Categories
Fake Tanks WW2 German Fake Tanks

Jagdpanzer E100

German tanks ww2 Germany (1944)
Hypothetical Tank destroyer – None built

The E100 super heavy tank is one of the most fascinating tanks of Nazi Germany. While it does not have near-mythical combat legends of the Tigers or the sheer weight of the Maus, its partially built hull was impressive enough to cement it into tank history for decades to come. The obscurity and nature of the project have resulted in a vast number of speculatory conversions and what-if modifications. One of these gray areas is the Sturmgeschütz E100, a short-lived plan of converting the E100 into an assault gun. Unfortunately, there are no remaining blueprints of the layout, which has left the appearance of this vehicle up to much debate. The most well-known representation is that with a rear-mounted casemate, made famous by Wargaming’s game, World of Tanks (WoT).

Wargaming used the Sturmgeschütz to fill in their Tier X German tank destroyer line in WoT. Due to the popularity that the game enjoyed throughout the 2010s, WoT quickly became a centerpiece of information and an introduction to tanks for most amateur tank enthusiasts, making the wrongly-named Jagdpanzer E100 what most think of when mentioning an E100 based self-propelled gun.

History

WoT provides a short but somewhat inaccurate bit of historical information on the vehicle:

“The E100 was conceived as the basis for a self-propelled gun, an antiaircraft vehicle, and a tank destroyer. However, development was never started.”

There were never any plans to build an anti-aircraft vehicle based on the E100 hull (or the Maus, for that matter). Many such designs have appeared online, but they are fake.

Likewise, there were never any plans to make an artillery self-propelled gun based on the E100, although that fake vehicle also made it into the game in the form of the Geschützwagen E100.

There was work made by Krupp and Porsche on an enclosed direct-firing self-propelled gun, but that particular vehicle was meant to be a Sturmgeschütz (an assault gun) and not a Jagdpanzer (tank destroyer). This was called the 15/17 cm Sturmgeschütz auf E100 Fahrgestell (15/17 cm Assault Gun on E100 Chassis). The project started on 9th May, 1944, when Porsche and Krupp representatives met to discuss the issue of a new heavy assault gun. Krupp showed plans for mounting either a 15 cm L/63 or a 17 cm L/53 gun inside a fixed casemate on a Maus chassis. This was in competition to what another firm, Adler, had planned, which was to mount these guns inside a fixed casemate, but on an E100 chassis. The production quota officer, Obering Hendel, preferred the E100 design over the Maus, as the Maus hull was significantly taller, and with a casemate mounted, would not fit through the standard railway tunnels of the time.

On 28th May 1944, it was requested that Krupp should build a 1:5th scale wooden mock-up of the E100 chassis Sturmgeschütz, with both gun variants.

Unfortunately, the only surviving blueprints from this program is the one showing the 150 mm gun mount, leaving the position of the casemate to much debate.

The plans for mounting the 15cm L/63 gun on the E100 chassis. Source: Warspot

The possibility that this program would have transformed into a Jagdpanzer E100 is not at all lacking if the program would have continued. While the name is unhistorical, many German Jagdpanzers started their life as Sturmgeschütz, such as the Ferdinand, Jagdpanzer IV, Jagdpanther and Jagdtiger. The difference between a Sturmgeschütz and a Jagdpanzer was not a matter of construction or shape, but a matter of deployment and doctrine. However, the Sturmgeschütz E100 project was terminated before the Panzerwaffe could steal it from the arms of the Sturmartillerie.

HD model of the Jagdpanzer E100 in WoT. Source: FTR

In World of Tanks

In WoT, the Jagdpanzer E100 has a large, thickly armored superstructure at the back of the hull, in a similar fashion to that of the Ferdinand, with the engine compartment being moved towards the middle of the vehicle. The crew consists of 6 men, a commander, a driver, a gunner, a radio operator, and 2 loaders. It is armed with a 17 cm Pak, most likely inspired by the real 17 cm Stu.K. L/53 gun. It can carry 24x 170 mm rounds and reload a shell in around 25 seconds. The engine is a “Maybach Neues Projekt” with a 1,200 hp output, allowing the 134-tonne vehicle to reach a maximum speed of 30 km/h. It is crucial to note that these numbers always change in attempts by the game developers to balance the vehicle within the game environment, and are often quite far from reality, but understandable from a gaming point of view.

The Maybach Neues Projekt name is most likely fictional, but there was actually a 1,200 hp engine for the E100. This was called the HL 234, a supercharged variant of the HL 230. It was to be coupled to an 8-speed Mekydro transmission. However, with these components, Adler moved the transmission and drive sprocket to the back, meaning that, on the E 100 tank version, the turret was moved forwards, requiring a longer hull – a very different look to the original E 100. Sadly though, Adler destroyed their plans at the end of the war to avoid capture. A rear transmission would also make it incompatible with the rear-mounted casemate possibility for the Sturmgeschütz. On the Jagdpanzer E100, the engine has been moved to the middle of the vehicle in order to make room for the superstructure at the rear.

At the rear left on top of the superstructure, a small turret was added, with what seems like a lower caliber autocannon or heavy machine gun. Within the game, it does not operate. Such an idea is sensible for a fixed casemate vehicle its size in order to protect the vulnerable rear and left side. On the side of the casemate, small pins can be seen. These would have held up track links. The 1,100 mm wide track links would be impossible to be mounted/dismounted by hand from that position. Therefore, a small crane would be required, often shown on different models.

The tank destroyer in WoT is extremely well armored, with 250 mm at the front of the superstructure, and 150 mm towards the sides and rear. However, this, along with the heavy gun breach and ammunition, would have placed considerable strain on the rear suspension. While the real armor thickness for the Sturmgeschütz are unknown, the surviving mantlet blueprints indicate that the rounded ball mount behind the mantlet was around 120 mm thick. The thick, angled frontal plate of the casemate would be around 200 mm thick. Side and rear armor of the casemate is up to speculation, but they would likely have been rather thin (around 80 mm) to keep the weight down and eliminate stress from the rear wheels, as was done on the real E100 turret.

Jagdpanzer E 100 as seen is WoT, rear view.
Source: Ilya Lezhava

Armament

In WoT, the Jagdpanzer E 100 has a 17cm PaK, inspired from the 17cm StuK L/53 gun. Krupp wanted to avoid using this gun as much as possible on the heavy Sturmgeschütz design, mainly because of its weight, but also the size of the breech and ammunition, which required a large casemate. On 29th April 1944, General Heinz Guderian requested that the penetration should be 200 mm at 4,000 meters. Essentially, this would have meant being able to knock out even the heaviest of Allied tanks from 4 km! Unfortunately, because most of the information around the 17cm L/53 is based on salvaged papers, data about its performance and shells is scarce.

Mechanical aspects

The placement of a rear casemate on the E100 would come with a host of mechanical challenges, none of which would be possible for Germany to manage at the time. According to former Wargaming historian, Yuri Pasholok, the Combined Intelligence Objectives Sub-Committee (CIOS) claimed that the transmission and drive sprockets were moved to the rear.

Moving the engine to the middle of the tank would be a complex task, but not impossible.

The placement of a well-armored casemate so far back would have moved a great deal of weight towards the rear wheels, but due to the heavy gun and thick armor resting on the center wheels, this might have balanced out. This did have the advantage of shortening the overhang of the gun over the hull, reducing problems in narrow spaces, such as streets and forests. The Soviet SU-100, a much smaller vehicle, experienced such issues.

The heat from the engine would distort the view of the gunner and could potentially warp the gun, another issue found with many rear casemate tank destroyers.

There would be a host of mechanical changes to the E100 hull that had to be made, increasing production time and cost. These would be adjusting transmission and drivetrain, adjusting the suspension to the different balance points, changing air intake and exhausts positions, etcetera.

This entire process had already been encountered in the Jagdtiger program. There was actually a proposal of having the Jagdtiger casemate in the rear of the hull and the engine in the middle, the Tigerjäger B, but the issues stated above, among others, led to a central casemate for the Jagdtiger to be chosen.

In recent years, model kit companies have even released models in 1:72 or 1:35 scale of the Jagdpanzer E100, further cementing the rear-mounted casemate alternative as the most popular one.

