Depending on their carrier, sea mines are divided into ship mines (thrown from the deck of ships), boat mines (fired from torpedo tubes of a submarine) and aviation mines (dropped from an airplane). According to their position after setting, mines are divided into anchored, bottom and floating (with the help of devices they are kept at a given distance from the surface of the water); by type of fuses - contact (explode upon contact with a ship), non-contact (explode when a ship passes at a certain distance from the mine) and engineering (explode from a coastal command post). Contact mines come in galvanic impact, mechanical impact and antenna types. The fuse of contact mines has a galvanic element, the current of which (during the contact of the ship with the mine) closes the electrical fuse circuit using a relay inside the mine, which causes an explosion of the mine charge. Non-contact anchor and bottom mines are equipped with highly sensitive fuses that react to the physical fields of the ship when it passes near the mines (changing magnetic field, sound vibrations, etc.). Depending on the nature of the field to which proximity mines react, magnetic, induction, acoustic, hydrodynamic or combined mines are distinguished. The proximity fuse circuit includes an element that senses changes in the external field associated with the passage of a ship, an amplification path and an actuator (ignition circuit). Engineering mines are divided into wire-controlled and radio-controlled. To make it more difficult to combat non-contact mines (mine sweeping), the fuse circuit includes urgency devices that delay bringing the mine into firing position for any required period, multiplicity devices that ensure the mine explodes only after a specified number of impacts on the fuse, and decoy devices that cause the mine to explode while trying to disarm it.

The first, albeit unsuccessful, attempt to use a floating mine was made by Russian engineers in the Russian-Turkish war of 1768-1774. In 1807 in Russia, military engineer I. I. Fitzum designed a sea mine, detonated from the shore along a fire hose. In 1812, the Russian scientist P. L. Schilling implemented a project for a mine that would be exploded from the shore using an electric current. In the 1840-50s, academician B. S. Jacobi invented a galvanic impact mine, which was installed under the surface of the water on a cable with an anchor. These mines were first used during the Crimean War of 1853-56. After the war, Russian inventors A.P. Davydov and others created shock mines with a mechanical fuse. Admiral S. O. Makarov, inventor N. N. Azarov and others developed mechanisms for automatically laying mines on a given recess and improved methods for laying mines from surface ships. Naval mines were widely used in the 1st World War 1914-18. In World War 2 (1939-45), non-contact mines (mainly magnetic, acoustic and magnetic-acoustic) appeared. Urgency and multiplicity devices and new anti-mine devices were introduced into the design of non-contact mines. Airplanes were widely used to lay mines in enemy waters. In the 60s, a new class of mines appeared - the “attack” mine, which is a combination of a mine platform with a torpedo or missile of the “water-water-target” or “water-air-target” class. In the 70s, self-transporting mines were developed, which are based on an anti-submarine torpedo that delivers a bottom mine to the mining area, where the latter lies on the ground.

The forerunner of sea mines was first described by the early Ming Chinese artillery officer Jiao Yu in a 14th-century military treatise called Huolongjing. Chinese chronicles also talk about the use of explosives in the 16th century to fight against Japanese pirates (wokou). Sea mines were placed in a wooden box, sealed with putty. General Qi Juguang made several of these delayed-detonation drift mines to harass Japanese pirate ships. Sut Yingxing's treatise Tiangong Kaiu (Use of Natural Phenomena) of 1637 describes sea mines with a long cord stretched to a hidden ambush located on the shore. By pulling the cord, the ambush man activated a steel wheel lock with flint to produce a spark and ignite the sea mine fuse.

The first project on the use of sea mines in the West was made by Ralph Rabbards; he presented his developments to Queen Elizabeth of England in 1574. The Dutch inventor Cornelius Drebbel, who worked in the artillery department of the English king Charles I, was engaged in the development of weapons, including “floating firecrackers”, which showed their unsuitability. The British apparently tried to use this type of weapon during the siege of La Rochelle in 1627. American David Bushnell invented the first practical sea mine for use against Great Britain during the American Revolutionary War. It was a sealed barrel of gunpowder, which floated towards the enemy, and its impact lock exploded upon collision with a ship. In 1812, Russian engineer Pavel Schilling developed an electric fuse for an underwater mine. In 1854, during an unsuccessful attempt by the Anglo-French fleet to capture the Kronstadt fortress, several British steamships were damaged by the underwater explosion of Russian naval mines. More than 1,500 sea mines, or “infernal machines,” designed by Boris Jacobi, were planted by Russian naval specialists in the Gulf of Finland during the Crimean War. Jacobi created a sea anchor mine, which had its own buoyancy (due to the air chamber in its body), a galvanic impact mine, and introduced the training of special units of galvanizers for the fleet and sapper battalions.

According to official data from the Russian Navy, the first successful use of a sea mine took place in June 1855 in the Baltic during the Crimean War. The ships of the Anglo-French squadron were blown up by mines laid by Russian miners in the Gulf of Finland. Western sources cite earlier cases - 1803 and even 1776. Their success, however, has not been confirmed. Sea mines were widely used during the Crimean and Russian-Japanese wars. During the First World War, 310 thousand sea mines were installed, from which about 400 ships sank, including 9 battleships.
Sea mines can be installed both by surface ships (vessels) (mine layers), and from submarines (through torpedo tubes, from special internal compartments/containers, from external trailed containers), or dropped by aircraft. Anti-landing mines can also be installed from the shore at shallow depths.

To combat sea mines, all available means are used, both special and improvised. The classic means are minesweepers. They can use contact and non-contact trawls, mine search devices or other means. A contact-type trawl cuts the mine, and the mines that float to the surface are shot with firearms. To protect minefields from being swept by contact trawls, a mine protector is used. Non-contact trawls create physical fields that trigger fuses. In addition to specially built minesweepers, converted ships and vessels are used. Since the 40s, aviation can be used as minesweepers, including from the 70s x helicopters. Demolition charges destroy the mine at the place of placement. They can be installed by search vehicles, combat swimmers, improvised means, and less often by aviation. Minebreakers - a kind of kamikaze ships - trigger mines with their own presence. Sea mines are being improved in the areas of increasing the power of charges, creating new types of proximity fuses and increasing resistance to minesweeping. https://ru.wikipedia.org/wiki

Marine mine weapons (we will here understand by this term only sea mines and mine complexes of various types) are especially popular today among countries that do not have powerful navies, but have a fairly long coastline, as well as among the so-called third world countries or terrorist (criminal) communities that, for one reason or another, do not have the opportunity to purchase modern high-precision weapons for their naval forces (such as anti-ship and cruise missiles, missile-carrying aircraft, warships of the main classes). http://nvo.ng .ru/armament/2008-08-01/8_mina.html

The main reasons for this are the extreme simplicity of the design of sea mines and the ease of their operation compared to other types of naval underwater weapons, as well as a very reasonable price, several times different from the same anti-ship missiles. “Cheap, but cheerful” - this motto can be used without any reservations apply to modern naval mine weapons.

The command of the naval forces of Western countries came face to face with the “asymmetrical” mine threat, as it is often called abroad, during recent counter-terrorism and peacekeeping operations, which involved the involvement of fairly large naval forces. It turned out that mines - even outdated types - pose a very serious threat to modern warships. The concept of littoral warfare, on which the US Navy has recently been relying, has also come under attack.

Moreover, the high potential of naval mine weapons is ensured not only due to their high tactical and technical characteristics, but also due to the high flexibility and variety of tactics of their use. So, for example, the enemy can carry out mine laying in its territorial or even internal waters, under the cover of coastal defense means and at the most convenient time for it, which significantly increases the surprise factor of its use and limits the ability of the opposing side to timely identify the mine threat and eliminate it . The danger posed by bottom mines with proximity fuses of various types installed in shallow areas of coastal seas is especially great: mine detection systems in this case function more effectively, and poor visibility, strong coastal and tidal currents, the presence of a large number of mine-like objects (false targets) and the proximity of naval bases or coastal defense facilities of the enemy complicates the work of mine-sweeping forces and groups of divers-miners of a potential aggressor.

According to naval experts, sea mines are “the quintessence of modern asymmetric warfare.” They are easy to install and can remain in position for many months or even years without requiring additional maintenance or issuing any commands. They are in no way influenced by any change in the conceptual provisions of warfare at sea, or by a change in the country's political course. They just lie there, at the bottom, and wait for their prey. To better understand how high potential modern mines and mine systems have, let's look at several samples of Russian naval mine weapons that are allowed for export.

For example, bottom mine MDM-1 Mod. 1, deployed both from submarines with 534 mm torpedo tubes and from surface ships, is designed to destroy enemy surface ships and their submerged submarines. Having a combat weight of 960 kg (boat version) or 1070 kg (installed from surface ships) and a warhead equivalent to a TNT charge weighing 1120 kg, it is capable of remaining in position in the “cocked state” for at least one year, and after the expiration of its assigned time During combat service, it simply self-destructs (which eliminates the need to search for and destroy it). The mine has a fairly wide range of application depth - from 8 to 120 m, is equipped with a three-channel proximity fuse that responds to the acoustic, electromagnetic and hydrodynamic fields of the target ship, urgency and frequency devices, and also has effective means of countering modern mine-sweeping systems of various types (contact, non-contact trawls, etc.). In addition, detecting a mine using acoustic and optical means is made difficult by the camouflage paint used and the special material of the body. For the first time, the mine, adopted for service in 1979, was demonstrated to the general public at the Abu Dhabi Arms and Military Equipment Exhibition (IDEX) in February 1993. Note that this is a mine adopted by the Russian Navy almost 30 years ago, but after it there were other bottom mines;

Another example of domestic mine weapons is the PMK-2 anti-submarine mine complex (export designation of the PMT-1 anti-submarine torpedo mine, adopted by the USSR Navy in 1972 and modernized in 1983 according to the MTPK-1 version), designed to destroy enemy submarines various classes and types at depths from 100 to 1000 m. The PMK-2 can be deployed from 534-mm torpedo tubes of submarines at depths of up to 300 meters and speeds of up to eight knots, or from surface ships at speeds of up to 18 knots, or from anti-submarine aircraft from altitudes of no more than 500 m and at flight speeds of up to 1000 km/h.

