Since the appearance of armored vehicles, the eternal battle between the projectile and the armor has escalated. Some designers sought to increase the penetration of the shells, while others increased the durability of the armor. The struggle continues now. Professor of the Moscow State Technical University named after V. I. N. E. Bauman, Director for Science of the Research Institute of Steel Valery Grigoryan
At first, the attack on the armor was carried out head-on: while the main type of impact was an armor-piercing projectile of kinetic action, the duel of the designers was reduced to an increase in the caliber of the gun, the thickness and angles of inclination of the armor. This evolution is clearly visible in the development of tank weapons and armor in the Second World War. The constructive decisions of that time are quite obvious: we will make the barrier thicker; if you tilt it, the projectile will have to go a longer way in the thickness of the metal, and the likelihood of a ricochet will increase. Even after the appearance of armor-piercing shells with a hard non-destructive core in the ammunition of tank and anti-tank guns, little has changed.
Elements of dynamic protection (EDS)
They are "sandwiches" of two metal plates and an explosive. EDZ are placed in containers, the lids of which protect them from external influences and at the same time represent throwable elements
Deadly spit
However, already at the beginning of World War II, a revolution took place in the striking properties of ammunition: cumulative shells appeared. In 1941, German artillerymen began to use the Hohlladungsgeschoss ("a projectile with a recess in the charge"), and in 1942, the USSR adopted the 76-mm BP-350A projectile, developed after studying captured samples. This is how the famous Faust patrons were arranged. A problem arose that could not be solved by traditional methods due to the unacceptable increase in the mass of the tank.
In the head of the cumulative ammunition, a conical recess is made in the form of a funnel lined with a thin layer of metal (bell-mouth forward). Explosive detonation begins from the side closest to the top of the funnel. The detonation wave "collapses" the funnel to the axis of the projectile, and since the pressure of the explosion products (almost half a million atmospheres) exceeds the limit of plastic deformation of the plate, the latter begins to behave like a quasi-liquid. This process has nothing to do with melting, it is precisely the "cold" flow of the material. A thin (comparable to the shell thickness) cumulative jet is squeezed out of the collapsing funnel, which accelerates to velocities of the order of the explosive detonation velocity (and sometimes even higher), that is, about 10 km / s or more. The speed of the cumulative jet significantly exceeds the speed of sound propagation in the armor material (about 4 km / s). Therefore, the interaction of the jet and the armor occurs according to the laws of hydrodynamics, that is, they behave like liquids: the jet does not burn through the armor at all (this is a widespread misconception), but penetrates it, just like a jet of water under pressure washes away sand.
Principles of semi-active protection using the energy of the jet itself. Right: cellular armor, the cells of which are filled with a quasi-liquid substance (polyurethane, polyethylene). The shock wave of the cumulative jet is reflected from the walls and collapses the cavity, causing the destruction of the jet. Bottom: armor with reflective sheets. Due to the swelling of the back surface and the gasket, the thin plate is displaced, running onto the jet and destroying it. Such methods increase the anti-cumulative resistance by 30-40
Layered protection
The first protection against cumulative ammunition was the use of screens (two-barrier armor). The cumulative jet is not formed instantly, for its maximum efficiency it is important to detonate the charge at the optimal distance from the armor (focal length). If a screen made of additional metal sheets is placed in front of the main armor, then the detonation will occur earlier and the effectiveness of the impact will decrease. During World War II, to protect against faust cartridges, tankers attached thin metal sheets and mesh screens to their vehicles (there is a widespread story about the use of armor beds in this capacity, although in reality special meshes were used). But this solution was not very effective - the increase in resistance was on average only 9-18%.
