T-64 - The evolution of the Soviet tank

In the second half of the 1960s, the Soviets started to project a replacement for the T-62, whose characteristics of maneuverability and effectiveness were poor in comparison with western main battle tanks, even if the initial impressions had been more favorable.

Background

The behavior of the T-62 in Middle East had been pitiful, and albeit this was due largely to the better training and tactical skills of the Israeli in respect of Syrians and Egyptians, the defects of these tanks had come to light and their capture in large quantities by the Israeli - who in addition delivered some of them to the Americans - allowed the western nations to know every secret about the T-62. Some observers pointed as well a question about policies regarding materials, as it existed a historical tendency on the Soviet Union of having tanks whose cannons were of larger caliber than those of their enemies. In the early Second World War, when the British used as their standard cannon the 2-pounder (40 millimeters) and the Germans the 50 millimeters one (and exceptionally the short one of 75 millimeters), the Soviets had already 76.2-millimeter cannons of medium length (about 30 calibers) in their T-34 tanks. As the conflict advanced, the Germans used preferently 75-millimeter cannons, like the Americans, whereas the British oscillated between the 6-pounder (57 millimeters) and the 17-pounder (76.2 millimeters). Parallely the Soviets introduced the 85-millimeter cannon in the last series of the T-34, from December 1943. This policy affected also their heavy tanks: to the 88/56 and 88/71 anti-tank cannons introduced in the last series of German World War Two tanks the Soviets opposed the 122/46 mounted in the IS-2. This practice continued during the postwar. In the 1950s the standard tank cannon in the NATO was the American 90/48, whereas the Soviets installed the 100/54 in their T-54/55. When the Atlantic Alliance adopted the caliber 105 millimeters in the early 1960s, the Soviets introduced the 115/55 - the first one of smooth bore - for the T-62. The British L11 120/55 deployed in the Chieftain and the western tendency towards cannons of this caliber, obvious in the late 1960s and culminating in the late 1970s with the introduction of the Leopard II armed with the smoothbore 120/44, was contested once more by the Soviets with the introduction of a larger caliber, the smoothbore 125 millimeters, in dotation in the three newest Soviet tanks introduced in the 1970s and 1980s, the T-64, T-72 and T-80.


American drawing from around 1980 showing the main characteristics of the tanks then in service with the Soviet Union.

It is obvious that the increase in caliber is not everything in a cannon. Apart from the fact that, probably, it would be reached the limit from which a marginal increment in effectiveness would not compensate the increment in the cost - of any type, not only economical - caused by the increase in the caliber, the growth in the destructive power of anti-tank artillery has been reached more thanks to the characteristics of the ammunition than to the caliber. The Israeli invasion of Lebanon, in 1982, allowed to note that the Merkava, armed with the classical L7 105/51 - albeit with a Israeli subcalibrated ammunition of great perforation power - could face and surpass the Syrian T-72 with their 125-millimeter cannon. And it is probably unnecessary to point that in the final ponderation regarding the effectiveness of a tank, the qualities of the cannon go together with the qualities of the armor, with the speed and other active or passive protection means, along with electronic equipment and the reliability of mechanical parts.

The T-64

As soon as the T-62 was in production, Soviet projectists started to work on its successor. Feeling that this time they had a break, thanks to the superiority of the cannon U-5TS installed in the T-62, they could dedicate themselves to make a different model more in depth. Actually, a series of models were outlined, being selected the best of them for the trials. United States had been following this procedure during some time, but this was the first time in which the Soviet Union adopted the same competitive method. The most visible difference between which would be the T-64 and its predecessors was the wheel arrangement. The T-64 had six smaller road wheels, each of them with its own hydropneumatic suspension, and four return rollers. This meant that, for the first time since 1930, a Soviet medium tank would be built with a suspension different to the Christie type. The width of the tracks was 58 centimeters, in similarity with preceding and succeeding models.

Also the engine of the T-64 was completely new. It was a Diesel with five cylinders and two crankshafts, having each cylinder a pair of opposing pistons. In its original modality, it developed about 750 horsepower, this is, much more power than previous models. The new engine was not totally exempt of problems, but it worked well when it was adequately treated; it was actually very good and it could move the 38 tonnes of the T-64 at a maximum road speed of up to 75 kilometers/hour. The new suspension system, albeit not without defects, allowed to keep this speed during quite long time and it also allowed much better speed accross countryside. The transmission had seven speeds forward and one backward (these were in the T-62 five and one, respectively). With a fuel capacity of 1000 liters, the operational range in road of the T-64 was estimated in 450 kilometers. Fording capabilities were similar to other contemporary Soviet tanks: 1.4 meters without preparation and 5.5 meters with snorkel.