A distinctive feature of this mine complex is the use of a small-sized anti-submarine torpedo as a warhead (the latter, in turn, has a warhead weighing 130 kg in TNT equivalent and is equipped with a combined fuse). The total weight of the PMK-2, depending on the modification (type of installation), ranges from 1400 to 1800 kg. After installation, the PMK-2 can remain in position in combat-ready condition for at least one year. The hydroacoustic system of the complex constantly monitors its sector, detects a target, classifies it and provides data to a computer to determine the elements of the target's movement and generate data for launching a torpedo. After the torpedo enters the target zone at the designated depth, it begins to move in a spiral, and its seeker searches for the target and subsequently captures it. An analogue of the PMK-2 is the American anti-submarine mine system Mk60 Mod0/Mod1 CAPTOR (enCAPsulated TORpedo), which has been supplied to the United States Navy since 1979, but has already been withdrawn from both service and production.

However, people abroad try not to forget about the “horned death”. Countries such as the USA, Finland, Sweden and a number of others are today actively working to modernize old and develop new types of mines and mine systems. Perhaps the only maritime power that has almost completely abandoned the use of live sea mines is Great Britain. For example, in 2002, in an official response to a parliamentary inquiry, the commander of the Royal Navy noted that they “have not held any stockpiles of sea mines since 1992. At the same time, the United Kingdom retains the ability to use this type of weapon and continues to carry out R&D in this area. But the fleet only uses practical (training) mines - during exercises to develop the skills of personnel.”

However, this “self-prohibition” does not apply to British companies, and, for example, BAE Systems produces the Stonefish mine for export. In particular, this mine, equipped with a combined fuse that reacts to the acoustic, magnetic and hydrodynamic fields of the ship, is in service in Australia. The mine has an operating depth range of 30–200 m and can be deployed from aircraft, helicopters, surface ships and submarines.

Among the foreign models of sea mine weapons, it is worth noting the American self-transporting bottom mine Mk67 SLMM (Submarine-Launched Mobile Mine), which is designed for covert mining of shallow-water (actually coastal) areas of the seas, as well as fairways, water areas of naval bases and ports, approach to which the submarine carrying out mine-laying is too dangerous due to the enemy’s strong anti-submarine defense or is difficult due to the characteristics of the bottom topography, shallow depths, etc. In such cases, the carrier submarine can carry out mine-laying from a distance equal to the range of the mine itself, which, after leaving from the torpedo tube, the submarine, due to its electric power plant, moves out to a given area and lies on the ground, turning into an ordinary bottom mine capable of detecting and attacking surface ships and submarines. Taking into account the fact that the range of the mine is about 8.6 miles (16 km), and the width of the territorial waters is 12 miles, it can be easily seen that submarines equipped with such mines can, in peacetime or on the eve of the outbreak of hostilities, actions without much difficulty to carry out mining of the coastal areas of a potential enemy.

Externally, the Mk67 SLMM looks like a standard torpedo. However, it does include a torpedo - the mine itself is built on the basis of the Mk37 Mod2 torpedo, the design of which was made about 500 changes and improvements. Among other things, the warhead underwent changes - instead of a standard warhead, a mine was installed (it used an explosive of the PBXM-103 type). The onboard guidance system equipment was modernized, and combined proximity fuses Mk58 and Mk70, similar to those installed on American bottom mines of the Quickstrike family, were used. The working depth of the mine ranges from 10 to 300 m, and the mine interval (the distance between two adjacent mines) is 60 m. The disadvantage of the Mk67 SLMM is its “analog” nature, as a result of which when using the mine on submarines with a “digital” BIUS it is necessary to perform additional actions to “adapt” to the carrier.

Development of the Mk67 SLMM began in 1977–1978 and initial plans called for 2,421 of the new type of mine to be delivered to the United States Navy by 1982. However, for a number of reasons, including the end of the Cold War, the work was delayed, and the complex reached its initial operational readiness state only in 1992 (which is equivalent to putting it into service). Ultimately, the Pentagon purchased from the manufacturer, Raytheon Naval and Maritime Integrated Systems Company (Portsmouth, formerly Davey Electronics), only 889 mines, of which the oldest are already being removed from service and disposed of due to the expiration of their shelf life. An analogue of this mine is the Russian self-transporting bottom mines of the SMDM family, created on the basis of the 533-mm torpedo 53-65KE and the 650-mm torpedo 65-73 (65-76).

Recently, work has been underway in the United States to modernize the Mk67 SLMM mine complex, which is being carried out in several directions: firstly, the mine’s self-propelled range is increasing (due to improvements in the power plant) and its sensitivity is increasing (due to the installation of a newer programmable proximity fuse of the TDD type Mk71); secondly, the Honeywell Marine Systems company offers its own version of the mine - based on the NT-37E torpedo, and thirdly, back in 1993, work began on creating a new modification of the self-transporting mine based on the Mk48 Mod4 torpedo (the highlight of the mine should be the presence two warheads that have the ability to separate and detonate independently of each other, thus undermining two separate targets).

The US military also continues to improve bottom mines of the Quickstrike family, created on the basis aircraft bombs Mk80 series in various calibers. Moreover, these mines are constantly used in various exercises of the Navy and Air Force of the United States and its allies.

The work in the field of naval mine weapons carried out by Finnish specialists deserves special mention. This is especially interesting due to the fact that the military-political leadership of Finland announced at the official level that the state’s defensive strategy in the maritime sector will be based on the widespread use of sea mines. At the same time, minefields designed to turn coastal areas into “dumpling soup” will be covered by coastal artillery batteries and coastal defense missile battalions.

The latest development of Finnish gunsmiths is the M2004 mine complex, serial production of which began in 2005 - the first contract for sea mines under the designation “Sea Mine 2000” was received by the Patria company (the main contractor for the program) in September 2004, committing to supply an unspecified number of them in 2004–2008 and then carry out maintenance of products in storage and operation areas.

Naval mine weapons are a “closed secret,” along with torpedo weapons, and are a source of special pride for those powers that can independently develop and produce them. Today, sea mines of various types are in service with the navies of 51 countries, of which 32 are capable of serial production themselves, and 13 export them to other countries. Moreover, in the US Navy alone after the Korean War, out of 18 lost and heavily damaged warships, 14 became victims of naval mine weapons.

If we evaluate the amount of effort expended by even the most advanced countries in the world to eliminate the mine threat, then it is enough to give the following example. On the eve of the First Gulf War, in January–February 1991, the Iraqi Navy deployed more than 1,300 sea mines of 16 different types in the coastal areas of Kuwait, in landing areas, which also caused the failure of the “brilliantly thought out” American amphibious landing operation. After the expulsion of Iraqi troops from Kuwaiti territory, it took the multinational coalition forces several months to completely clear these areas of mines. According to published data, the mine countermeasures forces of the navies of the United States, Germany, Great Britain and Belgium managed to find and destroy 112 mines - mainly old Soviet AMD aircraft bottom mines and KMD ship mines with Crab proximity fuses.

Everyone also remembers the “mine war” that took place in the Persian Gulf in the late 1980s. It is interesting that then the commanders of American warships allocated to escort commercial ships in the zone of the “blazing fire” bay quickly realized: oil tankers, due to their design features (double hull, etc.), were relatively invulnerable to the threat from sea mines. And then the Americans began to place tankers, especially empty ones, at the head of the convoy - even ahead of the escort warships.

In general, in the period from 1988 to 1991, it was mines that caused serious damage to American warships operating in the waters of the Persian Gulf: - 1988 - the guided-missile frigate Samuel B. Roberts was blown up by an Iranian mine of the M-08 type, which received a hole 6.5 m in size (mechanisms were torn from the foundations, the keel was broken) and then withstood repairs costing $135 million; - February 1991 - the landing helicopter carrier "Tripoli" was allegedly blown up by an Iraqi mine of the LUGM-145 type, and the URO cruiser " Princeton" - also on an Iraqi bottom mine of the "Manta" type of Italian design (the explosion damaged the equipment of the Aegis system, air defense system, propeller shafting, rudder and part of the superstructures and decks). It should be noted that both of these ships were part of a large amphibious formation with 20 thousand marines on board, which was tasked with conducting a naval landing operation(during the liberation of Kuwait, the Americans were never able to conduct a single amphibious landing operation).

In addition, the destroyer URO "Paul F. Foster" ran into an anchor contact, "horned" mine and only by luck remained unharmed - it turned out to be too old and simply did not work. By the way, in the same conflict, the American minesweeper Avenger became the first mine-resistant ship in history to detect and neutralize a Manta-type mine in combat conditions - one of the best “shallow-water” bottom mines in the world.

When the time came for Operation Iraqi Freedom, allied forces had to worry more seriously. In the areas of operation of the forces and assets of the joint group of naval forces, only according to data officially released by the Pentagon, 68 mines and mine-like objects were discovered and destroyed. Although such data raise reasonable doubts: for example, according to the American military, several dozen Manta-type mines alone were discovered, and in addition, 86 Manta rays were found by the Australians in Iraqi warehouses and minelayers. In addition, units of American special operations forces managed to detect and intercept a cargo ship literally “clogged” with Iraqi anchor and bottom mines, which were supposed to be placed on lines of communication in the Persian Gulf and presumably in the Strait of Hormuz. Moreover, each mine was disguised in a special “cocoon” made from an empty oil barrel. And after the end of the active phase of hostilities, American operational search groups came across several more small vessels converted into minelayers.

It should be especially noted that during the Second Gulf War, in the area of ​​​​combat operations and on the territory of naval bases and bases of the US Navy and its allies in the Persian Gulf, American units that had dolphins and California lions, specially trained to combat sea ​​mines and mine-like objects. In particular, “animals in uniform” were used to guard the naval base in Bahrain. Exact data on the results of the use of such units have not been officially released, but the American military command acknowledged the death of one dolphin sapper.

Additional tension during the operation was created by the fact that military personnel of mine-sweeping forces and units of divers-miners were often involved not only in the search and destruction of mines and mine-like objects of all types - floating, anchored, bottom, “self-burrowing”, etc., but also in destruction of anti-landing mine-explosive and other obstacles (for example, anti-tank minefields on the shore).

Mine clearance operations also left their indelible mark on the Russian Navy. Particularly memorable is the demining of the Suez Canal, carried out by the Soviet Navy at the request of the Egyptian government from July 15, 1974. On the USSR side, 10 minesweepers, 2 line laying ships and another 15 guard ships and auxiliary vessels participated; The French, Italian, American and British navies also took part in trawling the canal and bay. Moreover, the “Yankees” and “Tommies” trawled areas with exposed Soviet-style mines - which helped them a lot in practicing actions to combat the mine weapons of a potential enemy. By the way, permission for the American-British allies to mine these areas was issued by the military-political leadership of Egypt in violation of the Agreement on Military Supplies of September 10, 1965, signed by the USSR and Egypt.

