The sentiment among the few amateur academic-enthusiasts that haven't forgotten the T-62's existence is that it was a highly mediocre design with a whopping gun, and in many ways, that is perfectly true from a technological standpoint. In many ways, the T-62 is indistinguishable from the T-55 that preceded it.
Being a mere evolutionary stepping stone, though, we can observe the way Soviet school of thought on mechanized warfare evolved with it. In the early 60's, tank riding infantry was still considered a core part of mechanized warfare. The armoured APC had arrived on the scene in the form of the wheeled BTR-152 and tracked BTR-50, but infantry were sometimes obliged to move and fight as one with a tank, and so to that end, the T-62 had handrails over the circumference of the turret for tank riders to hold on to. When the BMP-1 was introduced in 1966, it drove a major revision of contemporary tank tactics, and the shift in paradigm can be very well seen in the T-62's successors. The T-64A did not have any handrails, nor did the T-72, and the T-62M introduced in the late 60's abolished them too.
The changes to the T-62 dutifully followed international trends as well, most notably the global shift to jet power in the aviation industry. Too fast to be harmed by machine gun fire, the ground attack jet rendered the normally obligatory DShKM machine gun obsolete. The birth of the AH-1 Huey Cobra and the subsequent heavy use of helicopters for fire support and landing missions during the American intervention (or invasion, if you prefer) in Vietnam permanently shifted the conventional ideals of armoured warfare, and the men and women at Uralvagonzavod obeyed. The DShKM was back by 1972.
In the Soviet Union, the T-62 was produced from 1963 to 1975, with the first pre-production models appearing in 1961. After 1975, all "new" T-62s are actually simply upgraded, modified, or otherwise overhauled versions from the original production run. By then, production at the Uralvagonzavod factory had irreversibly shifted to T-72 production.
The commander is seated on the port side of the turret, directly behind the gunner, and to his left is the R-113 radio station, created just as the T-62 first entered service in 1961.
The R-113 radio operates in the 20.00 to 22.375 MHz range and has a range of 10 to 20 km with its 4 m-long antenna. It could be tuned into 96 frequencies within the limits of its frequency range.
In 1965, the radio was swapped out for a newer and much more advanced R-123 radio. The R-123 radio had a frequency range of between 20 MHZ to 51.5 MHZ. It could be tuned to any frequency within those limits via a knob, or the commander could instantly switch between four preset frequencies for communications within a platoon. It had a range of between 16km to 50km. The R-123 had a novel, but rather redundant frosted glass prism window at the top of the apparatus that displayed the operating frequency. An internal bulb illuminated a dial, imposing it onto the prism where it is displayed. The R-123 had an advanced modular design that enabled it to be repaired quickly by simply swapping out individual modules.
It is quite clear that the commander's station is the most habitable one by far in the very spartan T-62. The close proximity between all the turret occupants with each other and the shortage of breathing space makes the internal climate hot and humid, contributing to the overall discomfort. This is compounded by the fact that the crew isn't provided with any local ventilators such as fans or directed air vents, so it can get quite stuffy inside. However, the commander seems to be the most well off, since he sits right in front of the sole ventilator in the turret and he isn't required to exert himself physically, unlike the loader.
Although the T-62 superficially resembles the T-54 from many angles, the dome-shaped turret is significantly larger and noticeably more spacious, even with the larger cannon. This can be largely attributed to the 2.245-meter diameter turret ring, a big improvement over the 1.825-meter one of the T-54 family. The T-62's turret ring is bigger than the one on the M48 and M60, which had the widest turret ring (2.16 m) among all Western tanks in service at the time. This is partially offset by the much larger cannon breech, whereas the M48 used a smaller 90mm gun and the 105mm M68 cannon used by the M60 was unusually compact, but the turret of the T-62 got rid of the needle-nose ballistic shaping of the T-54. This contributed to a modest increase in the amount of habitable room inside the turret.
Unique to the rest of this dome-shaped turret, the area around the commander's station was cast to be devoid of any vertical sloping or rounding whatsoever, which was necessary to enable his rotating cupola to be installed. This also meant that any debilitating effects of the shaping of turret (lack of headroom, for instance) do not apply on him. The crew stations in the T-55 tank were compromised by the egg shape of the turret, a shape optimized for ballistic protection, not comfort.
The commander's cupola cupola is mounted on a race ring. The fixed part constitutes half of the total size of the cupola, while the other half is occupied by the semicircular hatch with a maximum width of approximately 590mm. The hatch opens forward, which is quite convenient for when the commander wants to survey the landscape from outside - perhaps with a pair of binoculars - because being as thick as it is, the hatch is a superb bulletproof shield, protecting the commander from sniper fire.
There is also a small porthole in the hatch. It is meant for a panoramic periscope tube for indirect fire.
As befitting his tactical role, the commander's general visibility is facilitated by two TNPO-170 periscopes on either side of the primary surveillance periscope in the fixed forward half of the cupola, and further augmented by two more 54-36-318-R periscopes embedded in the hatch, aimed to either side for additional situational awareness. Overall, this scheme was sufficient for most purposes, but was deficient if compared to the much more generous allowance of periscopes and vision ports found on NATO tanks.
The TKN-2 had an active night channel which picked up infrared light from the OU-3 IR spotlight attached to the periscope aperture to provide a limited degree of night vision to the commander. With a nominal viewing range of only about 300 to 400 m, the TKN-2 was all but useless for serious target acquisition at night, serving only to give away the tank's position the moment the spotlight was turned on. Performance could be improved with mortar-delivered IR flares, of course, but that doesn't count as an intrinsic merit of the device itself.
Due to the fact that the periscope is unstabilized, identifying a tank type target at a distance is very difficult while on the move over very rough terrain. However, the commander is meant to bear down and brace against the handles of the periscope for a modicum of improvised stabilization, which is adequate for when cruising at a moderate speed (about 20 km/h to 30 km/h) over a dirt road, but not when traversing over rougher ground.
The left handle has a thumb button for turning the OU-3 spotlight on or off.
The OU-3 is a high-powered xenon arc lamp with an IR filter. The filter isn't totally opaque, though, and the spotlight will glow faintly red. It is mechanically linked to the periscope, enabling it to elevate with the TKN-2.
|OU-3 IR spotlight with the IR filter removed to transform it into a regular white light spotlight|
The OU-3 spotlight operates on 110 W of power.
The TKN-3 was a sufficiently modern observation device of its time. It featured target cuing, was very compact, and had a relatively advanced passive light intensification system, but it wasn't stabilised, and featured only rudimentary rangefinding capabilities as a cost saving measure. It offered rudimentary night vision capability in two flavours; passive light intensification or active infrared. In the passive mode of operation, the TKN-3 intensifies ambient light to produce a more legible image. This mode is useful down to ambient lighting conditions of at least 0.005 lux, which would be equivalent to an overcast, moonless and starless night. In these conditions, the TKN-3 can be used to identify a tank-type target at a nominal distance of 400m, but as the amount of ambient light increases such as on starlit or moonlit nights, the distance at which a tank-sized target is discernible can be extended to up to 800m in dark twilight hours. Any brighter, though, and the image will be oversaturated and unintelligible.
The active mode requires the use of the OU-3K IR spotlight, which is practically identical to the OU-3 in many respects. With active infrared imaging, the commander can identify a tank at 800m, or potentially more if the opposing side is also using IR spotlights, in which case, the TKN-3 can be set to the active mode but without turning on the IR spotlight. This way, the commander can see enemy tanks from many kilometers away at night.
Rangefinding is accomplished through the use of a stadiametric scale calibrated for a target with a height of 2.7 m, which is the average height of the average NATO tank. The ranging error margin is negligible at distances of around a kilometer, but at distances exceeding approximately 1.6 km, it becomes difficult to accurately find the range of the target due to a multitude of factors, including weather conditions, limited magnification power, mirages (a big problem in deserts), and obstruction of parts of the tank (tall grass can hide the lower part of the hull). At long distances, contrast between the target tank and the background is also often very poor, since there is usually some modicum of camouflage to conceal the tank.
It is also possible to find the distance to the target tank by using the horizontal and vertical mil scales printed on either side of the reticle. Knowing the width of a Patton tank to be around 3.6 meters, the commander will know that the distance to the tank is exactly 1000 meters if the tank can be slotted exactly between the reticle, which has a width of 3.6 mils. Depending on how exact the fit is, the commander can roughly estimate the range.
Like the TKN-2 and other previous binocular sights for the commander, the TKN-3 is unstabilized, making it exceedingly difficult to reliably identify enemy tanks or other vehicles at extended distances while the tank is travelling over rough terrain, let alone determine the range. The left thumb button initiates turret traverse for target cuing, and the right thumb button turns the OU-3K spotlight on or off. The range of elevation is +10° to -5°, just like the TKN-2. The OU-3K spotlight is also mechanically linked to the periscope (the arm to which the spotlight is linked to can be seen in the photo above) to enable it to elevate with the TKN-3. The way the spotlight is connected to the sight is eccentric, so that elevating the sight by, say, a degree will elevate the spotlight by more than a degree. This is so that the point of illumination of the spotlight will always match the point of aim of the sight. This is important because the hinge point of the spotlight is not the same as the sight, one being lower and the other being higher.
Target cuing is done by placing the crosshair reticle in the periscope's viewfinder over the intended target and pressing the cue button. The system only accounts for the cupola's orientation, though, and not the periscope's elevation, so the cannon will not elevate to meet the target, only the turret will. This wasn't really an issue, since the gunner needs to manually elevate the cannon to place the crosshair on target anyway (explained later in the Sights segment).
Because the cupola did not counter rotated as turret traverse was initiated, it will be spun along with the turret as it rotates to meet the target cued by the commander, potentially causing him to lose his bearings. To prevent this, there is a simple U-shaped steel rung for him to brace with his right arm as he uses his left hand to designate the target. This wasn't as convenient as a counter rotating motor, of course, but it was better than nothing.
Overall, the commander's facilities, furnished with the TKN-3, might be considered better than most Western tanks when it comes to target finding. As far as the author knows, the M60A1 and the Leopard 1 to 1A2 didn't have anything even approaching the TKN-3. Between 1972 and 1974, the TKN-3 was soundly out-matched by the new and quite excellent TRP 2A sight installed on Leopard 1A3s. But it should be mentioned that the Leopard 1A3 was only produced from between May 1973 and November 1973, and that only 110 examples were built. The rest of the Leopard fleet at that point consisted of inferior Leopard 1s, A1s and A2s, but the vast majority were Leopard 1s. Whether or not you can consider 110 tanks a significant fighting force is up to you.
Ventilation for the crew is facilitated by the KUV-3 ventilator, identifiable on the rear of the turret as a large, overturned frying pan-shaped tumor on the rear of the turret. The "frying pan" is quite thick.
A centrifugal fan inside the ventilator housing sucks in air and performs some low level filtration, ejecting dust and larger particles out of a small slit at the base of the housing (refer to photo above). The filtered air is then released into the crew compartment, passing through a drum-shaped NBC filter unit inside the tank proper. The air can be optionally cleaned of chemical and biological contaminants by the filter in contaminated environments where the centrifugal fan is simply not enough. The filter unit also contains a supercharger to increase the positive pressure inside the tank to produce an overpressure, preventing chemical and biological agents from seeping into the tank.
|Notice the PVC pipe connecting it to the ventilation dome on the outside of the turret rear|
The commander's station is the second most roomy one in the tank, besides the loader's station. Here in the photo above, you can see the backrest of his seat and the few pieces of equipment that he is responsible for. He has access to a communications control box that enables him to switch between radio and intercom communication channels, a few loops for strapping on personal effects like water tumblers, his pistol in its holster, and anything else that might need to be secured. He also has access to the turret traverse lock. Underneath his seat is the tank's heater unit.
Sometime during the 70's, a select few T-62s received a shield of sorts over the commander's hatch. It is a sheet steel face shield with a canvas skirt draping down. Being so thin, the face shield is not bulletproof.
Since it doesn't really do very well as ballistic protection, the main function of the shield appears to be to conceal the opening of the commander's hatch to disguise his exit from the prying eyes of snipers, and to shield the commander from dust and bugs if he feels like sitting outside during road marches. Either way, not many T-62s received the addition, though almost all T-72s did. The reason for the bias is unknown.
As was, and still is common among manually loaded tanks, the gunner doesn't have a hatch of his own. Instead, he must ingress and egress through the commander's hatch. The biggest flaw with this layout is that if the commander is unconscious, incapacitated or killed, then the gunner will suddenly find it extremely difficult to leave the tank unless the commander was somehow completely vaporized. Even worse, if the tank has been struck, there is a very distinct possibility that the interior is catching fire.
Another flaw with the layout is if the turret was perforated through the front on the port side cheek, both the gunner and commander would be killed, effectively rendering the tank useless in combat. If the tank was perforated on the upper glacis near the turret ring, the driver, commander and gunner would all be killed in one go. Quite morbid.
Nevertheless, Nicholas "The Chieftain" Moran has commented that the gunner's station in the T-55 is very well laid out, and overall quite satisfactory. The T-62 should offer a similar experience, but slightly better thanks to the much more voluminous turret.
For extra visibility, the gunner has a single TNP-165 periscope pointed forward and slightly to the right, though for what exact purpose this lone periscope is meant for is unknown, since the field of view from it is so small that the gunner can't really see very much, nor can the commander seated behind him. It is more useful for the commander for checking directly in front of the tank. The gunner can also use it to check the clearance of the gun when approaching a berm or when entering a tank hole, but that's about it.
In addition to all of the necessary switches and toggle buttons to activate this and that, there are also some other odds and ends at his station, including a turret azimuth indicator, which is used to orient the turret for indirect fire. It is akin to a clock, having two hands - one for general indication measured in degrees, and the other in 100 mil increments for precise turret traverse.
|TSh2B-41 sight aperture port, with nuclear attack seal in place|
The gunner is provided with either a monocular TSh2B-41 or a TSh2B-41U (in later models) primary sight and a TPN-1-41-11 night sight, which also functions as a backup sight in the event of the failure or destruction of the primary sight.
The TSh2B-41 is a monocular telescopic sight, functioning as the gunner's primary sight for direct fire purposes. It has two magnification settings, x3.5 or x7, and an angular field of view of 18° in the former setting and 9° in the latter setting. As was and still is common for all tank sights, it has an anti-glare coating for easier aiming when facing the sun. It comes with a small wiper to clean off moisture, and it comes with an integrated heater for defrosting.
Like most other tanks of its time, the T-62 lacked a ballistic computer. It had no FCS, only this sight. As the tank lacked a stereoscopic rangefinder like the M48 tank, it was also unusually deficient in the rangefinding department. For rangefinding, the gunner had to make use of a stadiametric ranging scale embossed on the sight aperture. Compared to optical coincidence rangefinders, stadia rangefinding was terribly imprecise, but also much simpler in both production and employment, and much more economical than, say, optical coincidence rangefinding. The savings made from the exclusion of an optical coincidence rangefinder were enormous, amounting to many thousands of rubles. However, by sticking with the stadia rangefinder, ranging errors of up to several hundred meters was often the norm, especially if some of the lower part of the target vehicle is obscured behind vegetation or other terrain features. It isn't uncommon for the first shot on faraway tank-sized targets to fall woefully short or fly clear over when using low velocity ammunition like HEAT rounds.
Below is the sight picture:
|Range scales from left to right: APFSDS, HEAT, HE-Frag, Co-Axial Machine Gun|
When the gunner has obtained range data, he manually enters the necessary correction into the sighting system by turning a dial. The dial adjusts the sight to calibrate it for that range.
