Category: Cold War Soviet Prototypes

Soviet Union (1963-1964)
Infantry Fighting Vehicle – 1 Prototype Built

The evolution of warfare and technologies in the years following the conclusion of the Second World War had a major impact on the way warfare would be conducted in the future. The appearance and proliferation of nuclear weapons led to the need for protection from nuclear fallout and radiation being a major requirement for combat vehicles meant to operate in a battlefield that could likely be saturated with tactical nuclear strikes. The truck-borne infantry of the past was also increasingly sidelined for infantry in armored personnel carriers, which could keep up with armored formations and allow for highly-mobile infantry protected from small arms fire and shell splinters. Following these conclusions, work began on a vehicle in the Soviet Union which would not only transport infantry while keeping up with tanks, but also provide protection from nuclear fallout and combat capabilities needed to supplement tanks and provide support to infantry. One of the prototypes created in the 1960s to fulfill such a task was Volgograd Automotive Plant’s Object 911.

The Infantry of a Mechanized, Nuclear Age

After years of development, the United States detonated the first nuclear warheads in 1945, first over the New Mexico desert and later over the Japanese cities of Hiroshima and Nagasaki. The Soviet Union had laid a keen eye on the development of this new type of weapon, which promised unprecedented levels of destructive powers achieved by a single bomb. On 29th August 1949, the Soviet Union followed suit by detonating its first atomic warhead in the RDS-1 test, years ahead of American and British expectations.

In the following years, the United States and the Soviet Union, soon followed, to a much lower extent, by the United Kingdom, and later France and the People’s Republic of China would pursue massive buildups of their nuclear arsenals. By 1960, the United States’ stockpile had already exceeded 15,000 weapons. The Soviet buildup was, at the time, much slower, but at more than 1,500 warheads, it would already be enough to cause massive destruction.

With the massive buildup of nuclear stockpiles, the perceived roles of nuclear weapons also evolved. The weapons would be used in strategic strikes against enemy cities, production, and logistical centers, as had been originally intended and tested against Japan in 1945, but new potential targets were soon considered. Value was also found in ‘tactical’ nuclear missiles and bombs, which would be used on a much smaller scale, against enemy troop concentrations, supply depots, or ways of communications on the frontline. This newfound purpose of nuclear weapons, coupled with the increasing realization of the major health effects of nuclear radiation, led to the understanding that many aspects of conventional warfare would find themselves struggling to find any purpose on this new, nuclear battlefield.

This was supplemented by the fact that, in the 1950s, the USSR considered a conflict in mainland Europe was a likely occurrence, as demonstrated by the heavy tensions of the late 1940s and early 1950s. At this point in time, and up to the early 1960s, while the Soviet Union did have nuclear weapons, the means of delivery were far less developed than those of the United States. While the United States had a large fleet of strategic bombers that could realistically become a threat to many Soviet cities, the USSR struggled to establish an equivalent force. The Soviets wanted to rely on a submarine fleet to counter this, but it was only starting to build itself up in the late 1950s, and NATO could rely on extensive naval forces. The only aspect where the Soviet Union had a somewhat reliable nuclear force was in its ground forces. Between the use of tactical nuclear weapons in the Soviet Army and the otherwise nuclear superiority of NATO, the Soviet Army expected to be forced to fight on a heavily irradiated battlefield. Many of the aspects of the post-WW2 Soviet Army could not be expected to operate in such an environment.

One of the prime examples was that of infantry moved by trucks, largely open vehicles that could hardly be protected from nuclear radiation and fallout. Armored vehicles, in comparison, were already often enclosed, and making them able to protect their crews from nuclear radiation, as well as chemical and biological threats, was a viable option. This suddenly highly increased the value of armored personnel carriers. While already vehicles with significant potential and increasing in popularity since the conclusion of the Second World War, they appeared as perhaps the most viable option to continue to make infantry relevant. Not only would they be able to keep up with armored vehicles and, in this way, considerably ease combined arms operations, but they would also protect infantry from small arms fire, and, perhaps even more importantly, from nuclear radiation. Because of this reason, after the rise of power of Khrushchev in the Soviet Union from 1953 onward, considerable emphasis was put on adapting the Soviet Army for nuclear warfare, and outfitting Soviet infantry with better vehicles for this purpose than mere trucks.

In the Soviet Union, the idea would be pushed further though. Rather than design pure troop carriers which would typically be armed with just a machine gun, the idea of a vehicle that could not only keep up with tanks while transporting infantry but also provide valuable combat support to both arose. The main recipients of this envisioned vehicle were to be motor rifle regiments, though it would in general be widespread through the Soviet Army.

The BMP Concept

The concept of this new type of vehicle was popularized in the late 1950s in the Soviet Union, though some similar concepts were being developed in other countries, notably the West German Schützenpanzer Lang HS.30.

The idea of the BMP ( Боевая Машина Пехоты, which translates to Infantry Fighting Vehicle) was to create a vehicle that would provide CBRN (Chemical, Biological, Radiological, and Nuclear) protection to the troops it carried. This was at first the factor separating the BMP from APCs like the BTR series, which at the same time included a significant amount of non-CBRN protected vehicles, such as open-topped BTR-40s, BTR-152s, and BTR-50s.

Beyond this nuclear protection aspect, the BMP was also meant as a vehicle that would have the mobility and armament necessary to offer support to tanks. This meant it should be able to engage many targets, from tanks to various armored fighting vehicles, to infantry and field fortifications. Another aspect that was desired was superior mobility, with the crossing of water obstacles being a major factor. There are many major rivers in Europe, and bridges could not be relied on in a very destructive major conflict on the continent. It was also hoped that the infantry would be able to fight from the inside of the vehicle itself, not necessarily having to dismount, another concept brought forward by the prospect of an irradiated battlefield.

The first task would be accomplished by the presence of firing ports from which the troops could fire their weapons. The idea of bow machine guns operated by the infantry dismounts (dismounts is a term widely used to refer to the infantry carried inside or on top of Soviet vehicles), rather than the crew of the vehicle itself, was also considered. Because of this firing port requirement, the position of the infantry towards the front and center of the vehicle, rather than the rear, was preferred. Enemy targets would typically be found towards the front and sides of the vehicle, rather than the rear.

Firepower-wise, the main purpose envisioned with the BMP was the ability to defeat enemy anti-tank capabilities as well as provide fire support to dismounts. This would translate into the main armament that could take out infantry positions equipped with recoilless rifles or anti-tank guided missiles as well as lightly armored vehicles. A number of armaments of various calibers were considered for this purpose. This included main guns firing 57, 73, or 76 mm shaped charges projectiles, or 30, 37, or 45 mm autocannons. Eventually, the 73 mm 2A28 Grom low-pressure smoothbore gun would be chosen. This main gun was to be supplemented with one or several 7.62 mm machine guns for anti-infantry duties. Since there was a high risk of encountering enemy tanks, while following friendly tanks, an anti-tank missile launcher, with 4 to 6 missiles, was also required and would have to offer the possibility of being fired from inside the vehicle, with hatches closed.

Protection-wise, the vehicle was to provide protection from heavy machine guns, such as the 12.7 mm/.50 cal Browning M2HB, or possibly even 20 or 23 mm autocannons, on the frontal arc. On the sides and rear, protection levels were to allow the vehicle to withstand 7.62 mm rounds, as well as artillery shell splinters. Heavier armor was impractical due to amphibious and air-transportability needs.

A very significant aspect of the protection was the one from NBC (Nuclear, Biological, Chemical) threats. The vehicle was to provide an enclosed environment in which the crew and dismounts would be able to operate, even on a highly irradiated battlefield. This would translate into high efforts being taken to seal the vehicle and fit it with an air filtering system as well as an anti-radiation lining. These design requirements would translate into the vehicles being the first troop carrier designs taking into account nuclear radiation protection.

By the late 1950s, Volgograd was already producing a tracked, amphibious armored personnel carrier in the form of the BTR-50. As designed, the BTR-50 was an open-topped vehicle, which would entirely prohibit any kind of radiation protection. By the late 1950s, this had been remedied by the BTR-50PK modification, which incorporated an enclosed roof.

Interestingly, whilst the Object 750 prototype had 2 firing ports per side for the dismounts, the serial BTR-50P did not.

One of the requirements for the BMP was to allow the whole infantry squad to engage targets from the inside.

However, it was thought that the IFV would provide far better-fighting capabilities, as well as protection for the infantry in an irradiated environment. Also, the BMP would allow for dismounts to engage from inside the vehicle, while a BTR-50 could really only transport the infantry or cargo through the irradiated terrain, but the troopers could not even exit and fight safely.

In terms of mobility, the vehicle’s main objective was to be more mobile than tanks, which meant a relatively high maximum speed but, most importantly, very good off-road capacities. The vehicle was also required to be amphibious to allow the crossing of rivers and marshes even without bridges. These requirements resulted in weight and size constraints inherent in all types of Soviet and Russian APCs and IFVs.