Conclusion

Veteran historians and casual tank enthusiasts have been discussing this vehicle for years and we may never know for sure how a tank destroyer or assault gun based on the E100 would have looked like. It remains one of the many fascinating and impressive projects to come out of Germany in the Second World War, alongside a similar project for the Maus and vehicles such as the Kugelpanzer. It is the simple fact that so little is known about it that allows one’s imagination to open up. The details that are known are also simply sensational, from the large gun to the heavy armor of the E100. However, it should be remembered that, behind these impressive numbers, equally impressive mechanical and engineering problems lay, which were not solved by the Germans even for their lighter vehicles. The Sturmgeschütz E100’s appearance in Wargaming’s video game, even under a false name, only boosted its fame within the tank community.

TheJagdpanzer E100 as commonly represented. Illustration by Pavel Alexe.

Jagdpanzer E100 specifications

Total Weight, Battle Ready over 134 tonnes
Crew 6 (Commander, Gunner, Radio Operator, Driver and 2x Loaders)
Propulsion Maybach Neues Projekt or HL 234
Speed 30 km/h
Armament 17 cm StuK L/53
Armor 250 mm max

Sources

https://wiki.wargaming.net/en/Tank:G72_JagdPz_E100
https://tanks.gg/tank/jgpz-e-100/model
https://warspot.ru/4351-sverhtyazhyolye-bumazhnye-istrebiteli-tankov
Frohlich, M. (2015). Schwere Panzer der Wehrmacht. Motorbuch Verlag, Germany
Jentz, T., Doyle, H. (2008). Panzer Tracts No.6-3 Schwere Panzerkampfwagen Maus and E 100.
https://warspot.ru/5659-bronetehnika-iz-taynyh-podvalov

Categories
Cold War Soviet Prototypes

Gremyakin’s Medium Tank (STG)

Soviet Medium tank (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.

Armor profile of T-54A, which also appeared in 1953. It was greatly inferior to that of Gremyakin’s tank, while still a larger tank.
Source: M.V. Pavlov, I.V. Pavlov. Domestic armored vehicles 1945-1965

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.

Surviving blueprints of the side of Gremyakin’s tank. Note the in-arm external suspension.
Source: Alex Tarasov

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 14.7 mm KPV 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.

Previously unseen plans of Gremyakin’s design, showing it from the top. Note the angling of the hull towards the edges and hatches.
Source: Alex Tarasov

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.

Top view of the turret, essentially the entire crew compartment. Note how the crew is encircled by ammunition, however considering the turret’s very thick armor, it is not as bad as it might originally seem.
Source: Alex Tarasov

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.

Torsion springs used on the Italian CV38.
Source: Unknown

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.

Plans of the Object 907 medium tank, also designed as a medium tank with heavy tank armament and armor. Despite complicated hull shape and extreme angles it did not offer a huge advantage over existing tanks.
Source: M.V. Pavlov, I.V. Pavlov. Domestic armoured vehicles 1945-1965
Illustration of the Gremyakin medium tank (STG) by Pavel Alexe, funded through our Patreon campaign.

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 14.7mm KPV 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
Categories
WW2 French Prototypes

Char de Forteresse ARL

France  (1939)
Super heavy tank – Blueprint only

In 1937, the French military requested the design of heavy breakthrough tanks to be able to take on the German Westwall Line being built alongside the French border, vis-à-vis the Maginot Line. This was the Char Lourd (Eng: Heavy tank) program. Three companies presented designs, ARL, AMX and FCM, but the program was halted, as the tanks would have been too expensive, and too few could have been built to have any significant impact on the battlefield.

So, naturally, the weight limits were lifted, allowing the companies to create even heavier and more expensive designs.

History

The authorities were most impressed by the design of the FCM F4, granting, in February 1938, some changes in the requirements: A 75 mm gun in the turret and no weight limits. As a result, the French Supreme Command granted FCM, on 6th April 1938, a contract for the development of such a super-heavy tank; the Char F.

Simultaneously, a commission headed by Julien François René Martin reanalyzed the threat presented by the Westwall, urging the revival of the Char Lourd program. These new versions would be differentiated by being called Char d’Attaque des Fortifications (Eng: Fortification Assault tank). The new design should have had a gun in the turret, suitable for close-range fire, and be immune to the best anti-tank guns in Germany at the time. Hence, speed was not of importance, with a 10 km/h top speed seen as satisfactory. In addition, it was to have outstanding trench, ditch, and river crossing capabilities, leading to a very long vehicle. In April 1938, the High Command approved the plans and dispatched another commission, with the task of fine-tuning the requirements and figuring out if the 45 tonne Char Lourd program could have been revived instead of making new, heavier designs.

Second Commission’s first meeting

On 4th May 1938, the Direction des Fabrications d’Armement (Eng: Armament Production Department) wanted to call this new program the Char H, but it was rejected, so as to not bring confusion with the Hotchkiss H35 tank. Five days later, the second commission, at its first meeting, wanted to make two types of tank, a 45-tonne tank and a superheavy tank. French author Pierre Touzin states in his book, ‘Les véhicules blindés français, 1900-1944’, that the commission wanted the tanks to be immune to at least 47 mm guns, so they agreed on 120 mm armor thickness. They would also give the option of 75 or 47 mm guns (or a combination of both) in a turret or more. The 75 mm would only be required to have a muzzle velocity of 640 m/s. The secondary armament had to include a flamethrower. However, the Commission did acknowledge the dangers and space taken by the flammable fluid, but they also had suspicions about the effectiveness of mounting such a weapon. Thus, they proposed either:

  • A towed trailer carrying the liquid fuel
  • A very bulky and heavy tank

Nonetheless, the problems of transporting such a vehicle by rail were solved by simply deciding to avoid rails and to carry it on roads.

45 tonne/articulated option

The first solutions came regarding the 45-tonne vehicles. It was to be armed with a cannon, a flamethrower, and machine guns. It was to be able to reach a top speed of 10 km/h. A prototype study was made, of slightly smaller dimensions, similar to that of the Char G1, with 100 mm of armor and a gun inside a casemate.

Mockup of one of the Char G1 from Renault. Despite sharing nothing in common to the Char de Forteresse program, the first prototype study was around the same size as the G1.
Source: Globalsecurity.org

The Commission did confirm that the 45 tonne Char Lourd program was not enough, as it was impossible to have 120 mm of armor, a 75 mm gun, and good trench crossing capabilities under 45 tonnes. After all, all Char Lourd designs exceeded that mark and had even thinner armor (100 mm). Therefore, to be able to fulfill the requirements, the creation of an articulated, modular design was brought up. It would be brought on roads via trucks and be reassembled before reaching the frontline.

Installment of a flamethrower could not be done either, as it would have required a special towed trailer, also with 120 mm thick armor. It was calculated that the fuel volume required was 6 m3 for just 4 minutes of firing. The concluding idea was that there should be a gun tank and a flamethrower tank, built jointly, in two parts.

Superheavy option

The second idea was the creation of a super-heavy tank. It was to also have a modular construction, but only with the weapons, main cannon, flamethrower, and machine guns, which could be demounted for easier transport. This was all the idea of the Infantry Directorate, which itself resumed General Estienne’s previous plans. However, the main problems with this variant were that:

  • The assembly would require a lot of resources
  • The turret would be overcrowded by the main gun and flamethrower

They did acknowledge that a tank with crossing abilities similar to that of the Char 2C (4.5 meters) and a fording depth of 1.4 meters but also with 120 mm armor would have weighed between 150 and 200 tonnes, a benchmark where even a modular vehicle would not be effective.

LEGO tank option

A third idea was brought up at the meeting. To be able to enjoy the advantages of a super-heavy tank but to also have the same transportability as a heavy tank, they came up with a 60 to 65-tonne tank that would be made entirely out of portable modules: turrets, ammunition, fuel, engine, etcetera. This would leave an empty hull of around 45 tonnes, which could be transported by trucks. Of course, the main downside was that the tanks had to be reassembled bit by bit before being combat-ready.

Second meeting

On 22nd July 1938, the new commission had its second meeting. Tests were made to see if 100 mm was in fact, sufficient protection. It was deemed enough to withstand fire from existing 75 mm guns then in service, but would not be enough for newer 75 mm guns firing AP, thus the 120 mm armor was necessary. The existence of the German 8.8 cm Flak gun was also seen as a reason to keep the original 120 mm threshold.

The results of the experiments surrounding the flamethrower and its dilemmas were to come in by the end of the summer.