Calibration is when the chevron is elevated or depressed to account for range. If the target is very far away, for example, then the chevron will be dropped significantly, forcing the gunner to sharply elevate the gun to line up the target with the chevron, thus forming a ballistic solution. Because APFSDS, HEAT and HE-Frag shells all have different ballistic characteristics, the gunner must refer to a set of fixed range scales drawn on the upper half of the sight in order to get the proper gun elevation. For instance, if the target is 1.6 km away, and the gunner wishes to engage it with high explosive shells, then he must line up a horizontal bar (which moves up and down with the targeting chevron but at different speeds due to a reduction gear) with a line on the range scale for "OF" shells that says "16". If the gunner wishes to use APFSDS instead, then he need only line up the horizontal bar with the "16" notch on the "BR" scale. Then, the chevron will show how much supraelevation is needed in order to hit the target with the selected ammunition. The gunner will then lay the chevron on the target and open fire.
The sight has an internal light bulb that when turned on, illuminates the reticle for easier aiming in poor lighting conditions such as during twilight hours or dawn.
It is more difficult hitting targets with lower velocity ammunition like HE-Frag and HEAT shells, and even harder for moving targets. However, the inclusion of near-hypersonic APFSDS ammunition in the T-62's loadout greatly helped counterbalance this issue, making it markedly easier for the gunner to hit both stationary and moving tank-type targets, while most targets requiring HE-Frag shells like machine gun nests and pillboxes and other fortifications would be stationary anyway, thus making pinpoint accuracy much less of a priority. On account of the extremely high speed of the APFSDS rounds fired from the 2A20 gun, the sight can be battlesighted at a very generous 1000 m, allowing the gunner to confidently hit a tank of NATO-type dimensions in the open at any distance between 200 to 1600 m by aiming at center mass without needing to ascertain the range beforehand.
However, one inescapable flaw of the TSh2B-41 was that it lacked independent vertical stabilization. The movable aperture assembly of the sight is directly linked to the 2A20 cannon via a pair of rods. Due to the "loader assist" function of the "Meteor" stabilizer, the aperture of the sight will raise along with the cannon when the loading procedure is underway. This can cause the gunner to (very annoyingly) lose sight of anything he is aiming at at the moment, thereby making the commander's the only pair of eyes to observe the 'splash' and give corrections or search for new targets. However, this can be bypassed if the gunner switched to the 3.5x magnification mode, whereby he will still be able to observe the 'splash' at the bottom part of the sight picture. He might also be able to get a glimpse at the bottom edge of his sight at 7x magnification, but this depends on the elevation of the cannon. On flat ground, this might be possible, but this will be impossible if the tank is peeking over a reverse slope. These complications led to the development of the independently stabilized TSh2B-41U.
But since we are on this topic, we cannot neglect to mention that it is nigh impossible to observe the fall of a shot when high velocity APFSDS rounds are being used. For one, the flash, smoke and fumes from ejected from the gun barrel will immediately block out any attempts to find the point of impact. Secondly, the shock and vibration from firing the cannon does not leave enough time for the gunner to recover and visually reacquire the target. These two factors are extremely relevant for any tank, but the T-62 suffers since the sight aperture is closer to the ground, so dust from the ground is an even bigger issue. Even if your tank has a thermal sight, it is not possible to escape this phenomenon.
The video below shows a Chieftain tank firing at a target on what appears to be a grassy field. Due to the clean environment, the amount of dust kicked up by the muzzle blast is very minimal. The target is visible in a mere two seconds after firing. The firing range was a grassy field.
|Video from here (link)|
The GIF below shows the view from the thermal sight of an Iraqi Abrams firing at ISIS fighters. The dusty environment obscures the gunner's vision for around five to six seconds immediately after firing.
|Video from here (link)|
Even if TSh2B-41 was independently stabilized, it might not improve things by much in dry conditions. When dust is not a problem, the TSh2B-41 may be a liability.
In the 1972 modification of the T-62, it was given the upgraded TSh2B-41U sight with independent vertical stabilization as a transient solution. It lacks the usual components of a true stabilization system, like its own gyrostabilizer system, so its performance is highly unimpressive. The sight has a mean vertical stabilization accuracy of 3 mils - meaning that it has an accuracy of 3 meters at 1000 m, or a maximum deviation of up to 1.5 m, which would incredibly inadequate for anything other than just general observation. Fortunately enough, that's all that it is meant for, as the sight is only stabilized when the cannon is elevated during the loading procedure. When the cannon elevates, the sight does not follow, allowing the gunner to use his handgrips to manipulate the elevation of the sight. Once the cannon is ready to fire again, the "Meteor" stabilizer reengages and "catches up" to the sight, whereby the sight's stabilizer deactivates and defers its work to Meteor once again. This is different from true independent stabilization where the sight's stabilizer can be as precise or more precise than the stabilizer for thecannon, and the stabilizer for the cannon is perpetually slaved to the sight.
One tangible benefit of the independent vertical stabilization of the sight is that the gunner will be able to survey the landscape if the tank is on the move after firing from a short halt or crawl, or if the tank is firing on the move.
The stabilization system of the sight enabled the aperture lens to elevate as high as the cannon, but it could only depress by -5 degrees. Because of this, T-62s from 1972 and onwards have a reduced gun depression of -5 degrees, as compared to the -6 degrees afforded by the original TSh2B-41.
Another modification was the addition of a range scale for the new and improved 3UOF18 HE-Frag shell, and the separation of it from the scale of the older 3UOF11. The aiming distance of HEAT ammunition was increased to 3.7 km and the aiming distance for OF-18 and OF-11 shells are listed as 4.8 km and 3.6 km respectively.
TSh2B-41U suffered from poor performance. Even if it did offer a modicum of independent vertical stabilization, it was not useful enough. TSh2B-41U was was not installed on many tanks.
Because the sight aperture is just left of the gun barrel, there is a very high likelihood that it will be rendered inoperable if the turret takes a hit anywhere near it. A very close miss may create a big enough shock to knock the sight out of alignment or even crack the lenses, not to mention the disastrous effects of a direct hit on the aperture itself. But for all of its inherent flaws, the TSh-2B-41 should not be seen as anything less than an extremely high quality product of its time. Lack of independent vertical stabilization notwithstanding, the glass was of superb quality and the insulation and shockproofing of the sight unit was sturdy enough to survive the blast wave of a nuclear explosion and ambient temperatures of over 200° C. Nevertheless, whereupon the TSh2B-41 is out of service, the gunner will have no choice but to rely on the TPN-1-41-11 backup night sight.
The TPN-1-41-11 is a monocular periscopic night or backup sight located on the turret roof just in front of the commander's cupola. The TPN-1-41-11 has a fixed magnification of x5.5 and a field of view of 6° in the daytime mode. It could operate in either passive or active modes. In the active mode, it must work in tandem with the L-2 Luna IR spotlight which moves along with the cannon though a mechanical linkage. The infrared light supplied by the spotlight is picked up by the sight, which allows the gunner to identify a tank-type target at distance of around 800m, which is only just decent, but not worse than its immediate counterparts'. In the passive mode, it employs light intensification for a nominal maximum identification distance of 400m for a tank-type target under lighting conditions of no less than 0.005 lux. As with the TKN-3, and indeed any optronics using light intensification, the viewing distance and resolution increases as ambient light intensity increases, but only up to a certain point before the sight is oversaturated and can no longer produce a legible image.
Like with the TSh2B-41/U, the sight has an internal lightbulb which facilitates aiming at night.
Unfortunately for the gunner, the TPN-1-41-11 is mechanically linked to the cannon, and does not have independently stabilization, nor is there any modified variant that features it. As such, just like the TSh2B-41, its range of vertical motion is limited to the cannon's range of elevation, which is -6° to +16°.
|T-62 with KDT-1|
The KTD-1 had a maximum measuring distance of 4000 m and a minimum of 400 m. The maximum margin of error in the measurement was 20 m.
KTD-1 does not directly interface with the existing fire control systems, except for the handgrips. There is a laser rangefinder control panel mounted in its own special corner, but the handgrips are replaced with one that had an additional trigger button for firing off the rangefinder. Range data is displayed on a digital readout. Now knowing the range, the gunner will then have to manually apply the data into the TSh2B-41/U sight by adjusting the range dial appropriately, and then continue the firing procedure in the normal manner.
Having a laser rangefinder in 1974 was quite a big deal at the time. The best that the Leopard 1 had at the time was the EMES 12A1 with a stereoscopic rangefinder, which could be found on the Leopard 1A4 model built in 1974. But it is understood - this does not mean that the shortcomings of the T-62's fire control system (or lack thereof) vanish into thin air. Rangefinding with the KTD-1 is fast, but the additional hassle of inputting the range data is a cumbersome chore that takes valuable seconds. The presence of the rangefinder is most helpful when firing on non-tank targets like bunkers and machine gun nests, as these targets cannot be ranged with stadiametric rangefinders. Additionally, the T-62's APFSDS ammunition makes up for the lack of rangefinder in the fire control system at short to medium ranges, but not so much at long ranges. The presence of a laser rangefinder further improves medium distance accuracy, and greatly fortifies long range accuracy.
VOLNA FIRE CONTROL SYSTEM (T-62M)
The T-62M introduced in 1983 came with an entirely new "Volna" fire control system. "Volna" is a comprehensive fire control system overhaul. All of the original components of the T-62's fire control system have been replaced, and some new technology has been added, including the KTD-2 laser rangefinder, the BV-62 analog ballistic computer, and the new TShS-41U sight purpose-built for "Volna", plus all of the necessary electrical equipment like the 9S831 transformer to adapt the new technology to the tank's electrical system.
Overall, "Volna" cannot be considered a cutting edge product for the 80's. Rather, it was an extremely cost effective modernization to raise the fighting capabilities of an old and outdated tank up to scratch and maintain a sufficiently large fleet of tanks.
TShS-41U can be described as a transition model in terms of capabilities, as it is superior to TSh2B-41U, yet it does not quite reach the level of the 1A40 sighting complex used in the T-72 since 1976. The new vertical stabilizer has an accuracy of up to 0.3 mrad, translating to an error margin of 0.15 meters at 1000 m. This is good by 80's standards. However, the sight-gun stabilizer interface was still mechanical, and the sight was still slaved to the gun.
Laser rangefinding had become standard worldwide by 1983, so it was only natural that TShS was fully adapted to the new add-on rangefinder system.
The KTD-2 laser rangefinder has a minimum measuring distance of 500 meters and a maximum of 4000 meters under perfect meteorological conditions, namely a visibility distance of 10 kilometers. The principal difference, though, is the installation of a viewfinder directly routed over to the gunner's sight. Through this viewfinder, the gunner can observe the battlefield within an angular field of view of 2.5° under a 7x magnification, and select and range up to 3 targets simultaneously.
The gun laying system is of an automatic type, similar to the TPD-K1. KTD-2 sends range information to the BV-62 analog ballistic computer, which then calculates a firing solution and adjusts elevation of the cannon accordingly. The ammunition type is selected by the gunner, and the selection will influence the elevation of the cannon to match the ballistic profile of the ammunition selected. The aiming chevron always remains static. All the gunner must do then is to simply lay the chevron on the target and open fire.
The aiming point for the laser rangefinder is just slightly above the aiming chevron, which is a little inconvenient. Besides the laser rangefinder interface and the overhauled viewfinder picture, TShS-41U features a greatly improved vertical stabilizer, much more precise than the vertical stabilizer of the Meteor-M.
TShSM-41U features an electronic interface with the updated Meteor-M1. With Meteor-M1, the gun stabilization arrangement was changed from a sight-slaved-to-gun regime to a gun-slaved-to-sight one. This promoted better firing accuracy. The sight could now be moved vertically using the gunner's handgrips with total independence.
TShSM-41U also introduced a simple target leading system. A secondary chevron (secondary chevrons are the small chevrons on either side of the center chevron) paired with the central chevron to allows lateral lead to be calculated as long as the distance to the target is between 800 m and 1800 m. Beginning with the center chevron, the time it takes for the target to reach the first secondary chevron is recorded by the gunner, done by pressing the button on an integrated digital stopwatch. Using the range data from the laser rangefinder, the sight will then calculate the lateral velocity of the target, and then display the required amount of lateral displacement that the gunner needs to apply in mils. The gunner will then choose one of the secondary chevrons and adopt that as the new aiming point.
This system is inferior to the already questionable UVBU lead calculator featured in the 1A40-1. The "stopwatch calculator" system was convoluted and was presumably largely ignored in favour of finely honed gunnery skills. Even if we ignore the complicated procedure for its operation, the time needed for the system to calculate lead is quite long. It is totally impractical to use the system in actual combat.
All T-62Ms received the 1K13-2 to replace the TPN-1-41-11, but as the 1K13-2 operates independently from the "Volna" FCS, it should not be placed under the same banner. For the sake of convenience, however, that is what we will do.
The 1K13-2 is a combined monocular auxiliary sight which introduced the ability to guide new 115mm GLATGMs like the 9K116-1 "Sheksna", among other things.
The sight has a nominal maximum identification range of 5000 m on a tank-type target in the daytime mode under a maximum 8x magnification, though the actual distance depends on meteorological and geographical conditions more than anything. Like with the previous auxiliary sighting complexes, the 1K13-2 has two modes; passive and active, both of which operate under a 5x magnification. The sight enables the gunner to detect a tank-type target at nominal maximum range of 800 m in the passive mode under lighting conditions of no less than 0.005 lux. Alternatively, the identification distance can be as high as 1100 m in the active mode under illumination from the L-2G IR spotlight. The sight has an internal lightbulb that illuminates the reticle to facilitate aiming at night.
In contrast to all of the previous sighting complexes, the 1K13-2 sight has two-plane stabilization. The accuracy of stabilization while the tank is on the move at 15 km/h is 0.15 mrad in the vertical plane and 0.2 mrad in the horizontal plane, translating to a stabilization accuracy of 0.02 m at 1000 m vertically and 0.03 m horizontally. which is a level of accuracy so high that it is practically the same as if the tank was not moving at all.
The sight can only be used to guide GLATGMs in the daytime mode.
From 1961 to 1971, the loader had a large (about two feet in diameter), perfectly circular hatch placed directly above his seat, built slanted so that it followed the curving contours of the turret, which was imperative to its overall protection scheme. In 1972, the installation of the DShK anti-aircraft machine gun required a level circular ring mount to operate, and so the loader's part of the turret was renovated completely. Now, he had his own semi-cupola, and the area of the turret around his station lost its domed curve to resemble the commander's station. His new hatch shrank by half and became an irregular semicircle with a maximum width of 580mm, making it half as easy to ingress and egress, especially with bulky winter clothing.
There are two variations of the same type of cupola. Early model T-62s upgraded to obr. 1972 standard have a separately cast cupola welded onto the original turret, while T-62s produced in 1972 and after have the cupola cast as part of the turret.
For general observation purposes, the loader is provided with a single MK-4S periscope with a rear view feature. It can be elevated and depressed, or rotated 360 degrees for all-round vision, though the geometry of the turret and the L-2 spotlight block out a large portion of the loader's leftward vision. It's not very useful in combat, since the loader must concentrate on his loading duties, but it may be intermittently useful under certain circumstances. For instance, the periscope gives the tank an extra pair of eyes to help ascertain the direction of enemy fire in an ambush during the first few seconds of the attack, which can prove critical to the tank's survival and prompt destruction of hostile forces. In theory.
