In general, of course, this whole situation with the transfer of Slovenian tanks The M-55S, which are upgraded T-55s, looks pretty interesting. Slovenia can hardly be blamed for excessive militarism and oversaturation of troops with armored vehicles. And there are no modern models of heavy combat vehicles. However, the fact remains: 28 units were taken out of the bins and given in exchange for 35 German trucks and 5 tankers. However, this is a topic for a separate discussion, so let's just see what these tanks are like.
In order not to create confusion, we will call the M-55 the familiar T-55, since both letters mean the same thing.
When old stuff comes in handy
As you know, Slovenia received its T-55s as a result of the events of the Ten-Day War of 1991, when the central Yugoslav government decided to send an army to pacify separatist sentiments in the republic that declared its independence. For a number of reasons, the troops did not achieve any sane results, but the Slovenes grabbed almost two battalions of equipment.
Slovenian territorial defense near the captured T-55
In fact, as a result, Slovenia, in addition to the T-72, got about sixty T-55 units, which, given the lack of money of the newly formed country and the absence of its own tank building, no one was going to throw in the trash. But to call these tanks, which began to become morally obsolete back in the 60s, did not turn out to be modern.
The T-55 actually had (and still has) a lot of problems, but it was necessary to pay attention to at least a few of them. Moreover, the Slovenes planned to use the machines in the long term - you won’t be able to keep old stuff in service.
A column of Yugoslav vehicles in Slovenia
First of all, the armor of the tank should be noted, which consists exclusively of a steel mass up to 100 mm thick along the forehead of the hull and up to 200 mm in the frontal part of the turret. This did not give any confident protection even from RPG-7 anti-tank grenades of not the first freshness, not to mention guided missiles and sub-caliber shells.
The T-55 sighting system was of no less concern: no means of automating the preparation of a shot in the form of a ballistic computer and a laser rangefinder, and sights - only optics for firing during the day and infrared "night lights" for shooting and detecting targets at night.
There were questions about the gun. Still, a rifled 100-mm gun against the background of larger-caliber counterparts did not look very advantageous both in terms of the power of high-explosive fragmentation ammunition, and in terms of penetration of sub-caliber and cumulative shells. In the USSR, by the way, they tried to solve the problem of the penetrating ability of the "weave" by introducing new shells, including those made from uranium alloys, but where did Slovenia get them from?
Also, something had to be done about the operating costs and insufficient mobility of the tank.
If you have to do it, then you have to do it. This is what they did.
Tank M-55S. Source: alterrnathistory.com
It would hardly have been possible for the Slovenes to modernize tanks exclusively on their own, since there was neither a full-fledged production base nor technologies for this. Therefore, they decided to entrust the case to the Israeli company Elbit Systems, which, as they say, ate the dog in service.
The changes were to affect the complex protection, main armament and sighting system of the tank. In addition, the driver's workplace, chassis and engine have undergone refinement.
For the Slovenes, the Israelis developed a project for the modernization of the T-55, supplying them with the appropriate materials, elements and systems. At the same time, no one planned to export tanks to Israel - they did everything at the local Slovenian STO metallurgical and machine-building plant in Ravno. This not only made it possible to gain useful production experience, but also to give people jobs and provide the enterprise with its subcontractors with financial support.
30 T-55 tanks out of 55 available were upgraded. All work lasted about five years - from 1996 to 2001. Modified machines received the M-55S index, or, translated into Russian, something like the T-55M.
What will the "NATO" caliber give?
After the modernization, the T-55 has changed quite a lot, and this primarily concerns the gun. Instead of the native D-10T, the machine acquired an Israeli-made "NATO" 105-mm L7A1 cannon. All NATO ammunition of the appropriate caliber is capable of digesting this weapon, but the modernization contract provided for the use of exclusively Israeli shells. They were delivered to the Slovenes in commercial quantities.
There is practically no exact data on the range of ammunition transferred to the Slovenes. Nevertheless, based on what Israel generally had at that time, we can talk about the following shells.