Further rework on the designs allowed for ditch crossings of 6.5 to 7 meters. It was also remarked that trucks could only carry a weight of 35 tonnes, with an 8 axle transport trailer. However, railway wagons could transport a weight of 100 tonnes and special axles could be built if necessary, reviving the option for rail transport.

Several design options were evaluated at this meeting as well.

Char Minimum: armored with 120 mm thick armor, a 75 mm gun in a turret, and two flamethrowers (probably in the hull). The cannon version weighed 56 tonnes and could be reduced to 40 tonnes for transport. The flamethrower variant was a bit heavier, at 57 tonnes, plus a towed trailer. The Char Minimum’s poor trench crossing distance of “just” 2.5 meters lead to it being rejected.

Char Maximum: Classical layout tank with 120 mm armor, 75 mm gun in a turret, and just one flamethrower. It could cross 3.6-meter trenches (still less than the Char 2C). Although it weighed around 89 tonnes, it could be demounted into two main pieces for transport.

Train Boirault: French engineer Monsieur Louis Boirault was, and still is, known for his unorthodox solutions regarding tank design, especially trench crossing. As early as 1915, he presented articulated tank trains that would, theoretically, improve cross country capabilities. This 1938 variant had three self-coupling main parts and weighed 125 tonnes in total (41.6 tonnes each). However, its turning radius was large and the couplings unreliable and hazardous. Reducing the train to just two modules fixed some issues but created others, and was ultimately rejected.

One of Boirault’s later inventions. This one uses several S35 like tanks plus a middle section.
The 1938 125 tonne version might have been something similar, just larger.
Source: Andrew Hills

Char Squelette: Inspired by the WWI ideas of the Skeleton tank and Boirault Machine, this variant greatly interested the Commission, both out of curiosity and also actual implementation. It had a small armored ‘box’ that was attached to rotatable beams, shifting the vehicles’ center of gravity, thus allowing it to cross 8 meter long trenches. Unsatisfactorily, the turret was unable to rotate a full 360° and many of the automotive elements and beams were exposed to potential enemy fire. The total weight was 110 tonnes.

The American Skeleton tank. The French version would have been rather similar, but much larger.
Source: Landships.info

The commission approved the Char Maximum and Char Squelette and insisted upon the 120 mm armor, 75 mm gun in the turret, and one flamethrower.

In September, the Supreme Command asked for the immediate design of a Char Maximum and a replacement solution for the Char Squelette.

L’Atelier de Construction Rueil (ARL), located on the outskirts of Paris, was tasked with the development and creation of blueprints. They had previous experience with heavy tanks, as they had presented three designs a year earlier for the Char Lour program. FCM, Somua and AMX, the other main French tank factories, were all busy with other programs. Besides the aforementioned characteristics of the Char Maximum, they were to also protect the bogies and wheels with side skirts, and the tank had to be demountable into 45-tonne sections.

In the summer of 1939, ARL presented the drawings of two different alternatives: an articulated and a classical long variant. Besides the layouts, they were more or less identical. They called it Char de Forteresse (literally Fortress tank).

Two drawings

The articulated variant had two 60 tonne modules, for a total weight of 120 tonnes. One was the fighting compartment, with the weapons and crew, and the other was the engine and fuel compartment. Each module had its own driven sprocket, indicating that the coupling between the two was more complex, as power would also have to be transferred between the two. It is unspecified if the vehicle turned by pivoting the modules, like a BV206, or by breaking the tracks. Considering this was never specified, it is unlikely to have included such a steering system, as it also added additional mechanical complications. The Commission noted that there were not any visible problems with the design, however, they did express a desire for a second gun in the “rear”. It is unclear if this would have been on the rear of the armament module or the engine module. They also wanted to test and check the effectiveness of the 75 mm gun against reinforced concrete armor, the type used in the bunkers on the Westwall. The flamethrower(s?) was to also be removed since it was seen as useless against fortifications. ARL added twin engines to the designs, but the Commission only wanted one. This would free up space for ammunition, better communication between the compartments, close-range defense, and providing the crew with sufficient space.

Plans of the articulated variant. Note the lack of design on the articulation, showing just how little the design had come.
Source: Chars Français

The other drawing was a much more classical layout for a tank of this type, with a very long hull, the engine in the rear, and the turret at the front. The turret used on both designs was somewhat hexagonal in shape, with a large extension behind the gun in order to provide a better view for the commander. It is possible that it might have mounted a rangefinder as well. The running gear was long, protected by heavy side skirts. Large idlers and sprockets ensured improved ditch and trench crossing.

The second design proposed by ARL. It was extremely long, around 12 meters, for excellent trench and ditch crossing.
Source: Chars Français

Layout and components

Very few technical details are available, and it is quite likely the designs never even got that far. The main armament was an unspecified 75 mm gun, but considering previous designs, it was most likely a 75 mm Mle. 1929. It also received additional armor around the gun, characterized by the mushroom-like object on the barrel. The hull length was around 12.05 meters, the width of around 3.20 meters, and the hull height of 2.125 meters. The total height would have been 3.65 meters.

The engine and powertrain are hard to determine. Later vehicles, such as the FCM F1 and ARL Tracteur C, used two Renault 550 hp engines, but since only one engine was desired, it is hard to say what contemporary French engines could propel this 120-tonne beast. On the other hand, a 10 km/h top speed was deemed sufficient, although some sources claim it would have reached 18 km/h. This engine would have probably been attached to an electrical generator that powered the drive sprockets. The crew number and positions are also a mystery. The most likely number would be around 5 crewmen, a commander, gunner, loader, driver, and radio operator or mechanic (the radio might have been handled by the commander).

The armor was 120 mm thick almost all around. It was common for French tanks to have the same thickness all around, with small exceptions, like the top and belly armor. This shows how the tank could easily reach the 120-tonne mark, despite the small turret and even smaller armament.

Armament

The main armament was most likely an APX 75 mm Mle. 1929. This gun was originally developed for the Maginot Line and was an improvement of the gun mounted on the Char B1. ARL had previously used it on their ARL 37 heavy tank and ARL V.39 tank destroyer. The Mle. 1929 normally had an armored sleeve, but ARL gave it a ‘head’ to deflect incoming rounds.

It is unclear which flamethrowers would have been used, and they were eventually to be removed from the tank, as they were deemed unnecessary.

The 3 machine guns would most likely have been MAC-31s. Also built for the Maginot Line, these heavy machine guns fired 7.5 mm cartridges from 150-round magazines, ideal for use in tight spaces like tanks. One was in the gun mantlet, one in the hull, near the driver and one mounted on the rear, for defense against flanking infantry.

MAC-31 machine gun with a drum magazine
Source: Wikipedia

Turret

The turret was a Tourelle ARL 4 with a hexagonal shape, made out of welded 120 mm thick plates. This was rather unusual, as most French turrets were cast. The commander had a large protrusion, providing an excellent view over the battlefield. He sat on the left side of the gun and had around 7 cutouts or slits for vision, a rather archaic solution, instead of using periscopes. It was hinged on the front side of the turret, allowing the commander to enter and exit, while also providing protection. The turret was large enough to fit 3 men, the commander, gunner, who sat below and in front of him, on the left side of the gun, and the loader, who was also responsible for the coaxial (or possibly independent) machine gun in the mantlet.

German threat and merging with FCM program

Since the final design by ARL was very similar to the one FCM was working on, the Char F, the Commission decided to end the development of the Char de Forteresse in order to allow both FCM and ARL to work on the same program and speed up the development of the Char Maximum. Things took a different turn in September of the same year, as Germany invaded Poland. The High Command was not too fond of the practicality and use of these super-heavy tanks, but the Commission proceeded regardless. In a meeting held in the same month, the Commission made changes to the FCM requirements, uparmoring it to 120 mm and requesting the mounting of a 105 mm gun in the hull. The Char Squelette was finally abandoned since it was too complex.

In October 1939, AMX would also join the program, and they would all work on different designs, getting heavier and with more and more guns. ARL cast aside their original plans of the Char de Forteresse, moving on towards other plans to keep up with the new demands. They did however use the general layout for further designs. Final outcomes were the mock-ups of the ARL Tracteur C or FCM F1, all of which were terminated prematurely due to the German invasion of France in the summer of 1940.

ARL Tracteur C uncompleted mock-up, with a German soldier posing next to it.
Source: Chars Francais

Conclusion

ARL’s Char de Forteresse was an insignificant and short-lived design, but, when put together with the previous Char Lourd program and future Char Maximum developments, it highlights the cluelessness of the French military, wasting valuable time and resources on trying to counter a mainly nonexistent defensive line. By the start of the Second World War, the Westwall was not more than just a series of ditches and dragon’s teeth.