The loader does not have much room to work with, but he does have a bit more room than the loader of a T-54, and the size of 115mm ammunition is actually more manageable than 100mm ammunition. Still there are some drawbacks. The section of turret floor on which the loader must stand on is very narrow, which impedes his ability to transfer rounds from the front hull stowage racks to the gun breech. The narrowness can also be a real problem if he is trying to load the cannon while the turret is traversing. The loader has a his own seat (which is attached to the turret), but he performs his duties standing, or rather, squatting, unless he is using the ready rack of ammo behind him - but we will examine that later.
One of the biggest drawbacks of the dome-shaped turret is that the loader hardly has any headroom while standing compared to a contemporary Western tank. To be precise, the loader's station has 1.6 m, or 5'4" of vertical space from the floor to the hatch . This is the same as the T-54, which is a bit surprising since the T-62 appears squatter than a T-54, but evidently that is an optical illusion caused by the much, much wider turret. The vertical space was increased in the 1972 model of the T-62, which raised the ceiling by removing the slope from the loader's sector of the turret to accommodate his new cupola. Now, a loader of average height could stand up straighter when ramming shells into the breech.
Furthermore, 115mm cartridges are surprisingly light. The T-62 has taken a lot of flak for its lack of amenities, especially for the loader, and there is even an apocryphal story about an Israeli loader being hospitalized for spinal injuries while evaluating a captured T-62. The truth is, the Soviet 115mm caliber is remarkably efficient. 115mm APFSDS rounds weigh only around 22 kg, lighter than 100mm steel AP rounds by an entire 8 kg! The 115mm 3UOF-1 cartridge itself is actually lighter than 100mm UOF-412 by 2kg, but fires a shell of similar mass at a similar velocity muzzle. The HEAT ammunition for both calibers weigh the same.
Compared to 105mm ammunition, a generic 115mm APFSDS round weighs about 4 kg more than a generic 105mm APDS or APFSDS round.
The T-62 can carry a total of 40 rounds of ammunition. The two sets of front hull stowage racks (both are conformal fuel tanks) hold 8 rounds each, for a total of 16 rounds of ammunition. These racks are pictured below. Another 20 rounds are stowed in the very back of the hull on the partition between the engine compartment and the fighting compartment. The loader has 2 rounds in a ready rack on the turret wall directly behind him for convenient loading, and another round secured by tension latches in a rack near his feet on the floor of the hull side wall. There is another round stowed in the same way near the commander's feet.
The loader must squat down to access these rounds. These racks are principally identical to the ones found on the T-54, only sightly modified for different ammunition. These racks are the most convenient for the loader. Once he has pulled a cartridge out of its slot, he needs only to stand up and ram the round into the chamber. There is no need to maneuver the extremely large shells around. The loader can be expected to load within 6 seconds using these racks.
The aforementioned 20 rounds stowed on the partition are stowed crosswise. There are rubber coasters to cup the base of each casing, and a metal frame to prop up up the shell at the tip.
|These rings are rubber collars to secure the base of the rounds|
|The ends of the shells are propped up by a metal frame, which has been removed in this photo (it's green and it's lying on the floor)|
|Here you can see the coasters on the parallel wall|
The loader is not able to easily get to these if the turret is oriented directly forward. He must squat down to extricate these rounds, which he may find slightly unnerving if the gunner is about to fire, since he will be directly behind and underneath the cannon breech. But he should be fine, since the arm guard doesn't move when the cannon recoils backwards. To load, he must simply pull the round forward, freeing it from its "coaster", then stand up and return to ram it into the cannon breech. After the first 10 rounds are used up, the frame that props up the shells is typically removed, and the shells are left on the floor. Based off of this video (link), it appears that a good loader can be expected to load a round in about 7 seconds or less.
Last but not least is the ready rack just behind the loader. It holds two rounds, mounted crosswise. Being located directly behind the loader (if he was to face the breech), these are the most easily accessible. To load, he must unlatch a round from a rack first, grab it and turn to face the cannon breech, then ram it in. This can be easily done in 6 seconds or so.
The theoretical absolute maximum rate of fire is around 8 to 10 rounds per minute using the front shell racks and the ready racks only, which is reasonable. In reality, the gunner typically takes longer to find a target and acquire a firing solution than it does for the loader to load. In an extremely target-rich environment where the cannon will be fired as quickly as the loader can load it, then the maximum rate of fire can potentially be as high as 10 rounds per minute, but this is extremely unrealistic, as this leaves no time to aim. The T-62 might be able to achieve something close to its theoretical maximum rate of fire if the commander and gunner forego the range finding procedure altogether and instead engage using battlesighting, as mentioned in the "Sights" section. This is a big advantage to the T-62, as the battlesighted range of distances is very large thanks to the high velocity of its APFSDS ammunition. In the average Central European battlefield, the gunner will only need to point, and shoot. This might mean that the rate of fire of a T-62 could be as high as 6 rounds per minute in a realistic scenario.
Official estimates of "4 rounds per minute", as listed in the operator's manual, are not to be taken at face value, as the testing committee usually presents the loading rate when using all ammunition stores, including the least convenient ones. Evidence of this practice is provided by Peter Samsonov in his article here (link). Plus, the commander or gunner is obliged to carry out the entire formalized firing procedure - including rangefinding - during such tests. In real life, the gunner will most probably forego this procedure as the trajectory of the tank's APFSDS shells is so flat that there is a big likelihood of achieving a hit by battlesighting.
It has already been said in the Commander's Station section of this article, but it must be said again. The turret ring of the T-62 has a diameter of 2.245 meters. To put that into perspective, know that the M103 heavy tank, with its massive 120mm M58 cannon has a turret ring diameter of only 2.16 meters. Keep this in mind to understand the conditions for the loader.
A reasonable estimate of the T-62's maximm average rate of fire while firing on short halts or on a crawl should be around 4 rounds per minute, as the loader is inconvenienced whenever the turret needs to turn when the tank is moving because of the narrow turret floor and the potential loss of access to his most convenient store of ammunition. How long the loader can maintain his speed under the most optimal conditions, fatigue notwithstanding, is a different matter entirely, of course, and this is a universal issue with all manually loaded tanks. The T-62 loses out in pure loading speed since the ammunition is far inferior to contemporaries that have a bustle, as the bustle stays put when the turret spins, unlike ammo in the hull like the T-62's front hull racks, but even though it's not the most optimal configuration, it is still acceptable. The loader has access to all of the ammunition in the tank from his station regardless of the turret orientation. Plus, the ability to access all of the tank's ammunition from the loader's station counts for something during lulls in combat, namely that the commander can continue to do his duties on standby. In terms of ammunition sustainability, the T-62 cannot hold a candle to its NATO counterparts. Counting the ready racks and the front hull racks, the T-62 has 18 ready rounds. The Leopard 1 must be considered excellent in that all of its 50+ ammunition is in convenient reach of the loader. The M60 is also quite good, as the loader has access to up to 37 rounds in the turret. With only 18 ready rounds, the T-62 cannot stay in continuous combat for as long as these tanks - assuming that tanks regularly expend dozens of rounds in most engagements, which they do not. After all, the Abrams tank with only 16 ready rounds in the turret bustle has never been complained about for any ammunition shortages.
But besides the ammunition for the main gun, the loader is also responsible for reloading the co-axial machine gun. Three ammunition boxes are stowed in simple sheet metal containers mounted on the turret ring bulge recess, and two more boxes are mounted on the turret rear. More boxes can be tucked away on the hull floor.
The chief justification for the T-62's existence was the 2A20 "Rapira" smoothbore cannon, also known as the U-5TS "Molot" as per its internal designation.
Compared to its predecessor the D-10T, the U-5TS is much, much more powerful, and also heavier. The U-5TS weighs 2350 kg, compared to just 1950 kg for the D-10T, but the U-5TS also had a maximum chamber pressure of 366 MPa, compared to just 289 MPA for the D-10T.
The 2A20 has all-round decent durability. It has an EFC rating of 450 shots. This means that the cannon should be able to safely shoot off at least 450 lower pressure rounds like HE-Frag and HEAT, and perhaps around 200 to 150 APFSDS rounds, which operate at a much higher pressure. After the 450 mark, the danger of a catastrophic failure of the barrel from excessive wear increases exponentially, which can result in a piece of the barrel fracturing off and becoming shrapnel in the worst of cases.
The cannon has a recoil stroke of between 350 mm and 415 mm, depending on the power of the ammunition used. The recoiling mechanism has a hard stop at 430 mm.
The cannon can be elevated to
The cannon has three triggers - the electric button trigger on the gunner's right hand grip, the solenoid button on the manual elevation flywheel, and the manual trigger on the breech itself.
Even as the first pre-production T-62s rolled off the factory gates in 1961, it was already fitted with the advanced 2E15 "Meteor" 2-plane stabilizer. This was not a common practice in the West at the time. Case in point, the M60A1, which was essentially the nemesis to the T-62, had just powered traverse and only received a serious two-plane stabilizer in 1972 in the form of the AOS (Add-On Stabilizer) system retrofit, which even then was not noticeably more useful (reading TankNet, it seems that the AOS system had a range of issues, including the tendency to sometimes spin the turret uncontrollably), though it was more advanced. The Leopard 1 caught up only in 1970 with the Leopard 1A1 upgrade, when it received a new Cadillac-Gage 2-plane stabilizer.
"Meteor" was not a new development at the time. It was assembled and adapted for the T-62 from two previously completed stabilizer projects - STP-2 "Tsyklon" and 2E12 "Liven". This greatly reduced the financial and time costs.
"Meteor" gave the T-62 top-notch fire-on-the-move capability, granting it a necessary advantage over contemporary Western tanks in highly mobile meeting engagements, which was considered the main format of tank combat by Soviet and Western experts. This also meant that on the T-62 was more flexible on the dynamic battlefield, being nearly equally adept on the defensive as on the offensive.
As the years went by, the T-62 received continuously updated versions of the Meteor. The 1964 version received the "Meteor-M", which was functionally identical to the Meteor, but replaced its vacuum tubes with transistors. The "Meteor-M1" was installed on the 1967 variant, and brought only minor modifications without changing the operating characteristics of the original "Meteor". With this in mind, only the original variant will be discussed in detail.
2E15 "Meteor" Hydroelectric Stabilizer
Turret traverse at the maximum rate is quite slow. It takes around 22.5 seconds to make a full revolution, or 16° per second. This is slow compared to NATO tanks which tended to be about twice as fast. The underwhelming turret rotation speed is broadly inconsequential during long to medium range engagements, but the T-62 suffers in non-linear combat where targets may appear suddenly from unexpected directions. The slow reaction time of the T-62 is typical of Soviet tanks, and is partially remedied when the tank is deployed as part of a platoon.
Minimum Traverse Speed: 0.07 deg/sec
Maximum Traverse Speed: 16 deg/sec
Minimum Gun Elevation Speed: 0.07 deg/sec
Maximum Gun Elevation Speed: 4.5 deg/sec
"Meteor" is not precise enough to be used for engaging targets on the move at long distances, but it must be reinforced that it was still quite advanced for its time. With a mean stabilization accuracy of 0.07 degrees, or 1.24 mils - translating to an accuracy of 1.24 m at 1000 m - it is accurate enough for the T-62 to achieve a greater than 70% hit rate at 1000 m on a tank-type target moving at 20 km/h at a relative angle of approach of 30°, according to a U.S TRADOC bulletin, pictured below.
"Meteor" was quite good for 1963, but by 1972, it was technically outclassed by the M60A1 stabilizer from the M60A1 AOS (Add-On Stabilizer). According to Direct support and general support maintenance manual: turret for tank, combat, full-tracked, 105-mm gun, M60A1 (2350-00-756-8497) and M60A1 (AOS) (2350-01-058-9487), the AOS stabilizer had a minimum traverse speed of 0.5 mils per second, or 0.028 degrees per second, and an equal minimum elevation speed. The AOS stabilizer also offered a vastly superior maximum turret traverse speed.
There are various methods to improve firing accuracy. The crew is trained to fire on short halts and on slow crawls, which is a process that must be coordinated by the commander. For either methods, the process is as follows: The commander spots a target, designates it for the gunner and cues the loader to load an appropriate round, while simultaneously using the stadia rangefinder in his periscope to determine the distance to the target as accurately as he can. The gunner then inputs the range data from the commander, lays the gun on target, and the driver is ordered to either stop or slow down the tank. Once stopped or slowed down, the gunner fires. If at all possible, the tank approaches the target straight ahead.
As mentioned before in the "Sighting complexes" section, "Meteor" features a "loader assist" function where it raises the cannon by about 3 degrees, or rather, lowers the breech by 3 degrees, thus making it easier for the loader to ram a shell in. Turret traverse will also be suspended. It is not known if the autoejector works independently of the loader assist system.
Control of gun elevation and turret traverse is conducted using the Meteor control handgrips. The right thumb trigger fires the main cannon and the left thumb trigger fires the co-axial.
In case of a failure of the electrical systems or some other malfunction, the gunner must use hand cranked flywheels located directly behind the Meteor control handgrips. The gearbox on the manual elevation mechanism has a button for disengaging the stabilizer and engaging the manual drives. The elevation flywheel handle has a solenoid trigger for firing the cannon. On a sidenote; the reason why the manual trigger is always on the elevation handle and not the traverse handle is because before the advent of gun stabilization, the gunner had to manually stabilize the cannon the best he could by spinning the elevation flywheel. Apparently, it was preferable to have the trigger on this flywheel.
There is an amplidyne amplifier for the turret traverse motor located at the very rear of the turret, immediately behind the commander. It takes an electrical current and amplifies its voltage to produce the immense power needed to rotate the heavy turret at an acceptable pace.
There is a gyroscopic tachometer for measuring the angular velocity of the turret and tank in relation to the intended target at the very front of the gunner's station, behind the sighting complexes. The gyro-tachometer was lifted straight out of the STP-2 two-plane stabilizer system for the T-54B, so "Meteor" can be considered a direct relation of STP-2.
|Gyroscopic tachometer for Meteor-M1|
The T-62 had a nifty automatic shell casing ejection system. As mentioned before, the interior of the tank is quite cramped, and a few dozen hot brass casings rolling around for the loader to trip over wasn't really desirable, to say the least. Apparently, during early testing of the Object 166, cannon fumes accumulating in the fighting compartment were twice higher than the acceptable standard. The culprit was apparently the spent shell casings. When ejected from the tank immediately after firing, concentration of fumes was reportedly slashed by half, and the loader was obviously saved from the trouble of manually removing the spent shell casings periodically.
The ejector mechanism is automatic, with an option for manual activation. In the automatic mode, the ejector mechanism immediately begins operating once the cannon has recovered from its recoil stroke, but there is also a failsafe microswitch for redundancy. It is triggered the instant that the shell is caught in the ejector tray.
When the shell casing is ejected from the breech from the recoiling cycle, it is caught by the ejector tray, affixed to the ejector mechanism. It is held in place by the rim of the casing by two spring-loaded pinball paddle-like grippers. A rubber-padded backplate on the arm guard placed just behind the ejector tray prevents the casing from bouncing back to ensure that the grippers have enough time to hold the casing in place.
Then, the ejector mechanism lifts up to the ejection port, the ejection port is opened briefly, and the shell casing is thrown out, or rather, kicked out very forcefully.