As the main anti-tank weapon in the M-55S ammunition, there may be three feathered tungsten alloy sub-caliber projectiles: Hetz-6, Hetz-7 or, less likely, Hetz-10, since it appeared in the 90s years, and whether it was put up for sale is not entirely clear. Armor penetration on steel armor at an angle of 60 degrees from 2 kilometers for these shells is as follows: "Hetz-6" - 300-310 mm, "Hetz-7" - about 380 mm, "Hetz-10" - 450-470 mm.
Active parts of sub-caliber projectiles: "Hetz-6" on the left and "Hetz-7" on the right. Source: tanknet.org
Even if we imagine the situation of a direct collision of the M-55S with our tanks, then the frontal armor of the T-72B / B3 and T-90A is quite capable of withstanding the impact of any of these projectiles. The T-80BVM, largely due to dynamic protection, will also not be a loser. Problems can only arise with obvious old men, such as T-72A, T-80B or T-62M.
Another armor-piercing projectile in the Slovenian tank range is the M152/3 cumulative fragmentation projectile (or M152/6 equipped with a remote fuse). Both projectiles have the same penetration - 350 mm of steel armor at a right angle, and are only suitable for destroying lightly armored vehicles and manpower. M152 / 3 as a whole, in terms of impact on openly located enemy infantry, is no better than ordinary 100-mm high-explosive fragmentation shells for the regular T-55 gun. But equipped with a remote fuse, they can cause a lot of damage due to an explosion in the air, when most of the fragments do not go into the sky and earth, but fall on the heads of the infantry. Unfortunately, we don't have enough of that yet.
A page from the brochure for the M152/3 cumulative fragmentation projectile. Source: yumpu.com
From land mines, the Israelis could add M156 armor-piercing high-explosive hashes with 2,2 kg of explosives to the tank. Against modern tanks, they are only suitable for firing at the least protected projections, since the combined frontal armor dampens the impact energy to the maximum. So light vehicles and not very powerful fortifications are his profile. But, again, its value in comparison with the standard 100-mm OFS T-55 is not so great.
Elbit Systems also offers M110 multifunctional projectiles with a programmable fuse. These munitions have three modes of operation: air blast above the target, instantaneous detonation upon impact with the target, and high-explosive mode, thanks to which the projectile can penetrate up to two reinforced concrete walls with a thickness of more than 200 mm and detonate behind them, hitting sheltered manpower. Whether it is in the M-55S ammunition load is not clear. Probably not.
Fire control complex
As you know, it is not enough to have a good gun and powerful shells. It is also necessary to confidently hit the target with them, which requires a modern fire control complex. Earlier, we already said that in the original version, the T-55 had trouble with this: only optics and infrared devices were used from sights, and there was no talk of such automation as a ballistic computer.
The components of the fire control system were manufactured by Fotona in the Slovenian capital, Ljubljana. It consists of sighting and observation systems for the commander and gunner, as well as related systems: a digital ballistic computer, a projectile ballistics selection device, a set of firing conditions sensors, and others.
The new SGS-55 gunner's sight is radically different from the previous Soviet design. It integrates a laser rangefinder and a night channel, which, depending on the choice of options, can be provided by a thermal imaging camera or an image intensifier tube. At the same time, the preparation of the shot is automated as much as possible: when measuring the range and speed of the target using a laser rangefinder, the ballistic computer automatically introduces the appropriate corrections for firing, also taking into account weather conditions and the position of your own tank.
The tank commander has at his disposal the sighting and observation system COMTOS-55. Of course, there is no panoramic multi-channel sight with circular rotation. Therefore, all-round visibility is provided by a device of the TKN type in the rotating part of the hatch cover. Through it, the tank commander can observe the terrain, identify targets, determine the approximate range to them and issue target designations to the gunner. A backup system is also available, which gives the commander an image from the gunner's sight, thanks to which this crew member can fully fire from the cannon and the machine gun coaxial with it.
