NATO submariners will be scared away by silent bombs

In the middle of the last century, the design of the atomic bomb was a closely guarded secret. Only an extremely limited circle of scientists close to the governments of the great powers were privy to this secret. Other mortals were only supposed to know that the formula E=mc² had something to do with the matter, that uranium was needed, and that all this was very powerful witchcraft.

Now everything has changed. Nowadays, the structure of the atomic bomb can be found out from open sources, but still few people understand how the most terrible weapon of mankind works. But it's worth figuring it out. For example, to determine where in books and films there are fantastic assumptions, where there is anti-scientific nonsense, and where the author read the reference book but did not understand anything.

Atomic weapons are based on the chain reaction effect. The nuclei of some isotopes of heavy metals are unstable and, having captured a passing neutron, immediately decay. In this case, both large fragments and several more free neutrons appear. They can trigger the decay of other nuclei, resulting in the release of even more neutrons. This avalanche-like process leads to a rapid release of energy - a nuclear explosion, the power of which is equivalent to 25 tons of TNT for every gram of decayed isotope.

Of course, a chain reaction will not start if the metal ingot is not large enough and most of the released neutrons simply fly away beyond its boundaries. For an explosion to occur, the amount of fissile material must exceed a certain critical mass. The minimum explosive quantity of the substance is 47 kilograms for uranium-235 and 10 kilograms for plutonium-239: in practice, only these two metals are used to create nuclear explosive devices.

Already the second “Fat Man” bomb dropped on Nagasaki had a ball charge

It may seem that creating a critical mass is easy: take two ingots of uranium, one and a half pounds each, and combine them. But this is not the best idea, which is why complex implosion or ball charges are used in the manufacture of nuclear weapons. Their effect is based on the fact that when a force is applied to the surface of a sphere, as it approaches its center, the pressure will increase by the square. As a result, the spherical charge is a “matryoshka doll”. The outer spherical layer is formed by ordinary “chemical” explosives, on the surface of which 64 detonators are evenly distributed. All detonators must fire simultaneously - then an explosion occurs, which generates a shock wave directed towards the center.

If at least one detonator does not fire in time, the compression will be asymmetrical and will only lead to the destruction of the ammunition. And this serves as reliable protection. A bomb can fall out of a plane, fall along with the plane, burn in a carriage as a result of a train accident, or even be hit by an artillery shell (although the latter was only tested on mock-ups). In the worst case, this will lead to the detonation of conventional chemical explosives, but there will be no unplanned detonation of a nuclear charge.

Following the explosives in the ball charge is a layer of aluminum. Light metal is needed to increase the radius of the charge, and therefore the resulting pressure in the center of the sphere. A tamper is placed inside the hollow aluminum sphere - a hollow sphere made of depleted uranium, which serves as a massive piston

Through the tamper, the concentric shock wave is transmitted to the third, smallest hollow sphere, made of nuclear explosives - uranium or plutonium. In the very center there is a miniature tritium-based neutron source. The mass of “nuclear explosives” in a ball charge is usually one and a half to three times less than the critical mass. The development of a chain reaction in ammunition occurs due to additional neutrons emitted by tritium, an increase in the density of the metal at the moment of maximum compression, and also because the uranium tamper reflects the neutrons generated during the decay of nuclei inward, preventing them from leaving the reaction zone.

Ball charge of the first Soviet atomic bomb RDS-1 (Photo: Museum of Nuclear Weapons RFNC-VNIIEF)

The “ball” design makes it possible to safely insert a supercritical charge of a fissionable isotope into the ammunition. The record here belongs to the British: they produced a thin-walled plutonium sphere, the mass of which exceeded the critical mass by 12 times! But then the sons of Foggy Albion were simply fed up with ambition: how could it be that the Soviets and the States have a hydrogen bomb, but they don’t. The kingdom spent a year's supply of fissile materials to produce this technological miracle.

It is possible to increase the power of ammunition without such a waste of scarce materials. In an activated ball charge, chain decay continues not until the fuel is exhausted, as in a conventional bomb, but until the device is destroyed. The evaporated uranium ball no longer has sufficient density to support a chain reaction. In the first implosion bombs, only 10% of the nuclear explosive had time to burn out before the charge was dispersed, while in modern ones this figure ranges from 30 to 60%. The degree of burnout can be increased by providing additional compression. For this, a large - up to a quarter ton - charge of chemical explosive is used. Increasing the thickness of the tamper also helps. Of course, the additional inert mass is only able to withstand a nuclear flame bursting from the reaction zone for a short moment. But when the intensity of the reaction increases exponentially, even this moment is of great importance.

At the stage of burning lithium and uranium, the thermonuclear bomb resembles a star in design. It consists entirely of plasma - hot ionized gas, but is denser than lead.