Lastly, the vehicle was to be small and light enough to be air-transportable, though it was not meant to be dropped from a plane as an airborne vehicle. It was also desirable to create a vehicle that would be as simple and easy to produce as possible. It was hoped it could then be produced in large numbers with relative ease, as well as form the base for a large family of vehicles that would use its components.

A formal call for design proposals following these requirements was issued by the GBTU (The General Armored Directorate, the service in charge of armored vehicles procurement) on 22nd October, 1960. The requirements were finalized in September 1961 and eventually sent to a large number of design bureaus. Initially, the Main Artillery Directorate, which issued the requirements, called for an 11-12 tonnes vehicle that would feature a crew of 2 and transport 6 to 8 dismounts.

At that time, three different views existed on how to design the future IFV. One was to create a new, wheeled vehicle, sometimes using some pre-existing technology. The second was to create the vehicle based on a pre-existing chassis. The third was to create an all-new, tracked vehicle. One of the designers which were issued the requirements was VgTZ (Volgorgadskii Traktornii Zavod, Volgograd Tractor Plant, the former STZ/Stalingrad Tractor Plant). Eventually, this relatively large design bureau would offer two different variants. The first would be based on VgTZ’s PT-76 amphibious tank, the Object 914 (VgTZ was attributed numbers in the 900s for the designation of its prototypes). The other would be a completely new vehicle, which used a tracked configuration, though with a number of unique elements; this would be Object 911.

Volgograd’s Object 911

The pilot projects for vehicles from different manufacturers were first presented at a meeting in November 1960. At this point, some of the characteristics of the future BMP were still uncertain. For example, the possibility of using a 14.5 mm machine gun as main armament was still being considered.

The Volgograd design bureau started elaborating various solutions following the November 1960 meeting. Their attempts at creating a BMP would typically, as had been with the Object 914, use a lot of elements from previous projects, in this case the PT-76 and the Object 906B, two light tank designs. The first was adopted and mass-produced, the second stayed on the drawing board.

Configurations studied by Volgograd generally used a rear engine configuration, though there was a draft project with a front engine and rear transmission, as on the PT-76 and related vehicles. An early set of plans for the Object 911 dated 1962 envision a vehicle featuring a two-man turret and a dismount compartment for six dismounts sitting in three rows of two. This configuration would be entirely changed before the vehicle would enter the prototype stage.

The draft project of the Object 911 was developed at VgTZ in 1963, and presented to the State Committee for Defense Technology (GKOT, Russian: ГКОТ, Государственный комитет по оборонной технике), which considered it and allowed for the production of a prototype on August 9th, 1963.

The prototype of the Object 911 was built in the same year under the supervision of the head engineer, I.V. Gavalov. The prototype went to the comparative trials in 1964, alongside several other prototypes of the BMP.

The prototypes tested largely varied in terms of configurations, and included the fully tracked Objects 914 and 765, the wheeled Object 1200, and the convertible Object 911. Usually, convertible designs used the wheels as the main means of motion and lowerable tracks for moving off-road. The Object 911 used the opposite configuration using retractable wheels for traveling on roads, a peculiar feature.

The Object 911’s Design

Hull

The overall design of the Object 911’s hull was a rectangular, welded steel box. Like most Soviet amphibious vehicles of the era, it featured a bow-shaped frontal part for the purpose of improving the vehicle’s hydrodynamic characteristics, further perfected by a retractable trim vane at the front of the hull. The whole upper front/roof plate was angled at a very steep angle, highly improving protection over its frontal arc. The Object 911 had a fairly low profile, with a total height of 2,068 mm, including the turret. According to Domestic Armored vehicles vol 3, at some point, the height of the hull was increased to 1,200 mm.

The Object 911 used a configuration where the crew and dismount compartment were concentrated at the front and center of the vehicle. The vehicle had a crew of two: a driver, who sat in the front center of the hull; and a gunner/commander, who sat behind in the left part of the centrally-mounted turret.

The eight dismounts were present in a symmetric configuration. Two were in front of the turret, one on each of the driver’s sides, and would presumably operate the squad’s machine guns. Six sat just behind the turret. Each dismount had a firing port in the sides of the vehicle, so they could fire their weapons from the inside of the hull. Considering the placement of the firing ports, four on each side of the vehicle, they would be able to create an arc of fire over about the front two thirds of the vehicle.

Each of the dismount positions featured an episcope. The driver’s post appears to have featured three, one to the front and one to each side. The driver would steer the vehicle via a steering wheel. The vehicle featured two headlights, mounted to the front sides of the bow. There was a ventilator just to the rear of the driver’s hatch.

The vehicle’s engine was mounted at the rear of the vehicle, which would typically make hatch placement harder on an infantry fighting vehicle. The use of a fairly small engine on the Object 911 allowed for a quite peculiar hatch design. The center of the vehicle to the rear of the turret was lowered in comparison to the side ‘flaps’, and a large hatch was located there, opening upward and locking at about a 90° angle. Six of the dismounts were to exit through this hatch. It was hoped that it was wide enough for two dismounts to evacuate at a time. The dismounts would then jump out of the vehicle, which would be a fairly short 0.75 m to 1.10 m drop to the ground. This configuration was far from ideal, as the dismounts would prove very vulnerable if forced to exit when the vehicle was under fire. However, there were not many safer options for a vehicle with a rear engine compartment. Despite these potential considerations, this very configuration would be adopted for the BMD series of vehicles, and eventually even make its way to the BMPs with the BMP-3.

As for the driver and gunner, they each had a dedicated hatch they could exit the vehicle through. Furthermore, there were also two hatches on the front sides of the turret. These would be used for the two front dismounts to exit the vehicle, the squad commander and machine gunner.

The combat weight of the Object 911 was 12.07 tonnes. Length was 6.735 m, width 2.940 m, and height 2.040 m including the turret, presumably at the highest ground clearance. The average ground pressure was 0.46 kg/cm².

The Object 911 had the same level of protection as its main competitor, the Object 765.

The vehicle featured an R-123 high/very high frequency radio transceiver, which at the time was a new introduction in Soviet vehicles, which could assure communications at ranges up to 20 km on two bands. It was coupled with an internal R-124 intercom system for communications between the gunner/commander and driver.

Engine and Hydrojets

The engine used in the Object 911 was common to all the vehicles presented in the program. This was the UTD-20 diesel engine. It produced 300 hp at 2,600 rpm and reached its maximum torque output of 981 N.m at 1,500 to 1,600 rpm. Without any fuel or oil, the engine weighed 665 kg, and had a consumption of 175 to 178 grams of fuel per hp an hour.

The UTD-20 engine was fairly limited in size, which was a major positive factor for installation in the various BMP prototypes. On the Object 911, this allowed for the engine block to be placed in the rear of the vehicle despite the large central lowered section where the dismounts would exit from. The transmission and drive sprocket were placed at the rear of the vehicle as well. The mechanical transmission had a two-disc main friction clutch and a two-shaft five-gears gearbox which would be actioned by the driver. The gearbox included two clutches and two coaxial planetary gearboxes.

In addition to this engine and transmission, the Object 911 also featured two hydrojets. These were found in the ‘wings’ or ‘flaps’ at the rear of the vehicle. They were taken straight from a previous design of Volgograd Tractor Plant, the PT-76. These hydrojets were powered via a driveshaft with a reducer, linked to the gearbox, and would allow for far quicker movement on water than vehicles using merely tracks or wheels for amphibious crossings.

Modern Wheel-Cum-Track?

By far the most uncommon and distinctive features of the Object 911 were to be found in the vehicle’s suspension and drivetrain.

The engineers of Volgograd Tractor Plant experimented heavily with the suspension on Object 911. They settled on a mainly tracked suspension, which was to be used systematically in operational conditions. The vehicle’s tracked suspension used a rear-drive sprocket and a front idler, with five road wheels. The road wheels appear to have been identical to those found on the PT-76, being stamped steel road wheels with reinforcement ribs, and internally hollow to improve buoyancy. Each road wheel was mounted on a suspension arm of which the movement was assured by a pneumatic suspension. The suspension’s height could be adjusted and considerably lowered, with a maximum ground clearance of 426 mm and minimum ground clearance of 96 mm. The tracks themselves were OMSH tracks, made of cast manganese steel and connected by a steel pin, with three connection points. The Object 911 also featured three return rollers: one located towards the front of the second road wheel; the second, or middle one, towards the front of the fourth road wheels; and the last just in front of the drive sprocket. They appear to have been made out of aluminum.

The most unusual aspect of the Object 911’s drivetrain was not the pneumatic, adjustable suspension, the same design as on the Object 906B, but rather the dual drive. Indeed, the Object 911 was not just a tracked vehicle, as it had been designed with a set of four wheels mounted on the internal sides of the tracks. They were located at around the same length as the sprockets and idlers. The wheels could be retracted or extended depending on whether the tracks or road wheels were to be used. This could be done from the inside of the vehicle, with no need to exit, and be performed in three minutes. However, even when fully retracted, the bottom of the wheels would still stick out of the hull bottom by a moderate extent.

