Cumulative jet: description, characteristics, features, interesting facts

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The cumulative effect in military affairs is the strengthening of the destructive effect of an explosion by concentrating it in a certain direction. The phenomenon of this kind in a person unfamiliar with the principle of its action usually causes surprise. Due to a small hole in the armor, when hit by a HEAT round, the tank often fails completely.

Where used

Actually, the cumulative effect itself was observed, probably, by all people without exception. It occurs, for example, when a drop falls into water. In this case, a funnel and a thin jet directed upwards are formed on the surface of the latter.

The cumulative effect can be used, for example, for research purposes. By creating it artificially, scientists are looking for ways to achieve high speeds of matter - up to 90 km/s. This effect is also used in industry - mainly in mining. But he, of course, found the greatest application in military affairs. Ammunition operating on this principle has been used by different countries since the beginning of the last century.

Projectile design

How is this type of ammunition made and working? There is a cumulative charge in such shells, due to their special structure. At the front of this type of ammunition there is a cone-shaped funnel, the walls of which are covered with a metal lining, the thickness of which may be less than 1 mm or several millimeters. There is a detonator on the opposite side of this notch.

After the last trigger, due to the presence of a funnel, a destructive cumulative effect occurs. The detonation wave begins to move along the charge axis inside the funnel. As a result, the walls of the latter collapse. With a strong impact in the lining of the funnel, the pressure increases sharply, up to 1010 Pa. Such values far exceed the yield strength of metals. Therefore, it behaves in this case like a liquid. As a result, the formation of a cumulative jet begins, which remains very hard and has a great damaging ability.

Theory

Due to the appearance of a jet of metal with a cumulative effect, not by melting the latter, but by its sharp plastic deformation. Like liquid, the metal of the ammunition lining forms two zones when the funnel collapses:

• actually a thin metal jet moving forward at supersonic speed along the charge axis;

• Pest tail, which is the "tail" of the jet, which accounts for up to 90% of the metal lining of the funnel.

The speed of the cumulative jet after the explosiondetonator depends on two main factors:

• explosive detonation speed;
• funnel geometry.

What ammo could be

The smaller the projectile cone angle, the faster the jet moves. But in the manufacture of ammunition in this case, special requirements are imposed on the lining of the funnel. If it is of poor quality, a jet moving at high speed may subsequently collapse ahead of time.

Modern ammunition of this type can be made with funnels, the angle of which is 30-60 degrees. The speed of the cumulative jets of such projectiles, arising after the collapse of the cone, reaches 10 km / s. At the same time, the tail part, due to the greater mass, has a lower speed - about 2 km / s.

Origin of the term

Actually, the very word "cumulation" comes from the Latin cumulatio. Translated into Russian, this term means "accumulation" or "accumulation". That is, in fact, in shells with a funnel, the energy of the explosion is concentrated in the right direction.

A bit of history

Thus, the cumulative jet is a long thin formation with a "tail", liquid and at the same time dense and rigid, moving forward with great speed. This effect was discovered quite a long time ago - back in the 18th century. The first assumption that the energy of the explosion can be concentrated in the right way was made by the engineer Fratz von Baader. This scientist also conducted several experiments related to the cumulative effect. Howeverhe did not manage to achieve any significant results at that time. The fact is that Franz von Baader used black powder in his research, which was unable to form detonation waves of the required strength.

For the first time, cumulative ammunition was created after the invention of high-bristle explosives. In those days, the cumulative effect was simultaneously and independently discovered by several people:

• Russian military engineer M. Boriskov - in 1864;
• Captain D. Andrievsky - in 1865;
• European Max von Forster - in 1883;
• American chemist C. Munro - in 1888

In the Soviet Union in the 1920s, Professor M. Sukharevsky worked on the cumulative effect. In practice, the military faced him for the first time during the Second World War. It happened at the very beginning of hostilities - in the summer of 1941. German cumulative shells left small melted holes in the armor of Soviet tanks. Therefore, they were originally called armor-burning.

The BP-0350A shells were adopted by the Soviet army already in 1942. They were developed by domestic engineers and scientists on the basis of captured German ammunition.