Post Scriptum – Char de Forteresse 1940

The name Char de Forteresse does show up later on, unrelated to ARL plans. On 28th February 1940, a new commission, the Commission d’Études des Chars (Eng: Tank Study Commission), set off to create the structure for future tank development and production doctrine. Similarly to General Estienne’s interbelic doctrine, there were to be three tank types:

Char d’Accompagnement: a light infantry support tank, equipped with a 37 mm SA 38 gun, 40 mm armor, and a total weight between 10 and 12 tonnes. Later models would have the 47 mm SA 35, 60 mm of armor, and a weight between 15 to 20 tonnes. Top speed of 20 to 35 km/h. This was something similar to the Somua S35.

Char de Bataille: a battle tank armed with a 75 mm and 47 mm gun and 60 to 80 mm of armor. Similar to the Char B1 and B1 bis.

Char de Forteresse: a fortress tank armed with a 75 mm, 90 mm, 135, and/or 155 mm gun. Weight of 80 to 100 tonnes and a top speed of 20 km/h.

Clearly, the French did not learn much from either the FCM 2C or any of the other designs. This second Char de Forteresse was canceled not because they were utterly pointless and unusable, but because there were not any 135 and 155 mm guns suitable for the tank.

First Char de Forteresse ARL design, consisting of two articulated sections. Illustration by Pavel Alexe, funded through our Patreon Campaign.
Second Char de Forteresse ARL design, with a more traditional, ‘battleship’ hull. Illustration by Pavel Alexe, funded through our Patreon Campaign.

Sources:

https://www.chars-francais.net/2015/index.php/7-archives/de-1930-1940/2428-1939-char-forteresse-arl
Les Vehicules Blindes Francais 1900-1944 – Pierre Touzin, 1979
Chars De France – Jean-Gabriel Jeudy

Char de Forteresse ARL specifications

Dimensions (L-W-H) 12.05 x 3.20 x 3.65 m
Total Weight, Battle Ready 120 tonnes
Crew 5 men (Commander, gunner, loader, driver, radio operator or mechanic)
Propulsion unkown, included electrical generators
Speed 10 – 18 km/h
Armament 1x 75 mm APX Mle. 1929,
3x MAC 31 machine guns
2x/1x flamethrower (later removed)
Armor 120 mm all around
Categories
Cold War Soviet Light Tanks

PT-76

USSR (1952-1967)
Amphibious Light Tank – circa 12,000 built

The PT-76 is a Soviet amphibious light tank designed in 1948 which saw service from 1952 up until its gradual retirement from 1967 onwards, partly replaced by the more versatile BMP-1 APC. Characterized by a wide hull and water jet propulsion, the PT-76 offered excellent amphibious capabilities. It was, however, plagued by a large silhouette, weak armor protection, and an underpowered 76 mm gun. Despite these flaws, the PT-76 enjoyed a long service life within the Soviet and Russian armed forces, which only placed it into its reserves in 2006. Comparable to other Soviet Cold War vehicles, it has seen combat in several wars and is still in use within smaller armies. Russia is attempting to replace them with BMP-3F amphibious IFVs.

A new war in Europe

During the Second World War, the Soviet amphibious light tanks left much to be desired. The T-37A and T-38 light tanks, armed only with machine guns, were useless against German Panzers, while the T-40 light tank, being inadequately armed, simply reinforced the failure of the earlier vehicles. Nonetheless, the end of the war left a state of tension between the USSR and western nations. It was very likely that central Europe would become a battlefield between the two superpowers. However, the geography of this area is problematic for tanks. Riddled with forests, rivers, and marshes, heavy and medium tanks would require mobile bridges and other logistic systems to cross obstacles. The Soviets knew what to expect of warfare in Europe. Namely, water obstacles up to 100 m every 35-60 km, 100-300 m every 250-300 km and over 300 m wide every 250-300 kmThe solution was to have a mobile and nimble light tank that could be amphibious. These tanks were to penetrate into enemy territory and scout the environment until the heavier tanks came. Learning from previous mistakes, this new amphibious tank had to be equipped with a powerful gun to make it more useful against enemy armor. Thus the PT-76 was born, having excellent buoyancy to allow it to cross those water obstacles.

Development

Right after the Second World War, when the new geopolitical and military climate became apparent, the USSR still had large amounts of obsolete light tanks, such as the T-60 and T-70, many of whom were in poor condition. Some of these simply ended up being dismantled to be used for spare parts in SU-76 tank destroyers and GAZ-AA trucks, while the majority were scrapped. This left the Soviet army effectively without light tanks. Initially, in 1946, many heads of the tank industry, ministers, and engineers disliked the idea of an amphibious light tank (and light tanks in general), as the development and propelling of an amphibious vehicle would add unnecessary cost, while the buoyancy requirement meant that the armor had to be extremely thin. They also believed that the small advantage gained in mobility over medium and heavy tanks was not justifiable considering the large sacrifice of armor and firepower.

However, in January of 1947, the headquarters of the USSR Naval Forces addressed the Main Operations Directorate of the Armed Forces about the creation of two amphibious vehicles: an APC and a light tank. Interestingly, they wanted the light tank to have a performance similar to that of the T-34-85. It was to weigh 20 tonnes (22 US tons), have an 85 mm gun, and a 400 hp engine. These requirements were eventually dropped, as the weight was lowered to 15 tonnes (16.5 US tons). The vehicles were to share the same platform, which could be used later for developing other vehicles.

Thus, in March of 1947, recognizing the geographic situation in central Europe, the commander of the Group of Soviet Occupation Forces in Germany (GOSVG) was interested in the revival of amphibious light tanks. A war in central Europe would be based on mobility and speed. A fast and amphibious light tank could advance quickly, conducting flanking maneuvers, surprise attacks, and more, something medium and heavy tanks could not. It was also added that light tanks could be air-transportable and that they would be crucial in wars in the Middle East, where the lack of infrastructure would be even more problematic for medium and heavy tanks. Even in the Far East, where railways and good road networks were absent, a light tank capable of driving under its own power was the best choice. As the threat of the use of tactical nuclear weapons became more serious, it was also envisioned that fighting in such conditions would be best done by light tanks, as they could move quickly and have low maintenance costs.

Object 101/R-39

As light tanks seemed more favorable, in 1947, at the Red/Krasnoye Sormovo No.112 factory, testing was done on various light tanks and APC, one of which was the PT-20. These were deemed unsuccessful for various reasons, the main being that these prototypes required aluminum boxes filled with air for floatation. In other words, the vehicle needed prior preparation for floating. In addition, the flotation devices had to be carried in trucks. This severely harmed the logistics and the agility of the tank. Ideally, and rather obviously, the vehicle would be able to float on its own without additional preparation.

As a result, on the 10th of June, 1948, the No.112 factory was tasked with redesigning the light tank and the APC to be ready for amphibious operations without any prior preparation. For the light tank, the specifications were the following:

The combat-ready weight should be below 15 tonnes (33,000 lbs.), the engine needed to deliver 300 hp (211 kW) and had to be able to allow the tank to reach speeds of up to 50 km/h (31 mph) on-road and 12 to 14 km/h (7 to 9 mph) in water. In addition, both the light tank and APC should be able to carry 2,000 kg (4400 lbs.) on top. The light tank had to be equipped with a 76.2 mm gun.

The designs were ready by July 1948 and were presented to the GABTU (Main Directorate of Armoured Forces) with promising feedback. On the 16th of July of the same year, the Ministry of Transport Engineering ordered the No.112 factory to produce two prototypes and test them by June 1949. These vehicles were given the name ‘Object 101’ (R-39) for the light tank and ‘Object 102’ (BTR R-40) for the APC. The first R-39 prototype was built between April and May 1949 and by the 27th of May, testing began. It was found that the center of gravity was a bit too far back, causing problems in water.

The second prototype was ready by June of the same year, with the turret moved forwards by 240 mm (9.4 inches). These prototypes, however, failed the factory tests – the reliability and strength of certain components were poor, and the vehicles did not even reach the desired speed on water (7 km/h out of the 10 to 12 km/h desired). On the second prototype, to fix the slow speed, the propellers were mounted externally and were supposed to be lifted onto the engine deck when not used. However, this left them vulnerable to enemy fire and overall damage. The second round of testing was done at VNII-100 institute, in Leningrad, but they failed those too. The poor performances led to the Sormovo No.112 factory being removed from the program. After this disappointment (the program was supervised by Stalin himself), some of the heads of No.112 factory alongside certain engineers, were removed from their offices and held accountable (it is unclear if this means simply losing their functions, or worse).