The wheels were taken from a pre-existing design. This was not a standard road vehicle design, but rather the K 157-300 designated aviation wheels taken from the Ilyushin Il-14 twin-engine transport aircraft. The main advantage was that aviation wheels were lighter than similar-sized ground vehicle ones, though they were also less sturdy. These wheels had a diameter of 840 mm and a width of 300 mm, and used arched tires. The vehicle used a 4×2 configuration, with the front wheels being used to steer the vehicle when on the wheel drive.

The main advantage envisioned behind these retractable wheels was higher maximum speed and reduced fuel consumption when driving on highway, notably for transfers or movement behind frontlines.

Turret and Armament

All the infantry fighting vehicles of the program used a standardized turret design, which was also present in the vehicle which would be adopted as the BMP-1, the Object 765. This standard design had been created by the Tula KBP Design Bureau and had a 1,340 mm turret ring. It used welded construction from rolled homogeneous armor plates. The turret had a frustoconical design. The turret featured a DGN-3 24 V 300 W motor for rotation, which could rotate at speeds from 0.1º to 20° per second. The gun elevation was powered by another electric motor, the DVN-1 24 V producing 65 W. The gun could elevate or depress at any speed from 0.07º to 6° per second, with maximum elevation angles of -4º to +30°.

Two hatches were present on the turret. There was a large top hatch opening frontwards, locking in an upright position, which the gunner could use to reach out of the turret to observe the surroundings, or to exit the vehicle. There was a much smaller hatch, located over the gun breech, which, when the gun was fully elevated, would be used to load a missile into the launching rail featured on top of the gun.

A single crewmember was located in the turret sat in the left half. The turret was typically considered to be quite cramped, even though it did not feature a basket and, as such, the crewmember could extend his legs into the hull when stationary. He sat on an adjustable seat that featured a backrest. He had five vision devices. Towards the front, he could observe the battlefield through the 1PN22 combined day-night sight. This sight had two channels, one for day and one for night, which would be toggled by rotating an internal mirror. The gunner would look through the same eyepiece in any case. Using the day channel, the sight had a magnification of 6x and a field of view of 15°. The night channel had a magnification of 6.7x and a field of view of 6°. It had a three-stage light intensifier system that would amplify light by 50,000 to 75,000 times. It also featured vastly simplified lead and range corrections scales in order to ease night firing. The other vision devices were four TNPO-170 episcopes, two on the flanks of the 1PN22 sight in order to provide vision to its sides, and two others on the side of the main hatch.

The main armament of the turret was a 73 mm 2A28 Grom low-pressure smoothbore gun. This was a fairly short gun, with a 2,117 mm tube and 2,180 mm total length. The design was overall made to be very simple and light. For example, it lacked any bore evacuator, and the gun fumes were instead to be evacuated from the turret, which featured a ventilator for this purpose. The gun overall weighed only 115 kg and had an average barrel life of 1,250 rounds. The recoil mechanism of the Grom was contained in an armored sleeve, wrapped around the base of the barrel. The launching rail for the Malyutka missile was placed on top of this sleeve.

There was only a single shell available to the 2A28 Grom in the 1960s. This was the PG-15V. It used the PG-9 HEAT (High Explosive Anti-Tank) anti-tank grenade already used by the SPG-9 73 mm recoilless gun, but swapped the original propellant charge with a more powerful PG-15P, which was meant to ensure a longer effective range. The projectile was fin-stabilized and featured a rocket engine towards the rear, with propellant present towards the middle of the grenade. This allowed it to reach a higher speed than would typically be expected from a gun as short as the Grom, with a maximum velocity of 655 m/s.

The explosive charge of the PG-9 grenade was a 322 g explosive mixture which would be equivalent to 515 g of TNT. An advantage of the PG-9 was that it featured a high standoff distance (i.e distance between the shaped charge and tip of the fuze) of 258 mm. In practice, this meant that, upon hitting a target, the jet of molten metal would have a significant length to take shape into a thin, dense jet. The results were a great armor penetration for the time and small size of the gun. The projectile’s armor penetration was officially rated at 300 mm at all ranges. In practice, this was slightly higher, as the official figure was based on the quantity of armor which would be pierced with the shell then having significant post-penetration effects inside. The maximum penetration achieved could vary between 302 and 346 mm, with an average value of 326 mm. In practice, this meant the Grom could quite reliably penetrate any tank operated by NATO in the 1960s.

The shell was not without issues, however. The downside of HEAT projectiles and a very short barrel were an overall low accuracy and high dispersion. The Grom’s PG-15V projectiles were notably very vulnerable to wind. The nominal maximum range of the Grom was of 800 m, but even at this range, only a 34% hit rate was achieved against a T-55 during trials. Although this tank was quite smaller than most NATO tanks, in practice it can still be said a vehicle wielding a Grom would have to get to close ranges to use this gun effectively against armored targets. Additionally, during the 1960s, the PG-15V was the only available shell for the 2A28 Grom. HEAT shells are not purely anti-tank projectiles, and by nature also have some capacities against other targets. They can notably be effective when used against field fortifications and bunkers. However, due to their design focusing on producing a jet of molten metal in one direction, they offer very limited capacities when attempting to fire at infantry in the open. For the vast majority of vehicles, this would fairly easily be dealt with by simply shifting to a high-explosive fragmentation shell, but no projectile of the type would be available for the Grom until 1973.

The 2A28 Grom was fed by an autoloading mechanism. It used a crescent-shaped conveyor which would occupy the 1 to 7 o’clock perimeter of the turret floor. Because the Grom only fired one shell type when the autoloader was created, its design was simplified, as there was no need to be able to cycle shell type. A total of 40 projectiles would be present within the autoloader. These would be all the projectiles carried within the vehicles of the BMP program. They would be fed into the gun to the right of the gunner. The gun elevation needed to be set to 3° each time it was to be loaded. The loading cycle was 6 seconds long. Though it used an autoloader, the 2A28 Grom could also be shifted to manual loading if need be.

This 2A28 Grom was supplemented by a 7.62 mm PKT coaxial machine gun. Mounted to the right of the gun, it would effectively be the only reliable means of dealing with infantry in the open. It fed to the right and ejected to the left. The PKT was fed from 250 rounds ammunition boxes and would fire at a cyclic rate of fire of 700 to 800 rounds per minute, at a muzzle velocity of 855 m/s. It would be able to expend two ammunition boxes in quick succession before the barrel would need to be replaced, or at least the firing interrupted for a bit to prevent overheating.

In addition to these two weapons, the turret featured an ‘ace up its sleeve’ when dealing with armor threats at ranges where the Grom would not be accurate. This was a 9M14 Malyutka missile launcher. The missile was located on a launching rail installed on top of the gun. Inside the turret, the gunner had a control box, which would be kept folded under the seat when not in use and be extended to guide the Malyutka when the need to fire it arose.

The Malyutka was a 860 mm long missile, 125 mm in caliber, and with a ‘wingspan’ of 393 mm with its 4 stabilizing fins. Overall, it weighed 10.9 kg, with a 2.6 kg shaped explosive warhead. The missile had a small rocket engine which would allow for a flight speed of 120 m/s. It was rated for firing ranges of 500 to 3,000 m. Due to the slow speed, the flight time to the longest effective range would reach a particularly long 26 seconds. When impacting a target, the 9M14 could be expected to penetrate 400 mm of armor at a flat angle. Once again, this would typically be sufficient to penetrate all NATO armor of the era with relative ease.

Guidance of the Malyutka was assured by wire, which was common for early missiles but also fairly unreliable. The gunner had a control box that featured a button to launch the missile and then a retractable joystick used to steer it. The missile was manually guided all the way through and, as such, the gunner was supposed to fully concentrate on missile guidance during the whole firing process.

As with the Grom, the Malyutka provided significant armor piercing capacities to the Object 911 if it was to hit, but this was far from a given considering the slow speed and manual guidance of the missile. Hit probability on a static tank-sized target was only 20% to 25%. Two missiles were carried within the turret. The vehicle was not supposed to travel outside of combat zones with a missile mounted, and as such these, alongside potentially missiles stored inside the hull (it is unknown whether the Object 911 would have any) were all the vehicle had to contend with. On the plus size, as with the PG-15V, the explosive nature of the Malyutka’s warhead means it could also be fired with good effects on field fortifications and fixed positions. The process of preparing for the firing of a Malyutka, including taking out the control box and loading the missile onto the firing rail, could take from 40 to 55 seconds depending on the skills of the gunner.

Performances

Trials for the Object 911, alongside Objects 19, 914, 765, and 1200 were held in 1964.

During these, the Object 911 was able to reach a maximum speed of 57 km/h on road when using tracked drive. This was fairly moderate. On water, top speed reached 10.3 km/h thanks to the hydrojets, which is on the higher end of amphibious vehicles of the era.