The ejection cycle takes only 3 seconds in total, including the recoiling cycle of the cannon and the ejection of the shell casing from the chamber. Proof of this comes from this video of a Vietnamese T-62 with a working ejector (link). The raising, ejection and lowering of the ejector arm takes about 2 seconds, while the third second is due to the recoiling cycle of the cannon itself. This means that the loader will never have to wait for the autoejector to finish when loading. The time spent by the autoejector coincides perfectly with the estimated time needed for a good loader to retrieve a round from the front hull racks. By the time the autoejector arm has lowered, the loader should be ready or just about ready to ram a fresh shell in.
The ejection mechanism works independently from the loader assist function.
One of the least-asked but also least-understood questions is "how does the autoejector actually eject spent shell casings?" The answer is actually quite simple - and so is the mechanism; when the shell casing is propelled rearwards and is caught in the ejector tray, it is also caught by an ejector hook at the floor of the tray. The hook is part of an spring-loaded ejector block, which is charged by the recoil of the cannon via a series of levers. It works similarly to typical shell casing ejector designs found in semi-automatic breech loaded cannons. The ejector tray is elevated with an electric motor located just under the breech, and when the ejector tray reaches the proper elevation to eject the spent shell casing, the ejector spring is tripped, causing the hook to slam into the rim of the casing with enough force to propel it clear off the back of the tank with a deafening "clang!". This system performs more than satisfactorily, and it is so simple that a malfunction is almost impossible unless it has never been maintained at all throughout decades of use.
|Spring, Arm which charges the spring, Axis on which the arm is attached to the ejector mechanism, Rod connecting arm to cannon breech|
Contrary to popular belief, shell casings would almost never bounce off the back of the turret and injure crew members because of "misalignment". The tray elevates right up to the ejection port, and even if by pure chance a shell casing does somehow miss the gaping ejection port opening, it will not bounce back and hit anyone, because the paddles will simply catch the casing rim again and prevent it from going any anywhere.
Interestingly, the ejection port could be left open for extra ventilation if needed, and it also doubled as a very convenient and loading hatch. Opening and closing the ejection port can be done from the control box placed just in front of the loader's handle. Beside this one, there is another control box. With it, the ejection mechanism can be set to either the autoeject mode whereby it automatically begins the ejection procedure as soon as the gun has finished its recoil stroke cycle, or the manual mode, whereby the ejection system will be activated only when prompted by the gunner. This control box can also be used to hold the ejection port open or closed. If the tank is operating in an NBC-contaminated environment, then the autoejection system is deactivated and the ejection port is left closed. Instead of being ejected, shell casings will bounce off the rubber pad at the rear of the breech arm guard and fall to the floor to be removed later instead.
The size difference between 115mm cartridges and 120mm cartridges is minimal. In terms of heft and dimensions, 115mm ammunition was bigger than NATO 105mm and Soviet 100mm ammuniton, but essentially identical to NATO 120mm ammunition (not British 120mm). In order to truly appreciate the burden on the loader, here's a photo comparison between a 120mm cartridge and a 115mm equivalent:
|M829 compared to 3UB56|
The similarities in the sizes of 115mm and 120mm ammunition can be proven by the T-62AG variant, a modernization package offered by the KMDB, which you can read about here (link). Looking past the fact that they managed to fit a 120mm tank gun (in reality a domestic production version of the French CN120 called the KBM2) into the T-62, it must be noted that the total amount of ammunition carried by the tank did not change. The T-62AG carries a total of 40 rounds of 120mm ammunition, stowed in the same positions as the 115mm cartridges it replaced, with only minor modifications to better fit the new ammunition.
115mm rounds are simply much bigger than 105mm rounds. Even though they are both given approximately the same width of space, the T-62 loader is fatigued more easily than an M60 loader, even more so since a ride in the T-62 isn't quite as smooth.
And of course, a T-62 loader didn't have nearly the same amount of space that loaders in NATO tanks sporting 120mm guns did. Here's another photo, this time of a 115mm cartridge container held up by what appears to be a Siberian tanker.
However, it must be reiterated that loading the U-5TS was still an easier task than loading the D-10T in a T-54.
The two biggest assets of the U-5TS cannon were the 3UBM3 shell, the first ever serial APFSDS tank shell to enter service, and the 3UBK-4 HEAT shell, which benefited from the lack of rifling on the cannon.
Shell casings had an atypical form, identifiable by a greatly elongated bottlenecked front section, which was necessary for properly seating the APFSDS shells for which the casings were specially designed for. There are two types of casings; steel 4G9 cases and brass 4G10A cases. The steel ones weigh less at 7.95 kg and cost less to manufacture, while the brass ones weigh more at 8.45 kg. The steel ones were used HE-Frag ammunition, to which accuracy was of less importance while the higher quality brass cases were used for APFSDS and HEAT-FS.
The "default" loadout for a T-62 for a breakthrough assault would be 12 APFSDS shells, 6 HEAT-FS shells and 22 HE-Frag shells. As usual, the loadout changes based on necessity, but generally speaking, APFSDS was preferred over HEAT.
High-explosive fragmentation shells are arguably the most important ammunition type for the T-62, given the expected tactical contributions of a Soviet tank to combined arms combat. Though tanks are obviously a major threat, the vast majority of the vehicular targets that a tank would encounter on the battlefield are thin-skinned APCs, IFVs and utility trucks, and the tank will always be called upon by infantry for fire support against bunkers, machine gun nests, and other garrisoned troops. HE-Frag shells may be used as a last resort against enemy tanks as well, serving to knock out various essential components for anything from a mobility kill to a firepower kill (though obviously rooting for the latter). The 2A20's selection of HE-Frag shells are characterized by very thick steel walls and a relatively high muzzle velocity. However, the stabilizer fins are a major source of drag. This means that 115mm HE-Frag shells tend to slow down considerably at long range.
First HE-Frag shell available to the 2A20 cannon. It had a cone-shaped nose and sharp, edgy aesthetics. It has a thin steel body suitable for fragmentation and splintering, but the bulk of the damage done by this shell is caused by blast. Explosive compound used is A-IX-1, a mixture of 96% RDX and 4% paraffin wax.
Maximum Direct Fire Range: 3600 m
Mass of Complete Round: 28 kg
Projectile Mass: 14.86 kg
Mass of Explosive Charge: 3.6 kg
Muzzle Velocity: 800 m/s
Vastly improved shell with an ogived nose and much thicker shell casing for superior fragmentation mass and volume as well as a better optimized spray pattern for increased casualties. The shell also boasts an extended firing range despite a 20.1% increase in mass over the OF-11 thanks to better ballistic properties and a more powerful propellant charge. Because of the increased muzzle velocity, this shell is also comparatively more accurate at all distances.
The V-429E variable sensitivity fuse was available later on.
Maximum Direct Fire Range: 4800 m
Mass of Complete Round: 30.8 kg
Projectile Mass: 17.86 kg
Muzzle Velocity: 940 m/s
Being widely considered to be a pioneer on the introduction APFSDS technology into widespread service, the T-62 essentially relies on it as its main selling point, and for good reason. Because of the remarkably high velocity of the T-62's APFSDS ammunition, their ballistic trajectory was essentially flat up to 1600m - quite different from APDS shells. This meant that in typical tank-on-tank combat scenarios, the T-62 gunner would only need to put the sight chevron on target and fire without even needing to determine the range. The extremely high velocity also meant that engaging moving targets was a lot easier, since it would tend to take less than a second for the shell to reach its target in normal European battlefields where combat distances typically don't exceed 1500m. This almost entirely negated the need for calculated target leading, even against relatively fast-moving vehicles. APFSDS shells would also be very useful against vehicles moving at irregular speeds, again because the gunner does not need to apply much lead. This greatly helped offset the retarded engagement time caused by limitations of the targeting system and increased first-round hit probability significantly.
According to this TRADOC graph, a stationary T-62 had a 50% chance to hit an exposed stationary M60A1 tank with its APFSDS rounds on the first try at 1500 m. The shots were conducted using 3UBM5 rounds - pure steel rounds.
It must be noted that the large, bore-riding stabilizing fins at the tail end of the projectile produced a great deal of aerodynamic drag. Because of these fins, the projectile lost up to 130 m/s per kilometer of travel. Contemporary 105 APDS rounds, on the other hand, lost only around 50 m/s per kilometer. The M392 APDS, for instance, had a muzzle velocity of 1478 m/s. That is only 122 m/s slower than the BM-3. At a distance of exactly 2.5 km, both projectiles will be travelling at the same velocity - the BM-3 will still get there faster, of course.
The 2A20 "Molot" cannot be considered a "bad" gun, but it had one major drawback related to the Iranian Chieftain in the photo below.
Steel was cheap, plentiful, easy to handle and reasonably strong, but is intrinsically inferior to heavy metals like tungsten and depleted uranium. The high elongation of the steel rod is absolutely critical in counteracting this. In the photo above, an eagle-eyed observer will note that the impact crater on the left shows evidence of deflection. It cannot be simply part of the channel made by a cumulative jet, because the photograph was taken at eye level with the turret, not at a downward angle, so it must be the crater left by an APFSDS round. This is congruent with the rather underwhelming performance of the 2A20's APFSDS shells, despite being long rod projectiles, but having said that, the Iranian Chieftain in the photo was knocked out all the same. Where they lacked in elegance, 115mm APFSDS made up for in raw power.
Note that Russian ammunition certification used a V80 standard, meaning that at least 80% of all ballistic kinetic energy-based shells must penetrate at least a certain thickness given a certain velocity. In effect, this means that in reality, the average penetration performance was most definitely higher than stated.
|Photo Credit: Stefan Kotsch|
Original APFSDS shell made for the 2A20 cannon, first introduced in 1961. It had a tungsten carbide slug in the bulbous region of the projectile at the tip, topped off with a flat steel armour piercing cap to prevent the slug from shattering outright on impact and to improve performance on sloped armour.
In 1961 terms, the BM3 was vastly superior to contemporary 105mm APDS ammunition such as the L28 and L36A1 and the American M392 derived from it, having at least 35% better penetration values at the same distance, accounting for different certification standards and different target steel strength and hardness. BM3 can be placed between 100mm 3BM6 APDS for the D-10T (T-55) and the 122mm 3BM11 APDS for the M-62 (T-10M) in "power" ranking. These two contemporaries were introduced quite a while after BM3 - in 1967 and 1968 respectively. 3BM6 penetrates 264mm at 0 degrees at 1 km, and 237mm at 0 degrees at 2 km, and 3BM11 penetrates 320mm at 0 degrees at 2 km. BM3 is also superior to the L15 APDS shell in terms of penetration on both sloped and unsloped armour, and generates more lethal after-armour effects on significantly overmatched armour as a result of its less optimal design; being much less efficient than a single solid tungsten carbide slug, it would produce a much more massive fragmentation pattern post penetration.
A small part of this is simple extrapolation, since the author hasn't seen any documents pertaining to this matter, but based after-armour lethality reports on extremely similar 125mm tungsten-cored APFSDS, there can be very little doubt about it. This article by Peter Samsonov is mandatory reading. The document featured in the article pertains to a lethality analysis done on 3BM-9, 3BM-15, 3BM-22 and 3BM-26 APFSDS rounds. 3BM-9 is an all-steel "torpedo" APFSDS round. 3BM-15 is the closest representation of BM-3, as both have a tungsten carbide core at the front of the projectile, as opposed to one at the rear, as in 3BM-22 and 3BM-26. All of the shots were for a 60 degree obliquity impact, and the velocity of all of the shells corresponds to their velocities at 2km (!!!).
Assuming that the round overmatches the armour plate by 100mm to 200mm (LOS), then a penetrating 3BM-15 shell will produce 150 to 200 pieces of fragmentation capable of penetrating 3-6mm of aluminium sheeting in a 110 degree cone.
According to graph (b):
The number of lethal fragments increases as the armour overmatch increases. The curve of this graph was drawn based on calculations from the tabulated data of all four APFSDS rounds, so it does not exactly represent any of them, but we know that the late model APFSDS designs with the core at the rear have a greatly improved fragmentation pattern and quantity compared to the earlier designs, so we can assume that 3BM-15 - and by extension, the BM3 - produces somewhat less fragments than listed in graph (b) per 100mm of overmatched armour. If we take 3BM-15 as a surrogate for BM-3, then when BM-3 is fired at the side of an M60A1 (74mm cast side armour) at 60 degrees, it will overmatch by 112mm. This means that it will generate slightly less than 80 lethal fragments (according to graph (b)), but it will also generate around a hundred other fragments that will badly injure the crew, cut electrical wiring, sever hydraulic fluid lines, and so on - and remember, the APFSDS rounds fired in the test had a velocity corresponding to their velocity at a distance of 2 km.
Fragments that are capable of penetrating at least 30mm of aluminium are few and far in between, but there are more that can penetrate slighly less than that. Such fragments will not be more useful than smaller fragments at harming or killing the crew, but they will be capable of detonating ammunition on a direct hit, which is something that the low penetration, low energy fragments cannot do.
This would make the BM3 incredibly potent against relatively lightly armoured tanks like the Leopard 1 and AMX-30 appearing in the late 60's. Additional evidence of the high lethality of BM3 comes from U.S Army evaluations, which assign a very high Pk (probability of kill) to BM6 rounds on an M60A1 - 71% - according to the TRADOC bulletin (so much for more space = better survivability). The lethality of BM3 is likely to be close. As shown in the report above, 3BM-9 steel APFSDS produces more fragments post-armour penetration than 3BM-15 cored APFSDS. This relationship should not be different for the BM3 and its all-steel counterparts.
Mass of Complete Round: 22 kg
Projectile Mass: 5.5 kg
Certified Penetration at 1000m:
300mm @ 0°
130mm @ 60°
Certified Penetration at 2000m:
270mm @ 0°
115mm @ 60°
Knowing the intimate details of the design of the M60A1 turret, thanks to Post #333 on this TankNet thread (link), this shell should have absolutely no trouble with the M60A1. The non-cheek regions of the cast steel turret of the M60A1 have V50 ratings ranging from 1310 meters to 3620 meters versus 100mm AP rounds in a head-on impact. More specifically, the mantlet itself is rated for 1310 meters, the sloped roof area above it is rated for 2850 meters, and the turret ring/collar area is rated for 3620 meters. This area comprises about 44% of the turret's total frontal area, meaning that about 44% of the turret is vulnerable to BR-412 APBC shots from at least 1310 meters. The BM3, being something of a quantum leap over the BR-412 with almost triple the penetration performance, could probably perforate the same areas from an additional 3 kilometers away, if not more. The cheeks of the turret, which are 76mm thick sloped at 62 degrees horizontally (plus negligible vertical slope), are able to deflect 100mm AP, but this is completely insufficient against the BM3.
The cast upper glacis of the M60A1 measures 109mm in thickness, angled at 65 degrees, making for a more formidable target than the turret, which is rather strange because the defensive nature of NATO tank doctrine meant that tanks were to spend more of their time hull-down rather than advancing across open ground. Wartime analysis done independently by all tank building nations during and after WWII showed that the majority of hits occur on the turret, and not the hull, so having a weaker turret than the hull is a universal problem. However, for a tank that is supposed to spend the majority of its time to have a weaker turret than the hull is a very serious design flaw. The upper glacis should be vulnerable to BM3 only out to distances of 1500 meters or less.
