M55S1

m55s1

„After the short and effective War of Independence (1991), Republic Slovenia become an independent state and war begun in our southeren neighbourhood countries: Croatia and Bosnia. From retreating and defeated exNugoslav Army great amounts of obsolete weapons remain, among it some 50 tanks T -55 and 60 M-84, Yugoslav produced version of popular Russian T -72 tank, also used in Operation Desert Storm by Kuwait forces. Those tanks become a framework of new Slovenian armored corps together with tracked armored personel carriers BVT -80.

T -55, small tank, but a lot of problems
Slovenia had a little choice, what to do with these tanks, because UN resolution forbide all weapons selling in region of the ex-Yugoslavia republics. It was very unpleasant for us, but it was a fact and reason, why we did not start buying a Western produced weapons. The only country, which was ready to help us in tank modernization was Israel, most experienced country in this job. In those times 1994 M-84 was only 8 years old, but T -55 was an obsolete, more than thirty years old, first after war generation bad maintained wehicle, which was more dangerous for user, than the enemy. There was two choices only: modernization or tank graveyard. We have not much choices, because war in our neighborhood (between Croatia and Serbia) could Iast ten years and was a constant threat to our borders.

Our modernization main goals were: -increase firepower
-increase protection and survivability -increase mobility

Our Project team Israel partner was Elbit Company, very experienced and one of the best in tank modernization in the world. They work with many Israelis companies, mentioned in text. The frame of work for 30 tanks includes following improvements:

A -Increased firepower
B -Improved optics and electronics and new FCS
C -Add -on eksplosive-reactive protection Superblaser D -Contemporary fire supression system E -New smoke self screening sistem
F -Contemporary communication and intercommunication sistem G -New drill equipment for the crew H -Running gear improvments

All of these improvements demands a perfect tank, especially electrical cables and all vehicles was dismounted and completely overhauled. We use overhaul only in cases, when we have not original spare parts. New cables are made by Slovenian company VR Electronics. Between overhaul, we also improved the track system with top rollers (same as in M-84 tank), and this enable to use the same tracks as M-84 with rubber pads. With Iihgts, which are the same as in our APC Valuk (Iicence from Austrian Pandur), tank is capable to use all public roads without Iimitation and this was important step in mobility of Slovenian Armour Corps. Complete new comand table was installed in drivers compartment to control the engine and use new Iights.

A -Increased firepower

WW II gun D-10T, 100 mm with obsolete selection of ammunition was converted in 105/L51 mm L7 gun with new rifeled barrel and contemporary Israeli and NATO ammo, produced in IMI: APDSFS- T (M426, DM 63), HEAT -T (M-152/3) and HESH- T M156). APDSFS- T with 3.rd generation tungsten penetrator is capable to penetrate 350 mm RHA on 2000+m (old gun: 200 mm on 1000 m). Gun mechanical ignition was replaced with eletrical one with minimal change of breech block. The new recoil mechanizem reduce recoil from 570 mm to 520 mm. Coaxial machine gun PKT 7,62mm and anti – aircraft machine gun DSK-M 12, 7mm remain the same despite we prefer of use two exterial MG 7,62 mm in the top of the turret. Ammo complet in tank is 39 grenades (in new amunnition racks) 1200 7,62mm and 360 12,7mm.
New gun with exchangeable barrel have a contemporary separate thermal sleeve which reduce the barrel bending for 70%. It is produced by Israeli company Vidco.

B -Improved optics and electronics

All new installed optics and electronics components are produced in in FOTONA Company, Ljubljana, Slovenija. Their fire control system for T -tanks was described in January 2000 issue, precisely fot tank M-84. Almost exact specter of products is available for T -55 tanks (EFCS 3-55), and following components are installed tank M-55S: .SGS -55T -Day/night stabilized gunner’s sight with Iaser range finder. .COMTOS -55 -Commander’s observation/aiming/take-over set. .CODRIS -55E -Combined driver’s day/night periscope. .LIRD -3A -Laser irradiation detector and warner. .FCC -55T -Fire control computer with sensors.
AII night optics is based on 2nd generation image intensifier, so on the tank is no more IR sources. Gunner can use stabilizen or non stabilized regime of shooting. Sistem enable him to shoot on moving target or from moving tank on moving target. The procedure is classical: with ammo selection the ballistic computer use proper ballistic, then gunner aim the target, use Iaser range finder and pull the trigger. When tank is movin and also the target, guner must aim some seconds so that the FCS can calculate the proper angle. Commander can take-over the gun and use the the same procedure for shooting. His CODRIS is connected with SGS so tank have not independent commander sight. LIRD- 3A is one of the worlds best irradiation detector and warner. It detect all sources of IR in battlefield including the direction and source of irradiation and also IR reflection from other vehicles.
CODRIS-55E is drivers day-night observation system, night optics is based on image intensifire and driver activate it with a switch. Codris instaling demand hull machining.