The use of wheeled drive would highly improve the maximum speed of the Object 911 on roads though. It was recorded at a maximum speed of 108 km/h on a paved road, and had an average cruise speed of 70 km/h on highways using wheeled drive. In addition to the superior maximum speed, the use of wheeled drive also had another major upside. It highly reduced the fuel consumption of the vehicle, to the point where the crossable distance reached a tremendous 1,350 km. In comparison, when driving on tracks on dry, dirt roads, the range would vary from 350 to 500 km. This maximum range advantage could be very significant if large movements had to be undertaken on roads without transporters.

In terms of cross-country capacities, Object 911 was able to cross a 30° degree slope. In practice, it provided better slope crossing capacities than the mostly or fully wheeled Object 19 or 1200. However, cross-country mobility was overall found to be inferior to the fully tracked Object 765 and Object 914.

The Flip Side of the Coin: an Overly Complex and Damaging Drive

When considering the improved road speed and range, one may find the dual drive with wheels featured on the Object 911 to be a major improvement in comparison to other vehicles. It is true that, in theory, the improvements gained in speed and range were considerable, but in practice, these were more than offset by a large quantity of issues with the wheels.

The first was that the wheels, located under the belly of the tank, were typically hard to reach and remove for maintenance. This issue was exacerbated by the fact the aviation wheels used in the Object 911 were more vulnerable to wear and tear in comparison to standard ground wheels and, as such, would need to be maintained or replaced more often when in active use. The wheels were also found to overly complicate the production of the vehicle and make it longer and more expensive to produce. This was once again a major issue, as the goal behind the program was to provide an easy and quick-to-produce vehicle which could be introduced in massive numbers.

Likely the most damning point of the wheels over the fate of the Object 911, however, was their impact on cross-country capacities. As stated previously, the wheels of the Object 911, even when retracted to their fullest extent, would not entirely be contained within the hull and would still stick out of the bottom by several centimeters. In practice, this was found to be a major issue when driving on uneven dirt roads or terrain. The wheels could occasionally touch the ground and get caught on it. The result would be that the track would lose tension and the vehicle would prove unable to negotiate the obstacle. Considering the requirements requested for a highly mobile vehicle that could move through all terrains, this was a major issue.

Another issue that likely arose by this point was the crew configuration. When compared to the favorite, the Object 765, which would eventually be chosen, the placement of dismounts to the center and front of the vehicle would prove unfavorable. While, at first, this had been the preferred solution due to the ability of the dismounts to engage with small arms towards the front of the vehicle, in practice, the rear dismounts compartment of the Object 765 allowed for a far easier and safer exit of the vehicle through dual rear doors. In this configuration, the dismounts would not have to exit from the top of the vehicle, which could be incredibly dangerous when under fire. The buoyancy of the Object 911 was also found to be overall lacking, with the vehicle being fairly unstable in water.

Conclusion – An Original Solution, Quickly Ditched

In practice, it appears the Object 911 was one of the first vehicles to no longer be considered for adoption, alongside the other vehicle which used a mixed tracks and wheels drive, the Object 19. One can fairly easily identify the reason behind the rejection of these vehicles. The dual drive would result in increasing complexity in a vehicle which would typically perform worse than a wheeled vehicle in areas generally favorable to wheeled vehicles, and worse than tracked vehicles in areas generally favorable to tracked vehicles.

Despite this rejection, the Volgograd Tractor Plant was not entirely out of the field of infantry fighting development, largely due to the parallel development of the more conventional Object 914. In comparison to the Object 911, the more standard Object 914 had more satisfying results and appeared to have been seriously considered for longer, though, eventually, the vehicle picked would be the more novel Object 765. Volgograd Tractor Plant would still obtain a notable success in the following years in the form of the Object 915, a small and light infantry fighting vehicle which was adopted as the airborne BMD-1.

As for the Object 911, it was not, for the time, an evolutionary dead-end, as alongside the infantry fighting vehicle, a light tank would be designed using the same chassis. This would be the very low Object 911B, which appears to have ditched the wheels drive entirely and featured a small two-man crew entirely present in the turret. As with the Object 911, it would also not be adopted for service. The Object 911 has been preserved in the Kubinka Armor Museum up to this day.

Object 911 specifications
Dimensions (L-W-H)	6.735 x 2.940 x 2.040 m (maximum ground clearance)
Ground clearance	96 to 456 mm (adjustable)
Combat weight	12.07 tonnes
Engine	UTD-20 6-cylinders 300 hp diesel engine
Suspension	Adjustable pneumatic springs
Transmission mount	rear
Forward gears	5
Road wheels (tracks)	5 per side
Wheels configuration	4×2
Wheels diameter	840 mm
Steering wheels	Front
Maximum speed (road)	57 km/h on tracks, 108 km/h on wheels
Cruise speed (road)	70 km/h on wheels
Maximum speed (water)	10.3 km/h
Range	350-500 km (dirt roads, tracked drive) Up to 1,350 km (highways, wheeled drive)
Crew	2 (driver, commander/gunner)
Dismounts	8
Main gun	73 mm 2A28 ‘Grom’ with 40 rounds
Autoloader	Electrically-driven horizontal conveyor belt
Secondary armament	Coaxial 7.62 mm PKT with 2,000 rounds
Missile armament	9M14 Malyutka ATGM with at least 2 missiles, possibly more
Effective armor protection	Heavy machine gun fire (frontal arc), rifle-caliber projectiles and artillery shells splinters (sides and rear)
Numbers produced	1

Sources

Solyankin, Pavlov, Pavlov, Zheltov. Otechestvennye boevye mashiny vol. 3
73-мм ГЛАДКОСТВОЛЬНОЕ ОРУДИЕ 2A28 Техническое описание и инструкция по эксплуатации (73-mm SMOOTHBORE WEAPON 2A28 Technical description and operating instructions)
БОЕВАЯ МАШИНА ПЕХОТЫ БМП-1 ТЕхничЕскоЕ ОПИсаниЕ И ИНСТРУКЦИЯ ПО ЭКСПЛУАТАЦИИ (COMBAT VEHICLE INFANTRY BMP-1 Technical Description AND THE OPERATING INSTRUCTIONS)
Bronya Rossii (Russia’s Armor) Episode 8
BMP-1 field disassembly, Tankograd
skylancer7441’s archive
Kubinka tank museum website

With special thanks to Alex Tarasov and Pavel Alexe for their help in researching and writing this article

Soviet Union (1963-1964)
Light Tank – 1 Prototype Built

The evolution of warfare and technologies in the years following the conclusion of the Second World War had a major impact on the way warfare would be conducted in the future. With the proliferation of nuclear armament, radiation protection became a major feature for new vehicles. Operations in the Second World War also showed that river crossing could sometimes prove difficult, as these could form major natural blocking points that most armored vehicles would find impossible to cross outside of a few heavy and sturdy bridges. Amphibious vehicles would prove to be a major asset to cross rivers even outside of these bridges, or in the event that they were destroyed or heavily defended. Many amphibious light tank designs were created in the late 1940s to early 1960s. The Soviet design bureau of the Stalingrad/Volgograd tractor plant was behind several of them. The most famous is without a doubt Object 740, which became the PT-76, the most produced light tank of the Cold War. In the early 1960s, Volgograd would design a prototype infantry fighting vehicle for the program which would lead to the BMP-1. A light tank prototype would also soon follow using the chassis and suspension of this infantry fighting vehicle. The infantry fighting vehicle prototype was designated Object 911, and, as such, the light tank would be Object 911B. Both included some innovative or original features, but none would be adopted by the Soviet military.

Volgograd’s Object 911 and 906

The idea of a combat vehicle that would combine amphibious capacities, a dismounted infantry complement, and an armament that could provide fire-support to these infantry dismounts and accompanying tanks was developed in the late 1950s Soviet Army. A formal call for prototypes fulfilling this role to be designed was issued by the GBTU (The General Armored Directorate, the service in charge of armored vehicles procurement) on October 22nd 1960. The requirements were sent to a large number of design bureaus, and, at that time, called for an 11-12 tonnes vehicle that would feature a crew of 2 and transport 8 to 10 infantry dismounts.

One of the manufacturers which began work on a design was the Volgograd tractor plant (VgTZ). Volgograd had extensive experience in amphibious vehicles design from the PT-76, which it had been producing since the early 1950s, and of which a number of derivative designs had already been designed.

Volgograd’s proposals, by 1963, took the shape of two distincts prototypes, the Object 911 and the Object 914. The Object 914 took the clear basis of the PT-76 chassis. The Object 911, however, was more distinct. Though there was still PT-76 inspiration and a number of common parts, such as the hydrojets and road wheels, the vehicle differed massively in other aspects. Likely the most noticeable were the four large, retractable aviation wheels which could give the Object 911 a wheeled drive, intended for use on roads during transfers to increase maximum speed and reduce fuel consumption. Object 911 also used an adjustable suspension which could be used to change the ground clearance of the vehicle.

