Corvette 20380 or 20386? Results of the discussion on the effectiveness of air defense
Assessment of the air defense of the corvette 20380 of the "Guarding" type
Article "What are we building - corvettes or flag demonstrators?" it was shown that the project 20380 corvette was unacceptably noticeable. Its effective scattering surface (ESR) can be estimated at 1000 sq. m. Fighter-bombers (IB) of the enemy at an altitude of 10 km will detect a target with such an RCS immediately after leaving the horizon, that is, at a distance of 400 km.
This series 20380 also had an unacceptably ineffective air defense system. There was no missile guidance radar on the corvette at all, and the Furke surveillance radar did not have a missile defense line. The presence of expensive missiles equipped with homing heads (GOS) - 9M100 and 9M96, did not eliminate the negative results of the lack of radio correction.
SAM 9M96 is designed to defeat IS and has a launch range of 40-50 km, but it will not hit the maneuvering IS without radio correction even at a range of 25 km. The fact is that the 9M96 has a narrow body, and the GOS antenna in it has a diameter, apparently, less than 200 mm. With such an antenna, the detection range of the F-16 type IS will not exceed 10-15 km.
The typical beam width of the seeker is about 6 °. That is, the width of the target search zone is 0,1 of the detection range, namely, no more than ± 0,75 km. Even if the Furke radar can absolutely accurately measure the coordinates of the IS and the vector of its speed, the radar will assume that the target will continue to fly without maneuver.
Accordingly, the missile defense system will be sent to the calculated meeting point, expecting that the target will be captured by the GOS at the right time before the meeting. In order to hit the subsonic IS at a range of 25 km, it is necessary to fire the missile defense system when the IS range is 32-35 km. But the IS, with the help of a radar or a heat direction finder, will detect the fact of launch and will begin to perform a calm anti-zenith maneuver. In 5 sec. it is possible with an overload of 1g to turn the IB by 60–70 °, and in the next 12–14 sec. The IB will fly off to the side of the aiming line by 3 km. Consequently, by the time the missile launcher approaches the detection range, there will be no target in the beam.
When flying anti-ship missiles, 9M100 missiles are used. The detection range of its IR seeker by subsonic anti-ship missiles will hardly exceed 3 km. Therefore, it is unreasonable to launch them on maneuvering anti-ship missiles at a distance of more than 5 km. At shorter ranges, the danger is different - there is a possibility that with a simultaneous approach of a group of three or more anti-ship missiles, all missiles launched at the same time will aim at one of them.
The result is sad.
Even if the enemy does not have anti-ship missiles, he will be able to use gliding bombs, Maevriks, etc. from close range.
Despite the disastrous result, this version of the corvette had many defenders. Some write that the main advantage of the 20380 is its cheapness. There are a lot of them that can be built and will replace the retiring IPCs.
Others say that reliable air defense cannot be created on a corvette, so they should operate only in BMZ and under cover aviation... How it is possible to guard a corvette around the clock with its IS, no one explains. If there is no guard, then the corvette, which has moved away from the coast for more than 70-100 km, may be unexpectedly attacked by low-altitude IS and will not have time to call its IS from the coast. The attacking IS will not see coastal radar and air defense systems.
The question arises - should 20380 solve the PLO problem only in peacetime?
Isn't it cheaper to maintain a hydrophone barrier and PLO aircraft with magnetometers, IR thermal imagers and radar for detecting a submarine trace on the surface for the BMZ protection? But this is no longer the author's area of competence.
Air defense corvettes of the following series
When the customer realized that he was building flag demonstrators, he decided to build an updated version of 20380. They renamed it 20385 and equipped it with a full-fledged radar complex (RLC) Zaslon, which was good for everyone, except for the exorbitant cost.
According to the author's indirect estimates, the price of the Barrier could be $ 100 million, which destroys the argument about the need to build corvettes due to their low cost. 20385 promised to make it less noticeable, but, apparently, this did not succeed. At least the appearance has changed little. Having laid two 20385s, they decided to stop the series. Maybe because 20380 has already been mastered, and the Zaslon radar can be placed on it.
Then they decided that it was a shame to lag behind the world level so much, and laid a fundamentally new project 20386, an order of magnitude less noticeable. Paradoxically, but it was 20386 that met the most fierce criticism. No one noticed the obvious advantages of the ship's appearance, and began to criticize the modularity of its design, inappropriate equipment, electric drive of the engine, etc.
The author does not undertake to judge these issues, perhaps this is so.
But why throw out the child with water?
