and control system from a carrier aircraft be installed on the new bombs in order to aim at the target using the three-point method. Already in the early fifties, this scheme could hardly be called modern and promising. Nevertheless, the military wanted exactly such ammunition.
To simplify the work, the designers decided to maximally unify the aggregates of the bombs. Thus, the body of the "Seagull" was an appropriately modified body of the "Crab". The same applies to the X-shaped wings spanning 2100 mm. At the same time, the tail of the bomb was changed. To ensure acceptable rear dimensions of the ammunition, we had to change the design of the stabilizer and the keels. The arrow-shaped stabilizers “Seagulls” of 1560 mm span had a greater length of the root part and bore two keels on themselves. At the same time, part of the stabilizer design protruded outside the keel plane. Two tracer were attached to these “processes”. The trajectory control system as a whole remained the same as it was at SNAB-3000. On the wings, stabilizers and keels were mounted small spoilers that served as rudders. At the same time, there was no homing equipment on the “Seagull”. Instead, radio control equipment was mounted inside the bomb. It received commands from the bomber and converted into electrical signals for the steering cars. Due to the absence of heavy elements of the homing equipment, the “Seagull” with its own weight in 2240 kilograms (the designers could not meet the initial conditions by weight) carried 1795 kg of trotyl.
In November, 1954, the experimental batch of the UB-2000F bombs "Chaika" went to factory tests. Until February of next year, the crew of testers dropped a dozen guided bombs from the Il-28 bomber. The use of guided munitions was not easy. Since the Gull was guided by the three-point method, the bomber could not maneuver after dropping the bomb until it hit the target. At this time, it was an easy target for enemy air defense. In addition, after the resetting, the navigator-operator had to constantly monitor the flight of the bomb and correct its trajectory with the help of a special console. Even with a special telescopic sight, this was far from easy, including in good weather conditions. With poor visibility, of course, the "Seagull" was useless.
The state tests of the UB-2000F bomb began in July 1955. Two dozen trial bombings with a number of reservations were found successful. In December of the same year, the “Seagull” under the name UB-2F (GAU index 4А22) was adopted by the Soviet army. The production of the “Seagull” did not last long: in just a few months, the entire 120 of new ammunition was manufactured. The carriers of the guided bombs were Il-28 and Tu-16 aircraft. The first could carry one “Seagull” under the fuselage, the second - two at once on the girder holders under the wing. It was recommended to make a discharge from a height of at least seven kilometers. In such conditions, an experienced navigator-operator could hit a target of 30-50 size with meters with only two or three bombs. To accomplish the same task, free-fall FAB-1500 required an order of magnitude greater consumption of ammunition.
The larger bomb of the UB-5000F "Condor" was a fairly increased "Seagull". The hull length has grown from a 4,7 meter to 6,8 m, the span of the X-shaped wings to 2670 mm, and the span of the stabilizer to 1810 mm. The total weight of the bomb was 5100 kilograms, of which 4200 accounted for the charge of TNT. The design of the stabilizer and the keel of the Condor was similar to that used on the UB-2F, and the wings were processing the Crab planes. The control system of the heavy bomb and the complex intended for installation on aircraft were taken from the Chaika without any changes. As it turned out, such an engineering “cannibalism” did not justify itself.
In March, the 1956 of the year during factory tests of the Tu-16 bomber was dropped 16 "Condor". It turned out that with dumping heights of more than ten kilometers and the speed of the aircraft carrier over 800 km / h, the bomb manages to accelerate to supersonic speed, because of which the rudders on the wings are ineffective. The consequence of this in most cases was the rotation of the bomb around the longitudinal axis. The area of the spoilers was increased, but later it was also required to correct the aerodynamics of the ammunition. Several UB-5000F bombs with an updated control system and a new hull shape were manufactured and tested. Work on the Condor theme continued until the autumn of 1956, when the country's leadership decided to roll out all the guided bomb projects and focus on the development of guided missiles for aviation. By that time, the tests of the Condor, equipped with a television guidance system, had already begun, but in connection with the order from above, they were hastily stopped.
After the closure of the project "Condor" work on the creation of new guided bombs stopped for a half decades. In 1971, the Research Institute of Applied Hydromechanics (now the State Scientific Production Enterprise “Region”) began the creation of several guided bombs for front-line aviation. The first of these were CAB-500 and CAB-1500. Both munitions were equipped with a laser homing head. It was located on the front cone-shaped part of the bomb shell. The new bombs were intended for use on front-line MiG-27 fighter-bombers equipped with a laser target designation system. After a reset, the semi-active laser homing bombs brought ammunition to the point where the pilot of the aircraft directed the laser beam. Thus, the bombs KAB-500 and KAB-1500 worked on the principle of "dropped-brought." The KAB-500 and KAB-1500 high-explosive warheads contained 200 and 450 kg of explosives, respectively.