However, this does not in any way detract from the invaluable experience gained by Soviet sailors in the Suez Canal. It was then that in real conditions, on live mines, actions were practiced to destroy bottom mines with the help of minesweeper helicopters that laid cord charges or towed non-contact trawls. The use of all types of trawls and mine detectors in tropical conditions, the use of the VKT trawl for breaking through the first tack and the BShZ (combat cord charge) for thinning a minefield of combat mines by helicopters were also tested. Based on the experience gained, Soviet mine specialists adjusted the minesweeping instructions that existed in the USSR Navy. It was also prepared a large number of officers, foremen and sailors who gained invaluable experience in combat trawling.

Due to the changing nature of mine warfare at sea and the expansion of the range of tasks of mine countermeasures forces, their units must be prepared to operate equally effectively both in deep and shallow areas of oceans and seas, and in extremely shallow areas of coastal zones, rivers and lakes, as well as in tidal zones. zone (surf strip) and even on the “beach”. I would especially like to note that in the last decade of the last century there was a clear tendency for the military of third world countries to use quite interesting way minelaying - old contact anchor and more modern non-contact bottom mines began to be used within the same minefield, which complicated the process of trawling itself, since it required the mine action forces to use different types of trawls (and to search for bottom mines, also underwater uninhabited mine action vehicles) .

All this requires from the mine-sweeping forces military personnel not only appropriate comprehensive training, but also the availability of the necessary weapons and technical means for detecting mines and mine-like objects, their examination and subsequent destruction.

The particular danger of modern sea mine weapons and their rapid spread around the world is that waters favorable for laying sea mines today account for up to 98% of global commercial shipping. The following circumstance is also important: modern concepts of the use of naval forces of the leading countries of the world Special attention pay attention to the ability of ship groupings to perform various maneuvers, including in the coastal, or “littoral” zone. Sea mines limit the actions of warships and auxiliary vessels, thus becoming a significant obstacle to the solution of their assigned tactical tasks. The result is that for the leading countries of the world with large navies, it has now become more preferable to create effective mine countermeasures forces than to develop mines and minelayers.

In connection with all of the above, the navies of the leading countries of the world have recently paid increased attention to the development of mine action forces and means. In this case, the emphasis is on the use of modern technologies and the use of uninhabited remote-controlled underwater equipment.

Modern sea mines seem to be the most formidable weapon on both sides, with the help of which it is possible to block sea communications around the world for a long time so that not only military operations will be impossible, but also trade and other peaceful activities will be stopped. Relevant agreements should be developed in this direction.

What are sea mines and torpedoes? How are they structured and what are the principles of their operation? Are mines and torpedoes now the same formidable weapons as during past wars?

All this is explained in the brochure.

It is written based on materials from open domestic and foreign press, and issues of the use and development of mine and torpedo weapons are presented according to the views of foreign experts.

The book is addressed to a wide range of readers, especially young people preparing for service in the USSR Navy.

Sections of this page:

Modern mines and their structure

A modern sea mine is a complex structural device that operates automatically under water.

Mines can be laid from surface ships, submarines and aircraft on the routes of ships, near enemy ports and bases. “Some mines are placed on the bottom of the sea (rivers, lakes) and can be activated by a coded signal.

Self-propelled mines, which use the positive properties of an anchor mine and a torpedo, are considered the most complex. They have devices for detecting the target, separating the torpedo from the anchor, aiming at the target and detonating the charge with a proximity fuse.

There are three classes of mines: anchored, bottom and floating.

Anchor and bottom mines are used to create stationary minefields.

Floating mines are usually used in river theaters to destroy enemy bridges and crossings located downstream, as well as his ships and floating craft. They can also be used at sea, but provided that the surface current is directed towards the enemy’s base area. There are also floating self-propelled mines.

Mines of all classes and types have a charge of conventional explosive (TNT) weighing from 20 to several hundred kilograms. They can also be equipped with nuclear charges.

In the foreign press, for example, it was reported that a nuclear charge with a TNT equivalent of 20 kt is capable of causing severe destruction at a distance of up to 700 m, sinking or disabling aircraft carriers and cruisers, and at a distance of up to 1400 m causing damage that significantly reduces the combat effectiveness of these ships .

The explosion of mines is caused by fuses, which are of two types - contact and non-contact.

Contact fuses are triggered by direct contact of the ship's hull with a mine (impact mines) or with its antenna (electric contact fuze). They are usually equipped with anchor mines.

Proximity fuses are triggered by exposure to the ship's magnetic or acoustic field or by the combined influence of these two fields. They are often used to detonate bottom mines.

The type of mine is usually determined by the type of fuze. Hence mines are divided into contact and non-contact.

Contact mines are impact and antenna, and non-contact mines are acoustic, magneto-hydrodynamic, acoustic-hydrodynamic, etc.

Anchor mines

An anchor mine (Fig. 2) consists of a waterproof body with a diameter of 0.5 to 1.5 m, a mine, an anchor, explosive devices, safety devices that ensure safe handling of the mine when preparing it on the deck of a ship for deployment and when dropping it into the water , as well as from mechanisms that place a mine on a given recess.

The body of the mine can be spherical, cylindrical, pear-shaped or other streamlined shape. It is made from steel sheets, fiberglass and other materials.

There are three compartments inside the case. One of them is an air cavity that provides the positive buoyancy of the mine, which is necessary to keep the mine at a given depth from the sea surface. Another compartment houses the charge and detonators, and the third contains various devices.

Minrep is a steel cable (chain), which is wound around a view (drum) installed on the mine’s anchor. The upper end of the minerep is attached to the body of the mine.

When assembled and prepared for deployment, the mine lies at anchor.

Min metal anchors. They are made in the form of a cup or cart with rollers, thanks to which the mines can easily move along rails or along the smooth steel deck of a ship.

Anchor mines are activated by a variety of contact and non-contact fuses. Contact fuses are most often galvanic impact, electrical impact and mechanical impact.

Galvanic impact and electric shock fuses are also installed in some bottom mines, which are placed in shallow coastal waters specifically against enemy landing craft. Such mines are usually called anti-landing mines.

1 - safety device; 2 - galvanic impact fuse; 3-igniter glass; 4-charging camera

The main parts of galvanic fuses are lead caps, inside of which glass cylinders with electrolyte are placed (Fig. 3), and galvanic cells. The caps are located on the surface of the mine body. Upon impact with the ship's hull, the lead cap is crushed, the cylinder breaks and the electrolyte falls on the electrodes (carbon - positive, zinc - negative). A current appears in the galvanic cells, which from the electrodes enters the electric igniter and sets it into action.

The lead caps are covered with cast iron safety caps, which are automatically released by springs after the mine is set.

Electric impact fuses are activated by electric shock. In a mine with such fuses, several metal rods protrude, which, upon impact with the ship’s hull, bend or move inward, connecting the mine’s fuse to an electric battery.

In impact-mechanical fuses, the blasting device is a percussion-mechanical device, which is activated by an impact on the ship’s hull. The shock in the fuse causes a displacement of the inertial load holding the spring frame with the striker. The released firing pin pierces the primer of the ignition device, which activates the mine charge.

Safety devices typically consist of sugar or hydrostatic disconnectors, or both.

1 - cast iron safety cap; 2 - spring for releasing the safety cap after setting the mine; 3 - lead cap with a galvanic element; 4 - glass container with electrolyte; 5 - carbon electrode; 6 - zinc electrode; 7 - insulating washer; 8 - conductors from carbon and zinc electrodes

The sugar disconnector is a piece of sugar inserted between the spring contact discs. When sugar is inserted, the fuse circuit is open.

Sugar dissolves in water after 10-15 minutes, and the spring contact, closing the circuit, makes the mine dangerous.

The hydrostatic disconnector (hydrostat) prevents the connection of the spring contact disks or the displacement of the inertial weight (in mechanical impact mines) while the mine is on the ship. When diving from water pressure, the hydrostat releases a spring contact or an inertial weight.

A is the specified mine recess; I - minrep; II - mine anchor; 1 - mine dropped; 2 - the mine sinks; 3- mine on the ground; 4-minrep is wound up; 5-mine settled at a given depth

According to the method of setting, anchor mines are divided into those floating from the bottom [* This method of setting anchor mines was proposed by Admiral S. O. Makarov in 1882] and those installed from the surface [** The method of setting mines from the surface was proposed by Lieutenant of the Black Sea Fleet N. N. Azarov . in 1882].

h is the specified mine recess; I-mine anchor; II - shtert; III-cargo; IV - minrep; 1-mine dropped; 2 - the mine has separated from the anchor, the mine is freely unwound from the view; 3. 4- mine on the surface, the mine continues to unwind; 5 - the load reached the ground, the minrep stopped reeling in; 6 - the anchor pulls the mine down and sets it at a given depth equal to the length of the rod

When setting a mine from the bottom, the drum with the mine is integral with the body of the mine (Fig. 4).

The mine is secured to the anchor with steel cable slings, which prevent it from being separated from the anchor. The slings at one end are tightly fixed to the anchor, and at the other end they are passed through special ears (butts) in the mine body and then connected to the sugar disconnector in the anchor.

When set, after falling into the water, the mine goes to the bottom along with the anchor. After 10-15 minutes, the sugar dissolves, releases the lines and the mine begins to float.

When the mine reaches a given depression from the water surface (h), a hydrostatic device located near the drum will stop the mine.

Instead of a sugar disconnector, a clock mechanism can be used.

Laying anchor mines from the surface of the water is carried out as follows.

A view (drum) with a minerep wound around it is placed on the mine’s anchor. A special locking mechanism is attached to the view, connected via a pin (cord) to the load (Fig. 5).

When a mine is thrown overboard, due to its reserve of buoyancy, it floats on the surface of the water, but the anchor separates from it and sinks, unwinding the mine from the view.

A load is moving in front of the anchor, attached to a rod, the length of which is equal to the specified recess of the mine (h). The load touches the bottom first and thereby gives some slack to the anchor. At this moment, the locking mechanism is activated and the unwinding of the minerep stops. The anchor continues to move to the bottom, dragging the mine with it, which sinks into the depression. equal to length Shterta.

This method of laying mines is also called shtorto-cargo. It has become widespread in many navies.

Based on the weight of the charge, anchor mines are divided into small, medium and large. Small mines have a charge weighing 20-100 kg. They are used against small ships and vessels in areas with a depth of up to 500 m. The small size of the mines makes it possible to accept several hundred of them on minelayers.