The destructive power of modern nuclear weapons can be increased even more by using a capsule with thermonuclear fuel. Next to the first ball charge, which plays the role of a detonator, a second one is placed, arranged somewhat differently. Instead of a layer of chemical explosives, it is covered with inert plastic. Immediately below it is a depleted uranium tamper. And between the tamper and the central hollow sphere made of plutonium, there is a layer of lithium-6 deuteride, a compound of a light lithium isotope with heavy hydrogen. This white powder is not radioactive and is completely safe as long as you do not pour water on it.

The detonation of the first ball charge turns the plastic layer into superheated plasma, the pressure of which leads to the implosion of the thermonuclear capsule. Its plutonium core reaches a critical density and also explodes. Lithium, absorbing the resulting neutrons, decomposes into helium and superheavy hydrogen - tritium. The temperature at the shock wave collision front at this moment is sufficient for the thermonuclear fusion reaction involving deuterium and tritium to begin. And this means a third explosion - about a hundred times stronger than the first two.

Tsar Bomba, aka “Kuzka’s Mother,” the most powerful thermonuclear bomb in history (Croquant | CC BY-SA 3.0)

But the detonation of thermonuclear fuel is only the second phase of a thermonuclear explosion. If a nuclear explosion stops after the destruction of the explosive device, then the mechanism of the hydrogen bomb continues to work after the transition to the plasma state of aggregation. The fusion of heavy and superheavy hydrogen nuclei produces helium nuclei and neutrons. The energy of neutrons is so high that they are not captured by heavy nuclei, but break them up, like a billiard ball breaking a pyramid.

Under a hail of neutrons, uranium-238 reacts, which is quite safe under normal conditions. This is the third phase of the explosion, increasing its power five more times. The contribution of energy from the decay of uranium nuclei is not so great, but this process generates new clouds of neutrons. And the denser the neutron flux, the more lithium will turn into tritium, the higher the efficiency of the explosive device will be. A hydrogen bomb can be assembled in such a way that the burnup of each of the three components - plutonium, lithium deutride and depleted uranium - exceeds 90%. And this is monstrous energy.

"Baby", the first atomic bomb used in battle, was a cannon type

Nuclear weapons are valued primarily for their power, but sometimes compactness is more important. As a result, so-called cannon charges have become somewhat widespread (almost only in the USA). They consist of a plutonium cylinder with a hole in the center, a rod made of the same metal, a small amount of gunpowder that drives the rod into the hole, a single detonator to initiate the processes and... that's it. The obvious advantages of the cannon circuit were extreme simplicity, impeccable reliability of operation and tiny dimensions.

But a cannon-type charge is not just reliable, but too reliable. This is its main drawback. Thermal or mechanical damage to the ammunition will not disable it, but on the contrary, may cause it to fire. In the USSR they thought that the Yankees were crazy, and they did not copy this horror.

"Davy Crockett" is an over-caliber nuclear mine for firing from anti-tank 106-mm recoilless rifles. The Americans really intended to fire Crocketts at Soviet tanks and riveted a lot of this ammunition. The ridiculous TNT equivalent - only 10 tons - made it possible to hit with direct fire

The second disadvantage of cannon charges was their wastefulness. The amount of nuclear explosive must be supercritical. That is, on average three times more fissile metal is consumed per shot than with another scheme. If you calculate it in kilotons, the difference turns out to be stunning: the efficiency of a cannon charge is no higher than 1%. This was the case with the only strategic ammunition in history with a cannon-type charge—the “Baby” bomb dropped on Hiroshima. But there the entire device weighed four tons, and the uranium parts were placed in a piece of a gun barrel. And when using a cannon charge without a heavy-duty housing, the efficiency drops to 0.01–0.004%. The Americans, however, believed that the extremely low—from 10 to 150 tons of TNT equivalent—yield for tactical nuclear weapons was not a flaw, but an advantage.

The primitive design of the cannon charge gave rise to the myth that a nuclear bomb could be assembled in a garage. But it is impossible for a private individual to obtain several tens of kilograms of almost pure uranium-235. In addition, plutonium rapidly oxidizes in air, is very toxic and practically cannot be processed mechanically. Having tried to make parts of an explosive device using a homemade method from small plutonium ingots, the homemade worker will die from radiation sickness, from poisoning, or as a result of a fire that broke out in the garage, but will achieve nothing.

The Soviet 420-mm mortar 2B1 "Oka" was intended for firing nuclear weapons

2S7 "Peony". In the 1970s, miniature ball charges appeared in the USSR, which were placed in a 203-mm cannon shell, but their power was usually 5–15 kilotons, and such ammunition could only be called “tactical” only conditionally

Operating principle

Based on the practical incompressibility of water. A bomb explosion destroys or damages the hull of a submarine at depth. In this case, the energy of the explosion, instantly increasing to a maximum in the center, is transferred to the target by the surrounding water masses, through them destructively affecting the attacked military object. Due to the high density of the medium, the blast wave along its path does not significantly lose its initial power, but with increasing distance to the target, the energy is distributed over a larger area, and accordingly, the damage radius is limited.