On the other hand, the turret seemed, externally, slightly different from the one designed for the IS-3, which had not been changed in the T-54 nor in the T-62. But important things had been made in the interior of the turret, because the new tank mounted not only an even larger cannon, the D-81TM of 125 millimeters, fitted with bore evacuator and thermal sleeve, but the crew in the turret was reduced to two, having replaced the fourth crew member with an automatic loader. To preserve the turret with a low profile meant that the depression angle of the cannon (-5 degrees) was still inadequate, while the elevation angle reached 18 degrees. Western tanks have wider depression angles (-10 degrees in the M-1 and -9 degrees in the Leopard II), which grants them better chances to make tactical use of the terrain. But despite of the poor balance in Middle East, the Soviets were since the 1930s splendid tank designers and the T-64 reunited notable characteristics which, since its apparition, increased the unrest in the military chiefs of the Atlantic Alliance.

Among these characteristics was the obvious firepower of its smoothbore cannon, shared with the T-72 and the T-80 and which, according to American estimations of that time, was able to fire fin- stabilized subcalibrated piercing projectiles (APFSDS or Armor-Piercing Fin-Stabilized Discarding-Sabot), of great muzzle speed (1750 meters/second). There was also a provision for shaped-charge projectiles (HEAT or High-Explosive Anti-Tank), with a muzzle speed of 905 meters/second, and breaking projectiles (HE or High-Explosive), with a muzzle speed of about 850 meters/second. The reserve of projectiles reached 40 units, a number notably lesser than the one usually stored in western tanks. The provision for the 12.7-millimeter machine gun was 500 projectiles and for the 7.62-millimeter machine gun it reached 3000. The first one could be actuated from inside by the commander. The T-64 seen in Germany were fitted with smoke launchers, characteristic not present in the T-62 nor in the T-72, which are fitted with a smoke generator integrated in the engine. This detail was then interpreted as a proof of the different characteristics of the engine.

The T-64 was fitted as well with a completely new fire-control system, based in a laser rangefinder and stabilized optical sights, along with new headlights and infrared projectors, NBC (Nuclear- Bacteriological-Chemical) protection and snorkel as standard equipment. It was made a variant with removable armored skirts and a second one - denominated T-64B in United States - fitted with the improved 125-millimeter cannon that was also mounted in the T-80. This weapon could fire either anti-tank/helicopter missiles AT-8 or conventional ammunition. The missile AT-8, fitted with a two- phase rocket engine fed by solid fuel and a shaped-charge warhead, was believed to be capable of perforating up to 600 millimeters of conventional armor from a distance of up to 4000 meters. The missile was guided by a semiactive laser system, with the target designator installed in the front part of the turret. It was said that the effective range against helicopters was twice than against a tank but, since the maximum speed of the missile was only 500 meters/second and this one was not reached immediately after the shot, the effective range would depend also on the type of helicopter and the direction of its movement (attitude) in respect of the tank. The T-64B, used exclusively by the Red Army, had as well reactive armor: a total of 111 plates, all of them hanging around the turret, in the glacis and in the sides of the hull until reaching the gratings of the engine.

It was estimated that about 8000 exemplars of the T-64 were built, but this is a pure conjecture because it is not known how many of them could be T-64B, of better characteristics, or how many of the former tanks were later reconverted to the improved specifications, if there was any. At the same time, the circumstance that this tank was produced in relatively small quantities and its quick overcoming by the T-72 and T-80 suggested that serious problems arose in the design. A relative mystery surrounded the T-64 during years. Albeit this tank was deployed in thousands of exemplars - being counted more than 2000 in the Soviet divisions in East Germany -, this tank was not exported by the Soviets and little information was facilitated by them. Both facts were the polar opposite of which happened with the more perfected T-72. The Americans estimated that in 1984 the T-64, T-72 and T-80 constituted already more than 50 percent of the Soviet tanks deployed in Central Europe.


The T-72 is a perfected derivative of the T-64.



