Difficult target
What needs to be done to destroy a modern double-hull submarine? First of all, it is necessary to pierce up to 50 mm of the outer acoustic rubber layer, followed by about 10 mm of steel of the light body, a layer of ballast water up to one and a half meters thick, and, finally, about 8 cm of high-strength steel of the main body. To ensure the destruction of such "armor", it is required to deliver at least 200 kilograms of explosives to the boat, and for this the carrier, that is, a torpedo or a rocket, must be very large. As one of the outputs, weapons engineers propose to use several small torpedoes to attack (it is required that they also hit approximately one part of the submarine), which is not much more effective than using one large 400-mm torpedo.
There is a need to develop new schemes for underwater ammunition, the design of which departs from the traditional high-explosive combat charging compartments with contact and proximity fuses. As an option, the use of plastisol and aluminized explosives is considered, providing an excellent high-explosive effect in combination with a low shock-wave sensitivity. To increase the effective impact of a high-explosive torpedo on the submarine's hull, multi-point charge initiation is used, which makes it possible to direct most of the detonation wave energy in the desired direction. The superposition of shock waves from a synchronous explosion when exposed to the hull of a submarine also looks effective - for this, several small-sized torpedoes can be used. Finally, the most promising is the development of cumulative torpedoes by analogy with "land" methods of dealing with heavily armored targets.
At first glance, a cumulative torpedo is just a godsend for submarine hunters. The dimensions of such ammunition can be much smaller than traditional torpedoes, which makes it possible to mount them in several pieces at once, even on an anti-submarine helicopter. In addition, the submarines have not yet been equipped with specific protection against such torpedoes, by analogy with ground armored vehicles, which makes them especially vulnerable to narrowly directed gas-cumulative detonating ammunition flows. Among the specific conditions for the use of shaped-charge torpedoes stands out the requirement to comply with the direction of the shaped charge axis with the least deviation from the normal. Simply put, if a high-explosive projectile does not make much difference from what angle to approach the target, then it is important to orient the cumulative torpedo in time relative to the submarine's hull. In full analogy with modern anti-tank roof-piercing ammunition, the developers of domestic anti-submarine weapons propose to move away from the axial arrangement of the shaped charge. You can arrange charges either obliquely to the axis of the torpedo, or even transversely - this allows you to hit the target on the "miss". The transverse arrangement of the shaped charge has an advantage in the absence of a massive torpedo head part on the path of the damaging flow (no need to pierce the instrument compartment of the ammunition) and allows increasing the diameter of the shaped funnel without particularly increasing the dimensions of the ammunition. New difficulties in the design are torpedoes will be a sensitive proximity fuse, taking into account the position of the ammunition relative to the skin of the submarine - the requirement for the smallest deviation from the normal has not been canceled.
Researchers at MSTU im. NE Bauman's problems with cumulative weapons indicate another potential drawback of such torpedoes - the small diameter of the hole. In the case of using a large high-explosive charge, a deflection is formed on the skin, which subsequently breaks with the formation of elongated cracks. This occurs mainly in the areas of greatest stress in the areas of the frames. The cumulative jet leaves behind a through hole not exceeding a width of 0.2-0.3 of the diameter of the internal cumulative lining of the ammunition. It is for this reason that now the most promising direction is the development of ammunition with a high-explosive cumulative effect, combining high penetration and destruction of the submarine's skin by the mechanism of cracking.
324 mm
Mathematical calculations have shown that it is possible to sink such a complex target as a Los Angeles-type submarine at half the maximum depth by making a "hole" in the skin with a diameter of 180 mm, and at a small 50-meter depth, the width of the hole should be no less 350 mm. That is, the diameter of the shaped charge in this case expands to 500 mm - and this is the minimum possible option. Only such a torpedo, which can no longer be called small-sized, can be guaranteed to sink an atomic submarine missile carrier. Only now, small-sized torpedoes with a shaped charge now have a diameter of only 324 mm, which, even in the most successful outcome of the attack, will form a through hole in Los Angeles with a diameter of only 75 mm.
Among domestic developments in the 324-mm form factor, the TT-4 small-sized anti-submarine torpedo aircraft with a mass of 34 kilograms of explosives stands out. In domestic cumulative torpedoes, cast explosive compositions of the TNT-RDX and TNT-HMX type with powdered aluminum are used as a charge: mixtures MS-2, MS-2Ts, TG-40, TGFA-30 and TOKFAL-37. Such explosives have relatively low parameters of detonation and density, but high calorific value and fire and explosion safety.
In NATO countries, similar torpedoes Mk-46, modification 5A, have become widespread, containing 44.5 kilograms of powerful high-explosive PBXN-103 or PBXN-105 explosives, as well as expensive copper conical shaped-charge lining. The torpedo allows, when approaching the submarine's hull, to orient the warhead along the normal, or close to the perpendicular direction. Since 1997, a serial joint Franco-German-Italian production of a small-sized cumulative torpedo MU-90 Umpact with a diameter of 324 mm has been carried out. This ammunition contains, according to various sources, from 32, 8 to 59 kg of explosive, supposedly made on the basis of triaminotrinitrobenzene. The next in the regiment of 324-mm torpedoes is the improved Stingray with 45 kilograms of explosives of the PBX-104 type and the traditional copper conical lining of the cumulative warhead. This torpedo is also equipped with a warhead positioning system, which ensures the output of the ammunition on a course perpendicular to the surface of the submarine's hull.
However, all the presented cumulative torpedoes have one common drawback - the presence of a head instrument compartment, which contributes to the dispersion of the cumulative jet. That is why the development of torpedoes with a transverse shaped charge, as mentioned above, is of particular importance. Naturally, engineers are trying to increase the power of the shaped charge with additional high-explosive effects. This allows, in addition to the narrow through hole, to form dents on the surface of the submarine with extensive ruptures of steel, which can be fatal for the submarine. Another way out of the situation may be the strengthening of the beyond-barrier action of cumulative torpedoes, when explosives or other, as they are called, "active materials" are introduced into the hole. However, now this approach has not yet received more conceptual and real implementation. In part, this problem is solved by giving the cumulative lining the shape of a meniscus, which makes it possible to form an impact nucleus during detonation. As you know, such a core will leave a hole in the skin of a submarine serious and destroy a lot inside the hull, but the penetration depth leaves much to be desired. Alternatively, the Russian TT-4 torpedo uses a combined cone and sphere lining, which makes it possible to obtain a hybrid jet with a large penetration depth and a short focal length, as well as with a relatively large hole diameter.