In the same timeframe as it worked on infantry fighting vehicle prototypes, Volgograd had also designed and produced three prototypes of the Object 906. This was a vastly modernized and improved design based on the PT-76. It included a new, more powerful diesel engine, as well as an autoloaded 85 mm gun which significantly improved firepower in comparison to the PT-76’s 76 mm gun, particularly against armored targets and at range.

The Object 911B

By 1963, the Object 906 was at the testing stage with three prototypes, and would eventually be rejected within the year. At the same time, work had concretized on the Object 911, and manufacturing of the prototype took place within this year.

If the Object 911 was to be adopted, it had been made clear by the GBTU’s requirements that the vehicle’s chassis was to be used for a whole family of various derivatives. This could, for example, include a light amphibious tank, something Volgograd had extensive experience with. The other Volgograd prototype from the program, the Object 914, used a more conventional drivetrain which could perhaps be easier to modify into derivatives. But, being very similar to the PT-76, there would be little reason to design a light tank version of the Object 914, seeing as the Object 914 could already be described as an infantry fighting version of a light tank. In comparison, the Object 911 could provide a more interesting base, particularly as the vehicle had an overall low profile enhanced by an adjustable height suspension.

Volgograd had already worked on a very low-profile amphibious light tank in the form of a derivative of the Object 906. This was the Object 906B, which was armed with a 125 mm tube missile launcher and featured two crewmembers in the turret. While work on the Object 906 and the Object 906B was discontinued during 1963, re-using components from them, notably the autoloader from the Object 906 and the general layout of the Object 906B, could prove valuable.

As such, in 1963, the designing of a light tank version of the Object 911 would be carried out. The resulting vehicle would be named Object 911B. While using the chassis of the Object 911, it introduced a large variety of changes, not all directly linked to its function as a light tank. While keeping the same 73 mm Grom armament, it took inspiration from the Object 906B’s layout and the Object 906’s autoloader. A prototype of the Object 911B would be manufactured and tested in 1964.

The Object 911B’s Hull and Armor Layout

The Object 911B was a particularly low vehicle. Its height would vary between 1,265 mm and 1,615 mm depending on the set height of the suspension. This was particularly small. At its lowest, the height of a child, and even at its highest, the height of an average to small man. This would result in increased survivability, as the vehicle would be a hard target to hit at range, though at the same time creating proper crew conditions with such a low profile could be difficult. Length was 7.1 m, and width was 2.8 m. The weight of the Object 911B when loaded with crew, fuel, and ammunition would have been 12.5 tonnes. Thanks to its fairly small dimensions and reduced weight, the Object 911B was air-transportable by the Antonov AN-12.

The Object 911B used a peculiar hull and armor layout in order to increase the survivability of the vehicle and crew. This is typically not an easy task on a light amphibious tank, which has to use light armor protection and cannot afford to have large, thick metal plates in order not to compromise buoyancy and to retain a light weight.

To the front of the vehicle was what is typically described as a “cargo compartment”. This section was quite long, and did not contain any vital parts necessary for the vehicle to function. This storage space was reportedly capable of containing two men lying down, which could allow Object 911B to evacuate wounded servicemen. One can also imagine this feature may have been used to evacuate the crew of another knocked out or broken down Object 911B, seeing as the vehicle had a crew of two. The cargo compartment’s possible use to transport personnel in emergencies is further supported by the presence of two access hatches on the roof sides. When empty, the large size but low weight brought by this compartment would likely also help with the Object 911B’s buoyancy. The armor protection of this part of the vehicle can only be described as minimal. The front plate was only 10 mm thick, angled at 45° towards the back, while the roof was 6 mm thick and the floor a mere 4 mm. The sides likely had the same 10 mm thickness as the front, but without the considerable angling of the front plates

Behind this cargo compartment would be the crew compartment. The two were separated by an armored bulkhead. Being 35 mm thick, though mostly vertical with no or minimal angling, this bulkhead was actually intended to be the main frontal armor of the vehicle’s hull. An advantage of its position inside the vehicle was that it covered significantly less space, and as such, was much lighter than a similar armor layout applied to the front of the vehicle. When added to the 10 mm of the front armor and the considerable empty space of air separating it from the 35 mm bulkhead, this armor layout was actually quite considerable for a light infantry tank, and would typically protect the crew from heavy machine-gun fire, and often even autocannons. The front armor of the turret, which would not benefit from the 10 mm of armor of the cargo compartment and spacing separating it from the bulkhead received 40 mm of armor angled backward at 48° frontally, and 40 mm angled backward at 30° on the sides, with the same thickness to the rear. The hull sides were also quite thickly armored, with 45 mm on the upper sides and 20mm on the lower sides. The roof and floor of the crew compartment were also thicker, at 10 mm each. The crew compartment, within the vehicle’s turret, contained the two crewmembers, a driver to the right and a commander/gunner to the left.

The crew compartment was then separated from the rear compartment by another 35 mm bulkhead. The vehicle’s powerplant and transmission were to the rear. This part of the vehicle had the same light armor layout found on the front cargo compartment. The floor was 4 mm thick, while the roof and rear were 6 mm, and the sides likely 10 mm. The lower rear plate was angled at 48°, while angling on other plates was inexistant or minimal. This light armor protection was a necessity to keep weight down, but penetrating hits in this section of the vehicle would obviously be much more damaging than in the cargo compartment, easily leading to the vehicle’s engine being damaged or destroyed.

Engine and Transmission

The Object 911B used the same UTD-20 diesel engine as had been used on the Object 911. This engine had previously been set as part of requirements sent to different manufacturers to produce an infantry fighting vehicle prototype and all competitors to the Object 911 also featured it. It produced 300 hp at 2,600 rpm, and reached its maximum torque output of 981 N.m at 1,500 to 1,600 rpm. Without any fuel or oil, the engine weighed 665 kg, and had a consumption of 175 to 178 grams of fuel per hp and hour. A total of 500 liters of fuel were stowed within the Object 911B.

An advantage of the UTD-20 was its limited size compared to its output, which was a very favorable feature for mounting it in light armored fighting vehicles such as the Object 911 or the Object 911B, allowing for the very low silhouette adopted by the vehicles. The engine was used to drive a rear transmission. The Object 911B’s transmission used a two-disc main friction clutch, composed of dry steel and asbestos, a two-flow non-differential gear and rotation mechanism, and two single-row planetary on-board gearboxes. The Object 911B used a two-shaft, 5-speeds gearbox. It was reversible, meaning the vehicle could drive with the same maximum speed and gear ratios backward. The vehicle was also capable of neutral steering.

In addition to this engine and transmission, the Object 911B also featured two hydrojets. These were found in the rear sides of the vehicle. They were taken straight from the PT-76. These hydrojets were powered via a driveshaft with a reducer, linked to the gearbox, and would allow for far quicker movement on water than vehicles using merely tracks or wheels for amphibious crossings. A trim vane could also be deployed to prevent waves from washing over the vehicle.

Suspension and Drivetrain

The suspension of the Object 911B was directly based on the one found on the Object 911, but incorporated a number of changes. A standout feature of the Object 911 had been its four retractable aviation wheels, which allowed for wheeled drive. The advantages of such a design were higher maximum speed and reduced fuel consumption when driving on roads, which would prove useful out of combat. However, it led to increased complexity in production, maintenance, crew training, and cross-country mobility. As such, these retractable wheels were removed from the Object 911B’s design.

The Object 911 also included another innovative feature, an adjustable suspension. This was found to be less of a hassle, while at the same time having more uses, including in combat, and as such was retained on the Object 911B.

The suspension of the vehicles was not exactly identical. The Object 911B was longer and had a longer track run, and as such used an additional road wheel, bringing the number to six per side. These were stamped steel hollow road wheels, the same type as used on PT-76, or at least a very similar type. Their main advantage was that their hollow construction both saved weight and improved buoyancy. Each road wheel was mounted on a suspension arm of which the movement was assured by a pneumatic suspension. The suspension’s height could be adjusted and considerably lowered. The highest ground clearance the Object 911B could raise itself to was 450 mm, which was more than any other Volgograd amphibious tank design from the era, including the PT-76 and the Object 906. When fully lowered, the ground clearance would be reduced to 100 mm. These changes in ground clearance would result in the Object 911B’s height varying from 1,625 mm to 1,265 mm. The higher ground clearance would be useful when the vehicle was driving over rough or irregular terrain, preventing risks of the lower hull being stuck on an obstacle, which would damage it or result in the vehicle losing track tension and getting bogged down and stuck. The lower ground clearance, on the other hand, would have the obvious advantage of significantly reducing the already tiny silhouette of the Object 911B. The vehicle’s drive sprocket was mounted to the rear, with a front idler. As on the Object 911, three return rollers, made of aluminum, were also present.

The tracks used on the Object 911B reportedly varied from the RMSH type used on the Object 911.

Crew compartment and turret

The crew compartment of the Object 911B was mostly in the vehicle’s turret. Both crewmembers were seated in this turret, with the driver to the right of the gun and the commander/gunner to the left. The turret had a frustoconical shape. It was of a fairly wide but very low design, differing significantly from the standardized turret featured in the Object 911.The turret rotation speed seems to have been of 30 degrees/second.