The fuse is triggered when it hits the hull of the boat, at a certain depth, or when passing next to the hull.

Typically, depth charges are rolled from the stern of the ship or fired from a bomb launcher. Depth charges can also be dropped from aircraft (planes, helicopters) and delivered to the location where the submarine is detected using missiles.

Depth charges are characterized by their low accuracy, so to destroy one submarine a significant number of them is required, sometimes about a hundred bombs.

The evolution of depth charges in the USSR

Domestic samples were often equal to the indicators issued by foreign analogues. In general, the military industry of states in this component demonstrated amazing unanimity, releasing generations of projects with comparable characteristics. This also applies to the USSR’s eternal rival, the United States, as well as to the pioneers in the creation of depth charges, the British.

Depth charges have low range, power and accuracy. Unfortunately, this is a given with ease of use. These weapons have become a relic of the past, which were once in great need, but less so today.

Today, the progress of the submarine fleet has made it possible to achieve its own protective mechanisms on each side, the strength of the plating, and the speed of movement.

To counter submarines, it has become much more profitable to order missile systems that include nuclear warheads and detection equipment. Dropping bombs or launching simple torpedoes has become a pointless exercise.

It is probably reckless to say that the time of depth charges has passed. Still, they will remain an additional protective tool for each ship. But such weapons are not suitable for strategic warfare, and therefore are absolutely rightly considered obsolete.

Story

Depth charges found widespread use in the First World War.
The lessons of the first months of the war forced the naval leadership of the Entente powers to pay special attention to the creation of new anti-submarine weapons and the development of forms and methods of combating submarines. As such, they began to use demolition cartridges, which were, in essence, the prototype of depth charges: six-kilogram cartridges with a lit fire cord were dropped from destroyers at the supposed location of the submarine

The first sample of a depth charge was created in 1914 and, after testing, entered service with the British Navy.

Depth charges remained the most important type of anti-submarine weapon in World War II. The depth charge was improved in the direction of increasing the depth of the explosion and creating a variety of bomb calibers. The number of carriers of these weapons grew, including, in particular, aviation. All such bombs were immersed under the influence of gravity at a speed of 2.1-2.3 m/s, and were structurally made in the form of a cylindrical-conical body filled with an explosive charge inside which a fuse was placed; this design did not undergo fundamental changes until the 1950s.

Nuclear depth charges, which appeared after the war, were withdrawn from service in the 90s. Nowadays, depth charges are being intensively replaced by more accurate weapons (for example, a torpedo rocket).

Currently, the PLAB-250-120 anti-submarine aircraft bomb is in service with the Russian Navy aviation: bomb weight - 123 kg (of which the explosive weight is about 60 kg), length - 1500 mm, diameter - 240 mm.

Modern sea mines

The M-26 is recognized as the most powerful of the domestic mines created in pre-war times. Its charge is 250 kg. This is an anchor “explosive” with a shock-mechanical activation type. Due to the significant volume of the charge, the shape of the ammunition was changed from spherical to spherocylindrical. Its advantage was that when anchored it was positioned horizontally and it was easier to transport.

Another achievement of our compatriots in the field of military armament of ships was the KB galvanic impact mine, used as an anti-submarine weapon. It was the first to use cast iron safety caps, which left their place automatically when immersed in water. In 1941, a sinking valve was added to the mine, allowing it to sink to the bottom on its own when separated from the anchor.

In the post-war period, domestic scientists resumed the race for leadership. In 1957, the only self-propelled underwater missile was launched. It became a pop-up rocket mine KRM. This became the impetus for the development of a radically new type of weapon. The KRM device made a complete revolution in the production of domestic naval weapons.

In 1960, the USSR began implementing advanced mine systems consisting of mine-missiles and torpedoes. After 10 years, the Navy began to actively use anti-submarine mine-missiles PMR-1 and PMR-2, which have no analogues abroad.

The next breakthrough can be called the MPT-1 torpedo mine, which has a two-channel target search and recognition system. Its development lasted nine years.

All available data and testing have become a good platform for the formation of more advanced forms of weapons. In 1981, the first Russian universal anti-submarine torpedo mine was completed. It was slightly behind the American Captor design in its parameters, while being ahead of it in installation depths.

UDM-2, which entered service in 1978, was used to damage surface and submarine ships of all types. The mine was universal from all sides, from installation to self-destruction on land and in shallow water.