Therefore, when developing a new generation of tanks (T-64, T-72, T-80), the designers used a different solution - multi-layer armor. It consisted of two layers of steel, between which was placed a layer of low-density filler - fiberglass or ceramics. Such a "pie" gave a gain in comparison with monolithic steel armor up to 30%. However, this method was inapplicable for the tower: in these models it is cast and it is difficult to place fiberglass inside from a technological point of view. The designers of VNII-100 (now VNII "Transmash") proposed to melt into the tower armor balls made of ultra-porcelain, the specific extinguishing ability of which is 2–2, 5 times higher than that of armored steel. The specialists of the Research Institute of Steel chose another option: between the outer and inner layers of the armor were placed packages of high-strength solid steel. They took on the impact of a weakened cumulative jet at speeds when the interaction no longer occurs according to the laws of hydrodynamics, but depending on the hardness of the material.
Typically, the thickness of armor that a shaped charge can penetrate is 6–8 of its calibers, and for charges with plates made of materials such as depleted uranium, this value can reach 10
Semi-active armor
Although it is not easy to decelerate the cumulative jet, it is vulnerable in the lateral direction and can easily be destroyed even by a weak lateral impact. Therefore, the further development of the technology consisted in the fact that the combined armor of the frontal and side parts of the cast turret was formed due to an open top cavity filled with a complex filler; from above, the cavity was closed with welded plugs. Towers of this design were used on later modifications of tanks - T-72B, T-80U and T-80UD. The principle of operation of the inserts was different, but used the mentioned "lateral vulnerability" of the cumulative jet. Such armor is usually referred to as "semi-active" protection systems, since they use the energy of the weapon itself.
One of the variants of such systems is cellular armor, the principle of operation of which was proposed by employees of the Institute of Hydrodynamics of the Siberian Branch of the USSR Academy of Sciences. The armor consists of a set of cavities filled with a quasi-liquid substance (polyurethane, polyethylene). A cumulative jet, entering such a volume bounded by metal walls, generates a shock wave in the quasi-liquid, which, being reflected from the walls, returns to the jet axis and collapses the cavity, causing deceleration and destruction of the jet. This type of armor provides up to 30-40% gain in anti-cumulative resistance.
Another option is armor with reflective sheets. It is a three-layer barrier consisting of a plate, a spacer, and a thin plate. The jet, penetrating into the slab, creates stresses, leading first to local swelling of the back surface, and then to its destruction. In this case, significant swelling of the gasket and the thin sheet occurs. When the jet pierces the gasket and the thin plate, the latter has already begun to move away from the back surface of the plate. Since there is a certain angle between the directions of motion of the jet and the thin plate, at some point in time the plate begins to run onto the jet, destroying it. In comparison with monolithic armor of the same mass, the effect of using "reflective" sheets can reach 40%.
The next design improvement was the transition to towers with a welded base. It became clear that developments to increase the strength of rolled armor are more promising. In particular, in the 1980s, new steels of increased hardness were developed and ready for serial production: SK-2Sh, SK-3Sh. The use of towers with a base made of rolled steel made it possible to increase the protective equivalent along the base of the tower. As a result, the turret for the T-72B tank with a rolled base had an increased internal volume, the weight growth was 400 kg compared to the serial cast turret of the T-72B tank. The tower filler package was made using ceramic materials and high-hardness steel or from a package based on steel plates with "reflective" sheets. Equivalent armor resistance was equal to 500–550 mm of homogeneous steel.
How dynamic protection works
When the DZ element is penetrated by a cumulative jet, the explosive in it detonates and the metal plates of the body begin to scatter. At the same time, they intersect the trajectory of the jet at an angle, constantly substituting new sections under it. Part of the energy is spent on breaking through the plates, and the lateral impulse from the collision destabilizes the jet. DZ reduces the armor-piercing characteristics of cumulative weapons by 50-80%. At the same time, which is very important, DZ does not detonate when fired from small arms. The use of DZ has become a revolution in the protection of armored vehicles. There was a real opportunity to influence the penetrating damaging agent as actively as it had previously affected the passive armor
Explosion towards
Meanwhile, technologies in the field of cumulative ammunition continued to improve. If during the Second World War the armor penetration of shaped-charge projectiles did not exceed 4–5 calibers, then later it increased significantly. So, with a caliber of 100-105 mm, it was already 6-7 calibers (in the steel equivalent of 600-700 mm), with a caliber of 120-152 mm, armor penetration was raised to 8-10 calibers (900-1200 mm of homogeneous steel). To protect against these ammunition, a qualitatively new solution was required.