The low height of the vehicle likely resulted in the turret being quite cramped. Taking the minimum height and ground clearance of the vehicle into account, the vehicle must have been at most 1.15 m from hull floor to turret roof, not even accounting from the spacing which would exist between the floor and the seat’s bottom. This particularly low profile, though it could be commended in a way, necessitated for men of below-average height to operate the vehicle reasonably.

Comprehensive work was invested in making the crew compartment safe against nuclear threats. It was given good insulation, using special materials in addition to the steel. The Object 911B also included a radiation and chemical reconnaissance device, which would be able to measure level of radiation in an area and would be able to automatically shut the hatches if the nuclear elements that precede the shockwave of a nuclear detonation were detected.

Other equipment fitted inside Object 911B included four thermal detectors present in the cargo compartment and a further two in the engine compartment. If excessive heat was detected, these would trigger a fire extinguisher that spat out an extinguishing chemical mixture. A 2 l cylindrical container for this mixture was present in both the cargo and engine compartment.

The crew compartment featured the R-123 high/very high-frequency radio transceiver, by this point a new introduction in Soviet vehicles, which could assure communications at ranges up to 20 km on two bands. The radio antenna was on the left side of the turret. It was coupled with an internal R-124 intercom system for communications between the gunner/commander and driver. It also featured a TNA-2 navigation device and a “Brusok” encryption device for the vehicle’s outside communications. Power for this electrical equipment was provided by a 5 kW VG-7500 generator that powered two 12ST-70 batteries. 10 F1 fragmentation hand grenades, as well as a signal pistol with ten cartridges, were also stored within the crew compartment.

Crew Positions

The gunner on the Object 911B was located to the left of the gun. Right on top of his head was a fairly large rectangular hatch he could enter or exit from.

Vision devices at the gunner’s disposal included a large periscope to the front and three TNPO-170 prismatic periscopes to the side. The gun was automatically loaded, but could also be loaded manually, a task he would handle if the autoloader was no longer working. Sources refer to the vehicle’s main sight as the PKB-62, with a field of view of 15° at day and 6° at night. This appears identical to the 1PN22 combined day-night sight used on the Object 911, and this may simply be two different ways of referring to the same sight. If the 1PN22 was indeed used, this sight had two channels, one for day and one for night, which would be toggled by rotating an internal mirror. The gunner would look through the same eyepiece in any case. Using the day channel, the sight had a magnification of 6x and a field of view of 15°. The night channel had a magnification of 6.7x and a field of view of 6°. It had a three-stage light intensifier system that would amplify light by 50,000 to 75,000 times. It also featured vastly simplified lead and range corrections scales in order to ease night firing.

The driver had by far the most peculiar position on Object 911B. His seat, as well as the controls, were placed in a sort of ‘bathtub’. This ‘bathtub’ itself rotated within the turret. It would systematically remain aligned with the front of the tank. This was meant to allow the driver to always look straight in the position he was driving towards, but on vehicles with similar devices, such as the MBT-70, this is known to have made drivers disorientated and sick, and this may have been an issue here as well. Advantages included much better visibility for the driver, as well as, in most vehicles, resulting in less chances of crew casualties from anti-tank mines (mines would usually explode under the first road wheel, which the driver would be further away from thanks to his placement in the turret – the presence of the armored bulkhead would also grant protection against fragments). In the matter of crew survivability, the driver being in the turret could also usually escape the vehicle faster, and there would be no risk of the opening of his hatch being compromised by the gun barrel at an unfortunate time.

When reversing, this crew position was even more peculiar. A mechanism was built within the transmission gear mechanism to allow the vehicle to be driven in reverse. When wanting to reverse, the driver would be able to disconnect the clutch and pedals of his position, which t would then rotate 180°, and the controls would then be reconnected to the gearbox. In this fashion, when reversing, the driver would face towards the rear and could look straight towards where he was driving, making this essentially quite similar to driving towards the front.

When it came to vision, the driver had three TNPO-170 prismatic periscopes as well as a TVN-2B night vision device to enable safer and easier night driving. The position’s periscopes were placed on a cupola which was slaved to the movement of the driver’s position inside the vehicle, so as with the driver’s position, they would always face in the direction the tank was driving, regardless of the turret’s position.

Armament

The main armament of the turret was a 73 mm 2A28 Grom low-pressure smoothbore gun. This was a fairly short gun, with a 2,117 mm tube and 2,180 mm total length. The design was overall made to be very simple and light. For example, it lacked any bore evacuator, and the gun fumes were instead to be evacuated from the turret, which featured a ventilator for this purpose. The gun overall weighed only 115 kg and had an average barrel life of 1,250 rounds. The recoil mechanism of the Grom was contained in an armored sleeve, wrapped around the base of the barrel. Gun elevation angles in the Object 911B extended from +30° to -3°, which was limited even by Soviet standards. The gun could elevate electrically and manually.

There was only a single shell type available to the 2A28 Grom in the 1960s, the PG-15V. It used the PG-9 HEAT anti-tank grenade already used by the SPG-9 73 mm recoilless gun, but swapped the original propellant charge with a more powerful PG-15P, which was meant to ensure a longer effective range. The projectile was fin-stabilized and featured a rocket engine towards the rear, with propellant present towards the middle of the grenade. This allowed it to reach a higher speed than would typically be expected from a gun as short as the Grom, with a maximum velocity of 655 m/s.

The explosive charge of the PG-9 grenade was a 322 g explosive mixture which would be equivalent to 515 g of TNT. An advantage of the PG-9 was that it featured a high standoff distance (i.e distance between the shaped charge and tip of the fuze) of 258 mm. In practice, this meant that, upon hitting a target, the jet of molten metal would have a significant length to take shape into a thin, dense jet. The results were a great armor penetration for the time and small size of the gun. The projectile’s armor penetration was officially rated at 300 mm at all ranges. In practice, this was slightly higher, as the official figure was based on the quantity of armor which would be pierced with the shell then having significant post-penetration effects inside. The maximum penetration achieved could vary between 302 and 346 mm, with an average value of 326 mm. In practice, this meant the Grom could quite reliably penetrate any tank operated by NATO in the 1960s.

The shell was not without issues, however. The downside of HEAT projectiles and a very short barrel were an overall low accuracy and high dispersion. The Grom’s PG-15V projectiles were notably very vulnerable to wind. The nominal maximum range of the Grom was of 800 m, but even at this range, only a 34% hit rate was achieved against a T-55 during trials. Even if this tank was quite smaller than most NATO tanks, in practice it can still be said a vehicle wielding a Grom would have to get to close ranges to use this gun effectively against armored targets. Additionally, during the 1960s, the PG-15V was the only available shell for the 2A28 Grom. HEAT shells are not purely anti-tank projectiles, and by nature also have some capacities against other targets. They can notably be effective when used against field fortifications and bunkers. However, due to their design focusing on producing a jet of molten metal in one direction, they offer very limited capacities when attempting to fire at infantry in the open. For the vast majority of vehicles, this would fairly easily be dealt with by simply shifting to a high-explosive fragmentation shell, but no projectile of the type would be available for the Grom until 1973.

The 2A28 Grom was fed by an autoloading mechanism. This was not the same as the crescent-shape conveyor present on the Object 911’s standardized turret design, which would contain all 40 73 mm Grom projectiles carried inside the vehicle.

While the Object 911B also had a 40 rounds ammunition stowage, its autoloader only held 27 at a time. The commander/gunner could feed more rounds into it once some were expended, or in the unlikely scenario all rounds within the autoloader were expended and no new shells had been placed into it, he could manually reload the gun as well. The autoloader mechanism was a horizontal electrically-driven conveyor belt. It would ensure a rate of fire of 9 rounds per minute. The autoloader could be installed or removed from the vehicle for repair or replacement via a special hatch.

The 2A28 Grom was supplemented by a 7.62 mm PKT coaxial machine gun. Mounted to the right of the gun, it would effectively be the only reliable means of dealing with infantry in the open. It fed to the right and ejected to the left. The PKT was fed from 250 rounds ammunition boxes and would fire at a cyclic rate of fire of 700 to 800 rounds per minute, at a muzzle velocity of 855 m/s. It would be able to expend two ammunition boxes in quick succession before the barrel would need to be replaced, or at least the firing interrupted for a bit to prevent overheating. A total of 2,000 7.62 mm rounds were stowed within the Object 911B.

Crucially, the Object 911B did not feature the 9M14 Malyutka missile or control system featured on the Object 911. This technically meant that the light tank was less armed than the infantry fighting vehicle, a considerable disadvantage. The Grom had a limited effective range, and while the Malyutka was not the most accurate or reliable missile, it was still a much better weapon to take out armored targets at longer ranges. Without the Malyutka, the Object 911B could only engage enemy armor within the reduced effective range of the Grom.

Trials and Performances

The Object 911B prototype was completed and trialed in 1964.