HOWEVER, we have not yet taken the difference in ballistic standards into account yet. The Soviets use V80 ballistic limit, as opposed to V50, meaning that given a data sample of 'x' number of rounds, 80% must penetrate a certain amount of armour within a reasonable range of velocities. Also, the American criteria of what constitutes full armour perforation is based on the recovery of 50% of projectile mass behind the armour plate. The Soviet criteria uses 75%, but 80% is also used. Taken together, all this means that if BM3 can penetrate 300mm at 1km according to the Soviet penetration criteria, it can do significantly more when expressed in the Western penetration criteria, and for every successful armour perforation, the behind armour effect is much stronger.
In short, the BM3 round enables the T-62 to kill an M60A1 much farther than the M60A1 can kill the T-62. This is undoubtedly an advantage, but to be frank, this is not a huge advantage. The average engagement distance is only 1.5 km in Central Europe, and the T-62 is not accurate enough to score hits on tank-sized targets at 4 km anyway.
Knowing the armour thickness of the Chieftain Mk.5 tank from ultrasound measurements, it can be reasonably surmised that the 3BM3 is capable of reliably perforating the turret on any point from at least 1000 m, but probably more, because the Chieftain has cast steel armour and not rolled armour, and we are basing our estimations on Soviet penetration values based on Soviet penetration criteria.
The true ingenuity behind the 3UBM3 round wasn't that it was radically more powerful than anything on the planet. The innovation of the BM3 projectile was that the tungsten carbide slug within only only weighed about 300 grams, but was still more effective than the 3kg slug in the 100mm BM-8 APDS shell for the T-55. For every BM-8, they could have made ten 3BM3 shells that were more powerful and more accurate. This was a huge incentive to prioritize the T-62 if a major conflict erupted. Recall that tungsten for APCR rounds was very scarce in Nazi Germany in the late war period. A similar scenario would be disastrous for the Soviet Union, as the technology for producing depleted uranium ammunition was still decades away, and the only alternative was steel-only ammunition. For this reason alone, the 3UBM3 round deserves nothing but praise. But let's take a look at that steel ammunition...
Introduced in 1963 as an even cheaper alternative to the 3UBM3, presumably having the secondary function of a training round. It was basic in construction; It was all-steel, was torpedo-shaped and very cheap to manufacture, but most importantly this shell clocked in at an unheard-of 1650 m/s at the muzzle, just a fraction above a mile a second.
The entire projectile functions as the penetrator. There is no internal core, only an armour piercing cap at the tip. It is made entirely of solid 60KhNM tool steel with a hardness of around 310 BHN. It had 6 steel fins, which were of a bore riding type that worked alongside the sabot to stabilize the shell as it travels down the barrel. The ends of the fins have copper lugs embedded in them to minimize abrasive damage to the much tougher chrome lining of the gun barrel. The soft armour piercing cap is made of 35KhGSA steel, built with a flat tip to decrease the likelihood of a ricochet on sloped armour as well as to protect the projectile from shattering upon impact.
Furthermore, the presence of the armour piercing cap protects the round from the effects of single plate light spaced armour, such as the type present on upgraded Leopard 1 turrets. The spaced plate will successfully destroy the armour piercing cap, but the penetrator will be unharmed, and it will continue to pass through the turret armour with extreme ease even at high obliquities.
Furthermore, the after armour effects of BM4 are even greater than BM3, as shown
The main factors contributing to the penetrating performance of the shell is the relatively high length-to-diameter ratio of 13:1, and the fantastic speed of the projectile, but because it was made entirely from steel, its performance falls short of the BM3. However, that is not the point of the 3UBM4. If the 100mm BM-8 APDS projectile penetrates around 264mm of RHA steel at 1 km using a 3 kg tungsten carbide slug, then the BM4 projectile is an extremely reasonable alternative, as it is capable of penetrating about 228mm RHA at the same distance, without needing any tungsten or special manufacturing techniques to build. Furthermore, the performance of BM-8 APDS was very underwhelming on sloped targets. As all Cold War era NATO tanks featured heavily sloped armour, BM4 would have been much more useful than BM-8 in practice.
Mass of Complete Round: 22 kg
Projectile Total Mass: 5.5 kg
Penetrator Mass (Without Sabot): 3.196 kg
Armour Piercing Cap Mass: 0.187 kg
Certified Penetration at 1000 m:
228mm RHA @ 0°
110mm RHA @ 60°
Certified penetration at 2000 m:
200mm RHA @ 0°
100mm RHA @ 60°
Alternate Russian source lists the penetration at 1000 m as:
250mm RHA @ 0°
130mm RHA @ 60°
However, there must be something wrong here. The astute reader will notice that this all-steel APFSDS round can penetrate more armour at 60 degrees than it can at 0 degrees. This is not possible.
With this shell, the T-62 had a respectable (but by no means dependable) chance of defeating tougher customers like the M48 or M60 frontally out to more than 2000 meters, and no trouble at all defeating an AMX 30, Leopard 1 or Centurion frontally out to 2000m. The Chieftain's turret is generally immune to this shell at any range, but the prominent lower hull is vulnerable at a distance of up to 1000 m, but no more.
Introduced in service in 1970 as a slightly more advanced but similarly cheap alternative to the 3UBM4, although in reality production had already switched over to 3UBM5 from the 3UBM4 between 1966 to 1968.
The stabilizing fins are made from 40KhFA steel alloy with high thermal resilience. The fin assembly weighs a total of 0.651 kg.
Externally identical, the BM6 projectile can be distinguished to the 3UBM4 by the presence of "teeth" on the edge of the sabot, which are absent from the one on the 3BM4 projectile. Internally, they are quite different. The penetrator is made from 35KhZNM tool steel with a hardness of around 600 BHN - a huge step forward over the previous standard, although it is nothing special as 100mm BR-412B rounds for the D-10T/S had already achieved this standard of hardness in the late 40's. The penetrator now had a rounded nose, and it had an armour piercing cap made from softer 35KhGS steel. Although still made entirely of steel, this shell offers appreciably higher performance, but still far from being comparable to the BM3.
Here is what the penetrator without the armour piercing cap and the windscreen (ballistic cap) looks like:
Projectile Maximum Diameter: 42mm
Diameter of Stabilization Fins: 114mm
Total Projectile Length: 550mm
Total Cartridge Length: 950mm
Mass of Complete Round: 21.66 kg
Total Projectile Mass: 5.34 kg
Projectile Mass In Flight: 4.00 kg (Other source says 3.9 kg)
Penetrator Mass: 3.009 kg
Armour Piercing Cap Mass: 0.167 kg
Muzzle Velocity: 1680 m/s
Certified Penetration at 1000 m:
280mm RHA @ 0°
135mm RHA @ 60°
Certified Penetration at 2000 m:
240mm RHA @ 0°
110mm RHA @ 60°
This shell deserves special attention for the huge improvement over the BM4. The new armour piercing cap appears to have improved the performance of the projectile on sloped armour to the point where it is superior to the BM3, making this shell even more useful than its predecessor on the heavily sloped armour of contemporary NATO tanks like the Chieftain and the M60A1. It must also be noted that the all-steel projectile offers better performance than the L28 or M392 APDS shells for the L7 cannon. The L28/M392 had a very substantial tungsten carbide core, larger than the 3 kg slug in the 100mm BM-8, in fact, but they achieved less penetration (than both the BM-8 and 3BM6) at the same distances; at 1 km distance, the L28/M392 could penetrate 252mm at 0 degrees, and 117mm at 60 degrees. To add insult to injury, combat experience in the 1973 Yom Kippur conflict apparently revealed that these shells could not perform reliably on heavily sloped armour, which was quickly solved with a tungsten tilting cap on the M392A2. However, this upgraded version is still inferior to the 3BM6 in performance on sloped armour.
This round made up the bulk of ammunition exported to client states, making it the most numerous type of APFSDS ammunition available to Egyptian and Syrian tank crews during the Yom Kippur war.
Like with the previous designs, an armour piercing cap with a flat tip is present to reduce the likelihood of a ricochet, and in this case, to protect the tungsten core from shattering upon impact. The difference between 3BM21 and previous models is that this cap is now much bigger. The enlarged cap effectively neutralized any difference in performance on sloped targets compared to flat targets. Here, the armour piercing cap and the tungsten carbide core are clearly visible.
Mass of Complete Round: 23.50 kg
Projectile Mass: 6.26 kg
Muzzle Velocity: 1600 m/s
Certified Penetration at 1000 m: (Extrapolated)
360mm RHA @ 0°
175mm RHA @ 60°
Certified Penetration at 2000 m:
330mm RHA @ 0° (From Andrei Tarasenko's site (link)
165mm RHA @ 60° (Inferred)
Between the mid-50's to late 60's, shaped charge warheads was widely appraised as being the 'great equalizer' of tank warfare. Tube-launched HEAT warheads were decently popular, being tremendously useful in a variety of roles, from general tank-killing to bunker busting or simply as a more flexible alternative to HE-Frag or HEP shells thanks to their thick steel bodies, but because of the immaturity of shaped charge technology in those days, manufacturing a HEAT warhead tended to be costlier than manufacturing a kinetic energy one. Still, the typical HEAT shell on both sides of the Iron Curtain was so powerful that they rendered all contemporary tank armour essentially useless in the event of a direct hit, but the problem was exactly that - scoring a direct hit. Because of the vastly lower velocity - even lower than contemporary 105mm HEAT shells - the 2A20's selection of shaped charge ammunition can be generally characterized by subpar accuracy but excellent armour penetration and fragmentation effects.
Complementary HEAT shell entering service alongside the T-62. It had a cone-shaped nose and generally unremarkable ballistic properties. The nose cone design could be problematic on extremely high angle impacts because of the possibility that the flat side of the cone was struck instead of the nose fuse, potentially defusing the shell upon impact, though the chance of this happening was still miniscule. This phenomenon would be unnoticeable at extended distances where ballistic drop would orient the shell slightly downwards, but it could theoretically prove disastrous at very close ranges - but in theory only. There is no evidence showing that this was ever an issue, neither in testing nor in combat. The warhead uses a steel liner. The explosive compound used in the warhead is A-IX-1, a composition of 96% RDX and 4% paraffin wax.
Thanks to a combination of the lack of spinning and a larger diameter warhead, among other things, the 3BK-4 shell had 18.6% greater penetration performance than its 105mm counterpart, but to achieve that sort of performance, great compromises had to be made.
Though extremely capable of knocking out an M60-type tank on the first hit, the chances of scoring a hit are extremely low. At 1500 m, the chances of hitting an M60-sized target is only 20%, and though this rises to about 48% at 1000 m, this still only means that just one out of two shots will connect. This is not really related to the accuracy of the shell itself, which is excellent according to Soviet certification standards (provided by Vasily Fofanov on his site), but the lower velocity of the shell and the lack of precise rangefinding equipment. As mentioned in the TKN-3 section of this article, the stadiametric rangefinder is not precise past approximately 1.6 km. The stadia rangefinder on the gunner's sight is more useful because the sight has a higher magnification, but according to procedure, the commander is the one who determines the range to the target, and the gunner usually does not conduct rangefinding. If it was the gunner who conducted rangefinding, the results may be slightly more positive.
The warhead uses the GPV-2 fuse. It is the same fuse used in the 100mm 3BK-5 for the T-54.
Mass of Complete Round: 26.00 kg
Projectile Mass: 12.97 kg
Muzzle Velocity: 900 m/s
440mm @ 0°
200mm @ 60°
Improved variant of the 3BK-4 replacing the steel liner with a copper one, yielding slightly better penetration power. The copper liner was more elongated, which reduced the mass of the explosive filling slightly. The shell uses the GPV-2 point-initiating base detonating (PIBD) piezoelectric fuse
Mass of Complete Round: 26.00 kg
Projectile Mass: 12.97 kg
Mass of Explosive Charge: 1.478 kg
>440mm @ 0°
>200mm @ 60°
Apparently, the replacement of the steel liner with a copper one was not considered sensitive technology. These shells were freely exported to the Syrians and Egyptians. It is difficult to imagine that this shell was less prolific in the Red Army.
The 3BK-15 had a greatly improved warhead design, doing away with the traditional conical aerodynamic fairings for a flat-sided cylindrical body and a ballistic probe carried over from contemporary 125mm HEAT shells. The novel "shape stabilization" mechanism involves the manipulation of pressure zones to reorient the shell in flight if it begins to tumble from external disturbances (explanation accredited to Bronezhilet from the sturgeonshouse forum. See here). The stabilizator fins are a niche addition as they only take over when the projectile is too slow for shape stabilization to work properly.
The higher pressure acts upon the edge of the procjectil and forces the projectile down until stable airflow is achieved again. According to these simulations, a shape-stabilized projectile should have around 20% more aerodynamic drag than a ogived projectile (not accounting for additional stabilization fins), but since the biggest grinch to accuracy is wind and the tumbling effect caused by it, and since HEAT rounds do the same damage regardless of warhead velocity, the trade off was well worth it.
Simulations of representations of Soviet-style HEAT shells like the 3BK-15 have shown that it is not as aerodynamic as Western HEAT shells like the 105mm M456. This is because of the shape of the fuse. The M456 has a squared-headed fuse, while the 3BK-15 uses a conical one, although the conical shape is probably cosmetic, as you can see in the cutaway photo above. It is unfathomable that the engineers at the munitions factory were not aware of the drawbacks of the conical shape, so the only explanation is that the conical type fuse had other, perhaps more important advantages. bojan from TankNet stated the 100mm BK-5M HEAT shell (with the GPV-2 fuse, pictured below) worked at slope angles of 65 to 70 degrees, whereas the square-headed (M509A1) fuse on the 90mm M431 HEAT only worked up to 60 degrees.
|Photo credit to PzGr40 of the wk2ammo site|
Therefore, the decision to not use a square-headed fuse might have been a deliberate compromise to trade velocity for superior performance on very steeply sloped armour plate. Indeed, during the famous Yugo tests, the 90mm M431 had high probability of failing to detonate when it struck the upper glacis of the target (a T-54A tank) when the tank was angled 20 degrees sideways. It would not have been acceptable for a Soviet HEAT shell to exhibit similar limitations, as the upper glacis of an M60A1 tank was already more sloped than 60 degrees (it was sloped at 65 degrees) and the upper glacis of the Chieftain was even more sloped (72 degrees). But besides the fuse...
The warhead also implemented some new old technologies to improve jet formation characteristics, including the use of a slightly tapered cylindrical wave shaper to optimize the direction of the blast wave from the explosive filling, more precisely drawn liner cones, and compressed explosives to increase the density of the explosive filling for more punch per volume.
The use of more energetic 12/7 stick powder boosted the shell's muzzle velocity to 1060 m/s, yielding significantly better accuracy at longer distances, though still less accurate than 105mm HEAT shells.
For some very interesting reason, the tracer was not placed at the base of the shell assembly. Instead, it is embedded into the wall of the warhead at the very front. As with all of the previous warheads, this one uses the GPV-2 point-initiating base detonating (PIBD) piezoelectric fuse.
Mass of Complete Round: 26.3 kg
Total Projectile Mass: 12.2 kg
Muzzle Velocity: 1060 m/s
Penetration: (Unknown, estimated)
450mm @ 0° (?)
225mm @ 60° (?)
Improved warhead using a copper liner instead of steel for improved penetration power. All other properties remain identical.
Mass of Complete Round: 26.3 kg
Total Projectile Mass: 12.2 kg
Muzzle Velocity: 1060 m/s
480mm @ 0° (?)
240mm @ 60° (?)