Medium mines with charges of 150-200 kg are intended to combat ships and vessels of medium displacement. The length of their minrep reaches 1000-1800 m.

Large mines have a charge weight of 250-300 kg or more. They are designed to operate against large ships. Having a large reserve of buoyancy, these mines allow you to wind a long minerep onto a view. This makes it possible to lay mines in areas with a sea depth of more than 1800 m.

Antenna mines are conventional anchor percussion mines with electric contact fuses. Their operating principle is based on the property of inhomogeneous metals, such as zinc and steel, placed in sea water, to create a potential difference. These mines are used primarily for anti-submarine warfare.

Antenna mines are placed in a depression of about 35 m and are equipped with upper and lower metal antennas, each approximately 30 m long (Fig. 6).

The upper antenna is held in a vertical position by a buoy. The specified buoy recess should not be greater than the draft of enemy surface ships.

The lower end of the lower antenna is fastened to the mine's mine. The ends of the antennas facing the mine are connected to each other by a wire that runs inside the mine body.

If a submarine collides directly with a mine, it will detonate it in the same way as an anchor strike mine. If the submarine touches the antenna (upper or lower), then a current will arise in the conductor; it flows to sensitive devices that connect the electric igniter to a constant current source located in the mine and having sufficient power to activate the electric igniter.

From the above it is clear that antenna mines cover the upper layer of water about 65 m thick. To increase the thickness of this layer, a second line of antenna mines is placed in a larger depression.

A surface ship (vessel) can also be blown up by an antenna mine, but the explosion of an ordinary mine at a distance of 30 m from the keel does not cause significant destruction.

Foreign experts believe that the minimum deployment depth allowed by the technical design of anchor shock mines is at least 5 m. The closer the mine is to the sea surface, the greater the effect of its explosion. Therefore, in obstacles intended against large ships (cruisers, aircraft carriers), it is recommended to place these mines with a given depth of 5-7 m. To combat small ships, the depth of the mines does not exceed 1-2 m. Such mine placements are dangerous even for boats.

But shallow minefields are easily detected by airplanes and helicopters and, in addition, are quickly thinned out (scattered) under the influence of strong waves, currents and drifting ice.

The combat service life of a contact anchor mine is limited mainly by the service life of the mine, which rusts in water and loses its strength. If there is excitement, it can break, since the force of jerks on the minerep for small and medium-sized mines reaches hundreds of kilograms, and for large mines - several tons. The survivability of minereps and especially the places where they are attached to a mine are also affected by tidal currents.

Foreign experts believe that in ice-free seas and in areas of the sea that are protected by islands or coastal configurations from waves caused by prevailing winds, even a shallow minefield can stand for 10-12 months without much depression.

Deep minefields designed to combat submerged submarines are the slowest to clear.

Contact anchor mines are characterized by their simplicity of design and low cost of manufacture. However, they have two significant drawbacks. Firstly, the mines must have a reserve of positive buoyancy, which limits the weight of the charge placed in the hull, and therefore the effectiveness of using mines against large ships. Secondly, such mines can easily be lifted to the surface of the water by any mechanical trawls.

Experience in the combat use of contact anchor mines in the First World War showed that they did not fully satisfy the requirements of fighting enemy ships: due to the low probability of a ship encountering a contact mine.

In addition, ships that encountered an anchor mine usually escaped with limited damage to the bow or side of the ship: the explosion was localized by strong bulkheads, watertight compartments, or an armor belt.

This led to the idea of ​​​​creating new fuses that could sense the approach of a ship at a considerable distance and detonate the mine at the moment when the ship was in the danger zone from it.

The creation of such fuses became possible only after the physical fields of the ship were discovered and studied: acoustic, magnetic, hydrodynamic, etc. The fields seemed to increase the draft and width of the underwater part of the hull and, if there were special devices on the mine, made it possible to receive a signal about the approach of the ship.

Fuses triggered by the influence of one or another physical field of the ship were called non-contact. They made it possible to create a new type of bottom mines and made it possible to use anchor mines for laying in seas with high tides, as well as in areas with strong currents.

In these cases, anchor mines with proximity fuses can be placed in such a depression that their bodies do not float to the surface during low tides, and during high tides the mines remain dangerous for ships passing over them.

The actions of strong currents and tides only slightly deepen the body of the mine, but its fuse still senses the approach of the ship and explodes the mine at the right moment.

The design of anchored non-contact mines is similar to anchored contact mines. The only difference between them is the design of the fuses.

The weight of a charge of proximity mines is 300-350 kg, and, according to foreign experts, their deployment is possible in areas with a depth of 40 m or more.

The proximity fuse is triggered at some distance from the ship. This distance is called the sensitivity radius of a fuse or proximity mine.

The proximity fuse is adjusted so that its sensitivity radius does not exceed the radius of the destructive effect of a mine explosion on the underwater part of the ship's hull.

The proximity fuse is designed in such a way that when a ship approaches a mine at a distance corresponding to its sensitivity radius, a mechanical contact closure occurs in the combat circuit into which the fuse is connected. As a result, a mine explodes.

What are the physical fields of the ship?

For example, every steel ship has a magnetic field. The strength of this field depends mainly on the amount and composition of the metal from which the ship is built.

The appearance of the ship’s magnetic properties is due to the presence of the Earth’s magnetic field. Since the Earth's magnetic field is not the same and changes in magnitude with changes in the latitude of the place and the course of the ship, the magnetic field of the ship also changes when sailing. It is usually characterized by tension, which is measured in oersteds.

When a ship with a magnetic field approaches a magnetic mine, the latter causes the magnetic needle installed in the fuse to oscillate. Deviating from its original position, the arrow closes a contact in the combat circuit, and the mine explodes.

When moving, the ship forms an acoustic field, which is created mainly by the noise of rotating propellers and the operation of numerous mechanisms located inside the ship's hull.

Acoustic vibrations of the ship's mechanisms create a total vibration, perceived as noise. The noises of different types of ships have their own characteristics. In high-speed ships, for example, high frequencies are more intensely expressed, in slow-moving ships (transports) - low frequencies.

The noise from the ship spreads over a considerable distance and creates an acoustic field around it (Fig. 7), which is the environment where non-contact acoustic fuses are triggered.

A special device for such a fuse, such as a carbon hydrophone, converts the perceived sound frequency vibrations generated by the ship into electrical signals.

When the signal reaches a certain value, it means that the ship has entered the range of a proximity mine. Through auxiliary devices, the electric battery is connected to the fuse, which activates the mine.

But carbon hydrophones only listen to noise in the audio frequency range. Therefore, special acoustic receivers are used to receive frequencies lower and higher than sound.

An acoustic field travels over a much greater distance than a magnetic field. Consequently, it seems possible to create acoustic fuses with a large area of ​​effect. That is why during the Second World War, most non-contact fuses worked on the acoustic principle, and in combined non-contact fuses one of the channels was always acoustic.

When a ship moves in an aquatic environment, a so-called hydrodynamic field is created, which means a decrease in hydrodynamic pressure in the entire layer of water from the bottom of the ship to the bottom of the sea. This decrease in pressure is a consequence of the displacement of a mass of water by the underwater part of the ship's hull, and also arises as a result of wave formation under the keel and behind the stern of a fast-moving ship. So, for example, a cruiser with a displacement of about 10,000 tons, sailing at a speed of 25 knots (1 knot = 1852 m/h), in an area with a sea depth of 12-15 m creates a decrease in pressure by 5 mm of water. Art. even at a distance of up to 500 m to your right and left.

It was found that the magnitudes of the hydrodynamic fields of different ships are different and depend mainly on the speed and displacement. In addition, as the depth of the area in which the ship moves decreases, the bottom hydrodynamic pressure it creates increases.

To capture changes in the hydrodynamic field, special receivers are used that respond to a specific program of changes in high and low pressures observed during the passage of the ship. These receivers are part of hydrodynamic fuses.

When the hydrodynamic field changes within certain limits, the contacts move and close the electrical circuit that activates the fuse. As a result, a mine explodes.

It is believed that tidal currents and waves can create significant changes in hydrostatic pressure. Therefore, to protect mines from false alarms in the absence of a target, hydrodynamic receivers are usually used in combination with non-contact fuses, for example, acoustic ones.

Combined proximity fuses are used quite widely in mine weapons. This is due to a number of reasons. It is known, for example, that purely magnetic and acoustic bottom mines are relatively easy to clear. The use of a combined acoustic-hydrodynamic fuse significantly complicates the trawling process, since acoustic and hydrodynamic trawls are required for these purposes. If on a minesweeper one of these trawls fails, then the mine will not be cleared and may explode when the ship passes over it.

To make it difficult to clear non-contact mines, in addition to combined non-contact fuses, special urgency and frequency devices are used.

An emergency device equipped with a clock mechanism can be set for a period of validity from several hours to several days.

Until the expiration date for installing the device, the proximity fuse of the mine will not be included in the combat circuit and the mine will not explode even when a ship passes over it or the action of a trawl.

In such a situation, the enemy, not knowing the setting of the urgency devices (and it can be different in each mine), will not be able to determine how long it is necessary to mine the fairway so that the ships can put to sea.

The multiplicity device begins to operate only after the expiration of the time limit for installing the urgency device. It can be set to allow one or more passages of a ship over a mine. To detonate such a mine, the ship (trawl) needs to pass over it as many times as the multiplicity setting. All this greatly complicates the fight against mines.

Proximity mines can explode not only from the considered physical fields of the ship. Thus, the foreign press reported on the possibility of creating proximity fuses, the basis of which could be highly sensitive receivers capable of responding to changes in temperature and composition of water during the passage of ships over a mine, to light-optical changes, etc.

It is believed that the physical fields of ships still contain many unexplored properties that can be learned and applied in mining.

Bottom mines

Bottom mines are usually non-contact mines. They usually have the shape of a waterproof cylinder rounded at both ends, about 3 m long and about 0.5 m in diameter.

Inside the body of such a mine there is a charge, a fuse and more. necessary equipment(Fig. 8). The weight of the bottom non-contact mine charge is 100-900 kg.

/ - charge; 2 - stabilizer; 3 - fuse equipment

The minimum depth for laying bottom non-contact mines depends on their design and is several meters, and the greatest, when these mines are used against surface ships, does not exceed 50 m.

Against submerged submarines a short distance from the ground, bottom non-contact mines are placed in areas with sea depths of more than 50 m, but not deeper than the limit determined by the strength of the mine body.