R-39 prototype at the Krasnoye Sormovo No.112 factory in Nizhny Novgorod. The prototype, rather similar in design to what the PT-76 would look like, was poorly built and failed miserably during tests.
Source: Rulit.me
Rearview of the R-39, also called the Object 101 (not to be confused with SU-101) during testing.
Source: PT-76 amphibious tank, Mikhail Borisovich Baryatinsky
R-39 while swimming. Note the open wave deflector.
Source: PT-76 amphibious tank, Mikhail Borisovich Baryatinsky
R-39 after amphibious testing, 1949.
Source: PT-76 amphibious tank, Mikhail Borisovich Baryatinsky

The Council of Ministers of the USSR decided on the 15th of August of 1949 that the VNII-100 research institute in Leningrad should restart the development of the two vehicles, with testing to be started in 1950.

Object 270 & Object 740

The remaining researchers and workers from Krasnoye Sormovo and VNII-100 came to ChKZ (Chelyabinsk tractor plant) to continue work on the 15th of August, 1949. The blueprints were ready by the 1st of September. Two different sets of drawings were made, one set by Grigory Moskvin and A. Sterkin, named ‘Object 270’, and drawings made by L. Troyanov and Nikolai Shashmurin, named ‘Object 740’. The latter made ‘Object 750’ as well, which was the APC version. To fix the problems encountered on the initial R-39, engineers came up with four different solutions. These were: propellers in water tunnels, conventionally mounted propellers on hinges, water jets, and lastly, tracked propulsion. Engineers Kotin and L.Troyanov wanted to implement hinged propellers, as they had worked on vehicles with this propulsion system before. Shashmurin, however, wanted to implement water jets designed by Nikolai Konowalow. Shashmurin went to the Minister of Medium Machine building, Viacheslav Malyshev, to get his idea materialized. Malyshev agreed, terminating all other projects for propulsion systems and placing efforts entirely on a vehicle with two waterjet engines, the Object 740. Plans in 1:20th scale were drawn on 15th November 1949, and the first Object 740 prototype was completed in February of 1950.

Object 740 from the front. One of the largest differences between it and the production PT-76 was the curved, boat-shaped hull sides and clear stamped wheels.
Source: m.blog.naver.com
Object 740 during testing in Polotsk, 1950. Note the open ports at the rear on both sides for the integrated waterjets.
Source: m.blog.naver.com
Object 740, Polotsk, modern-day Belarus, 1950. Note that the water jet covers are in place.
Source: m.blog.naver.com

Testing was done on the Object 740 from the 15th of May, and the vehicle passed them by August. After the initial bugs and issues were fixed on the prototypes, it was deemed suitable for adoption in the Soviet military. The decree of the USSR Council of Ministers on the 23rd of November, 1950, assigned the first 10 vehicles to be produced at Stalingrad Tractor Plant (STZ), for which a specialised construction bureau was made, headed by M. M. Romanov. The first 10 units were manufactured between May and June of 1950. These were sent to the Soviet military for active trials with troops, during which refinements and final touches were made. On the decree of USSR Council of Ministers, 6th of August, 1952, the Object 740 was adopted into service under the name PT-76, плавающий танк (Romanized: plavayushchiy tank) meaning floating tank 76, from the 76 mm gun. It was first unveiled to the public on Victory day, 9th of May, 1952. The tank was mass-produced at STZ, later renamed VgTZ (Volgograd Tractor Plant).

Interesting to add are the Object 728 and Object 270-M (built by VNII-100). These were testbeds for the new water-jet engines. This was the first time the Soviet Union made a tank using water-jets. The Object 728 had a weight of 14 tonnes (30,900 lbs) to simulate the Object 740 in water.

Object 270-M testbed.
Source: PT-76 amphibious tank, Mikhail Borisovich Baryatinsky
Object 728 testbed at VNII-100, Leningrad. The large tower on top was placed there in case the testbed sank. Note the T-34 wheels.
Rear view of Object 728. Noteworthy are the large waterjet outlets in the rear.
Chart showing the PT-76 complex development and its ‘relatives’.
Source: Solyankin-Pavlov-Pavlov-Zheltov

Unsuccessful rival – K-90

The Object 740 did, in fact, have a competitor, in the form of the K-90. The K-90 was developed at VRZ No.2 Plant in Moscow, under A. F. Kravtsev. He was well aware of the complexities and price of designing such a vehicle from scratch, so he wanted to use automotive parts, as well as parts from decommissioned materiel, such as the Ya-12 tractor, T-60, and T-70 light tanks from the war. The K-90 was smaller and simpler, having a boat shaped hull for buoyancy and two propellers with individual rudders for water steering. Like the PT-76, it too was armed with a 76 mm cannon inside a rounded turret. However, it was rather slow both on land (43 km/h) and water (9.6 km/h), and after trials, it was eventually rejected in favour of the Object 740. The Moscow plant also designed the K-75 and K-78, meant to compete with the Object 750 APC, but small size and poor mobility plagued the developments as well, and were never adopted.

K-90 amphibious light tank in Patriot park, Moscow. Note the welded boat-like hull and T-60 wheels.
Source: Vitaly Kuzmin

Usage & Tactics

PT-76 tanks were assigned to amphibious companies and reconnaissance companies of tank and motorised rifle regiments. They had dedicated roles within the regiment, such as securing river banks, allowing for the other tanks, troops and equipment to cross the water obstacle with conventional river-crossing equipment, which took a lot longer.

When used in reconnaissance missions, they would move ahead of the regiment, securing areas, scouting for enemy positions, but also – if attacked, fulfilling the duties of medium tanks, which were not present.

The Soviet Naval Infantry (Morskaya Pekhota) was revived in 1963 as a subordinate of the Soviet Naval Forces, with three regiments; Northern, Baltic, and Black Sea. These were equipped as a mixed armor force, with PT-76 and T-55 tanks. Here, the PT-76 tanks were used as assault tanks in water areas, such as beaches and riverbanks, providing armored support and firepower to marine infantry battalions. The only Naval Infantry division in the Pacific also added a mixed PT-76/T-55 regiment, in addition to its existing tank regiments.

PT-76 tanks of the Naval Infantry landing on a beach in a military exercise. They would be transported close to the shore with landing ships, like the Ropucha-class, pictured above.
Source: (bastion-karpenko.ru)

Layout & Design

The PT-76 was a revolutionary tank for the Soviet Union, yet its basis was very simple. The wide and long hull allowed for excellent buoyancy in water, but it had to sacrifice the armor, with the thickest part being only 15 mm (0.6 inches) on the front of the turret. The engine was placed in the rear, behind the turret. The hull itself was divided into two sections, engine and jets in the rear and fighting compartiment in the front. These were separated by a metal bulkhead. The water jets, two on each side, had an inlet in the floor of the hull and the exit hole in the rear. Two smaller ports on the side were used for propulsion in reverse. The turret had a low profile and had both the commander (who was also the gunner) and the loader. It housed the D-56T 76.2 mm gun (in 1957, this was replaced with a D-56TM). The main engine was named the V6, but was a 6 cylinder in-line, 4-stroke, water-cooled diesel capable of outputting 240 hp (179 kW) at 1,800 rpm. This gave the 14 tonne (32,000 lbs.) tank a power to weight ratio of 16.4 hp (12.1 kW) per tonne, and allowed it to reach a top speed of 44 km/h (27 mph) on roads.

Cutout of a PT-76 model 1957 (often referred as PT-76B in western literature).
Source: m.blog.naver.com

Despite being used as a reconnaissance tank on many occasions, the PT-76 was not designed with this in mind. It was never equipped with any proper equipment for such tasks, and, probably one of the most significant drawbacks of the PT-76 was its poor visibility. With a grand total of 11 periscopes, excluding the sight of the main gun, the PT-76 was behind many Soviet tanks of the time. As an example, the T-10 heavy tank had double the amount of vision ports and periscopes. This begs the question why was the PT-76 used in reconnaissance roles but the answer is deceptively simple. Soviet doctrine in the 1930s saw amphibious tanks, like the T-37A, as primarily for reconnaissance purposes. They were light and small, and their poor armament did not allow for any other tasks to be performed well. The PT-76, however, was much larger than a T-54 and was rather underpowered. Yet the PT-76 was, in fact, used in such missions because it was the only amphibious light tank in the Soviet arsenal. In this sense, it could be considered that the tank design had outpaced an older doctrine of use for tanks in the absence of dedicated reconnaissance vehicles.