The original 1961 preproduction model T-62 was armed with the SGMT machine gun chambered for the 7.62x54mmR cartridge as a co-axial machine gun. It had a cyclic rate of fire of 600 rounds per minute, and it is fed from a 250-round box, of which ten more are stowed inside the tank for a total of 2750 rounds of ammunition. The SGMT could be fired with the left trigger button on the gunner's handgrip, or with the solenoid trigger button attached to the machine gun in case of a total failure of the tank's electrical systems.
In 1964, the SGMT was swapped out for the then-new PKT machine gun. Performance-wise, the two were practically indistinguishable, though the PKT does fire faster at 800 rounds per minute, so the true impetus for the change was not to have a better machine gun, but to standardize the PK general purpose machine gun among the entire armed forces.
The PKT machine gun is fed from proprietary 250-round boxes, of which 10 more are stowed, exactly as with the SGMT. Like the SGMT, the PKT can be fired from the left trigger button on the gunner's handgrips, or with the inclusive solenoid trigger button if the situation calls for it.
Because both machine guns use the same ammunition and have similar barrel lengths and rifling twists, the ballistic trajectory of the shots fired are essentially identical, so there was no need to modify the sights to accommodate the new machine gun. The nominal maximum effective range of both machine guns is around 1500 m, while the effective range against a running target is around 650m. Ball and tracer ammunition are usually linked in a 2:1 ratio, but sometimes tracers are used exclusively. Spent casings and emptied links are collected in a metal bin to the left of the machine gun.
The exact use of the co-axial machine gun is dependent on the gunner more than anything. It is usually used instead of cannon rounds to engage enemy personnel to save ammunition. It is useful for when excessive destruction is undesirable; when friendly forces intend to occupy an evicted foe's garrison, for instance.
The installation of the DShKM necessitated that the loader was given a more developed cupola with a race ring and a mount to place the machine gun. Elevating and depressing the machine gun cradle is done with a flywheel, and slewing the cupola side-to-side is done by moving it with body weight.
The DShKM has a rate of fire of around 600 rounds per minute, but it is characterized by somewhat mediocre accuracy in comparison with the later NSV and KORD machine guns.
It is fed with 50-round boxes, with another five strapped close to the side of the turret (see photo above) for easy access by the loader, who needs only to bend down to reach them.
Aiming can be done with either the K-10T anti-aircraft collimator sight kept in the raised box mounted to the cradle, or the classic leaf-type iron sights on the machine gun. The K-10T facilitates accurate aiming at both ground level and high altitude targets, though the leaf sights on the DShK would be more appropriate for aiming at ground targets. The collimator sight has a tinted screen in front of the holographic screen to reduce glare.
The K-10T is electrically powered by the tank's electrical systems. When not in use, the protective cover is closed, mainly to shelter it from the weather.
The DShKM was technically sufficient against attack helicopters of its day, given that common examples like the AH-1 Cobra did not have enough cockpit armour to protect the pilot from 12.7mm shots, and the windscreen was only a thin polycarbonate sheet. The rest of the fuselage lacked any meaningful armour protection.
The T-62's hull retains the same general layout as the T-54, differing only slightly in dimensions. Armour thickness remains unchanged from its predecessor, which was a perpetual liability because of how vulnerable this made the T-62, in contrast to the T-54 which enjoyed a high level of immunity from contemporary anti-tank guns. Like the T-55 before it, the hull of the T-62 was essentially immune to American 90mm shot and resistant to 20 pdr. APDS (at ranges of 1 km or more). The guns that fired them were good for tanks like the Panther, which had 80mm of rolled steel angled at 55 degrees for the glacis. (See here for 90mm performance) A The front hull armour is composed of upper and lower glacis plates. The upper glacis measures 102mm at a 60° slope for a LOS thickness of 204mm, and the lower glacis is the same thickness but with a 55° for a LOS thickness of 178mm, though the angle of incidence can be made bigger due to ballistic drop over distance, and conversely, the angle of incidence on the upper glacis can be made smaller the same way. Regardless, the lower glacis can be considered a weak point of sorts, though it is mostly inconsequential since the lower glacis is only a third of the height of the upper glacis.
The hull side is 80mm thick, thinning down slightly to 70mm over the engine compartment, while the rounded hull side "collars" for mounting the turret are 45mm thick cast steel, angled at 60°.
The T-62 uses MBL-1 armour grade cast steel for the turret, which has a hardness of 270 to 290 BHN. The steel used for the all-welded RHA hull is 42SM armour steel, which has a hardness of 280 to 340 BHN, harder for the thinner plates (i.e side hull) and softer for thicker plates (glacis). Though the glacis armour of the T-62 is nominally thinner than that of, say, an M60 (252mm LOS), the T-62 uses RHA steel instead of cast steel, and not only that, the hardness of said RHA steel was significantly harder than that of American cast steel at the time. The M60's cast glacis, for example, was unusually soft at 220 BHN, and because of its cast nature, it wasn't as effective as the rolled steel on the T-62. One very excellent demonstration of this difference can be found in Yugoslavian testing of T-54A tanks and their own M47s. Both tanks had 100mm of steel glacis armour sloped at 60 degrees. The only difference being that the M47 had a cast hull, and the T-54 had a rolled and welded hull. It was found that BR-412B fired from a D-10TG could penetrate the upper glacis of the M47 at 750 m, while the T-54 was fully immune from any distance down to point blank range. The thicker armour of the M60 does not give it superiority to the T-62, only parity. Therefore, although the T-62 had a thinner glacis, it cannot be considered less well armoured.'
Now for the turret:
The original production turret was 214mm thick at the thickest. 1972 saw the appearance of the up-armoured T-62 obr. 1972 with a new 242mm cast turret. Only the flat belt of the lower half of the turret (see photo and diagrams above) is so thick. The sloped roof above it is much stronger, boasting a maximum thickness of 58mm sloped at an angle of 80°, thinning down very slightly to 54mm at the same angle, and then transitions to 30mm sloped at 83°, where it becomes the turret roof proper. This is more than enough to deflect 105mm APDS.
The transitioning area between the totally unsloped "belt" (0 degrees) and the highly sloped roof (80+ degrees) is only 95mm thick but curves very sharply to join the two together. Overall, the areas of the turret besides the 214mm / 242mm flat regions should be capable of deflecting L-28 and M392 APDS at around 1 km, maybe closer.
Beginning from the mantlet area, which is 214mm thick, the steel gently thins down until it reaches the side of the turret at the commander's cupola, where it is only 122.5mm thick. The photo below shows part of the left side of the turret of an early model T-62 (pre-AA machine gun cupola). The cut-up hull in the background is of a T-64.
From the area around the commander's cupola, the steel sharply declines to only about 65mm at the lower belt of the rear of the turret, and only about 55mm at the upper half where it just begins to form the roof, below the ejection port and ventilator housing. The turret hatches themselves are respectably thick, the commander's being around 30mm thick and the loader's being just under 20mm. The roof armour is 30mm thick.
Overall, the armour should be sufficient against M392 and L-28 105mm APDS at distances exceeding 1.5 to 2.0 km at the best protected areas, but even so, it is by no means reliable protection. These APDS rounds, introduced at the turn of the decade to complement the upgunned Centurion and the new M60, could penetrate 250mm RHA at 0 degrees at 1 km, but the T-62's turret was made of cast steel. For all intents and purposes, the T-62, with its sloping glacis and turret, has some degree of protection at very long distances with earlier 105mm APDS, but only at very long distances, and only from the direct front. But let us not forget that the majority of tank battles in Central Europe should occur at distances of less than 1.5 km, so in practice, the T-62 and its Western are more or less evenly matched.
It must be noted that the glacis armour is stronger than the LOS thickness may suggest due to the inherent positive qualities of rolled armour in tandem with the high hardness of the plate. Both of these factors boost the glacis' ability to deflect armour-piercing ammunition. Overall, the steel used in the T-62 was of a higher quality and of a higher hardness than the steel used in the American Patton series of tanks, which admittedly doesn't mean much if the thickness discrepancy is big, but it does place Soviet metallurgy in a positive light. Still, the glacis should have some chances of resisting M392 at distances of 1.5 km and more, keeping in mind that M392 can penetrate 117mm at 60 degrees at 1 km.
While the T-62 was not originally equipped with side skirts, most T-62s were retrofitted with steel-reinforced plastic ones (interwoven textile skirt), similar to that of the T-72.
The main function of the side skirts was to reduce the amount of dust kicked up by the tank while travelling, which was highly undesirable because the dust clouds could give away the tank's position, not to mention blinding the vehicles following it, if the T-62 was travelling in a convoy. And of course, they acted as spaced armour for the hull. They are about 10mm thick and quite stiff; enough to ensure that an RPG grenade fuse activates reliably, but not thick enough or strong enough to be of much use against kinetic energy penetrators. The skirts were mounted 610mm away from the hull.
But let us not forget that the protection scheme of a tank is not solely dependent on raw armour thickness. The crampedness of the interior was very well justified by a seemingly impossibly small frontal silhouette, if the tank were to be compared to foreign analogues of the time.
Although similarly wide and similarly long compared to its NATO counterparts at 3.30 m and 6.63 m respectively, it is significantly shorter at just 2.40 meters tall, which is 0.50 m shorter than the Chieftain, 0.80 m shorter than the M60 pictured above, and slightly shorter still compared to the French AMX-30 and German Leopard 1. This is an extremely important aspect to the T-62's survivability. Getting hit and shrugging it off is one thing, but not getting hit in the first place is crucial, so in this sense, the T-62 is arguably on par with NATO tanks in the defensive role, while having a distinct, if small advantage in the offensive one chiefly due to its relatively small size.
The advent of mass produced thermal imaging equipment practical for combat use in tanks, the advantage of size as a concealment factor became largely immaterial, and new technologies such as superior sabot designs, highly precise stabilizers and ballistic computer made hitting even small targets so easy that you couldn't argue for that either. However, those innovations only came in the late 70's and early 80's, years after the T-62 arrived.
The T-62 had quite a hard time in the 1973 Arab-Israeli war, known to the Syrians and Egyptians as the Ramadan war and to the West as the Yom Kippur war. Hundreds were knocked out in combat, mostly by Israeli Magach (M60A1) and Sh'ot (Centurions) tanks. However, I contend that the T-62 cannot be blamed for its poor showing. One of the more famous tank-on-tank engagements involving the T-62 was the the Battle of The Chinese Farm in October 17.
See this excerpt from Zaloga's "T-62 Main Battle Tank 1965–2005":
"Egyptian tank column was spotted in advance by the Israelis, and elements of the 217th Armored Brigade were assigned to lay an ambush. The 25th Armored Brigade advanced northward with the Great Bitter Lake on their Western flank.
Centurion Sh'ot tanks suddenly emerged over the sand dunes of their Eastern flank, initiating a violent engagement around 1445 hours. The Egyptian tank battalions were caught by surprise due to a lack of flank security and began taking heavy losses. The Egyptian column was hemmed in by a large Israeli minefield that had been laid in 1970 during the "War of Attrition". Although the T-62 companies tried to rally and attack the advancing Israeli wave, they were unprepared for the ferocity of the attack and the brigade was decimated.
In his account of the battle, Lieutenant-General Saad el Shazly later wrote: "When our tanks rolled north into the killing ground, they were attacked from three sides and trapped against the lake on the fourth. Our crews fought desperately against the odds. But when night came there were only a few survivors to pull back to the Third Army bridgehead. It was an utter waste."
About 50 to 60 T-62 tanks were destroyed in the attack by the 217th Armored Brigade, and others were lost in the neighboring skirmishes. By day's end, only 10 of 25th Armored Brigade's original 96 T-62 tanks survived; Israeli losses were only four tanks."
An ambush by hidden and hull-down tanks, from three directions! On a column of tanks with no flank protection! Trapped by a minefield! Now, this isn't the whole story. The initial ambush was conducted by Sh'ot tanks, but later on, Magach tanks joined the fight. This is only a short anecdote, and I recommend doing some serious reading of your own. I am confident that you will reach the same conclusions that I have: There was nothing wrong with Arab equipment. They were simply incompetent fighters, and the Israelis were exceedingly competent.
All T-62Ms are equipped with applique BDD armour, and older T-62s may be retrofitted. BDD armour is more popularly known as "Ilyich's Eyebrows" in humorous reference to Soviet Premier Leonid Ilyich Brezhnev's bushy facial features:
BDD armour covers the hull glacis and the turret front on either side of the gun, but not the lower hull area nor the turret top. It is a form of NERA armour, composed of a laminate of alternating steel plates and a solid polyurethane filling. First entering inventories in 1980, BDD armour boosted the T-62's protection level close to that of the T-64's or T-72 Ural's, giving it the ability to intermittently resist widespread 105mm APDS ammunition from the upper boundaries of typical combat ranges as well immunity from lightweight portable anti-tank rockets like the LAW and RPG-7 families.
Method Of Operation
BDD armour most likely operates on the transfer of kinetic energy from impacting projectiles to the thermoplastic polyurethane (TPU) layer, which is violently displaced out of the projectile's path like a fluid due to its elastomeric properties. The TPU layer thus impart all of the energy to the first steel plate, which then deforms inwards and moves into the projectile's path laterally. When the projectile enters the layer of TPU behind the first steel plate, that layer expands like the first layer, pushing the first steel plate outwards and pushing the second steel plate inwards, thus imparting energy onto the penetrating projectile in two different lateral directions. This is repeated again in the third plate, for a total of at least three "reactions" - hence the 'R' in NERA; Non-Explosive Reactive Armour. This lateral motion would have the effect of either disturbing the delicate flow of cumulative jets or eroding and destabilizing a kinetic energy penetrator.
The single hull block is 150mm thick - or 300mm thick taking into account the hull sloping - complete with an array of steel plates within. Each internal steel plate is just 5mm thick, and the polyurethane layer fills the gaps in between. The front wall is 30mm thick, or when angled at 60° as the glacis is, 60mm thick. The internal steel plates are angled at 65°.
The turret blocks are uniformly 296mm thick, but the front plate becomes thinner as it curves upwards. The front plate itself is cast steel, 71mm thick at the top half and 85mm down the bottom half. The added thickness compared to the glacis plate is intended to compensate for the relative weakness of cast steel, which is only about 90% as effective as generic rolled steel, and the positive influences of the slope on the glacis. The internal steel plates in the turret array are angled at 50° instead of 65°.
|Notice the thickness of the front wall of the turret BDD modules|
The BDD blocks give uncompromising coverage of the upper glacis, but the turret front is not protected over the mantlet and the immediate sides. Only the turret cheeks are protected. The two "brows" weigh 1.8 tons together, and the upper glacis block weighs about 1.5 tons. Equipped with BDD armour, the T-62M bloated to 41.5 tons, 3 tons greater than the vanilla T-62, and about the same as a T-72 Ural.
A Hungarian test at the end of the Cold War showed that the side of the turret of a T-54 equipped with "Brow" armour (taken from a modernized T-55) could not resist a Fagot missile. The results of the test are detailed on this TankNet post. This effectively means that the "Brow" armour for the turret, plus 120mm of cast steel, cannot resist a shaped charge warhead with 400mm of penetration. However, the front of the turret of a T-62 has much more than the side of the turret of a T-54 (242mm vs 120mm), so there is no reason why it cannot resist a Fagot missile or something similar.
The video cannot affirm or disprove anything, as the missile struck the turret approximately where the gun breech is. There is no way to know if the missile defeated the side armour or not, because even though the loader is fine, this could be because he was seated below his hatch, meaning that he would not have been in the line of fire had the missile perforated the base armour. If the missile did not manage to get through, it is still more than possible that the crew bailed as a matter of principle.