Why it breaks through armor: the principle of operation of a cumulative jet

During the Second World War, the features of the "work" of such shells have not yet been well studied. That is why the name “armor-burning” was applied to them. Later, already in 49, the effect of cumulation in our country was taken upclose. In 1949, the Russian scientist M. Lavrentiev creates the theory of cumulative jets and receives the Stalin Prize for this.

In the end, the researchers managed to find out that the high penetrating ability of shells of this type with high temperatures is absolutely in no way connected. When the detonator explodes, a cumulative jet is formed, which, upon contact with the tank's armor, creates enormous pressure on its surface of several tons per square centimeter. Such indicators exceed, among other things, the yield strength of the metal. As a result, a hole several centimeters in diameter is formed in the armor.

Jets of modern ammunition of this type are capable of piercing tanks and other armored vehicles literally through and through. The pressure when they act on the armor is really huge. The temperature of the cumulative jet of the projectile is usually low and does not go beyond 400-600 ° C. That is, it cannot actually burn through armor or melt it.

The cumulative projectile itself does not come into direct contact with the material of the tank walls. It explodes at some distance. Moving parts of the cumulative jet after its ejection at different speeds. Therefore, during the flight, it begins to stretch. When the distance is reached by 10-12 funnel diameters, the jet breaks up. Accordingly, it can have the greatest destructive effect on the tank's armor when it reaches its maximum length, but does not begin to collapse yet.

Defeat the crew

The cumulative jet that has pierced the armor penetrates intothe interior of the tank at high speed and can hit even the crew members. At the moment of its passage through the armor, pieces of metal and its liquefied drops break off from the latter. Such fragments, of course, also have a strong damaging effect.

A jet that has penetrated inside the tank, as well as pieces of metal flying at great speed, can also get into the combat reserves of the vehicle. In this case, the latter will light up and an explosion will occur. This is how HEAT rounds work.

Pros and cons

What are the advantages of cumulative shells. First of all, the military attribute to their pluses the fact that, unlike sub-caliber ones, their ability to penetrate armor does not depend on their speed. Such projectiles can also be fired from light guns. It is also quite convenient to use such charges in reactive grants. For example, in this way, the RPG-7 hand-held anti-tank grenade launcher. The cumulative jet of such weapons armor tanks with high efficiency. The Russian RPG-7 grenade launcher is still in service today.

The armored action of a cumulative jet can be very destructive. Very often, she kills one or two crew members and causes an explosion of ammunition.

The main disadvantage of such weapons is the inconvenience of their use in the "artillery" way. In most cases in flight, projectiles are stabilized by rotation. In cumulative ammunition, it can cause the destruction of the jet. Therefore, military engineers are trying in every possible way to reduce the rotation of suchprojectiles in flight. This can be done in a variety of ways.

For example, a special lining texture can be used in such ammunition. Also, for shells of this type, they are often supplemented with a rotating body. In any case, it is more convenient to use such charges in low-velocity or even stationary ammunition. These can be, for example, rocket-propelled grenades, light gun shells, mines, ATGMs.

Passive Defense

Of course, immediately after the shaped charges appeared in the arsenal of the armies, means began to be developed to prevent them from hitting tanks and other heavy military equipment. For protection, special remote screens were developed, installed at some distance from the armor. Such funds are made of steel gratings and metal mesh. The effect of the cumulative jet on the armor of the tank, if present, is nullified.

Because the projectile explodes at a considerable distance from the armor when it hits the screen, the jet has time to break up before it reaches it. In addition, some varieties of such screens are capable of destroying the contacts of the detonator of a cumulative ammunition, as a result of which the latter simply does not explode at all.

What protection can be made of

During the Second World War, rather massive steel screens were used in the Soviet army. Sometimes they could be made of steel 10 mm and carried out by 300-500 mm. The Germans, during the war, everywhere used lighter steel protection.grids. At the moment, some durable screens are able to protect tanks even from high-explosive fragmentation shells. By causing a detonation at some distance from the armor, they reduce the impact on the machine of the shock wave.

Sometimes multi-layer protective screens are also used for tanks. For example, a sheet of steel by 8 mm can be carried out behind the car by 150 mm, after which the space between it and the armor is filled with light material - expanded clay, glass wool, etc. Further, a steel mesh is also carried out over such a screen by 300 mm. Such devices are able to protect the car from almost all types of ammunition with BVV.