The weight was distributed amongst the components was as following:
Armored Hull: 4,942 kg (34.6%*)
Turret: 751 kg (5.26%*)
Armament: 1,111 kg (7.78%*)
Powerplant: 1,307 kg (9.15%*)
Transmission: 1,548 kg (10.8%*)
Chassis: 2,548 (17.8%*)
*; % of total mass

The remaining 2 tonnes (15%) was ammunition, fuel, equipment, etc.

Russian chart comparing Soviet and Western tanks. The hull of the PT-76 appears massive compared to the T-54 and rivaling light tanks, like the AMX-13 and M41 Walker Bulldog.
Source: thesovietarmourblog.blogspot.com

Crew positions

The light tank had a crew of three: a driver, a loader, and a commander that also operated the gun. The driver was placed centrally in the hull, beneath the gun. The commander sat on the left side of the gun, in the turret, while the loader was on the other side, to the right of the turret. The turret ring of the PT-76 was very large, at a diameter of 1,800 mm (6 feet). For reference, the T-34-85’s turret ring had a diameter of 1,600 mm, and T-55, 1,850 mm. Compared to contemporary Soviet tanks, the large turret ring combined with one less crew member and a smaller-caliber gun meant the PT-76 had some of the best ergonomics of its time in the USSR.

Driver

The driver, as mentioned before, sat inside the hull and had three periscopes for vision. Despite the rather good visibility given by the three periscopes, he still relied on commands from the turret. The central periscope could be mechanically lifted up to improve vision when driving through water. The driving position was rather interesting, as the pedals were located on the angled front hull, while the seat was mounted on the hull floor. This meant that his feet would be above the hips when driving. Above him, next to the main hatch, which swung to the right when opened, he had a single dome light. In case of an emergency exit, he had a round exit hatch to his left in the hull floor.

Driver’s position in the PT-76.
Source: PT-76 manual
POV of the drivers seat in the PT-76. Note the three batteries on the right side.

Commander/Gunner

Besides his gun sight, the commander had three periscopes in a cupola capable of rotating 360°. However, there was nothing to grab the cupola with directly, resulting in the commander having to grab onto the periscopes, which were not especially ergonomic, if he wanted to rotate the cupola. If he wanted clearer external vision (as many tank commanders prefered), he could open the hatch in which the cupola was incorporated. Despite having just 6 mm (0.2 inches) of armor, the hatch was rather large, making it very obvious to enemy snipers when the hatch was open and the commander may be looking out. This hatch was built within another, much larger hatch, running across the entire turret. The reasoning behind this was to make it easier for the crew to bail out in case of emergency. The weight of the hatch made it rather cumbersome and difficult to open, especially if a crewman was injured. In the same manner as the smaller hatch, it opened forwards to provide some kind of protection while exiting.

The already overworked commander also operated the radio, a 10RT-26E, standard to Soviet vehicles of the period. It was mounted to his left, to give him the maximum amount of space. The obnoxious overworking of the commander is rather reminiscent of commanders in French tanks in the Second World War. While the PT-76 has nothing in common with them, the situation the Soviet Union found itself after WW2 is akin to that of France in the 30s. Both nations had just fought a bloody war, bringing their population numbers low. Having fewer crewmen per tank would mean, in the greater picture, a significant saving in resources and manpower necessary for operating the tanks.

View of the turret and crew positions with the breech of the gun in the center.
Source: PT-76 Manual
Main hatch in the turret. The commander’s hatch was built inside the main hatch. Exiting and entering the tank for the two crew members in the turret was done by opening the main hatch.
Source: thesovietarmourblog.blogspot.com
Inside view of the main hatch. The three periscopes from the commander’s smaller hatch can be seen.
Source: thesovietarmourblog.blogspot.com
The field of vision for the periscopes in the PT-76 1952 alteration.
Source: thesovietarmourblog.blogspot.com

Loader

The loader sat on the right side of the turret, to the right of the main gun, meaning he had to load the gun with his left arm, a common feature of Soviet tanks of the time. He had three main duties, loading the 76 mm gun, loading the coaxial machine gun and, when not loading, he was responsible for assisting the commander in surveilling the surroundings with his single rotating MK-4S periscope. Due to the design and placement of the periscope, the loader has vision forwards and slightly to his right. To extend his vision, he has to swap and reverse the periscope, allowing him to look to his rear. This was rather inefficient, making it hard for the loader to aid the commander in spotting targets and with overall vision.

The only periscope for the loader. With a bit of imagination, it can be imagined how the loader cannot look behind him, the turret wall is in the way. This requires for the periscope to be reversed.
Source: thesovietarmourblog.blogspot.com

The loader had plenty of space to operate. He had a folding seat mounted to the turret ring, meaning that he could work standing or seated. His comfort did not stop there, he had a dome light and a backrest, conveniently tilted so that it faced the gun. There was so much room in the turret that, after folding the recoil guard to 90°, there was a large gap between the two crew positions, through which the crewmembers were able to pass.

Polish PT-76 loader.
Source: 7ldd.ocalicodzapomnienia.eu

Thanks to the large amount of real estate in the turret and the relatively small size of the 76 mm shells, the loader’s job was not that complicated. This allowed for quite a short reload time in between shots, with a theoretical 15 rounds per minute (4 second reload). However, actual firing speed, taking aiming into consideration, would be below seven rounds a minute.

Overview of the loader’s station. His rounded foldable seat is facing the gun. Meanwhile, the machine gun is very close and easy to access. Note the empty ammunition ready rack in the bottom corner.
Source: thesovietarmourblog.blogspot.com

The ammunition was stored in a ready-rack, in two stacks of seven (14 rounds), to the loader’s left, inside the turret bustle. On top of this ready rack, on the turret wall, were an additional two rounds. On the other side of the turret bustle, underneath the gun, there was the storage ammunition rack, with an additional 24 rounds, bringing the total ammunition to 40. This is rather low for a tank its size, but it was a considerable improvement over the R-39 prototype, which had just 30. Extracting ammunition and loading the gun directly from the storage rack was rather cumbersome. Ideally, the rounds had to be taken out and put inside the ready rack when not in immediate combat.

Ammunition storage in the tank. Worthy of note are the positions of the ready rack and large storage ammunition box.
Source: thesovietarmourblog.blogspot.com

Armament

The PT-76 used a 76 mm D-56T gun. Developed by Factory No. 9 in 1949 based on the F-32 and ZiS-3 guns, it in fact had identical ballistical capabilities and fired the same ammunition. Both the F-32 and ZiS-3 were deemed obsolete by the end of WWII, and rightfully so. Their replacement with 85 mm and larger guns could be seen with the T-34-85. In 1947, an 85 mm gun was wanted, but due to the weight reduction to only 15 tonnes, a 76 mm gun had to be used. It is noteworthy to mention that the doctrine of the PT-76 meant that this otherwise obsolete tank gun was enough. The purposes of the PT-76 were to support troops during amphibious landing by neutralizing machine gun nests and recoilless rifles and other soft targets. The gun could depress -3.5° (-4 according to other sources) and elevate +31°. Executing a complete rotation of the turret took around 21 seconds with manual hand crank. The gun was also capable of indirect fire with an azimuth sight. It was capable of firing 15 rounds per minute, but most loaders managed 6 – 8 rounds a minute.

The D-56T inside a cutout PT-76 turret. Note the long, TsAKB muzzle brake. This version of the gun would be replaced in 1957 with a D-56TM, when the PT-76 would be revised and called PT-76B.

The D-56T on early PT-76 tanks used the TsAKB style muzzle brake, with many vertical slots, pushing the blast backward, greatly decreasing the recoil. Another innovative feature of this gun was that the recoil buffer was mounted underneath the breach, to the right, and the recuperator to the left. Usually, in guns of the time, especially in Soviet tank guns, these components were mounted on top and or in front of the breech. This new placement allowed for less space needed over the gun, increasing gun depression or allowing to decrease the height of the turret.