The T-62M can be considered superior to the T-72A but much inferior to the T-72B in armour protection against both KE and CE threats. "Brow" armour leaves the mantlet area uncovered by the NERA armour array, but at least the thick steel wall of the BDD blocks forms spaced armour over the machine gun and gunsight ports. With the applique armour, the maximum total thickness of the turret armour of the T-62M is 512mm (296mm BDD block plus ~70mm air gap plus 200mm turret) over the areas covered by the NERA armour. The total amount of steel is less than in the T-72A turret, but needless to say, it should be self evident that the NERA array and airspace combo is more effective than "Kvartz".
Judging by the configuration of the BDD blocks, 105mm M735 APFSDS would not be sufficient against a T-62M from the front where the NERA array is present, not to mention M392 and L28 APDS. The area over the machine gun and gunsight ports is definitely resistant against M392 and L28 as the 71-85mm spaced plate will shatter the tungsten core and prevent it from doing much against the ~242mm mantlet. Even without the spacing, the added thickness of steel would have been enough.
Even when totally expended by multiple hits, the thick front wall of the blocks can still perform as simple spaced armour. In effect, the armour still provide a respectable amount of protection even if it is hit in the same area twice in a row, certainly still enough to immunize the T-62 from the shaped charge warhead of the less advanced versions of LAW rockets to the frontal arc. Going by steel thickness alone, an expended block and the main armour will still be too thick to be defeated by an M72A3 LAW from 1977.
Overall, "Brow" armour on the T-62M can be viewed as a case of "too little, too late". Portable threats such as the 105mm M40 recoilless rifle (400mm penetration), LAW, Carl Gustav (400mm penetration), and the anaemic M47 Dragon (450mm of penetration) were effectively neutered, and "brow" armour can be considered very successful as a low cost equalizer of the status quo in that context. However, the ITOW was just around the corner by the time the T-62M was introduced, and it would have been able to defeat this new armour with relative ease from the front. "Brow" armour could not change the status quo of the T-62 against opposing tanks given the relatively recent introduction of 105mm APFSDS ammunition, so even if it could offer full protection from 105mm M456 HEAT, M392A2 APDS and probably M735 APFSDS, the T-62 could never truly achieve the level of protection of the latest T-72, T-64 and T-80 tanks. This, combined with the general obsolescence of the chassis itself, meant that the T-62 was well on its way to the scrapyard. On the other hand, these "scrapyard tanks" reigned supreme in Afghanistan in the absence of heavy anti-tank weapons, and it was there that "brow" armour proved to be the difference between life and death.
"Brow" armour was not exclusive to Volna-equipped T-62Ms. Many T-62s have been seen in Afghanistan with "Brow" armour and sideskirts, but no other upgrades. The lack of a laser rangefinder is a dead giveaway for the tanks below:
This is expected, as "Brow" armour is an applique armour kit that is intrinsically compatible with the T-62. There is nothing to limit the installation of it to non-M versions of the T-62. In fact, it was not uncommon to see a pre-1972 model T-62 equipped with "Brow" armour in Afghanistan, as field technicians did the best they could to armour up valuable assets with whatever they had. The photo below shows an early model T-62 (distinguished by the loader's hatch) equipped with "Brow" armour leading what appears to be a tank platoon. The second tank in the line is a T-62M, as we can see by the smoke launchers on the right side of the turret.
The photo below shows another early model T-62 with "Brow" armour.
And the photo below shows another one in a partially hull down position.
But besides the (lack of) additional protection from new NATO weapons, the BDD armour also came with added belly armour for extra mine protection in light of the tactical situation in Afghanistan at the time. The applique belly armour is quite simple in construction, composed of a large spacer frame with many reinforcing ribs, and twelve steel plates individually welded on to it, as you can see in the photo above. The total thickness of the armour is 20mm. The new armour reduced the ground clearance of the T-62M from the original 430mm to 397mm. This affected its ability to drive over some of the larger tree stumps, large rocks and overcome vertical obstacles, but the otherwise, it was business as usual.
Slat armour was often used to cover areas unprotected by BDD armour. This was a not an uncommon combination during the Soviet campaign in Afghanistan, where it proved more useful than the basic rubber side skirts originally installed onto the T-62M. The full slat armour set weighs 0.55 tons.
|Photo from Andrei Tarasenko's website|
When Kontakt-1 became available in the early 80's, some T-62s were formally equipped with the armour, but only on an evaluatory capacity. Instead of Kontakt-1, T-62s were invariably given slat armour instead, which could not be often seen on tanks that used Kontakt-1 like the T-64 and T-72. They both had the same basic function, but slat armour was much cheaper and easier to install, and since the T-62 became more or less obsolete by that era, it was only ever given slat armour instead of more effective ERA kits. However, some units in Afghanistan ignored the official regime and retrofitted their T-62s with Kontakt-1 anyway.
|Photo from Andrei Tarasenko's website|
Each Kontakt-1 block consists of two 4S20 explosive elements - plastic explosives packed into a flat steel plates. Each plate of plastic explosive weighs 260 grams, and have an explosive power equivalent to 280 grams of TNT. The plastic explosives have a very low sensitivity to ensure that they can survive being hit by machine gun fire and even autocannon fire without detonating. The weight of each block is 5.3kg, and a full set covering the entire tank weighs approximately 1.2 tons, meaning that there are around 220 blocks of Kontakt-1.
Method of Operation
The operation of Kontakt-1 is quite simple, utilizing two angled explosive plates to disrupt cumulative jets. When a cumulative jet passes through the explosive plates, the resulting explosions will separate and propel the many steel plates within each module backwards and forwards at different angles. When these plates intersect the cumulative jet from a shaped charge, the jet is disrupted (but the tip of the jet outrun the plates as it which travels at hypersonic speeds of 8,000 m/s to 10,000 m/s, so it is too fast to intercept by Kontakt-1). By disrupting the cumulative jet, the residual penetration power of the offending warhead then becomes completely tied to just the tip. The main limitation of Kontakt-1 is the slow reaction rate of the 4S20 explosive compound used the explosive cells. This means that the reaction time is quite slow, and that a significant portion of the cumulative jet may have already penetrated the block before it can explode.
The overall ERA coverage is uncompromising. The entire tank is covered in all areas save for the rear of the hull and turret, though the turret ring belt is left exposed. Each Kontakt-1 block can reportedly reduce the penetrating effects of cumulative jets by up to 55% at 0 degrees obliquity, and up to 80% when angled at 60 degrees. The addition of Kontakt-1 would have made the T-62 immune to all handheld anti-tank weaponry, and the vast majority of anti-tank missiles without a tandem warhead.
MINE CLEARANCEEquipment for clearing a path through minefields was issued to tank platoons, one each. One tank in any given platoon would be a model appropriately modified from the factory to mount any mine clearance devices from the early PT-54 all the way up to the KMT-8.
PT-55 Mine Rollers
Mine rollers meant to detonate anti-tank mines before the tracks do. Main disadvantage of mine rollers is that it is not safe for the cannon barrel to be pointing forward, due to the negative effects of the blast on its integrity. They weigh in at a hefty 8.8 tons, and quickly wear out the front suspension of the tank.
Later on, the improved and progressively lighter PT-54M and PT-55 could be mounted. They could not clear as wide a path as the original PT-54, but are more sustainable because of their weight.
KMT-4 Mine Ploughs
Mine ploughs that dig up and shove anti-tank mines out of the way, creating a path just wide enough for the tracks to pass through They weigh 1.2 tons, and are lowered with a hydraulic piston powered by the tank's electrical system. The tank can move at normal speeds with the plough raised, but must slow down to 12 km/h with the plough lowered. The plough is light enough that it will not affect the frontmost torsion bars, which is helped by the better optimized arrangement of roadwheels on the T-62. The large gap between the first and second pair of roadwheels in the T-54 and T-55 designs meant that they would have been placed under excessive strain, possibly breaking them.
Neither of these devices could remove or safely detonate tilt-rod mines, but tank crews could tie a piece of steel wire or cable across the two plows or rollers for a makeshift standoff detonator. Later mine clearance devices like the KMT-5 combined rollers with a plough while weighing less than the original PT-54-type rollers. Later on, the T-62 could mount more sophisticated KMT-6, 7 and 8 devices capable of detonating both tilt-rod mines as well as electromagnetically fused ones. This is mostly thanks to the completely standardized mounting system used for all Soviet mine clearance devices.
Like any other tank, the T-62 can be decontaminated swiftly by being blasted with jets of hot air to remove chemical and biological agents, which is what is happening to the T-62 below:
Before external decontamination can begin, it must be made sure that NBC contaminants cannot slip through gaps in the tank's armour to incapacitate or even kill the crew, and the effects of a nuclear blast may cause severe illnesses in the long run. To combat all of these effects, the T-62 was furnished with a comprehensive NBC protection suite, something which no other tank in the world save its predecessor had at that time.
With the need for nuclear protection firmly established with the appearance of tube artillery-delivered tactical nukes, the requirement for such a system remained the same for the T-62 as it did for the T-55, which had the most advanced nuclear protection scheme in the world of tanks, being the only tank that had one. For simplicity's sake, the T-62 simply adopted the same ERB-1M system as the T-55. ERB-1M could detect a nuclear explosion through a gamma radiation sensor located in the middle of the hull, just beside the commander's seat (red box), and activate the tank's collective protection suite.
When gamma radiation was detected and determined to be at or above a dosage indicative of a nuclear explosion or leak, all portholes would be sealed with steel shutters to prevent contamination, as the tank was not airtight unless sealed. The shutters were activated via explosive squibs detonated through an electric impulse. The engine would be immediately stopped and the radiator cooling fan suspended. The radiator louvers would be automatically shut closed and to fully assure the impenetrability of the fighting compartment from radioactive particles, the ventilator is powered up to create a slight overpressure to ensure that nothing can enter even in still air. As any middle school student would know, high winds from a low yield nuclear blast would create a pressure differential causing air from within the tank to be sucked out. The driver has manual switches for activating the nuclear attack seals.
|TSh2B-41/U sight aperture with nuclear attack seal activated|
Although the T-62 did not have equipment capable of detecting chemical and biological agents, the supercharged filter-ventilator can be manually activated from a control box near the shell casing ejection port. The control box is easily within the loader's reach (red box below in the photo below). If the crew notices clouds of suspicious smoke or have been informed of contaminated sectors, they have the opportunity to safeguard themselves on their own initiative by activating the supercharged filter-ventilator to produce an overpressure to prevent the ingress of any such contaminants.
Compared to a plug-in system where crew members must plug in their gas masks into the tank's air filter unit - a system that is very commonly found in American armoured vehicles - the collective-type protection suite of the T-62 is ergonomically superior by far. The crew does not need to wear masks that obturates their vision, and they can breath without restrictions.
Like the T-54, the T-62 has an on-board smokescreen generation system. Diesel fuel is injected into the exhaust manifolds, vaporizing it with the heat which produces wonderful plumes of white, opaque smoke. One of the most positive aspects of this system is that smoke produced with this method will be the exact same temperature as the exhaust manifold would be. This makes it impossible to differentiate the heat signature of the tank from the heat of the smoke, giving the T-62 a reliable way of self-concealment from NATO thermal imaging sights appearing in the mid-80's.
902V "Tucha" Smoke Grenade System
The T-62M was outfitted with the Tucha smoke grenade system for instant concealment. Since the T-62M was introduced rather late into the Cold War in 1983, they skipped ahead of the early 3D6 and would (or could) be straightaway equipped with the more advanced 3D17 IR-obscuring smoke grenades.
The 3D17 is an advanced IR-blocking aerosol smoke grenade. It completely obturates the passage of IR signatures or IR-based light as well as light in the visible spectrum. It is effective at concealment from FLIR sights and cameras as well as at blocking and scattering laser beams for tank rangefinders and laser-homing missiles. Unlike the 3D6, the 3D17 grenade detonates just 1 second after launch, allowing it to produce a complete smoke barrier in 3 seconds flat. The drawback to this is that the lingering time of the smokescreen is only about 20 seconds, depending on environmental factors and the number of grenades detonated. This is enough for the tank to hastily shift its position, but not much more. This grenade detonates in mid air about 50m away from the tank. It has a caseless design with a propulsion method identical to that of the VOG 30mm and 40mm grenades which came later.
The system can operate in either 'automatic' or 'semi-automatic' modes. In the 'automatic' mode, the system alerts the driver of the source of the fire and immediately closes all of the radiator louvers, shuts off the engine, cuts off the engine air intake and shuts down the radiator fan to deprive the fire of air. Then, the integral fire extinguishers are activated, and if it is unable to put out the flame with a direct blast, the fire will still die down from being totally starved of oxygen.
In the 'semi-automatic' mode, the system only alerts the driver of the source of the fire, but takes no action on its own. The driver can then choose whatever action he deems most suitable at the moment. He can control the deployment of the fire extinguishers from his station, and the commander has a master switch for deploying the fire extinguishers as well.
In addition to the automatic fire extinguishing system, the driver is supplied with a single manual OU-2 carbon dioxide fire extinguisher. Carbon dioxide is suitable against Class B and C fires, namely fuel and electrical fires, which are the predominant causes or victims of fire in a tank.
The T-62 mounts an escape hatch for the crew to use in the very worst of emergencies. It is located directly behind the driver's seat and in front of the gunner. All of the turret's inhabitants can (relatively) easily swing down and out, but for the driver to exit, he must first fold his seat backwards, enter the turret, and then fold his seat forwards (the driver must fold as well) before he can egress.
|(The one at the bottom of the photo)|
Though small as always, the hatch has one highly redeeming feature, and that is that it is opened inwards on a hinge as opposed to being a drop out-type. Not only does this practically eliminate any potential concerns of the hatch dropping out on its own accord from bad securings, it means that it can be opened if the tank is submerged.
The driver's station is practically identical to the one in the T-54, with only very minor differences. It is located at the front left quadrant of the hull, and the driver absconds through an elliptical hatch. When swung open, the turret cannot be turned owing to a built-in safety mechanism to prevent the driver's head from being lopped off, and there is a small indicator light that alerts the driver that the gun is over the hatch.
The driver's station is exactly identical to the one in the T-55. Steering is accomplished using the obligatory pair of tiller levers. To save legroom for the driver, the instrument panel is moved to the right. The speedometer is placed on a pedestal to the driver's left, and the gear shift is placed to his right. The driver is also in charge of the tank's automatic firefighting system. Two 5-liter compressed air tanks for cold weather engine starting are located just behind the driver on the left wall. They are replenished by an engine-driven AK-150SV air compressor. The compressed air reserves are also used for the pneumatic clutch assist, but the air compressor can be used with a pneumatic hose and used as a pneumatic washer for detailed cleaning of the more sensitive parts of the tank. The driver's left periscope also has an air nozzle to blast away dirt and debris, which is around as effective as a traditional wiper. It takes about an hour to refill both air tanks using the AK-150SV air compressor if the tanks are empty. The AK-150SV is powered by the engine, so that a continuous supply of air is provided the moment the engine is started.
Starting the engine is done with the VB 404 ignition device. You can find out how it works by watching Nicholas "The Chieftain" Moran's video on the T-55.