On land, mines did not acquire any particular tactical significance, remaining an additional type of weapon. Sea mines have received a perfect role. Having just appeared, they became a strategic weapon, often displacing other species into the background. This is due to the cost for combat of each individual vessel. The number of ships in the navy is determined and the loss of even one galleon can change the situation in favor of the enemy. Each ship has strong combat power and a sizable crew. The explosion of one sea mine under a ship can play a huge role in the entire war, which is incomparable to many explosions on land.

Naval mines during World War II

In certain years, among naval forces, mines were “weapons of the weak” and were not popular. Major naval powers such as England, Japan and the USA did not pay much attention to this type of weapon. During the First World War, attitudes towards weapons changed dramatically, when it was estimated that approximately 310,000 mines were delivered.

During the war, weapons were constantly improved. Everyone tried to increase his effectiveness in battle. It was then that magnetic, acoustic and combined sea mines were born. The use of this type of weapon not only from water, but also from aviation expanded their potential. Ports, military naval bases, navigable rivers and other water bodies were under threat.

There was heavy damage in all directions from sea mines. Approximately a tenth of transport units were destroyed using this type of weapon.

About 1,120 mines were installed in the neutral parts of the Baltic Sea at the start of hostilities. And the characteristic features of the region only contributed to the effective use of ammunition.

Excerpt characterizing Depth Charge

“To resist the evil that reigns in the world...” Pierre repeated, and he imagined his future activities in this field. He imagined the same people as he himself was two weeks ago, and he mentally addressed them with an instructive and mentoring speech. He imagined vicious and unhappy people whom he helped in word and deed; imagined the oppressors from whom he saved their victims. Of the three goals named by the rhetorician, this last one - the correction of the human race - was especially close to Pierre. Some important sacrament mentioned by the rhetorician, although it incited his curiosity, did not seem significant to him; and the second goal, cleansing and correcting himself, occupied him little, because at that moment he felt with pleasure that he was already completely corrected from his previous vices and ready for only one good thing. Half an hour later, the rhetorician returned to convey to the seeker those seven virtues corresponding to the seven steps of the Temple of Solomon, which every Mason had to cultivate in himself. These virtues were: 1) modesty, respect for the secrets of the order, 2) obedience to the highest ranks of the order, 3) good morals, 4) love of humanity, 5) courage, 6) generosity and 7) love of death. “Seventhly, try,” said the rhetorician, “by frequently thinking about death to bring yourself to the point that it no longer seems to you a terrible enemy, but a friend... who frees the languishing soul from this miserable life in the works of virtue, to introduce it to a place of reward and calm. “Yes, this must be so,” thought Pierre, when after these words the rhetorician left him again, leaving him to solitary reflection. “This should be so, but I am still so weak that I love my life, the meaning of which is only now gradually revealed to me.” But the other five virtues, which Pierre remembered as he ran through his fingers, he felt in his soul: courage, generosity, kindness, love for humanity, and especially obedience, which did not even seem to him a virtue, but happiness. (He was so happy now to get rid of his arbitrariness and subordinate his will to those and those who knew the undoubted truth.) Pierre forgot the seventh virtue and could not remember it. The third time, the rhetorician returned quickly and asked Pierre if he was still firm in his intention, and whether he dared to subject himself to everything that was required of him. “I’m ready for anything,” said Pierre. “I must also tell you,” said the rhetorician, “that our order teaches its teaching not only in words, but by other means, which, perhaps, have a stronger effect on the true seeker of wisdom and virtue than verbal explanations alone.” This temple, with its decoration, which you see, should have already explained to your heart, if it is sincere, more than words; You will see, perhaps, with your further acceptance, a similar image of explanation. Our Order imitates ancient societies that revealed their teachings in hieroglyphs. A hieroglyph, said the rhetorician, is the name of some thing not subject to feelings, which contains qualities similar to the one depicted.

History of creation

The earliest mentions of sea mines are recorded in the records of the Ming officer Jiao Yu in the 14th century. In the history of China, similar use of explosives is mentioned in the 16th century, when there were clashes with Japanese robbers. The ammunition fit into a wooden container, protected from moisture with putty. Several mines drifting in the sea with a planned explosion were planted by General Qi Jugang. Subsequently, the mechanism for activating the explosive was activated using a long cord.

A project on the use of marine worlds was developed by Rubbards and presented to Queen Elizabeth of England. In Holland, the creation of weapons called “floating firecrackers” also took place. In practice, such weapons turned out to be unsuitable for use.

The electronic mine fuse was developed in 1812. This innovation was created by the Russian engineer Schilling. Jacobi later discovered an anchor mine capable of floating. The latter, in an amount of more than one and a half thousand pieces, were placed in the Gulf of Finland by the Russian military during the Crimean War.

According to official statistics of the Russian naval forces, the first successful case of using a sea mine was considered to be 1855. Ammunition was actively used during the Crimean and Russian-Japanese military events. During the First World War, with their help, about four hundred ships were sunk, of which nine were battleships.