The recoil buffer (right) and recuperator (left).
Source: thesovietarmourblog.blogspot.com

Another unusual feature of the D-56T was the vertical sliding breech lock. On most Soviet tanks of the time, the breech lock was horizontal, and on the right side. There were two reasons. Primarily, Soviet doctrine stated that if the axis of the gun breech is lower than 950 mm to 1000 mm from the floor, a vertical breech lock should be used. Anything higher than that should use a horizontal breech. This rule was set as vertical breeches are easier to load when lower down, however, much harder to load when higher up. The exact measurements are made in proportion to the elbow and shoulder of the average Soviet tanker, at 1.70 m (5’ 6” feet). Lastly, as it was a small field gun, the ZiS-3 already had a vertical breech lock.

Later, in 1957, this gun would be changed to the D-56TM gun, with a German-style muzzle brake and more. Furthermore, in 1961, a second gun upgrade was made, with the D-56TS. It now received a two-plane stabilization device.

Ammunition

The ammunition used by the D-56T in the PT-76 is identical to that on the ZiS-3. They used 76.2 x 385 mm rimmed munitions. Since the two guns shared ammunition, there was a large variety of munitions readily available. A battle-ready PT-76 would have the following ammunition loadout:

24 High Explosive (HE) rounds
4 Armor-Piercing High Explosive (APHE)
4 Armor-Piercing Composite Rigid (APCR)
8 High Explosive Anti-Tank (HEAT)

This loadout changed in the 1970s. It now had 20 HE shells and 12 HEAT shells instead.

It is worth mentioning that, despite the age of the rounds used and the gun itself, the PT-76 was capable of, theoretically, countering western counterparts, such as the M41 Walker Bulldog or AMX-13, and even lightly armored MBTs, such as the AMX-30 or Leopard 1. However, towards the end of the 50s, it was clear that the gun and ammunition were not capable of dealing with modern medium and main battle tanks.

Secondary armament

The secondary armament on the PT-76 was, as standard on Soviet tanks of the time, a coaxially mounted 7.62 mm SGMT machine gun. Four magazines were carried in the tank, each of 250 rounds, making a total of 1,000 rounds. This is very little considering that the PT-76 was the only tank used by Soviet naval infantry. To put this into perspective, a T-55 carried 3,500 rounds. The crewmen had AK-47s as their personal defence weapons.

SGMT machine gun for mounting on tanks.
Source: Arundel Militaria

Engine

As mentioned earlier, the PT-76 mobility and top speed are not as impressive as many other light tanks of the era, focusing more on its amphibious aspect. The main engine was a V-6, 6-cylinder in-line, 4-stroke, water-cooled diesel, capable of delivering 240 hp (179 kW) at 1,800 rpm. This engine was a simplified version (literally cut in half) of the well-known V-2 engine, used on the T-34, KV, and IS tanks. Originally, a T-34 transmission was proposed, but a more complex one was needed to power the waterjets, thus a new transmission was created, specifically for the PT-76. Nonetheless, it was similar to that on the T-34, a manual shaft transmission, with four gears forwards and one in reverse. It also used a simple clutch braking steering system.

This engine gave the 14.6 tonne (16 US tons) vehicle a power to weight ratio of 16.4 hp/ton, a top speed of 44 km/h (27.3 mph) and a range of up to 400 km (249 miles). Initially, it had a 250 liter fuel tank on the rear right side of the hull. Additional fuel tanks of either cylindrical drum or flat rectangular types could be stowed on the engine deck for additional autonomy. They were not connected to the fuel system. On the PT-76B, fuel consumption was 4.5 liters a minute.

V-6 in-line engine, very similar to the famous V-2.
Source: thesovietarmorblog.blogspot.com

Suspension

Like the majority of vehicles of the era, the PT-76 used torsion bar suspension. On the first and last torsion arm, hydraulic shock absorbers and a volute spring were mounted to improve the ride quality when crossing over larger obstacles. Having a 670 mm diameter (26.4 inches), the road wheels were of completely new design, and are now one of the most recognizable aspects of Cold War Soviet armor, as the PT-76 served as a basis for a multitude of vehicles.

Originally, the wheels were made out of smooth surfaced stamped steel, but slowly got replaced by wheels with stamped reinforcement ‘ribs’. These wheels were hollow on the inside, helping the buoyancy of the PT-76. The indentations in the wheel improved traction in snowy or muddy environments.

The tracks were of cast manganese steel, connected with steel pins with between 96 and 108 links per side. Additional spare track links (typically 3) were stowed on the rear of the turret.

View of the sprocket and wheel of the PT-76. The tracks had a single pin, was 360 mm (14.2 inches) wide and 96 links were used per side, with no return rollers. Note the distinctive stamped hollow wheels.
Source: Brittmodeller.com

Water propulsion

The most important feature on the PT-76 was its ability to swim. A lot was sacrificed on the tank to allow this, like the smaller gun and little armor, combined with a longer and wider hull. As mentioned previously, there were many proposals on what the water propulsion system should be. Among these were propellers in water tunnels, conventionally mounted propellers on hinges, water-jets, and lastly, tracked propulsion. Eventually, water-jets were chosen. These worked by using two main jets with openings in the floor of the tank. Water would be pumped up and propelled out the back of the vehicle through two holes, creating thrust. To steer, either one of the holes was shut. For example, to turn to the right, the right hole was closed while the left was still running causing the vehicle to slew to the right. Closing the ports to the jets forced the water to exit under pressure through the ports on the side, forcing the water forwards. When reversing, both rear jet holes were shut, redirecting the water to the two smaller ports on the side of the vehicle. This system was designed by Nikolai Konowalow.

Diagram showing steering of PT-76 in water.
Source: m.blog.naver

The PT-76 is famous for its outstanding amphibious capabilities, being the primary reason for its prolonged service life. The top speed when swimming of 10.2 km/h (6.3 mph) or 11 km/h, depending on source, is more than adequate.

PT-76 Model 1957 (or later) during a massed amphibious assault practice.
Source: thesovietarmourblog.blogspot.com

Armor

With amphibious assaults and reconnaissance in mind, the PT-76’s armor protection was comparable to other amphibious armored vehicles of the time. This was considered enough to protect from small arms fire or fragmentation, though the overall level of protection was still relatively poor compared to other light tanks of the time.

The turret is conical in shape, angled at 35°, improving its armor effectiveness. At the front, it is 15 mm (0.6 inches) and narrows down to 10 mm (0.4 inch) at the rear.

Armor profile of the initial PT-76 light tank. The armor profile changed in 1962 and in 1967.
Source: thesovietarmourblog.blogspot.com

The hull was equally lightly armored. The front upper plate was 10 mm angled at 80°. This greatly improved the chance of ricochets from small arms. The lower plate, being tall and only angled at 45° was thicker, at 13 mm. The flat side armor was 13 mm on the top half, and 10 mm on the lower. The rear and roof plates are 6 mm (0.23 inch) thick. The bottom was only 5 mm (0.19 inch). Theoretically, this made the PT-76 vulnerable to heavy machine gun fire from the side and rear, yet this was very unlikely in battlefield conditions. The light tank was vulnerable to the Soviet 14.7 mm KPVT heavy machine gun, but the western countries did not have such large machine guns in service.

Service Upgrades

Like many Soviet vehicles of the time, many changes were made throughout its lengthy service life, as the potential battlefield changed, and different obstacles appeared. These were named with “Обр” (obrazets) essentially meaning year model.

PT-76 Mod. 1951

This was the very first production model, essentially the Object 740.

PT-76 model 1951 at Kubinka
Source: m.blog.naver

PT-76 Mod. 1952

The splash guard was made thicker (from 10 mm to 20 mm) and a second water pump was added. The most noticeable change is the introduction of the rib model stamped wheels.

The new, stamped model wheels provide better traction. Note that they are hollow, for better buoyancy.
Source: M.Blog.Naver

PT-76 Mod. 1953

Armor was increased slightly and a MK-4 observation device port was added. Furthermore, various structural designs were improved.

PT-76 Mod. 1954

Driver’s hatch opening and closing was changed to that of the T-54 mechanism, improving driving in bad conditions. Oil filters, antifreeze filters, and other such equipment was changed and added.

PT-76 Mod. 1955

Track center guide width was increased from 4 mm to 6 mm. Clutch and brake pedals received springs for easier and more comfortable usage by the driver. Improved fuel absorption pump for starting in low temperatures.