For daytime driving, the driver is provided with two 54-36-317-R periscopes. They can be pulled straight down for removal, which causes spring-loaded shutters to clamp down and reseal the periscope port to prevent irradiated particles from passing through. The 54-36-317-R periscope has 1x magnification. The periscopes have special K-108 windows infused with cerium. Whereupon the windows are blasted with gamma radiation from a nuclear explosion, they begin to darken to give the driver eye protection from the intensity of the visible light and infrared and UV radiation emitted from the explosion. They will return to their original undarkened state under daylight within several hours, depending on the time of day (intensity of sunlight). Just like the periscopes everywhere else on the tank, the 54-36-317-R periscopes are heated through the RTS electrical heating system to prevent fogging.
For nighttime driving, the driver is equipped with the TVN-2 binocular infrared nightvision periscope. It has a fixed 1x magnification and a 30° field of view. The left periscope can be replaced with the TVN-2. The driver must then connect the TVN-2 to a special cable from BT-6-26 power supply box. Infrared light is sourced from the single IR headlamp on the hull glacis and another similar lamp on the turret, just underneath the L-2G Luna spotlight. The driver can see about 60 m in front of him, so the speed of the tank must be carefully controlled. It is not possible to navigate at night using only the TVN-2, as the driver will be unable to see the landscape and recognize landmarks.
Navigation is facilitated by a simple GPK-48 gyrocompass located near the driver's feet. The main function of the gyrocompass is of course to let the crew know which direction they are travelling in, but it is particularly useful when driving underwater or when driving at night. With the GPK-48, it is possible for the driver to perform maneuvers when driving underwater (provided that certain conditions are met, including riverbed integrity and so on) and at night, with assistance from the commander.
|Photo credit: mashpriborintorg from flikr|
In 1966, the T-62 received the GPK-59 gyrocompass, which had more knobs and dials.
The use of gyrocompasses can perhaps be labeled as a rudimentary form of an Inertial Navigation System (INS), advanced versions of which are often present in modern combat vehicles due to their independence from outside input contrary to a GPS-based navigation system.
The tactical mobility of the T-62 - that is, its ability to maneuver under its own initiative as opposed to piggybacking on transporters like by lorry, rail, by plane or by ship - is only just admissible. One of the T-62's main grievances, though minor, is that it is just slightly underpowered compared to its predecessor the T-55, mainly because it uses the same V-55V diesel engine of the T-55, but weighs over a ton more than it, bringing its mobility characteristics down to the level of the T-54.
The speed of the tank for each gear is as follows:
- 1st Gear: 14.5 km/h
- 2nd Gear: 20.0 km/h
- 3rd Gear: 29 km/h
- 4th Gear: 45.5 km/h
- 5th Gear: 50.0 km/h
- Reverse: 6.8 km/h
The T-62 uses an dual epicyclic geared steering system - otherwise simply known as a geared steering system - of the exact same design as the T-55, with an auxiliary clutch and brake system for tight turns at any gear and in neutral. A similar steering system was employed on the IS-1 heavy tank. Steering is achieved by having two separate final drives with separate gear boxes connected to a common transmission. This design is extremely compact and highly durable. Unlike a (very outdated) single differential or a clutch and brake steering system, full power is sent to both tracks while steering. By manipulating the gear ratio, either the left or right track can be slowed down incrementally rather than braked for smoother and more precise steering. This is done by stepping down the gear box of the inside track to a higher gear ratio (more torque, less speed), thus creating a difference in speed, causing the tank to turn. However, this system will have the same fixed turning radius regardless of which gear you are in when driving.
The driving tillers (or levers) each control the track on its side. Each tiller has three positions, the first (1) for full forward, the second (2) for engaging the planetary mechanism to reduce speed for that track, and the third (3) to engage the brake. Each gear had a fixed (but not the same) turn radius, except the first gear, where steering can only be done by clutch and brake. The T-62's geared steering system was capable of a form of neutral steering called pivot turning, but not true neutral steering. The turning radius when pivoting the tank on the spot in neutral is 2.64 m.
By the early 1960's, this method of steering could still be considered modern, but it had been surpassed by more advanced Western designs. Western tanks generally had double differential or triple differential transmissions that were capable of true neutral steering and were additive in addition to being regenerative. Something also worth mentioning is that while the geared steering system of the T-62 was a regenerative system and just as efficient as the triple and double differential steering systems used by the M60A1 and Leopard 1 respectively, it was not additive, and this is important. It means that in addition to being regenerative, the outside track of an M60A1 or Leopard 1 will gain power. The steering systems for the M60A1 and Leopard 1 also have multiple turn radii, so that steering precision is even better. It does not need to be said that the Leopard 1 is faster and more agile than the T-62, of course, but when comparing the M60A1 with the T-62, the additive feature of the steering system of the M60A1 be enough to nullify what few advantages the T-62 may have with its higher power-to-weight ratio.
The V-55V engine puts out 580 hp at 2000 rpm with a maximum torque of 240 kgm at 1200 to 1250 rpm. It has a specific fuel consumption of 180 g/hph, which is reasonable for an engine of its size. The average fuel consumption per 100 km of travel is 190-210 liters on paved roads, and 300-330 liters on dirt roads. Mounting the this engine, a production model T-62 weighing in at up to 37.5 tons combat loaded would have a nominal power to weight ratio of just 15.46 hp/ton. This placed the T-62 firmly in the category of contemporary medium tanks like the M48 Patton and the Centurion and better than the then-brand new Chieftain, and only slightly better than the M60 that it was to compete against. The T-62 could attain a top speed of 50 km/h on paved roads, and the average speed when going cross country was around half of that at 25 km/h, which was more or less the same as the M60. The reverse speed, however, was horrendously bad by Western standards at just 6.8 km/h.
As with its plainly average performance on the highway and off, the T-62 was also more or less averagely deft at traversing difficult terrain. It could climb vertical obstacles up to 0.8m tall, climb a 32° upward slope and drive on a side slope of 30°. The tank can cross trenches 2.85m wide at slow speeds, but it is possible to jump the tank over much wider trenches provided that it travels fast enough. It would be even better if there was a natural ramp or perhaps a bump to help the tank catch air.
The engine could be started either electrically or by a combination of air pressure and electricity in extremely cold weather, as mentioned before. Electric starting is done with the ST-16M electric starter and the air is supplied by the compressed air tanks.
The engine powers the F-6.5 alternator with a maximum output of 6.5 kW for the tank's power supply.
This engine was fitted to the T-62M. Thanks to a more optimized direct fuel injection system, it had a slightly increased output of 620 hp to compensate for the added weight of "Brow" armour on the T-62M, but was identical to the V-55V in every other way. The small increase in power does not adequately balance out the gain in weight, so the T-62M has noticeably poorer acceleration.
Instead of the F-6.5 alternator, the V-46-5M is equipped with the G-6.5 model with the same output, differing only in the method of installation and the input capacity.
The T-62 has the exact same powertrain and steering system as the T-55, which in turn is exactly the same as the one from the T-54. It is not known if the gearboxes were changed when the V-46-5M was installed.
Like the T-55 before it, the T-62 had individual torsion bar suspension and had five wholly uninteresting hollow die-cast aluminium alloy roadwheels with a thick rubber rim. The T-62's suspension is aesthetically nearly identical to that of the T-54 and T-55, but it can be differentiated by the three evenly spaced roadwheels at the front of the tank and the two more widely spaced ones at the rear. This was done due to the slightly increased front weight of the tank, making it more front heavy than the T-54/55, thus necessitating more suspension elements at the front to ensure better load distribution for a longer lasting suspension as well as a smoother ride across bumpy terrain. The diameter of the roadwheels is 810 mm. They have a standard layout with a central channel for guide horns on the tracks to pass through. The same 5-spoked wheel was kept throughout the T-62's service life. The tank had 430mm of ground clearance.
The T-62 used OMSh single pin tracks, carried over from the T-54/55. The full set of 96 links weighs 1386 kg. The tracks are of a simple hinged type, with no inner rubber padding or rubber bushings, nor were there any rubber track pads available for this type of track during the T-62's years of service, so travelling on paved roads was not very good for the asphalt. The tracks are 488mm wide, with standard centered guide horns.
The idler wheel is of a skeletal design with 10 spokes. The drive sprocket has 4 spokes.
Contrary to popular belief, Soviet tanks and other armoured fighting vehicles are typically not much better off in terms of ground flotation when contrasted with most other NATO tanks. Exerting a ground pressure of 0.77 kg/sq.cm, the T-62 was no better than the 12-ton-heavier M60A1 (0.76 kg/sq.cm), and only slightly better than the then-common M48A1/A2 (0.83 kg/sq.cm), but it was positively lightfooted compared to tanks on the heavier side of the spectrum like the clumsy old Centurions (~0.95 kg/sq.cm) and the advanced Chieftain which arrived much later (0.90 kg/sq.cm).
During the 70's, the T-62 along with the T-54/55 series was retrofitted with RMSh single-pin tracks from the T-72, which are wider by 92mm and considerably more durable thanks to larger and tougher connecting pins and a reduced rate of wearing thanks to internal rubber bushings. A full set of 97 links weighs 1655 kg. All T-62Ms are fitted with the RMSh track.
This reduced the ground pressure to a measly 0.65 kg/sq.cm, much lower than any other tank of the time, enabling the T-62 to traverse poorly accessible terrain much more easily than other tank can.
The easiest way to tell apart an OMSh track from an RMSh track is to observe the ends of a track link. An OMSh-type track has an open loop at the ends of the track links whereas an RMSh track doesn't (check the photos above to confirm).
The engine deck was renovated twice since the original iteration in 1961. The original engine deck had maintenance hatches to allow easier inspection of the engine and air cleaner without removal of the engine deck. The hatches aren't very large, though, so doing any sort of detailed repairs will be difficult.
Replacing the engine or doing more extensive maintenance can only be done with the removal of the entire deck.
The T-62M brought with it a revised deck design with a large T-72-style engine access hatch, giving a clear, unobstructed view of the innards of the engine compartment.
|Photo credit: Andrei Tarasenko's website|
None of the engine deck designs have enough armour to resist 30mm DU rounds from the legendary A-10 Warthog's GAU-8 cannon, but it is still strong enough stop the extremely anaemic 20x102mm cartridge, which isn't saying much, but very relevant given that the A-10 did not even exist until the T-62 was already well on its way out of Soviet frontline units.
The radiator is located directly behind the engine. It can be accessed by lifting the protective radiator access panel, which is hinged. Directly underneath the radiator unit is the cooling pack into which coolant carries heat from the engine to be dissipated by air sucked in through the radiator unit and out the rear of the engine compartment via a centrifugal fan.
The fan is powered by the engine via a drive shaft connected to the gearbox, thus allowing the fan to meet the engine's cooling needs following its power output, which is proportional to its heat output. The fan housing has its own armoured cover, which has rubber seals to prevent water ingress while the tank is driving under water.
The radiator air intakes are protected by a set of armoured louvers to protect from air burst artillery and mortar shells or even molotov incendiary bombs. These are further augmented by auxiliary armoured covers, which must be manually closed, but can be sprung open with the press of a button in the driver's station. They are too thin to be of much use against air attack, so their main function is to seal the radiator from the ingress of water.
|Engine air intake (Credit: Alex Chung)|
The VTI-4 engine air intake filter is located the beside the engine, just under the air intake grille. It is a dual-stage fabric-type filter, good for many hours of operation under highly dusty conditions. Dust filtered out from the air to ensure that the engine is not clogged up and has sufficient oxygen to run at normal rates. Larger particles of pollutants are ejected from the filters via compressed air.
Whereupon the engine air intake is sealed and the vehicle is underwater, the engine draws air from inside the hull via a respirator fan located just behind the commander's seat, on the partition between the engine compartment and fighting compartment. There is no filter in this channel, because the air in the fighting compartment is already filtered.
|(Notice the fan duct at the top of the photo)|
There is an electric air heater just in front of the fan duct and under the commander's seat (cylindrical tank in photo below). It supplies hot air to warm up the engine during cold weather, and it also functions as the heater for the crew compartment.
The tank's electrical supply needs are handled by four 6-STAN-140 accumulators located at the front of the hull, adjacent to the driver's station. These are simple lead acid batteries connected in series. They supply 24 volts when the engine is turned off, and 27 volts when the engine is on.
Fuel storage is divided between 3 internal tanks and 3 external tanks for a sum total of 960 liters. Two of the internal fuel tanks are also the two front hull shell stowage racks (as seen previously) and the other fuel tank is located at the starboard side of the hull, at the very rear of the fighting compartment, right next to the partition between the engine compartment and the fighting one. The two front hull fuel tanks hold 280 liters each, and the solitary fuel tank at the rear of the fighting compartment in front of the engine compartment partition holds 115 liters
Since all of the fuel tanks are interconnected, the driver-mechanic need only top up the tank from one fuel filler port. There is one at the rear of the hull leading to the rear fuel tank:
And another two for the pair of conformal front hull fuel tanks at the front of the hull:
The three external fuel tanks are mounted atop the starboard fenders, each with their own fuel filler cap.
|Here you can see how the fuel tanks are connected|
Total internal fuel capacity is 675 liters, plus another 285 liters carried on the external fender tanks. An additional 400 liters of fuel is carried in two 200-liter auxiliary fuel tanks mounted on brackets at the rear of the tank to augment the tank's operational range. With all fuel tanks filled, the tank carries a sum total of 1360 liters of fuel. With auxiliary fuel tanks, the T-62 has a highway cruising range of about 650 km, or 450 km without. The cruising range on dirt roads with auxiliary fuel tanks is 450 km, and 320 km without.
All the fuel tanks are interconnected. The driver has a control knob just beside the right steering lever to select which set of fuel tanks he wants to draw from, choosing between the internal fuel tanks only, external and the auxiliary drums only, or all together, or the driver may cut off all fuel flow entirely. This is quite helpful if one of the tanks were to be compromised, because by shutting off a set of fuel tanks, the rate of leakage can be greatly reduced and this may even help control a potentially catastrophic internal fire if the driver reacts promptly.
There are certain procedures that need to be followed prior to snorkeling, however. In order to prevent water from entering the engine air intake and radiators, they must all be sealed by locking their armoured covers down, and the bilge pump should be activated, which can be done with a switch on the driver's instrument panel. It is only necessary to close the armoured louvers for both the radiators and the air intakes when fording. Once the engine air intake is shut off, however, the engine must draw air from inside the tank through a respirator fan located just behind the commander's seat.
When snorkeling, it is also necessary for the exhaust outlet to be sealed with a valve bank, which is a bolt-on cover for the exhaust outlet equipped with four spring-loaded circular exhaust ports that prevents exhaust gasses from being released until they can build enough pressure to blow out forcefully enough that water will not have a chance to leak in.
If the tank is to be snorkeling deeper than three meters, the last step is to seal all of the hatch gaps with a waterproof paste, which has the consistency of clay. The entire preparation process takes around 30 minutes for snorkeling, but the tank can readily ford across any stream without any preparations whatsoever.
The air supply for both the crew and engine is provided by the single snorkel erected from the turret roof.
The snorkel is broken down into three parts and latched onto the rear of the turret and under the auxiliary fuel tanks for convenient stowage during road marches and combat. The snorkel must be assembled on site by the crew before it can be used. It is possible to install only one or two of the three parts depending on the depth of the body of water to be crossed. The snorkel is installed in a small port in the turret roof, just in front of the loader's hatch. Once the tank resurfaces and drives off, it is not necessary to remove any of the snorkeling accessories except the snorkel (for obvious reasons), which can be simply cast away by pushing on it from the inside.
The porthole plug itself has a thick rubber seal to prevent rainwater from dripping into the tank, as do all of the hatches.