The explosion of a bottom proximity mine occurs under the bottom of a ship, where there is usually no mine protection.

It is believed that such an explosion is the most dangerous, since it causes both local damage to the bottom, weakening the strength of the ship's hull, and general bending of the bottom due to the uneven intensity of the impact along the length of the ship.

It must be said that the holes in this case are larger in size than when a mine explodes near the side, which leads to the death of the ship.-

Bottom mines in modern conditions have found very wide application and have led to some displacement of anchor mines. However, when deployed at depths of more than 50 m, they require a very large explosive charge.

Therefore for great depths Conventional anchor mines are still used, although they do not have the same tactical advantages as bottom proximity mines.

Floating mines

Modern floating (self-transporting) mines are automatically controlled by devices different devices. Thus, one of the American submarine automatically floating mines has a floating device.

The basis of this device is an electric motor that rotates a propeller in the water, located at the bottom of the mine (Fig. 9).

The operation of the electric motor is controlled by a hydrostatic device, which operates from; external water pressure and periodically connects the battery to the electric motor.

If the mine sinks to a depth greater than that installed on the navigation device, then the hydrostat turns on the electric motor. The latter rotates the propeller and forces the mine to float to a given recess. After this, the hydrostat turns off the engine power.

1 - fuse; 2 - explosive charge; 3 - battery; 4- hydrostat for electric motor control; 5 - electric motor; 6 - propeller of the navigation device

If the mine continues to float, the hydrostat will turn on the electric motor again, but in this case the propeller will rotate in the opposite direction and force the mine to deepen. It is believed that the accuracy of holding such a mine at a given depression can be achieved ±1 m.

In the post-war years in the United States, a self-transporting mine was created on the basis of one of the electric torpedoes, which, after being fired, moves in a given direction, sinks to the bottom and then acts as a bottom mine.

To combat submarines, the United States has developed two self-transporting mines. One of them, designated “Slim,” is intended for placement at submarine bases and along the routes of their intended movement.

The design of the Slim mine is based on a long-range torpedo with various proximity fuses.

According to another project, a mine called "Captor" was developed. It is a combination of an anti-submarine torpedo with a mine anchor device. The torpedo is placed in a special sealed aluminum container, which is anchored at a depth of up to 800 m.

When a submarine is detected, the mine device is activated, the container lid is opened and the torpedo engine is started. The most important part of this mine is the target detection and classification devices. They allow you to distinguish a submarine from a surface ship and your submarine from an enemy submarine. The devices respond to various physical fields and give a signal to activate the system when registering at least two parameters, for example, hydrodynamic pressure and frequency of the hydroacoustic field.

It is believed that the mine interval (distance between adjacent mines) for such mines is close to the response radius (maximum operating range) of the torpedo homing equipment (~1800 m), which significantly reduces their consumption in the anti-submarine barrier. The expected service life of these mines is two to five years.

Similar mines are also being developed by the German Navy.

It is believed that protection against automatically floating mines is very difficult, since trawls and ship guards do not clear these mines. Their characteristic feature is that they are equipped with special devices - liquidators, connected to a clock mechanism, which is set for a given period of validity. After this period, the mines sink or explode.

* * *

Speaking about the general directions of development of modern mines, it should be borne in mind that over the last decade the navies of NATO countries have been paying special attention to the creation of mines used to combat submarines.

It is noted that mines are the cheapest and most widespread type of weapon, which can equally well hit surface ships, conventional and nuclear submarines.

By type of carrier, most modern foreign mines are universal. They can be installed by surface ships, submarines and aircraft.

Mines are equipped with contact, non-contact (magnetic, acoustic, hydrodynamic) and combined fuses. They are designed for a long service life, equipped with various anti-sweeping devices, mine traps, self-destructors and are difficult to mine.

Among NATO countries, the US Navy has the largest stockpile of mine weapons. The US mine arsenal includes a wide variety of anti-submarine mines. Among them we can note the Mk.16 ship mine with an enhanced charge and the Mk.6 anchor antenna mine. Both mines were developed during World War II and are still in service with the US Navy.

By the mid-60s, the United States had adopted several types of new non-contact mines for use against submarines. These include aircraft small and large bottom non-contact mines (Mk.52, Mk.55 and Mk.56) and an anchored non-contact mine Mk.57, intended for deployment from submarine torpedo tubes.

It should be noted that the United States mainly develops mines intended for laying by aircraft and submarines.

The weight of the aircraft mine charge is 350-550 kg. At the same time, instead of TNT, they began to equip them with new explosives, exceeding the power of TNT by 1.7 times.

In connection with the requirement to use bottom mines against submarines, the depth of their placement site has been increased to 150-200 m.

Foreign experts consider a serious drawback of modern mine weapons to be the lack of anti-submarine mines with a large range of action, the depth of which would allow them to be used against modern submarines. It is noted that at the same time the design has become more complicated and the cost of mines has increased significantly.

German aircraft bottom mine LMB
(Luftmine B (LMB))

(Information on the mystery of the death of the battleship "Novorossiysk")

Preface.

On October 29, 1955, at 1:30 a.m., an explosion occurred in the roadstead of Sevastopol, as a result of which the flagship of the Black Sea Fleet battleship"Novorossiysk" (formerly Italian "Giulio Cezare") received a hole in the bow. At 4:15 a.m., the battleship capsized and sank due to the unstoppable flow of water into the hull.

The government commission that investigated the causes of the death of the battleship named the most likely cause an explosion under the bow of the ship of a German sea-bottom non-contact mine of the LMB or RMH type, or simultaneously two mines of one or another brand.

For most researchers who have studied this problem, this version of the cause of the event raises serious doubts. They believe that an LMB or RMH type mine, which could possibly lie at the bottom of the bay (divers in 1951-53 discovered 5 LMB type mines and 19 RMH mines), did not have sufficient power, and its explosive device could not lead to mine to explosion.

However, opponents of the mine version mainly point out that by 1955 the batteries in the mines were completely discharged and therefore the explosive devices could not go off.
In general, this is absolutely true, but usually this thesis is not convincing enough for supporters of the mine version, since opponents do not consider the characteristics of mine devices. Some of the supporters of the mine version believe that for some reason, the clock devices in the mines did not work as expected, and on the evening of October 28, being disturbed, they went off again, which led to the explosion. But they also do not prove their point of view by examining the design of the mines.

The author will try to describe as fully as possible today the design of the LMB mine, its characteristics and methods of activation. I hope that this article will bring at least a little clarity to the causes of this tragedy.

WARNING. The author is not an expert in the field of sea mines, and therefore the material below should be treated critically, although it is based on official sources. But what to do if experts in naval mine weapons are in no hurry to introduce people to German naval mines.
A dedicated land traveler had to take on this matter. If any of the maritime specialists deems it necessary and possible to correct me, then I will be sincerely glad to make corrections and clarifications to this article. One request - do not link to secondary sources ( works of art, memoirs of veterans, someone’s stories, justifications of naval officers involved in the event). Only official literature (instructions, technical descriptions, manuals, memos, service manuals, photographs, diagrams).

German seaborne, aircraft-launched mines of the LM (Luftmine) series were the most common and most frequently used of all non-contact bottom mines. They were represented by five different types of mines installed from aircraft.
These types were designated LMA, LMB, LMC, LMD, and LMF.
All these mines were non-contact mines, i.e. for their operation, direct contact of the ship with the target sensor of a given mine was not required.

The LMA and LMB mines were bottom mines, i.e. after being dropped they fell to the bottom.

The LMC, LMD and LMF mines were anchor mines, i.e. Only the mine’s anchor lay on the bottom, and the mine itself was located at a certain depth, like ordinary sea mines of contact action. However, the LMC, LMD and LMF mines were placed at a depth greater than the draft of any ship.

This is due to the fact that bottom mines must be installed at depths not exceeding 35 meters, so that the explosion could cause significant damage to the ship. Thus, the depth of their application was significantly limited.

Non-contact anchor mines could be installed at the same sea depths as conventional contact anchor mines, having the advantage over them that they can be placed not at a depth equal to or less than the drafts of ships, but much deeper and thereby complicate their trawling .

In the Sevastopol Bay, due to its shallow depths (within 16-18 meters to the silt layer), the use of LMC, LMD and LMF mines was impractical, and the LMA mine, as it turned out back in 1939, had an insufficient charge (half as much as in LMB) and its production was discontinued.

Therefore, to mine the bay the Germans used only LMB mines from this series. No other types of mines of this series were found either during the war or in the post-war period.

LMB mine.

The LMB mine was developed by Dr.Hell SVK in 1928-1934 and was adopted by the Luftwaffe in 1938.

There were four main models - LMB I, LMB II, LMB III and LMB IV.

The mines LMB I, LMB II, LMB III were practically indistinguishable from each other in appearance and were very similar to the LMA mine, differing from it longer(298 cm versus 208 cm) and charge weight (690 kg versus 386 kg).

The LMB IV was a further development of the LMB III mine.
First of all, it was distinguished by the fact that the cylindrical part of the mine body, excluding the explosive device compartment, was made of waterproof plasticized pressed paper (press paper). The hemispherical nose of the mine was made of bakelite mastic. This was dictated partly by the characteristics of the experimental explosive device "Wellensonde" (AMT 2), and partly by a shortage of aluminum.

In addition, there was a variant of the LMB mine with the designation LMB/S, which differed from other options in that it did not have a parachute compartment, and this mine was installed from various watercraft (ships, barges). Otherwise, she was no different.

However, only mines with aluminum casings were found in Sevastopol Bay, i.e. LMB I, LMB II or LMB III, which differed from each other only in minor design features.

The following explosive devices could be installed in the LMB mine:
* magnetic M1 (aka E-Bik, SE-Bik);
* acoustic A1;
* acoustic A1st;
* magnetic-acoustic MA1;
* magnetic-acoustic MA1a;
* magnetic-acoustic MA2;
* acoustic with low-tone circuit AT2;
* magnetohydrodynamic DM1;
* acoustic-magnetic with low-tone circuit AMT 1.

The latter was experimental and there is no information about its installation in mines.