If for the first time in Russia a ship's hull appeared, for which you are not ashamed, then insist on improving the equipment, and do not destroy the entire ship.
For example, placing a helicopter below deck is inconvenient. But then do not disfigure the hull with such a hangar as in 20380, but dock the hangar to the superstructure without gaps. Then there will be no harmful effect when the radio wave, reflected from the front wall of the hangar, hits the superstructure and scatters from it into a wide sector of corners.
The advantage of 20386 is that an increase in displacement by 1000 tons will increase the ammunition load of missiles and anti-ship missiles, improve the seaworthiness and living conditions of the crew, which has also been reduced from 100 to 80 people. An increase in displacement will hardly increase the price of a ship by more than 10-12%.
The article indicated what minor defects of the corvette 20386 need to be eliminated in order to meet the requirements of the Stealth technology. Moving more advanced equipment from the smaller 20385 corvette to the larger 20386 should not be difficult. If the redesign of 20386 is carried out, then the resulting qualitatively more advanced corvette should be renamed 20387 and declared that it is intended to replace the frigate 11356 as much more efficient.
From 11356 it is immediately clear that it was not made for themselves, but for the Indians who ordered it for us. Its appearance resembles a dump of equipment unclaimed on other ships. It's a shame to talk about RLC. Instead of one radar with four HEADLIGHTS (according to the model 22350), it was possible to place 4 separate guidance radars with a mechanical antenna drive only because of the brutal haste. 11356 is much more visible than even 20380.
What are the requirements for the visibility of a corvette?
For IS radar, the detection of targets located on the sea surface is always a much more difficult task than the detection of an air target in free space. The power of the reflected signal from the waves can exceed the power of the reflected signal from the ship and prevent the ship from being detected. Therefore, the radar uses very short pulses to detect ships.
For example, the pulse width can be 0,1 microseconds. Then along the sea surface it will stretch for 15 m. When the sea is 0–1 points, the surface turns into a mirror. And all the sounding signal reflected from the sea goes further and does not interfere with the detection of the ship. With an excitement of 2 points, the back reflections from the waves begin to worsen the detection of the ship, and with 4 points, a special technique has to be used - a decrease in the IS flight altitude.
If the radar beam hits the surface at very small angles (less than 1 °), then the surface again becomes mirror-like, even with increased waves. And the back reflections become smaller with further decrease. And at 0,2 ° they practically disappear. The angle of incidence is calculated from the sea surface at the point where the ship is located. Then, so that the angle of incidence does not exceed 1 °, the flight altitude of the IS, for example, at a distance of 400 km, should not exceed 10 km.
The reflecting properties of the sea can be characterized, just as for the target, by the RCS value, which at a given angle of incidence will be proportional to the sea surface area simultaneously irradiated by the probing pulse. With a given radar beam width and a given pulse duration, the irradiated sea area is proportional to the distance to the ship. Therefore, the RCS of the sea grows in proportion to this distance. The radar can detect the target when the RCS of the sea is less than the RCS of the target.
So, we get the first conclusion - the ship can have the greater EPR, the greater the range of its air defense system will not allow the IS. The more the sea is rough, the larger the ship's RCS is permissible. Since it is impossible to predict the conditions of the hike in advance, one has to rely on an expert assessment of the permissible EPR - for example, 30 sq. m, that is, we are not talking about either 1000 or even 100 sq. m.
When repelling an attack of low-altitude IS, it is necessary to take into account that IS emerges from the horizon gradually. Initially, its radar detects only the upper part of the superstructure and, only after flying another 10–20 km, will it see the entire ship. Therefore, it is important that the upper half of the superstructure has a minimum RCS - less than 1 sq. m. Otherwise, the IS will have time to launch the anti-ship missile system and turn around even before the ship's air defense missile system starts firing at it.
Consequently, all sorts of structures and rotating antennas of the surveillance radar from the top of the superstructure must be removed. Fixed flat AFARs located at the top of the lateral plane of the superstructure will reflect radio waves very little.
Requirement for radio countermeasures complex (KREP)
In the previous article, "Possibilities for improving the air defense of corvettes," it was once again emphasized that the contribution of the KREP to the effectiveness of air defense can be no less than the contribution of the air defense system. However, this statement did not attract the attention of readers. Perhaps because the KREP is traditionally considered the most classified part of the air defense, and perhaps because it is easier to deal with the air defense system. The method of using missiles is clear and generally understandable, but the effect of KREP is not obvious, and only a specialist can judge it. On the other hand, if you do not understand the main principles of the KREP functioning, then you can easily make the mistakes that were made in the design of the Zaslon radar.