Work on anti-cumulative, or "dynamic", armor, based on the principle of counter-explosion, has been carried out in the USSR since the 1950s. By the 1970s, its design had already been worked out at the All-Russian Research Institute of Steel, but the psychological unpreparedness of high-ranking representatives of the army and industry prevented it from being adopted. They were convinced only by the successful use of similar armor by Israeli tankers on the M48 and M60 tanks during the 1982 Arab-Israeli war. Since the technical, design and technological solutions were fully prepared, the main tank fleet of the Soviet Union was equipped with the Kontakt-1 anti-cumulative explosive reactive armor (ERA) in record time - in just a year. The installation of DZ on the T-64A, T-72A, T-80B tanks, which already had quite powerful armor, practically instantly devalued the existing arsenals of anti-tank guided weapons of potential adversaries.
There are tricks against scrap
The cumulative projectile is not the only means of destruction of armored vehicles. Much more dangerous opponents of armor are armor-piercing sub-caliber projectiles (BPS). The design of such a projectile is simple - it is a long scrap (core) of heavy and high-strength material (usually tungsten carbide or depleted uranium) with a tail for stabilization in flight. The core diameter is much smaller than the barrel caliber - hence the name "sub-caliber". Flying at a speed of 1.5–1.6 km / s, a "dart" weighing several kilograms has such kinetic energy that, if it hits, it can penetrate more than 650 mm of homogeneous steel. Moreover, the methods described above for enhancing anti-cumulative protection practically do not affect sub-caliber projectiles. Contrary to common sense, the tilt of the armor plates not only does not cause the ricochet of a sub-caliber projectile, but even weakens the degree of protection against them! Modern "fired" cores do not ricochet: upon contact with the armor, a mushroom-shaped head is formed at the front end of the core, which plays the role of a hinge, and the projectile turns towards the perpendicular to the armor, shortening the path in its thickness.
The next generation of DZ was the Contact-5 system. The specialists of the research institute began to do a great job, solving many contradictory problems: the DZ was supposed to give a powerful lateral impulse, allowing to destabilize or destroy the core of the BOPS, the explosive should have reliably detonated from the low-speed (compared to the cumulative jet) core of the BOPS, but at the same time detonation from hitting bullets and shell fragments was excluded. Block design helped to deal with these problems. The cover of the DZ block is made of thick (about 20 mm) high-strength armor steel. Upon impact, the BPS generates a stream of high-speed fragments, which detonate the charge. The impact on the BPS of a moving thick cover is sufficient to reduce its armor-piercing characteristics. The impact on the cumulative jet also increases in comparison with the thin (3 mm) Contact-1 plate. As a result, the installation of DZ "Contact-5" on tanks increases the anti-cumulative resistance by 1, 5-1, 8 times and provides an increase in the level of protection against BPS by 1, 2-1, 5 times. The Kontakt-5 complex is installed on Russian serial tanks T-80U, T-80UD, T-72B (since 1988) and T-90.
The last generation of the Russian DZ - the "Relikt" complex, also developed by the specialists of the Research Institute of Steel. In the improved EDZ, many disadvantages were eliminated, for example, insufficient sensitivity when initiated by low-speed kinetic projectiles and some types of cumulative ammunition. Increased efficiency in protection against kinetic and cumulative ammunition is achieved through the use of additional throwing plates and the inclusion of non-metallic elements in their composition. As a result, the armor penetration of subcaliber projectiles is reduced by 20-60%, and due to the increased exposure time to the cumulative jet, it was possible to achieve a certain efficiency in cumulative weapons with a tandem warhead.