Modifications of the above explosive devices could also be installed:
*M 1r, M 1s - modifications of the M1 explosive device, equipped with devices against trawling by magnetic trawls
* magnetic M 4 (aka Fab Va);
* acoustic A 4,
* acoustic A 4st;
* magnetic-acoustic MA 1r, equipped with a device against trawling by magnetic trawls
* modification of MA 1r under the designation MA 1ar;
* magnetic-acoustic MA 3;

Main characteristics of the LMB mine:

Frame	-aluminum or pressed damask
Overall dimensions:	-diameter 66.04 cm.
	- length 298.845 cm.
Total mine weight	-986.56 kg.
Weight of explosive charge	-690.39 kg.
Type of explosive	hexonite
Explosive devices used	-M1, M1r, M1s, M4, A1, A1st, A4, A4st, AT1, AT2, MA1, MA1a, Ma1r, MA1ar, MA2, MA3, DM1
Additional devices used	-clock mechanism for bringing the mine into firing position types UES II, UES IIa
	-timer self-liquidator type VW (may not be installed)
	-timer neutralizer type ZE III (may not be installed)
	-non-neutralization device type ZUS-40 (may not be installed)
	-bomb fuse type LHZ us Z(34)B
Installation methods	- parachute drop from an airplane
	-dropping from a watercraft (LMB/S mine option)
Mine application depths	- from 7 to 35 meters.
Target detection distances	-from 5 to 35 meters
Mine use options	- unguided bottom mine with a magnetic, acoustic, magnetic-acoustic or magnetic-barometric target sensor,
Time to bring into combat position	-from 30 min. up to 6 hours in 15 minutes. intervals or
	-from 12 o'clock up to 6 days at 6-hour intervals.
Self-liquidators:
hydrostatic (LiS)	- when lifting a mine to a depth of less than 5.18 m.
timer (VW)	- in time from 6 hours to 6 days with 6-hour intervals or not
hydrostatic (LHZ us Z(34)B)	-if the mine after being dropped did not reach a depth of 4.57m.
Self-neutralizer (ZE III)	-after 45-200 days (may not have been installed)
Multiplicity device (ZK II)	- from 0 to 6 ships or
	- from 0 to 12 ships or
	- from 1 to 15 ships
Mine tamper protection	-Yes
Combat work time	- determined by the serviceability of the batteries. For mines with acoustic explosive devices from 2 to 14 days.

Hexonite is a mixture of hexogen (50%) with nitroglycerin (50%). More powerful than TNT by 38-45%. Hence the mass of the charge in TNT equivalent is 939-1001 kg.

LMB mine device.

Externally, it is an aluminum cylinder with a rounded nose and an open tail.

Structurally, the mine consists of three compartments:

*main charge compartment, which houses the main charge, bomb fuse LHZusZ(34)B, clock for bringing the explosive device into firing position UES with hydrostatic self-destruction device LiS, hydrostatic mechanism for switching on the intermediate detonator and device for inactivating the bomb fuse ZUS-40..
On the outside, this compartment has a yoke for suspension to the aircraft, three hatches for filling the compartment with explosives and hatches for the UES, bomb fuse and mechanism for activating the intermediate detonator.

*explosive device compartment in which the explosive device is located, with a multiplicity device, a timer self-liquidator, a timer neutralizer, a non-neutralization device and a tamper-evident device.

*parachute compartment, which houses the stowed parachute. The terminal devices of some explosive devices (microphones, pressure sensors) go into this compartment.

UES (Uhrwerkseinschalter). The LMB mine used clock mechanisms for bringing the mine into firing position of the UES II or UES IIa types.

The UES II is a hydrostatic clock mechanism that begins timing only if the mine is at a depth of 5.18 m or more. It is turned on by the activation of the hydrostat, which releases the anchor mechanism of the watch. You should know that the UES II clock mechanism will continue to operate even if the mine is removed from the water at this time.
UES IIa is similar to UES II, but stops working if the mine is removed from the water.
The UES II is located under the hatch on the side surface of the mine on the opposite side to the suspension yoke at a distance of 121.02 cm from the nose. The diameter of the hatch is 15.24 cm, secured with a locking ring.

Both types of UES could be equipped with a hydrostatic LiS (Lihtsicherung) anti-recovery device, which short-circuited the battery to an electric detonator and exploded the mine if it was raised and it was at a depth of less than 5.18 m. In this case, the LiS could be connected directly to the UES circuit and was activated after the UES had completed its time, or through a forecontact (Vorkontakt), which activated the LiS 15-20 minutes after the start of the UES operation. LiS ensured that the mine could not be raised to the surface after it was dropped from the craft.

The UES clock mechanism can be preset to the required time to bring the mine into firing position, ranging from 30 minutes to 6 hours at 15-minute intervals. Those. the mine will be brought into firing position after being reset in 30 minutes, 45 minutes, 60 minutes, 75 minutes,......6 hours.
The second option for UES operation is that the clock mechanism can be pre-set for the time it takes to bring the mine into firing position within the range from 12 hours to 6 days at 6-hour intervals. Those. the mine will be brought into firing position after being reset in 12 hours, 18 hours, 24 hours,......6 days. Simply put, when a mine hits water to a depth of 5.18 m. or deeper, the UES will first work out its delay time and only then will the process of setting up the explosive device begin. Actually, the UES is a safety device that allows its ships to safely move near the mine for a certain time known to them. For example, during ongoing mining work in the water area.

Bomb fuze (Bombenzuender) LMZ us Z(34)B. Its main task is to detonate the mine if it does not reach a depth of 4.57.m. until 19 seconds have elapsed since touching the surface.
The fuse is located on the side surface of the mine at 90 degrees from the suspension yoke at 124.6 cm from the nose. Hatch diameter 7.62cm. secured with a retaining ring.
The fuse design has a clock-type timer mechanism that opens the inertial weight 7 seconds after the safety pin is removed from the fuse (the pin is connected by a thin wire to the aircraft's release device). After the mine touches the surface of the earth or water, the movement of the inertial weight triggers a timer mechanism, which after 19 seconds triggers the fuse and the explosion of the mine, if the hydrostat in the fuse does not stop the timer mechanism until this moment. And the hydrostat will only work if the mine by that moment reaches a depth of at least 4.57 meters.
In fact, this fuse is a mine self-destructor in case it falls on the ground or in shallow water and can be detected by the enemy.

Non-neutralization device (Ausbausperre) ZUS-40. The ZUS-40 non-neutralization device can be located under the fuse. It is intended to The enemy diver was unable to remove the LMZusZ(34)B fuse, and thereby make it possible to lift the mine to the surface.
This device consists of a spring-loaded striker, which is released if you try to remove the LMZ us Z(34)B fuze from the mine.

The device has a firing pin 1, which, under the influence of a spring 6, tends to move to the right and pierce the igniter primer 3. The movement of the firing pin is prevented by a stopper 4, resting on the bottom of a steel ball 5. The non-destructive device is placed in the side ignition cup of the mine under the fuse, the detonator of which fits into the socket of the non-destructive device . The striker is moved to the left, as a result of which the contact between it and the stopper is broken. When a mine hits water or soil, the ball flies out of its socket, and the stopper, under the action of spring 2, falls down, clearing the way for the striker, who is now restrained from puncturing the primer only by the fuse detonator. When the fuse is removed from the mine by more than 1.52 cm, the detonator leaves the liquidator socket and finally releases the striker, which pierces the detonator cap, the explosion of which explodes a special detonator, and from it the main charge of the mine explodes.

From the author. Actually, the ZUS-40 is a standard non-neutralization device used in German aerial bombs. They could be equipped with most high-explosive and fragmentation bombs. Moreover, the ZUS was installed under a fuse and a bomb equipped with it was no different from one that was not equipped with one. In the same way, this device could be present in the LMB mine or not. A few years ago, an LMB mine was discovered in Sevastopol, and when trying to dismantle it, two home-grown deminers were killed by the explosion of the mechanical guard of the explosive device (GE). But only a special kilogram charge worked there, which was designed specifically to shorten excessive curiosity. If they had begun to unscrew the bomb fuse, they would have saved their relatives from having to bury them. Explosion 700 kg. hexonite would simply turn them into dust.

I would like to draw the attention of all those who like to delve into the explosive remnants of war to the fact that yes, most German capacitor-type bomb fuses are no longer dangerous. But keep in mind that under any of them there may be a ZUS-40. And this thing is mechanical and can wait for its victim indefinitely.

Intermediate detonator switch. Placed on the opposite side of the bomb fuse at a distance of 111.7 cm. from the nose. It has a hatch with a diameter of 10.16 cm, secured with a locking ring. The head of its hydrostat protrudes onto the surface of the side of the mine next to the bomb fuse. The hydrostat is locked by a second safety pin, which is connected with a thin wire to the aircraft's release device. The main task of the intermediate detonator switch is to protect against a mine explosion in case of accidental activation of the explosive mechanism before the mine reaches depth. When the mine is on land, the hydrostat does not allow the intermediate detonator to connect to the electric detonator (and the latter is connected by wires to explosive device) and if the explosive device is accidentally triggered, only the electric detonator will explode. When the mine is dropped, simultaneously with the safety pin of the bomb fuse, the safety pin of the intermediate detonator switch is pulled out. Upon reaching a depth of 4.57 meters, the hydrostat will allow the intermediate detonator to connect with the electric detonator.

Thus, after separating the mine from the aircraft, the safety pins of the bomb fuse and the intermediate detonator switch, as well as the parachute pull pin, are removed using tension wires. The parachute cap is dropped, the parachute opens and the mine begins to descend. At this moment (7 seconds after separation from the aircraft), the bomb fuse timer opens its inertial weight.
At the moment the mine touches the surface of the earth or water, the inertial weight due to impact with the surface starts the bomb fuse timer.

If after 19 seconds the mine is not deeper than 4.57 meters, then the bomb fuse detonates the mine.

If the mine has reached a depth of 4.57 m before the expiration of 19 seconds, then the timer of the bomb fuse is stopped and the fuse does not take part in the operation of the mine in the future.

When the mine reaches a depth of 4.57 m. The hydrostat of the intermediate detonator switch sends the intermediate detonator into connection with the electric detonator.

When the mine reaches a depth of 5.18 m. The UES hydrostat starts its clockwork and the countdown begins until the explosive device is brought into firing position.

In this case, after 15-20 minutes from the moment the UES clock starts operating, the LiS anti-recovery device may turn on, which will detonate the mine if it is raised to a depth of less than 5.18 m. But depending on the factory presets, LiS may not be turned on 15-20 minutes after starting the UES, but only after the UES has completed its time.

After a predetermined time, the UES will close the explosive circuit to the explosive device, which will begin the process of bringing itself into a firing position.

After the main explosive device has brought itself into a combat position, the mine is in a combat alert position, i.e. waiting for the target ship.