Security and more
The armor protection of the T-55, even in the 60-70s, already left much to be desired, and what can we say about the 2000s? Almost 40 years ago, in the USSR, they tried to solve this problem in two ways: by installing armor modules on the forehead of the hull and turret, consisting of steel sheets and a polyurethane layer, or by equipping tanks with dynamic protection - T-55M and T-55MV, respectively.
The Slovenes, together with the Israelis, went just the second way and installed dynamic protection on the M-55S, which is often referred to as the "Super Blazer". Structurally, it consists of throwable metal plates and explosives, working in general similar to our "Contacts".
The Slovenes themselves claim that the installation of dynamic protection makes it possible to protect the tank from penetration by all RPG-7 monoblock grenades and monoblock anti-tank guided missiles. And here it is hard to disagree, since the previous version of the Blazer, installed by Israel on the M48 and M60 tanks, gave resistance to cumulative weapons in the region of 400 mm. In our case, the equivalents against cumulative jets may be greater. However, against tandem munitions, of which there are many in Russia's arsenal, ranging from grenade launchers to man-portable/portable ATGMs and tank guided missiles, the Super Blazer's value is questionable. However, the passive armor of the tank in combination with reactive Israeli armor will not be able to oppose anything even against sub-caliber shells - our Mangos and Leads will, on occasion, make holes quite calmly.
In addition, the M-55S is equipped with anti-cumulative screens on the sides of the hull. There is little use for them, but they can be useful in the course angles of maneuvering a tank.
A very useful protective innovation was the laser detection system. The sensors of this contraption are able to recognize the laser beam of some kind of rangefinder or target designator for missiles aimed at the tank, after which the crew is immediately notified of the threat. Paired with this system are smoke grenade launchers, which install a dense aerosol screen that hides the tank from view.
As for the rest of the improvements, here we can note the installation of a new night vision device for the driver, which literally switches from day to night mode and back with just one click; a new and more efficient fire extinguishing system with optical sensors; a diesel engine boosted from 520 to 600 horsepower, a modified anti-aircraft machine gun mount with a 12,7 mm machine gun and an improved undercarriage with caterpillars with a rubber-metal hinge and asphalt shoes.
The further fate of the tank and Ukraine
Upgrading the tanks to the M-55S level raised a lot of financial questions, largely due to the fact that the entire program cost a record 52-odd million euros - a considerable amount for a small and not very rich state. Nevertheless, all 30 vehicles were put into service with the 44th battalion of the Slovenian army, but their century was short-lived. After the next transfer of the tank fleet to the 74th mechanized battalion, after 2006, the tanks were transferred to storage as a result of its reorganization.
A few years ago, the Slovenian defense department tried to put the M-55S up for sale. The demand was, apparently, so "great" that the press took seriously questions about whether private individuals could buy tanks. In the end, they nevertheless agreed that they could, but with the appropriate license from museums and other institutions. Well, in fact, only one tank was bought for 820 thousand euros.
Commercial success was "very not very". Although even now, when these machines are transferred to Ukraine, the benefits are not very clear. Yes, the Slovenes tried to push through their M-84 (T-72) in exchange for German infantry fighting vehicles - at least some benefit is obvious here. But almost 30 tanks for 35 conditional trucks and 5 tankers? Forced?
Presumably M-55S on railway platforms. Source: bmpd_cast telegram channel
What about their use by Ukraine. There have already been many fantastic and unrealistic assumptions that old tanks can be used almost as a replacement for infantry fighting vehicles and so on. A tank is a tank, and will be used as a tank.
However, the M-55S, albeit with the maximum increased combat effectiveness, will not become a new machine. It is not worth comparing it with our T-72B3 or T-90A - it will lose to them both in terms of firepower and, importantly, in terms of armor. But there were no tank battles with large tank raids in the special operation zone either. The priority, as there were fortified and unfortified positions with manpower, remains. Here, as they say, practice will show the ammunition used and how careful the Ukrainian military will be in using these vehicles so as not to get "responses" that can become fatal due to the extremely low security of Slovenian tanks. In any case, they will obviously not be subject to excessive demands, and we should not be.