The T-80

The United States Department of Defense published in the first edition (October 1981) of its periodic report Soviet Military Power a drawing of the new Soviet tank. The first photograph would not appear until the second issue (April 1983). The next images of this tank were published in the third edition of the same publication (April 1984), which included new photographs, one of them in color. The Pentagon denominated T-80 the new tank but the Soviets used then the officious designation T-74. The last tank produced in the Soviet Union was as well a derivative from the T-64, but this time it was a much more sophisticated vehicle, with a very improved engineering instead of a simplified one (T-72). Western observers presumed in that time that the engine would be similar to the one of the T-64, a Diesel of 750 horsepower, and that the maximum speed would be around 60 kilometers/hour, with an operational range of about 450 kilometers. But in this aspect, the T-80 brought the most notable innovation in a Soviet tank: its gas turbine engine of 985 horsepower, which along with a new transmission granted a maximum road speed of 75 kilometers/hour and an operational range of 400 kilometers with 1000 liters of fuel. But this turbine engine was criticized because of its high consumption and technical problems, and some later series of the T-80 adopted again the conventional Diesel engine.

Regarding armor, the improvement was reflected by the increase of weight in the new tank, about six tonnes in respect of the T-64 (the weight of 42 tonnes was estimated by the Pentagon in 1983). It was believed in the beginning that the turret would be made with armor of Chobham type, and so the first drawing published in 1981 of the new tank presented it with a turret of rectilinear shapes. When the first photography was known in 1983 it was seen that the turret was one of rounded shapes, probably made of composite armor, but without the characteristics of the Chobham armor, which allowed to estimate the weight of the T-80 in 42 tonnes, instead of the 48.5 tonnes that some other sources had stated previously. Still so, it was the heaviest Soviet tank since the IS series. In fact, the three crew members had a protection improved by laminated armor in the glacis and the possibility of adding plates of reactive armor in other parts to counteract shaped-charge projectiles, but the turret was not really made of composite armor, but conventional steel armor. As main armament it was reused the 125-millimeter cannon/missile launcher that had been discarded in the T-72, being directed this weapon by a digital calculator which received basic data from optical sights linked to a laser rangefinder, but with LLTV (Low-Light Television) and active/passive thermal image systems, which could present images in the sights in conditions of low visibility.

It was estimated already from the early 1980s that the cannon had available, apart from the three conventional types of projectiles, a new one denominated HVAPFSDS (High-Velocity Armor-Piercing Fin-Stabilized Discarding-Sabot), subcalibrated piercing projectile of hard core. The core was not made of tungsten carbide, as it was since the Second World War, but of depleted uranium. This formula had been used previously in other types of projectiles, being the most significative example the piercing ammunition fired by the 30-millimeter cannon GAU-8 installed in the American tactical aircraft A-10 Thunderbolt, but it was unknown in tank ammunition. However, despite of the denomination "High-Velocity", the muzzle speed of these projectiles was estimated to be the same than the one of the conventional APFSDS, and the increased piercing power would be achieved solely due to the new material, of higher density and resistance to compression. Among the confirmed improvements was as well the full stabilization of the cannon. Thanks to its ammunition of separated charge, the automatic loaders in the tanks T-64, T-72 and T-80 are notably compact. However this advantage is paid by carrying a carousel with the ammunitions in the basket of the turret. The deflagration of the ammunition causes always the destruction of the tank along with its crew.

Curiously, even if the hydropneumatic system had worked well in previous vehicles, in the T-80 it was adopted again the suspension system of torsion bars. The road wheels were of a revised model, but regarding everything else, the wheel arrangement was the same one that in the T-72, with armored skirts to protect the upper part of the tracks. The first T-80 were delivered in 1984 and the number of them produced was a speculation. According to the Pentagon, in 1984 existed already 1400 tanks T-80 in service in East Germany. The tendency of Soviet production pointed that in the late 1980s the number of T-72 and T-80 could constitute the largest part of the Soviet assault tank forces, five times superior than the American respective force. In the time of the desmembering of the Soviet Union, there were probably in service between 4000 and 8000 exemplars. None of them had been served by the Soviet Union to the armed forces of any country, not even the closest allies. Obviously, the T-80 could be developed much further, and it was a subject of speculation as well how far this process could have gone, if carried out.

Categories: Tanks - Cold War - 20th Century - [General] - [General]

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Article submitted: 2015-06-05