Reactive Defense

Such a screen is also called reactive armor. For the first time, the protection of this variety in the Soviet Union was tested in the 40s by engineer S. Smolensky. The first prototypes were developed in the USSR in the 60s. The production and use of such means of protection in our country began only in the 80s of the last century. This delay in the development of reactive armor is explained by the fact that it was initially recognized as unpromising.

For a very long time, this type of protection was not used by the Americans either. The Israelis were the first to actively use reactive armor. The engineers of this country noticed that during the explosion of ammunition stocks inside the tank, the cumulative jet does not pierce the vehicles through and through. That is, the counter-explosion is able to contain it to some extent.

Israel began to actively use dynamic protection against cumulative projectiles in the 70slast century. Such devices were called "Blazer", made in the form of removable containers and placed outside the tank's armor. They used RDX-based Semtex explosives as a bursting charge.

Later, the dynamic protection of tanks against HEAT shells was gradually improved. At the moment, in Russia, for example, the Malachite systems are used, which are complexes with electronic control of detonation. Such a screen is able not only to effectively counteract HEAT shells, but also to destroy the most modern NATO sub-caliber DM53 and DM63, designed specifically to destroy the Russian ERA of the previous generation.

How the jet behaves underwater

In some cases, the cumulative effect of ammunition can be reduced. For example, a cumulative jet under water behaves in a special way. Under such conditions, it disintegrates already at a distance of 7 funnel diameters. The fact is that at high speeds, it is about as "hard" for a jet to break through water as it is for metal.

Soviet cumulative munitions for use under water, for example, were equipped with special nozzles that help form a jet and are equipped with weights.

Interesting facts

Of course, in Russia, work is currently underway to improve, including the most cumulative weapons. Modern domestic grenades of this variety, for example, are capable of penetrating a layer of metal more than a meter thick.

The weapons of this variety are used by differentcountries of the world for a long time. However, various legends and myths still circulate about him. So, for example, sometimes on the Web you can find information that cumulative jets, when they enter the interior of a tank, can cause such a sharp pressure surge that this leads to the death of the crew. About this effect of cumulative waves on the Internet, scary stories are often told, including by the military themselves. There is even an opinion that Russian tankers during the fighting deliberately drive with open hatches in order to relieve pressure in the event of a cumulative projectile.

However, according to the laws of physics, a metal jet cannot cause such an effect. Projectiles of this type simply concentrate the energy of the explosion in a certain direction. There is, therefore, a very simple answer to the question of whether a cumulative jet burns through or pierces armor. When meeting with the material of the walls of the tank, it slows down and really puts a lot of pressure on it. As a result, the metal begins to spread on the sides and be washed out in drops at high speed into the tank.

The material is liquefied in this case precisely because of the pressure. The temperature of the cumulative jet is low. At the same time, of course, it does not create any significant shock wave itself. The jet is able to pierce through the human body. Drops of liquid metal that have come off the armor itself also have serious destructive power. Even the shock wave from the explosion of the ammunition itself is not able to penetrate into the hole made by the jet in the armor. Accordingly, nothere is no excess pressure inside the tank.

According to the laws of physics, the answer to the question of whether a cumulative jet pierces or burns through armor is thus obvious. Upon contact with metal, it simply liquefies it and passes into the machine. It does not create excessive pressure behind the armor. Therefore, opening the hatch of the car when the enemy uses such ammunition, of course, is not worth it. In addition, this, on the contrary, increases the risk of concussion or death of crew members. The blast wave from the projectile itself can also penetrate into the open hatch.

Experiments with water and gelatin armor

You can recreate the cumulative effect if you wish, even at home. To do this, you need distilled water and a high-voltage spark gap. The latter can be made, for example, from a cable by soldering a copper washer coaxially with the main residential washer to its braid. Next, the center wire must be connected to the capacitor.

The role of a funnel in this experiment can be played by a meniscus formed in a thin paper tube. The arrester and the capillary must be connected by a thin elastic tube. Next, pour water into the tube using a syringe. After the formation of a meniscus at a distance of about 1 cm from the spark gap, you need to start a capacitor and close the circuit with a conductor fixed on an insulating rod.

A lot of pressure will develop in the breakdown area with such a home experiment. The shock wave will run towards the meniscus and collapse it.