The vehicle was able to reach a maximum speed of 72.5 km/h on road. This was a considerable improvement from the Object 911 which would only manage 57 km/h on tracks. The main reason likely was the removal of the extendable wheels and changes to the suspension. On water, the vehicle could reach a similar maximum speed of 10 km/h, which was generally the norm for vehicles equipped with the PT-76’s hydrojet design. The maximum range on road was 500 km, similar to the Object 906 and exceeding the PT-76. Ground pressure was 0.42 kg/cm².

The vehicle’s armor protection was tested against two different threats. The first was against 76.2 mm projectiles fired at ranges of 2,000 m with a muzzle velocity of 665 m/s. These were likely kinetic projectiles fired from the PT-76’s D-56T (this velocity matches with the BR-350B and BR-354 APBC-HE shells, the latter of which was more common by this point in time). The frontal crew compartment armored bulkhead and turret armor were both found to resist penetration at this range. These were satisfactory performances. While the D-56T was not a very powerful gun and the projectiles were fired at a long range, a light amphibious tank is not a vehicle that is expected to resist armor-piercing weapons at pretty much any range, and indeed many vehicles fulfilling a similar role, such as the PT-76 or M551 Sheridan, would still be fairly easily penetrated even at this range.

More representative of the armament a light tank with good armor protection for the type may be expected to resist, the Object 911’s crew compartment was also tested against the 14.5 mm KPV. The weapon failed to penetrate both the front bulkhead and the hull sides. This was once again quite a considerable feat. The 14.5 mm KPV was one of the most powerful mass-produced heavy machine guns around, and if the Object 911B’s crew compartment was impervious to it, it would certainly resist NATO’s .50 cal Browning M2HB. In certain conditions, such as with some range and with imperfect firing angles, which are to be expected in combat, the crew compartment of the Object 911B may have stood decent chances to resist fire from many NATO autocannons of calibers around 20 mm, which would be an impressive performance for a light amphibious tank.

Conclusion – Interesting Performances with no Niche to Fulfill

Ultimately, the Soviet Army did not adopt the Object 911B, and work on the vehicle was discontinued after the trials ended in 1964.

A number of reasons can be found for the rejection of the vehicle. The most obvious was that the original Object 911 was not picked to become the BMP-1, being ruled out of the candidates due to complications with its drivetrain fairly early on. The other Volgograd prototype, the Object 914, was a more serious candidate but was eventually rejected in favor of the Object 765, which would become the famed BMP-1 that remains widely in use across the world today. There would have been little motivation in adopting a light tank derived from an infantry fighting vehicle which was rejected. Even though the Object 911B had significant parts commonality with vehicles already in service, such as the engine, road wheels, or armament, it would still lead to increased logistical complexity.

However, outside of these external considerations, the Object 911B had faults of its own. Some aspects of the vehicle were genuinely quite impressive, with the exceptionally low profile at the foremost. The armor protection given to the crew was also significant for a vehicle of the type. The crew of an Object 911B would have much more chances to survive enemy fire than the one of another amphibious light tank, such as the previous Soviet PT-76, the American M551 Sheridan, or the British FV 101 Scorpion fitted with a floatation device. Being able to resist heavy machine-gun fire or even light autocannons is significantly better than most vehicles of the type and would protect the Object 911B’s crew from some widely-encountered threats. This level of protection only extended to the crew, with the cargo and crucially engine compartment only being protected against rifle-caliber projectiles, but it was still significant.

However, the vehicle’s firepower was far too low to justify its existence. The Object 911B was only armed with the same 73 mm 2A28 Grom as the BMP-1 and a coaxial machine gun, and its lower profile and better armor protection could hardly create the need for it. In comparison, the BMP-1 would not only transport eight dismounts, but also feature a 9M14 Malyutka missile, which means it would be far better equipped to deal with enemy armor at range. Indeed, for all of the Object 911B’s advantages in survivability granted by its low profile and armor protection, these would be in large part negated by the need to be at small ranges for the Grom to have a good chance to hit enemy targets. At those ranges, enemy guns would have far lower difficulty to target the smaller profile of the Object 911B, and the vehicle would likely fall prey to most tanks before it could be at short enough range to target them unless it could be undetected until the moment it fired. While this would be easier for the Object 911B than pretty much any other tank, it is still not something to be relied upon, particularly if the vehicle was to be used offensively. The issues of disorientation that could arise from the driver’s placement in the turret were also not resolved.

In short, while very interesting in several aspects, the Object 911B did not fulfill any niche where a vehicle of its kind was necessary, and as such it is not surprising it was not adopted by the Soviet Army. Unlike the Object 911, the Object 911B does not appear to be preserved at the Kubinka Tank Museum, or at least not in its visitable parts, as no modern photos of the vehicle have emerged. It may have been scrapped, or still be preserved outside of public view.

Object 911B specifications
Dimensions (L-W-H)	7.100 x 2.800 x 1.625 to 1.265 m
Ground clearance	100 to 450 mm (adjustable)
Combat weight	12.5 tonnes
Engine	UTD-20 6-cylinders 300 hp diesel engine
Suspension	Adjustable pneumatic springs
Transmission mount	rear
Forward gears	5 (reversible)
Road wheels	6
Maximum speed (road)	72.5 km/h
Maximum speed (water)	10 km/h
Range	500 km (road)
Crew	2 (driver, commander/gunner)
Gunner’s vision devices	Main periscope 3 x TNPO-170 prismatic periscopes PKB-62 (1PN22 ?) sight
Driver’s vision devices	3x TNPO-170 prismatic periscopes in a rotating cupola facing towards the direction the vehicle is driving in TVN-2B night vision device
Main gun	73 mm 2A28 ‘Grom’ with 40 rounds (27 stowed in autoloader)
Autoloader	Electrically-driven horizontal conveyor belt
Secondary armament	Coaxial 7.62 mm PKT with 2,000 rounds
Hull armor	Cargo compartment: 10 mm/45° (front) 4 mm (floor) 6 mm (roof) Likely 10 mm (sides)Crew compartment: 35 mm (front bulkhead) 45 mm (upper sides) 20 mm (lower sides) 35 mm (rear bulkhead) 10 mm (roof and floor) Turret: 40 mm /40° (front) 40 mm /30° (sides) Likely 40 mm (rear) 10 mm (roof) Engine compartment: 4 mm (floor) 6 mm (roof and rear) Likely 10 mm (sides)
Effective protection of crew compartment	76.2 mm projectile fired at 665 m/s and a range of 2,000m (front bulkhead and turret) 14.5 mm KPV fire from all angles
Numbers produced	1

Sources

Solyankin, Pavlov, Pavlov, Zheltov. Otechestvennye boevye mashiny vol. 3
73-мм ГЛАДКОСТВОЛЬНОЕ ОРУДИЕ 2A28Техническое описание и инструкция по эксплуатации (73-mm SMOOTHBORE WEAPON 2A28 Technical description and operating instructions)
БОЕВАЯ МАШИНА ПЕХОТЫ БМП-1 ТЕхничЕскоЕ ОПИсаниЕ И ИНСТРУКЦИЯ ПО ЭКСПЛУАТАЦИИ (COMBAT VEHICLE INFANTRY BMP-1 Technical Description AND THE OPERATING INSTRUCTIONS)
BMP-1 field disassembly, Tankograd
skylancer7441’s archive

Soviet Union (1953)
Medium Tank – Blueprints Only

The STG was a tank designed by Soviet engineer Gremyakin around 1952 to 1953. It came as a proposal to the Ministry of Defence of the USSR, which wanted a new medium tank, but with the armor and firepower of a heavy tank, and with the dimensions and mobility of a medium tank. Gremyakin’s proposal did not get far, and it is likely that it was never given any official name, with no names in the blueprints, which are all that remains. It is now commonly known as the STG (Abbrev. of romanized Russian, Sredniy Tank Gremyakin, Eng: Gremyakin’s Medium Tank).

History

On 20th May 1952, the Defence Ministry of the USSR held a meeting with the heads of the largest tank plants and the Marshal of Armored Forces, Semyon I. Bogdanov, on the topic of modernization and development of new tank projects. Shortly after, on 18th June, the decision to develop a new medium tank was made. The chairman at the GABTU (Main Directorate of Armored Forces), V.V. Orlovsky, held a meeting with N.A. Kucherenko, who was part of the leadership of the tank production department of the Ministry of Transport Engineering of the USSR, and sent the requirements to several factories, including:

• Plant No.75 (Malyashev Factory), Kharkiv
• Plant No. 174 (Lenin Factory), Omsk
• Plant No. 183
• VNII-100 (research institute of Kirov Plant), Leningrad

It was meant to be superior to the T-54 in most categories, from firepower to range, to armor and speed. The T-54 itself was equipped with a 100 mm D-10T gun, very competent for the time. Armor was between 100 mm and 120 mm on the front hull (depending on the production model). The engine was a 520 hp ‘V-54’ water-cooled diesel engine.