Firstly, in each article it was repeated that the KREP installed on the ship cannot completely hide the location of the ship. It can only suppress the channel for measuring the range to the target in the IS radar, but it is not able to prevent the measurement of the bearing to the source of interference. Therefore, a pair of ISs, separated by 50–100 km, can determine the bearings on the KREP from two directions and by the triangulation method (finding the point of intersection of two bearings) they find the coordinates of the KREP. Worst of all, the more the interference power is, the more confidently the IS pilot determines that it is the shipboard KREP, and not any KREP placed on the UAV, that interferes with it. The accuracy of determining the coordinates of the KREP also increases.
The second drawback of the shipboard KREP manifests itself when trying to disrupt the guidance of the anti-ship missile system. A typical GOS anti-ship missile will have a very short detection range for stealth ships, for example, 8-10 km. Therefore, the seeker will be able to detect the ship only with accurate control and radio correction. If the KREP turns on the interference, then the GOS will not be able to determine the range to the KREP, but it will determine the exact bearing to it immediately after leaving the horizon, for example, from a range of 30 km, and will aim at the ship with greater accuracy than without interference.
The use of a powerful KREP can only appear with mutual protection as part of a KUG of at least three ships. If, with the help of the radar, it is possible to find out on which of the ships the anti-ship missile is being guided, then it is possible to suppress the seeker with the KREP of the neighboring ship. It is highly doubtful that such algorithms have already been implemented. The confusion in the types of ships and the lack of unification raises doubts - is there even a much simpler group CIUS that unites all the KUG radars?
However, when examining the KREP Zaslon antennas, you notice that KREP on it is very powerful and, accordingly, expensive. It is not surprising if the price of such a KREP turns out to be $ 50 million. But nothing has been reported about the jammed transmitters. In the above article, possible options for light and heavy jammers on UAVs are given. At a cost several times lower than the cost of KREP Zaslon, they could provide a much more effective disruption to anti-ship missile attacks. Thus, the task of air defense of a single ship would also be solved, which would ensure the safe performance of the main task of the corvette - an ASW in the BMZ.
The power of the UAV transmitter should be proportional to the RCS of the ship, therefore, for the protection of the 20380, a light UAV will not work, and for the 20387, no problem.
Alternative radar
Instead of a surveillance radar and a targeting radar for the Zaslon radar, it was proposed to develop an MF radar consisting of subarrays unified for all ships of the Navy - 0,22 * 0,22 m clusters containing 64 transceiver modules operating in the 5,5 cm wavelength range. The AFAR shape in the form of a cross made it possible, with the same characteristics as the Zaslon radar, to reduce the cost of the MF radar by three times.
Readers reacted with suspicion to this form of the antenna and argued that such radars did not exist, there were only complexes of two mechanical radars: one with a vertical antenna, and the neighboring one with a horizontal one. It can be argued that the so-called Mills cross was developed 70 years ago, but did not find practical application due to the lack of APAR. Then it turned out to be easier to make rectangular or circular mechanical antennas. Today, AFAR allows you to simultaneously form several receiving beams and solve the problem of noise immunity by compensating for interference in one beam with the help of another.
Meteorological stability of the MF radar is significantly higher than that of the Zaslon guidance radar. This makes it possible to aim and super-long-range missiles, which is important for frigates and destroyers.
Readers doubt the possibility of placing the MF radar on small ships, for example, MRK. For RTOs, it is possible to propose to form an AFAR with narrower vertical and horizontal antennas, then, with approximately the same size of the cross, its cost will be reduced by 1,7 times. The detection range will be reduced by 1,5 times, but it will still be significantly greater than that of the existing radars. The use of Pantsir-M missiles instead of the Gibka air defense system on the MRK 21631 will allow, instead of simulating air defense, to get a workable, meteorological and inexpensive air defense system.
Conclusions
In a previous article "Possibilities for improving the air defense of corvettes" a proposal was formulated for the development of a unified family of radars and KREP, which allows to obtain an improved air defense efficiency of all ships of the Navy in comparison with the efficiency of the Zaslon radar with a simultaneous sharp cost reduction.
Reducing the visibility of the proposed modernization of corvette 20386, designated by the author 20387, will allow it to be used to replace frigate 11356 and provide the best export potential.
Corvette 20380 after the installation of the Zaslon radar began to cost more than 20387, and its efficiency remained insufficient. Such a flag demonstrator as part of the Pacific Fleet will not scare anyone - the neighbors are too serious there.
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