Shortly before adopting the first laser-guided bombs, in 1976, work began on improving this class of weapons. In the course of these works, the bomb KAB-500L-K was designed. It was based on a one-time bomb cassette of RBC-500. In view of this feature of the “warhead”, the striking elements of the KAB-500L-K steel 266 anti-tank bombs PTAB-1. The main use of this munition was the defeat of any type of armored vehicles in various conditions, on the march and in places of concentration. CAB-500L-K was adopted by the Soviet army only in 1988 year.
It took a little less time to create another guided bomb - KAB-500Kr. It was distinguished from other domestic guided bombs by the original guidance system. The previous bombs were induced with the direct assistance of the pilot of the carrier aircraft. KAB-500Kr, by contrast, has already worked according to the “dumped-forgotten” scheme. For this purpose, a gyrostabilized platform with a television camera was installed in the nose of the cylindrical bomb shell, under a hemispherical transparent fairing. Bombing is carried out on the so-called. television correlation method. This guidance works as follows. Before dropping the ammunition, the pilot turns on the television bomb system, which transmits a signal to the monitor in the cockpit. Then the pilot, using a separate control knob, finds a target on the screen and suggests a target mark on it. At the time the pilot confirms the target, the bomb “remembers” the appearance of the target and its surrounding objects. After resetting the GOS of the ammunition, it monitors what the television camera "sees" and makes the appropriate corrections to the flight trajectory. It is worth noting that the targeting algorithm developed at the Institute of Applied Hydromechanics is more reliable than that used on foreign analogues of the KAB-500Kr of the same time. As an example, the American bomb AGM-62 Walleye. The American GOS produces guidance by fixing optically contrasting sections of the target. The Soviet bomb, in turn, uses several contrast areas to identify the target at once. Due to this, for a confident defeat, the target does not have to have characteristic external signs - in this case, the bomb will independently calculate the necessary point of entry using characteristic landmarks around the target. The circular probabilistic deviation of the bomb KAB-500Kr lies within 4-8 meters. Such accuracy in combination with one hundred kilograms of explosive is enough to destroy a large range of targets. The bomb KAB-500Kr was put into service in 1984 year.
Subsequently, on the basis of the KAB-500, KAB-500Кр and KAB-1500 bombs, several other ammunition were developed, equipped with passive laser and television-correlation guidance systems. These types of guided bombs are equipped with warheads of various types, including penetrating (KAB-1500L-Pr) and volume-detonating (KAB-500OD). One of the latest developments is the bomb KAB-500С, adopted several years ago. This guided munition is a response to the current foreign trends in the field of homing systems. For the first time in domestic practice, a guided bomb has a satellite seeker. The ammunition electronics receives a signal from the satellites of the GLONASS or GPS navigation systems and tracks its position relative to the coordinates of the target. The deviation of the KAB-500С bomb with such a hover does not exceed 8-10 meters. The bomb is equipped with 195 kilograms of explosives. Another novelty is the 250 kilogram guided bombs. The KAB-250 and KAB-250L are equipped with a semi-active laser homing head and carry a high-explosive fragmentation charge.
Since the beginning of work on the Crab, domestic guided bombs have undergone significant changes. First of all, it is worth noting the reduction in caliber and the change in the tactical niche of similar ammunition. The first designs had a weight of several tons and were intended to attack large objects, primarily industrial enterprises. The large explosive charge and the considerable size of such targets made it possible to compensate for the relatively low accuracy. Over time, after a long break in development, the appearance of the guided bombs has changed significantly. Now it was a relatively small and light ammunition designed to hit point targets. In general, the concept of use remained the same - reducing the consumption of ammunition and, consequently, the financial costs of an attack at the cost of increasing accuracy and increasing the cost of a single bomb. However, the “look” of targets for precision weapons has changed. The result of all these changes was the appearance of kilograms 500 caliber and 250 kilogram. Perhaps, in the fifties of the last century, such guided munitions would have been accused of insufficient power. However, in modern conditions of the beginning of the XXI century, precisely guided bombs and missiles are the most promising aviation means of destruction.
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