The impact of an enemy ship on the sensitive elements of the mine leads to its explosion.

If the mine is equipped with a timer neutralizer, then depending on the set time in the range from 45 to 200 days, it will separate the power source from the electrical circuit of the mine and the mine will become safe.

If the mine is equipped with a self-liquidator, then, depending on the set time within up to 6 days, it will short-circuit the battery to the electric detonator and the mine will explode.

The mine can be equipped with a device to protect the explosive device from opening. This is a mechanically actuated discharge fuse, which, if an attempt is made to open the explosive device compartment, will detonate a kilogram charge of explosives, which will destroy the explosive device, but will not lead to the explosion of the entire mine.

Let's look at explosive devices that could be installed in an LMB mine. All of them were installed in the explosive device compartment at the factory. Let us immediately note that it is possible to distinguish which device is installed in a given mine only by the markings on the body of the mine.

M1 Magnetic Explosive Device (aka E-Bik and SE-Bik). This is a magnetic non-contact explosive a device that responds to changes in the vertical component of the Earth's magnetic field. Depending on the factory settings, it can respond to changes in the north direction (magnetic lines of force go from the north pole to the south), to changes in the south direction, or to changes in both directions.

From Yu. Martynenko. Depending on the place where the ship was built, or more precisely, on how the slipway was oriented according to the cardinal points, the ship forever acquires a certain direction of its magnetic field. It may happen that one ship can safely pass over a mine many times, while another is blown up.

Developed by Hartmann & Braun SVK in 1923-25. M1 is powered by an EKT battery with an operating voltage of 15 volts. The sensitivity of the early series device was 20-30 mOe. Later it was increased to 10 mOe, and the latest series had a sensitivity of 5 mOe. Simply put, M1 detects a ship at distances from 5 to 35 meters. After the UES has worked for a specified time, it supplies power to M1, which begins the process of tuning to the magnetic field that is present in a given place at the time the A.L.A (a device built into M1 and designed to determine the characteristics of the magnetic field and accept them for zero value).
The M1 explosive device in its circuit had a vibration sensor (Pendelkontakt), which blocked the operation of the explosive circuit when the mine was exposed to disturbing influences of a non-magnetic nature (impacts, jolts, rolling, shock waves of underwater explosions, strong vibrations from working mechanisms and ship propellers working too closely). This ensured the mine's resistance to many minesweeping measures of the enemy, in particular to minesweeping using bombing, pulling anchors and cables along the bottom.
The M1 explosive device was equipped with a VK clock spring mechanism, which, when assembling the mine at the factory, could be set to work out time intervals from 5 to 38 seconds. It was intended to prevent the detonation of an explosive device if the magnetic influence of a ship passing over a mine stopped before a specified period of time. When the M1 mine's explosive device reacts to a target, it causes the clock solenoid to fire, thus starting the stopwatch. If magnetic influence is present at the end of the specified time, the stopwatch will close the explosive network and detonate the mine. If the mine is not detonated after approximately 80 VK operations, it is switched off.
With the help of VK, the insensitivity of the mine to small high-speed ships (torpedo boats, etc.) and magnetic trawls installed on aircraft was achieved.
Also inside the explosive device was a multiplicity device (Zahl Kontakt (ZK)), which was included in the electrical circuit of the explosive device, which ensured that the mine exploded not under the first ship passing over the mine, but under a certain one.
The M1 explosive device used multiplicity devices of types ZK I, ZK II, ZK IIa and ZK IIf.
All of them are driven by a clock-type spring drive, the anchors of which are controlled by electromagnets. However, the mine must be brought into firing position before the electromagnet that controls the anchor can begin to operate. Those. the program for bringing the M1 explosive device into firing position must be completed. A mine explosion could occur under the ship only after the multiplicity device had counted the specified number of ship passes.
The ZK I was a six-step mechanical counter. I took into account triggering pulses lasting 40 seconds or more.
Simply put, it could be configured to pass from 0 to 6 ships. In this case, the change in the magnetic field should have lasted 40 seconds or more. This excluded the counting of high-speed targets such as torpedo boats or aircraft with magnetic trawls.
ZK II was a twelve-step mechanical counter. It took into account triggering pulses lasting 2 minutes or more.
ZK IIa was similar to ZK II, except that it took into account triggering pulses lasting not 2, but 4 minutes or more.
ZK IIf was similar to ZK II, except that the time interval was reduced from two minutes to five seconds.
The electrical circuit of the M1 explosive device had a so-called pendulum contact (essentially a vibration sensor), which blocked the operation of the device under any mechanical influences on the mine (moving, rolling, shocks, impacts, blast waves, etc.), which ensured the mine’s resistance to unauthorized influences. Simply put, it ensured that the explosive device was triggered only when the magnetic field was changed by a passing ship.

The M1 explosive device, being brought into firing position, was triggered by an increase or decrease in the vertical component of the magnetic field of a given duration, and the explosion could occur under the first, second,..., twelfth ship, depending on the ZK presets..

Like all other magnetic explosive devices, the M1 in the explosive device compartment was placed in a gimbal suspension, which ensured a strictly defined position of the magnetometer, regardless of the position in which the mine lay on the bottom.

Variants of the M1 explosive device, designated M1r and M1s, had additional circuits in their electrical circuit that provided increased resistance of the explosive device to magnetic mine trawls.

Production of all M1 variants was discontinued in 1940 due to unsatisfactory performance and increased battery power consumption.

Combined explosive device DM1. Represents an M1 magnetic explosive device
, to which a circuit with a hydrodynamic sensor is added that responds to a decrease in pressure. Developed by Hasag SVK in 1942, however, production and installation in mines began only in June 1944. For the first time, mines with DM1 began to be installed in the English Channel in June 1944. Since Sevastopol was liberated in May 1944, the use of DM1 in mines installed in Sevastopol Bay is excluded.

Triggers if within 15 to 40 sec. after M1 has registered the target ship (magnetic sensitivity: 5 mOe), the water pressure decreases by 15-25 mm. water column and remains for 8 seconds. Or vice versa, if the pressure sensor registers a decrease in pressure by 15-25 mm. water column for 8 seconds and at this time the magnetic circuit will register the appearance of the target ship.

The circuit contains a hydrostatic self-destruct device (LiS), which closes the explosive circuit of the mine if the latter is raised to a depth of less than 4.57 meters.

The pressure sensor with its body extended into the parachute compartment and was placed between the resonator tubes, which were used only in the AT2 explosive device, but in general were part of the wall of the explosive device compartment. The power source is the same for the magnetic and barometric circuits - an EKT type battery with an operating voltage of 15 volts.

M4 Magnetic Explosive Device (aka Fab Va). This is a non-contact magnetic explosive device that responds to changes in the vertical component of the Earth's magnetic field, both north and south. Developed by Eumig in Vienna in 1944. It was manufactured and installed in mines in very limited quantities.
Powered by a 9 volt battery. The sensitivity is very high 2.5 mOe. It is put into operation like the M1 through the UES armament watch. Automatically adjusts to the magnetic field level present at the mine release point at the time the UES ends operation.
In its circuit it has a circuit that can be considered a 15-step multiplicity device, which before installing the mine can be configured to pass from 1 to 15 ships.
No additional devices providing non-removal, non-neutralization, periodic interruption of work, or anti-mine properties were built into the M4.
Also, there were no devices that determined the duration of changes in magnetic influence. The M4 triggered immediately when a change in the magnetic field was detected.
At the same time, M4 had high resistance to shock waves of underwater explosions due to the perfect design of the magnetometer, which was insensitive to mechanical influences.
Reliably eliminated by magnetic trawls of all types.

Like all other magnetic explosive devices, the M4 is placed inside a compartment on a gimbal suspension, which ensures the correct position regardless of the position the mine occupies when it falls to the bottom. Correct, i.e. strictly vertical. This is dictated by the fact that magnetic power lines must enter the explosive device either from above (northern direction) or from below (south direction). In a different position, the explosive device will not even be able to adjust correctly, let alone react correctly.

From the author. Obviously, the existence of such an explosive device was dictated by the difficulties of industrial production and the sharp weakening of the raw material base during the final period of the war. The Germans at this time needed to produce as many of the simplest and cheapest explosive devices as possible, even neglecting their anti-mine properties.

It is unlikely that LMB mines with an M4 explosive device could have been placed in the Sevastopol Bay. And if they were installed, then they were probably all destroyed by mine trawls during the war.

Acoustic explosive device A1 ship. The A1 explosive device began to be developed in May 1940 by Dr. Hell SVK and in mid-May 1940 the first sample was presented. It was put into service in September 1940.

The device responded to the noise of the ship's propellers increasing to a certain value with a frequency of 200 hertz, lasting more than 3-3.5 seconds.
It was equipped with a multiplicity device (Zahl Kontakt (ZK)) of type ZK II, ZK IIa, ZK IIf. More information about the ZK can be found in the M1 explosive device description.

In addition, the A1 explosive device was equipped with a tamper-evident device (Geheimhaltereinrichtung (GE) also known as Oefnungsschutz)

The GE consisted of a plunger switch that kept its circuit open when the explosive compartment cover was closed. If you try to remove the cover, the spring plunger is released during the removal process and completes the circuit from the main battery of the explosive device to a special detonator, detonating a small 900-gram explosive charge, which destroys the explosive device, but does not detonate the main charge of the mine. The GE is brought into firing position before the mine is deployed by inserting a safety pin, which completes the GE circuit. This pin is inserted into the body of the mine through a hole located 135° from the top of the mine at 15.24 cm. from the side of the tail hatch. If the GE is installed in an enclosure, this hole will be present on the enclosure, although it will be filled and painted over so as not to be visible.

Explosive device A1 had three batteries. The first is a 9-volt microphone battery, a 15-volt blocking battery, and a 9-volt ignition battery.

The A1 electrical circuit ensured that it would not operate not only from short sounds (shorter than 3-3.5 seconds), but also from sounds that were too strong, for example, from the shock wave of depth charge explosions.

The variant of the explosive device under the designation A1st had a reduced sensitivity of the microphone, which ensured that it would not be triggered by the noise of acoustic mine trawls and the noise of the propellers of small ships.

The combat operation time of the A1 explosive device from the moment it is turned on ranges from 50 hours to 14 days, after which the microphone power battery fails due to the exhaustion of its capacity.