The requirements were to be:

• Mass of 34 tonnes
• Initially, 100 mm or 122 mm gun, later on, a 100 mm D-54 rifle gun with 50 rounds of ammunition
• Width of 3,300 mm and height no more than that of T-54
• Ground clearance of 425 mm
• 3 x machine guns: 2 x 7.62 mm and a single 14.5 mm AA
• Maximum speed of at least 55 km/h
• Off-road speed between 35 to 40 km/h
• Power/weight ratio of 20 hp/tonne
• Range 350 km

Several proposals were presented, one of the most popular being the Object 907 medium tank, which featured an unusual flying-saucer-shaped hull.

Gremyakin presented his blueprints in June 1953. He was a qualified engineer considering the detail and quality of the blueprints and might have worked for Factory No.75, which had previously made several rear turreted medium tanks, like the Object 416, or the Chelyabinsk tractor plant, which also had experience with rear-mounted turrets.

Layout & Design

Gremyakin’s surviving blueprints show a low silhouette tank with a large, rear-mounted turret. The engine and transmission were mounted in the front, driving front-mounted sprockets. Both the front hull and front of the turret were very thickly armored but got progressively thinner towards the roof. The side and rear armor, however, was still very thick, especially in proportion to the front.

To keep height and weight down, the designer opted for some interesting solutions. Firstly, the use of externally mounted suspension, using a drum-shaped spring, freeing up internal space. The rest of the tank design was also extremely slim. The hull was only as tall as the engine required, and the turret, in typical Soviet fashion, only allowed for a couple of degrees of gun depression, since the turret roof was so low. Otherwise, the running gear and tracks were the same as those of other contemporary heavy tanks.

Placing the turret to the rear allowed for a shorter barrel overhang and better weight distribution. However, it created a host of other problems. The most obvious one was the driver’s placement in the turret, creating an awkward driving position, further cramping up the turret, and creating a hazard when escaping the tank in an emergency. Additional problems, like sight distortion caused by engine and exhaust heat and barrel damage from the engine cooling/intake, might also have been serious, but which can only be confirmed and addressed when reaching a working prototype stage – which Gremyakin’s invention, and many others alike, never reached.

The unusually small size of the tank was to be praised, considering it was well armored and had mounted a large caliber gun. Total height was 2,140 cm, length was 6,700 cm (excluding barrel), and 9,085 cm including the barrel.

Gremyakin’s tank compared to the T-54 and T-10:

Armament

The gun shown in the blueprints was actually a D-25T 122 mm gun. This could easily have been replaced by the 100 mm D-54 or 122 mm M-62, as found on the T-10. It is important to highlight this, as the tank was meant to provide heavy tank-like firepower. The D-25T was the same gun as on the IS-2 and many other WWII-era Soviet vehicles, rendering it obsolete for 1953. This suggests it was added as a placeholder for another gun, suiting the competition. Its ammunition was two-part, stored in the turret. The projectiles themselves were stored alongside the turret wall, starting from the side of the driver, all the way around to the commander. The shell cases were placed in front, and started from the gunner, and ended at the loader. This suggests that there was some kind of moving system for the shells to make them accessible.

As secondary armament, it seems like the tank had one co-axially mounted 14.5 mm KPVT heavy machine gun, probably loaded by the loader, but operated by the gunner. It is also possible that an external roof-mounted machine gun could be mounted, on a pintle, perhaps a 12.7 mm DShK.

Crew

The tank had a crew of 4: commander, gunner, loader, and driver. They were all located in the large turret, encircled by the ammunition.

The gunner sat to the left of the gun, on a seat attached to the turret, from where he could aim and fire the gun, plus use the standard turret controls. Besides the main gun sight, he also had a rotating sight above him for vision. The blueprints do not show a hatch for the gunner.

The tank commander sat right behind the gunner. He had 3 or 4 periscopes for vision and also (probably) controlled the radio.

The loader sat on the right side of the gun, loading with his left (usual in Soviet tanks). He had the excruciating job of handling the large ammunition within the very tight space. Thankfully, a loading tray was given, so that he could rest the round on it. Unlike the rest of the crew members, he was faced directly towards the gun. He had one entry/exit hatch with a rotating periscope. There was another hatch behind him, probably for easier access when reloading the tank with ammunition. The loader was probably also tasked with loading the coaxial machine gun, however, it must have been near to impossible due to the driver being in the way. This does raise the possibility the driver would reload the machine gun or some other kind of innovative system.

The driver’s position, however, is the most interesting. Located in the turret, in front of the loader, he was in what appears to be a rotating device on its own axis, independent of that of the turret, yet still spinning along with the rest of the turret, consequentially meaning that the turret had limited traverse. Of course, this is all speculation. He appears to have a rotating device instead of the traditional tillers or steering wheel.

Armor

For a medium tank, Gremyakin’s design was unrealistically well protected. The thickest part of the frontal hull plate was around 320 mm thick. Likewise, the base of the turret was a whopping 355 mm thick, gradually getting thinner as it rounded upwards, to around 60 mm at the roof. It gradually got thicker again towards the rear of the turret, with 280 mm of armor at the base. Even the rear hull armor was, at the thickest, 140 mm angled at 60°, for a total effectiveness of 150 mm. The thinnest part of the tank was the hull belly armor, at 25 mm.

This sort of protection was far superior to contemporary heavy tanks. The T-10 had 120 mm at the front. This begs the question if the tank could even remain around the 34 tonnes area. It was larger than the T-54 (apart from being slightly lower), but with significantly more armor in raw thickness alone.

Engine

The engine was of an unknown type, but to reach the desired 20 hp/tonne, it needed around 680 hp. This would point to the V-12-5 engine used on the T-10. The fuel tank was placed on the other side of the hull, behind the turret.

Suspension

The suspension of the design is very peculiar. Most Soviet tanks used torsion bar suspension, in one form or another. External suspensions were common in pre-war Soviet designs, but their use diminished during the Second World War, both in the Soviet Union, but also in other nations. Gremyakin most likely used external suspension to lower the height of the vehicle and improve maintenance and replacement of the suspension, one of the main drawbacks of torsion bar suspension. Yet what exact system he used is unknown. Externally, it looks like hydropneumatic suspension, similar to that used on some modern main battle tanks. But using hydraulics does not make much sense, and the Soviet Union would not use hydropneumatic suspensions on tanks until the 1960s in tanks like the Object 911 and Object 911B. The only such systems used in the 1950s were on the BRDM-1 and 2 armored cars.

The rounded shape of the suspension indicates to a very unique suspension system; torsion springs. These were used on some Italian tanks and armored fighting vehicles. It consisted of a flattened coil, but instead of mounting it vertically, it was mounted inwards. The movement and tension would not be exerted by compression, but by torque. The most basic use of such springs today is in clothespins.

Fate: Failure

Considering that it never even got a proper name, Gremyakin’s design never got very far. It was plagued from the start by cramping heavy tank armor and guns into a medium tank. Terrible crew ergonomics and little gun mobility were also compromises Soviet tank designers often took in order to keep height and weight down.

The largest drawback of Gremyakin’s design was ambition. The tank had so many innovative and challenging characteristics.

First was placing the driver inside the turret. This presented a very complex and expensive system, cramping the turret. In addition, it would give a very awkward driving position and compromise turret rotation. It was not a new concept, tanks like the Object 416 used it previously, but with little success.

Secondly, all the features and gadgets on the tank would increase its cost of production, maintenance and complexity. An ammunition pushing system, completely unique suspension to name a few.

Lastly, and most importantly, the armor of the design was, to say the least, excessive. While there is nothing unusual with thick angled armor, it was surely ambitious for a medium tank program with a 34 tonne weight threshold. This would have significantly increased the weight from a vehicle of the weight of the T-54 more to that of the T-10. To maintain its 20 hp per tonne power to weight ratio, it would have required a much larger, more expensive engine.

Other designs were selected for trials, like the Object 907 medium tank from VNII-100. However, none of these tanks offered a substantial improvement over either the T-10 and T-54 tanks. Both of those tanks were already in service and were excellent at what they were designed for, not allowing any room for a very expensive medium-heavy hybrid.

Sources

TsAMO state archives
Опытный средний танк “Объект 907” (topwar.ru)
M.V. Pavlov, I.V. Pavlov. Domestic armored vehicles 1945-1965
С боевым отделением в корме: yuripasholok — LiveJournal

STG specifications
Dimensions (L-W-H)	≈ 5 x ≈ 3.5 x ≈ 2 m (excluding barrel)
Total Weight, Battle Ready	≥34 tonnes
Crew	4: Commander, Gunner, Loader, Driver
Propulsion	≈ 680 hp, possibly V-12-5
Speed	≈ 35 – 55 km/h
Armament	1x 122 mm D-25T or 122 mm M-62 Coaxial 14.5mm KPVT heavy machine gun Potential roof-mounted 12.7 mm DShk heavy machine gun
Armor	Approx: Front: 200 mm Side: 100 mm Rear: 100 – 120 mm