C -Add -on eksplosive-reactive armor -Superblaser This is one of the world best ERA protections produced by RAFAEL Co, Israel. It provides effective protection against all kinds of chemical ammunition, specially against shape charges (HEAT grenades and anti-tank guided and un-guided missiles including 11. generation) and high eksplosive grenades (HESH). Additional weight is about 2 tons, it have not influence on mobility of tank or angular speed of turret. In may 2002 our ERA was tested with HEA T tank ammunition and there was no penetration on the turret.

D -Contemporary fire supression system The new system produced by Spectronics Co. Israel was installed in battle and engine compartment of the tank. System include a BITE system, warning system (activate when one of the bottles which include halon 1301 gas is empty), reaction time is similar as in Iast generation tanks. The fire detection is enabled by optical sensors in time between 5 miliseconds and 500 miliseconds. Gas and pressure of gas don’t threaten the crew health.

E -New smoke self screening sistem This is one of most important part of tank defence, typ is 15-6 and is the same produced for contemporary Israel tanks, Iike merkava or magach. 6 grenades Every Iauncher in each side of the turret have 6 Iaunching wholes for CI 3030 smoke granades and is capable (with pair of grenades) to make 50 meters front of the vehicle 70 m wide and 1 Om high smoke screen, make by white phosporus. System is very efective and after 2 seconds, the whole platoon is under cover. System is connected with IR detector, and it can work automaticaly on detector signal (when the crew is out of vehicle). The mode of work depends on commander decisions. In weak wind smoke protection could Iast 2 minutes.

F -Contemporary communication and intercommunication sistem It consist of:
1 -Radio station CNR-900 produced by Tadiran Co. Israel, one of the worlds most sofisticated and capable such a devices. The turret need additional machinig and welded additional pocket on the back side for this station. Every tank have two new antenas on separate holders, and tanks of platon, company and batalion commanders have two radio stations.
2 -VIC-1 is analogous intercommunication system similar to those, which are install in western tanks.
3 -Racal helmets are part of the crew equipment, enabled them a normal conversation in tank, where the noises could reach more than 90 db. Helmet have a microphone with ANR (Automatic Noise Reduction). The microphones are opened on human voice only, and you couls speak wit Iow voice in every situation, even during the main gun fire. Helmet have a soft part and extra ballistic protection and coud be plug in in outside telephone also.
4 -Outside telephon set on the right back side of the tank enabel direct comunication with the crew for different users: infantry comanders, mechanich, tank crew members, instructors, etc.

G -New drill equipment for the crew
Four new devices are introduced in armor corps.

a -Gunner simulator is designed for trainig gunners under the instructors supervision.

b -ISTD (Inbore Subcaliber Training Device) is a short gun (tip Vulcan, calibre 20mm), which is instaled in housing similar to that of HEAT granate. This device is suitable for all Iive shooting trainings, including shoot from the move on the moving target, where we have not an adequate polygon. The procedure of Ioading the gun is similar to those in real tank shooting with extra Ioading of ISTD in breech block.
For the new Ioaders we have also a blind grenades for Ioading gun trainings specially during the move.

c -Cut view ammunition and blind ammunition are teaching aids in proces of qualifaying of a new young tankers.

H -New running gear It is mount to improve the mobility, stabilisation characteristic and enable road moving. Each complet is consist of five (original) road wheels, four top rollers, par of sprockets and „silent block” track, 580 mm wide with 94 single pins and with rubber pads. The producer is STO, Ravne, Slovenia, where the complete assembly of the tank was finished.

Conclusion
Upgrading of T -55 tank was seven years Iong proces in which participates Ministry of Oefence of Republic Slovenia, Elbit Haifa as main contractor for several companies from Israel, Fotona Ljubljana, Slovenija as main opto electronic supplier and STO Ravne, Slovenia as final assembly and overhaul.
The weight of vehicle raised up to 40 tonnes in battle conditions, but we decided to use old power pack with new 580 hp engine and 5 step gear, so the ratio between weigt and power is about 14,5 hp/t. AII tanks were tested in polygon with pretending shooting tests with main gun, co axial machine gun and ISTO for moving tank on the moving target shooting. After 900 pieces of 1 05mm grenades, thousands of 7 ,62 mm and 20 mm ammo, after shooting on ERA protected turret, we know, that the project was succesfully finished for Slovenian and Israeli tank industry.
Instead of sending the old tanks in the graveyard, we recive reliable battle systems for next ten to fiveteen years for price Iess than 1 mio$ for vehicle. Everybody who know the prices of armored technology, know very well why I emphasize this data.

Andrej Vilar
Adviser for Armour Technology, MOO Slovenija Author of M-55S tank configuration Leader of polygon testing”

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