From the author. I would like to draw the readers' attention to the fact that the microphone battery and blocking battery are constantly in operation. There is no absolute silence underwater, especially in harbors and ports. The microphone transmits all the sounds it receives to the transformer in the form of alternating electric current, and the blocking battery, through its circuit, blocks all signals that do not meet the specified parameters. The operating current ranges from 10 to 500 milliamps.

Acoustic explosive device A4. This is an acoustic explosive device that responds to the noise of the propellers of a passing ship. It began to be developed in 1944 by Dr.Hell SVK and at the end of the year the first sample was presented. It was adopted for service and began to be installed in mines at the beginning of 1945.

Therefore, encounter A4 in LMB mines. installed in the Sevastopol Bay is impossible.

The device responded to the noise of the ship's propellers increasing to a certain value with a frequency of 200 hertz, lasting more than 4-8 seconds.

It was equipped with a multiplicity device of the ZK IIb type, which could be installed for the passage of ships from 0 to 12. It was protected from the noise of underwater explosions due to the fact that the relays of the device responded with a delay, and the noise of the explosion was abrupt. It was protected from simulators of propeller noise installed in the bow of the ship due to the fact that the noise of the propellers had to increase evenly over 4-8 seconds, and the noise of the propellers emanating simultaneously from two points (the noise of real propellers and the noise of the simulator) gave an uneven increase .

The device had three batteries. The first is for powering the circuit with a voltage of 9 volts, the second is for powering the microphone with a voltage of 4.5 volts, and the third is a blocking circuit with a voltage of 1.5 volts. The microphone's quiescent current reached 30-50 milliamps.

From the author. Here too I would like to draw the attention of readers to the fact that the microphone battery and the blocking battery are constantly in operation. There is no absolute silence underwater, especially in harbors and ports. The microphone transmits all the sounds it receives to the transformer in the form of alternating electric current, and the blocking battery, through its circuit, blocks all signals that do not meet the specified parameters.

The A4st explosive device differed from the A4 only in its reduced sensitivity to noise. This ensured that the mine did not detonate against unimportant targets (small, low-noise vessels).

Acoustic explosive device with low-frequency circuit AT2. This is an acoustic explosive device that has two acoustic circuits. The first acoustic circuit reacts to the noise of the ship's propellers at a frequency of 200 hertz, similar to the A1 explosive device. However, the activation of this circuit led to the inclusion of a second acoustic circuit, which responded only to low-frequency sounds (about 25 hertz) coming directly from above. If the low-frequency circuit detected low-frequency noise for more than 2 seconds, then it closed the explosive circuit and an explosion occurred.

AT2 was developed in 1942 by Elac SVK and Eumig. Began use in LMB mines in 1943.

From the author. Official sources do not explain why the second low-frequency circuit was required. The author suggests that in this way a fairly large ship was identified, which, unlike small ones, sent quite strong low-frequency noises into the water from powerful heavy ship engines.

In order to capture low-frequency noise, the explosive device was equipped with resonator tubes that looked similar to the tail of aircraft bombs.
The photograph shows the tail section of an LMB mine with the resonator tubes of the AT1 explosive device extending into the parachute compartment. The parachute compartment cover has been removed to reveal the AT1 with its resonator tubes.

The device had four batteries. The first is for powering the primary circuit microphone with a voltage of 4.5 volts and the electric detonator, the second is with a voltage of 1.5 volts to control the low-frequency circuit transformer, the third is 13.5 volts for the filament circuit of three amplifying radio tubes, the fourth is 96 anode at 96 volts for powering the radio tubes.

It was not equipped with any additional devices such as multiplicity devices (ZK), anti-extraction devices (LiS), tamper-evident devices (GE) and others. Triggered under the first passing ship.

The American Handbook of German Naval Mines OP1673A notes that mines with these explosive devices tended to detonate spontaneously if they found themselves in areas of bottom currents or during severe storms. Due to the constant operation of the normal noise contour microphone (underwater at these depths is quite noisy), the combat operation time of the AT2 explosive device was only 50 hours.

From the author. It is possible that it was precisely these circumstances that predetermined that of the very small number of samples of German naval mines from the Second World War, now stored in museums, the LMB / AT 2 mine is in many. True, it is worth remembering that the LMB mine itself could be equipped with a LiS anti-detachment device and a ZUS-40 anti-neutralization device under the bomb fuse LHZusZ(34)B. It could, but apparently quite a few mines were not equipped with these things.

If the microphone was exposed to the shock wave of an underwater explosion, which is characterized by a very rapid increase and short duration, a special relay responded to the instantly increasing current in the circuit, which blocked the explosive circuit for the duration of the passage of the blast wave.

Magnetic-acoustic explosive device MA1.
This explosive device was developed by Dr. Hell CVK in 1941, and entered service in the same year. The operation is magnetic-acoustic.

After dropping the mine, the process of working out the delay time with the UES clock and adjusting to the magnetic field that exists in a given place is completely similar to that in the M1 explosive device. Actually, MA1 is an M1 explosive device, with the addition of an acoustic circuit. The process of turning on and setting up is specified in the description of turning on and setting up the M1 explosive device.

When a ship is detected by a change in the magnetic field, the ZK IIe multiplicity device counts one pass. The acoustic system does not take part in the operation of the explosive device at this time. And only after the multiplicity device has counted 11 passes and registered the 12th ship, the acoustic system is connected to work.

Now, if within 30-60 seconds after the magnetic detection of the target the acoustic stage registers the noise of the propellers, lasting several seconds, its low-frequency filter will filter out frequencies greater than 200 hertz and the amplification lamp will turn on, which will supply current to the electric detonator. Explosion.
If the acoustic system does not register the noise of the screws, or it turns out to be too weak, then the bimetallic thermal contact will open the circuit and the explosive device will return to the standby position.

Instead of a ZK IIe multiplicity device, an interrupting clock (Pausernuhr (PU)) can be built into the explosive circuit. This is a 15-day electrically controlled on-off clock designed to operate the mine in a firing and safe position on 24-hour cycles. Settings are made in intervals that are multiples of 3 hours, for example, 3 hours on, 21 hours off, 6 hours on, 18 hours off, etc. If the mine does not go off within 15 days, then this clock is taken out of the circuit and the mine will go off during the first passage of the ship.

In addition to the hydrostatic LiS device built into the UES watch, this explosive device is equipped with its own hydrostatic LiS, which is powered by its own 9-volt battery. Thus, a mine equipped with this explosive device is capable of exploding when raised to a depth of less than 5.18 meters from one of the two LiS.

From the author. The amplification tube consumes significant current. Especially for this purpose, the explosive device contains a 160-volt anode battery. The second 15-volt battery powers both the magnetic circuit and the microphone, and the multiplicity device or interrupting clock PU (if installed instead of the ZK). It is unlikely that batteries that are constantly in use will retain their potential for 11 years.

A variant of the MA1 explosive device, called MA1r, included a copper outer cable about 50 meters long, in which an electrical potential was induced under the influence of a magnetic linear trawl. This potential blocked the operation of the circuit. Thus, MA1r had increased resistance to the action of magnetic trawls.

A variant of the MA1 explosive device, called MA1a, had slightly different characteristics that ensured that the explosive chain was blocked if a decrease in noise level was detected, rather than a steady noise or an increase in it.

A variant of the MA1 explosive device, called MA1ar, combined the features of MA1r and MA1a.

Magnetic-acoustic explosive device MA2.

This explosive device was developed by Dr. Hell CVK in 1942, and entered service in the same year. The operation is magnetic-acoustic.

After dropping the mine, the process of working out the delay time with the UES clock and adjusting to the magnetic field that exists in a given place is completely similar to that in the M1 explosive device. Actually, the magnetic circuit of the MA2 explosive device is borrowed from the M1 explosive device.

When a ship is detected by a change in the magnetic field, the ZK IIe multiplicity device counts one pass. The acoustic system does not take part in the operation of the explosive device at this time. And only after the multiplicity device has counted 11 passes and registered the 12th ship, the acoustic system is connected to work. However, it can be configured for any number of passes from 1 to 12.
Unlike MA1, here, after the magnetic circuit is triggered when the twelfth target ship approaches, the acoustic circuit is adjusted to the current noise level, after which the acoustic circuit will issue a command to detonate a mine only if the noise level has risen to a certain level in 30 seconds. The explosive circuitry blocks the explosive circuit if the noise level exceeds a predetermined level and then begins to decrease. This ensured the mine's resistance to trawling by magnetic trawls towed behind a minesweeper.
Those. first, the magnetic circuit registers the change in the magnetic field and turns on the acoustic circuit. The latter registers not just noise, but increasing noise from quiet to a threshold value and issues a command to explode. And if the mine is encountered not by a target ship, but by a minesweeper, then since the minesweeper is ahead of the magnetic trawl, at the moment the acoustic circuit is turned on, the noise of its propellers is excessive, and then begins to subside.

From the author. In this fairly simple way, without any computers, the magnetic-acoustic explosive device determined that the source of the magnetic field distortion and the source of the propeller noise did not coincide, i.e. It is not the target ship that is moving, but the minesweeper, pulling a magnetic trawl behind it. Naturally, the minesweepers involved in this work were themselves non-magnetic, so as not to be blown up by a mine. Embedding a propeller noise simulator into a magnetic trawl does not give anything here, because the noise of the minesweeper's propellers overlaps with the noise of the simulator and the normal sound picture is distorted.

The MA2 explosive device in its design had a vibration sensor (Pendelkontakt), which blocked the operation of the explosive circuit when the mine was exposed to disturbing influences of a non-magnetic nature (impacts, jolts, rolling, shock waves of underwater explosions, strong vibrations from working mechanisms and ship propellers working too closely). This ensured the mine's resistance to many minesweeping measures of the enemy, in particular to minesweeping using bombing, pulling anchors and cables along the bottom.
The device had two batteries. One of them, with a voltage of 15 volts, fed the magnetic circuit, and the entire electrical explosion circuit. The second 96-volt anode battery powered three amplifying radio tubes of the acoustic circuit

In addition to the hydrostatic LiS device built into the UES watch, this explosive device is equipped with its own hydrostatic LiS, which is powered by the main 15-volt battery. Thus, a mine equipped with this explosive device is capable of exploding when raised to a depth of less than 5.18 meters from one of the two LiS.

The MA 3 explosive device differed from the MA 2 only in that its acoustic circuit was set not for 20, but for 15 seconds.

Acoustic-magnetic explosive device with low-tone circuit AMT 1. It was supposed to be installed in LMB IV mines, but by the time the war ended this explosive device was in the experimental stage. Application of this explosion)