PT-76 Mod. 1956

UBR-354M HEAT ammunition was added. Ventilators for the rear cover and special lids were added to prevent water leakage.

PT-76 Mod. 1957 (PT-76B)

By far the most important and extensive change made to the PT-76 durings its service life was the PT-76 Mod. 1957, also known as the PT-76B. Developed at STZ with chief designer S. A. Fedorov, this new upgrade received the name Object 740B.

The primary upgrade was to the gun, changing from the D-56T to the D-56TM. A new ‘German-style’ muzzle-brake was given. The previous slotted muzzle brake blew the gases towards the rear at very high pressures, potentially harming infantry riding on the tank. As Soviet doctrine implied the PT-76 was to carry 20 infantrymen over bodies of water and still be able to engage targets afloat, the last thing it needed was to have the infantry fall off or be injured because of the muzzle blast. Additionally, a hydraulic piston was added for elevation and depression of the gun. The ‘German-style’ muzzle brake was much shorter as well, minimising the risk of damaging the barrel or dirt clogging the barrel in amphibious operations. The hull was heightened to 2,255 mm.

The different types of muzzle brakes and the direction through which they push the gases. Type A was used on the D-56TM.
Source: thesovietarmourblog.blogspot.com

The vehicle also received designated CBRN protection, which included a gamma radiation meter.

PT-76 Model 1957 during an amphibious assault. Note the new D-56TM gun and longer TNP-370 periscope.
Source: m.blog.naver

PT-76 Mod. 1958

The hull was heightened by 60 mm (2.36 inch), reinforcement plates were added to prevent warpage in the structure from the waterjets, auxiliary fuel tanks (not connected to the engine) were added. Likewise, a gyro-compass was given to the driver and an additional external tow hook was mounted on the frontal side of the hull.

PT-76 Mod. 1959

New, more durable FG-10 and FG-26 headlights replaced the old ones and the hull was strengthened with plywood, to keep the weight down.

PT-76 model 1959. Note the new headlamps on the tank.
Source: m.blog.naver

PT-76B Mod.1961

Around the 1960s, many older Soviet AFVs underwent major changes, the ISU-152 and T-54 being good examples. The PT-76 was no exception and throughout the 1960s, significant changes were made.

PT-76B Mod. 1961 swimming. Note the external fuel tanks.
Source: m.blog.naver

The main improvement was the upgrade to the D-56TS gun. This new gun had a two-plane stabilizer named STP-2P ‘Zarya’, allowing the gun to stay locked on a horizontal and vertical level but also on one chosen by the gunner. It had two main modes, automatic and semi-automatic. The automatic mode was used in combat, with the entire system running. Semi-automatic was used during stabilization failure and was considerably slower.

After firing, the stabilization mechanism would hydraulically lock the gun in place. This prevented the gun from rising due to recoil, allowing the gunner to view the target and observe the shot. The gun remained locked until the loader pressed the safety button after he had loaded the gun. This restabilized the gun. Unlike other stabilizing equipment found on MBTs, the gun did not rise upwards (breech downwards) to ease the loading process. One such system was the STP-2 on the T-55. However, this feature was not deemed necessary, as the 76 mm shells used by the D-56TS are a lot lighter than the 100 mm ones on the T-55 or other MBTs with even larger guns.

The D-56TS also featured a recoil guard mounted to prevent the casing from hitting the crewmen. A hydraulic elevation piston was also added, as previously, the elevation mechanism of the gun was mechanical. The turret was heightened by 25 mm (0.98 inches), mainly because the turret rotation mechanism was changed. Waterproofing integrity of the turret was also improved.

Additionally, air filters and fuel tanks were reworked once again. New instrument panels were given to the driver and for the turret junction box. A TPU R-120 communication device was installed, and an R-113 Granat radio replaced the old 10RT-26E radio. The difference in frequencies was large; 3.75 to 6 MHz from the old one to 20 to 22.375 MHz. A smokescreen generator was also added, creating smoke that could last from two to 10 minutes (depending on the wind) over a distance of 300 to 400 meters (984 to 1,312 feet). The driver was given two situational periscopes. A TNP-370 elevated periscope was added, which allowed the driver to see better while the tank was swimming, since it was elevated by 370 mm (14.6 inches). Secondly, a TVN-2B night vision device was given to the driver, extending his vision up to 60 meters (197 feet) in the darkness.

All these new electric elements greatly increased the usage of electricity in the tank, so a G-74 generator was installed, alongside a PPT-31M relay controller.

Crew comfort was also improved, the commander received an adjustable backrest and footrests on the turret floor.

To the left is the driver’s control panel or dashboard pre-1961 and to the right is the new version.
Source: m.blog.naver

PT-76B Mod.1962

In January of 1962, a VTI-10 two-stage air filter was equipped, also giving a dust remover for the exhaust of pistons 3 and 4. Additionally, fuel capacity is increased to 390 liters (103 gallons). At the request of the Soviet Navy, a new air intake pipe was mounted in the turret, to improve landing conditions.

The hull was made 70 mm taller (2.75 inch) and the lower front hull was angled inwards at 55°, as opposed to 45°. Armor thickness changes were made as well.

The new armor layout for PT-76B Model 1962. The upper plate was thinner, while the lower plate was made thicker and more angled.
Source: m.blog.naver
PT-76B Mod.1962. The sharper nose, thanks to the 55° lower plate can be seen.
Source: m.blog.naver
PT-76 (left) and PT-76B Mod.1962 to the right. The differences in hull height can be seen.
Source: m.blog.naver

PT-76B Mod.1963

In May 1963, the torsion bars for each side were made interchangeable, improving repair and logistics. To prevent hazards when transporting, the engine deck was also fitted with a travel lock for the gun.

PT-76B Mod.1964

A more efficient engine heater was added, decreasing the time necessary to heat up the engine in low temperatures. Additionally, the driver’s gyrocompass was upgraded to a GPK-59 and the periscopes got thicker armor. The engine was replaced with a V-6B engine.

PT-76B Mod.1965 and PT-76 Mod.1966

Small technical improvements were made to the engine heater, oil filter, driver’s station light, etc. In May 1966, an armored cover was mounted over the TShK-66 sight to prevent debris and spalling from entering the turret.

PT-76B Mod.1967

The last year in which the PT-76 was produced. The track model was redesigned and the thickness of the steel they were made of was increased to 2 mm (from 1 mm). The radio and antenna were upgraded to the R-123 and TPU-R-124 models. More importantly, the co-axial machine gun was changed from an SGMT to a PKT. The armor profile was changed again, this time increasing the lower rear armor plate to 8 mm (0.31 inches).

The armor profile remained largely the same, however, the rear plate was thicker.
Source: m.blog.naver

Problems

Throughout its service life, the PT-76 suffered from a handful of fundamental issues that could not be solved through minor upgrades. Firstly, the main 76 mm gun was not seen as powerful enough and was ineffective against the more modern Western tanks, like the Patton and Centurion. Secondly, the very thin armor combined with a large hull made it a very vulnerable vehicle, regardless of its use on the battlefield. Lastly, it had poor scouting abilities, being very loud, tall, and without proper scouting equipment.

The PT-76 was excellent at what it was designed for – ‘swimming’. However, this came at the price of sacrificing essentially all other combat capabilities. As the only light tank in the Soviet arsenal, it could not perform deep penetration within enemy lines or take on other medium tanks or MBTs while it waited for the heavier tanks to arrive. The 76 mm gun was, at best, satisfactory at the time of development, but it was clear that it would be obsolete quickly.

Unfortunately for the light tank, it never got to be used at what it was designed for – eastern and central European fields and swamps, but rather in a variety of other wars and low-intensity conflicts in other parts of the world, from Vietnam to South Africa. Given the specific niche it was designed for, it is perhaps inevitable that these non-Soviet users ended up using it incorrectly. These deficiencies in its use were highlighted when it was pitted against other tanks and, especially, handheld anti-tank weapons. Alternatively, its bad reputation was mostly caused by bad doctrine and poor usage rather than a bad design, but this is a debatable point.

Although, when employed correctly, as the Indian army did in 1971, the PT-76 could surprise its attackers and cross terrain that no other tank could. Unfortunately, PT-76s were quite often operated as a medium or MBT, and lacked support from heavier tanks, like originally intended.

It is also valid that the tank was doomed from the start in terms of armament. It is possible that Soviet designers underestimated the evolution of medium and light tanks in the West, claiming that the gun was very adequate for WW2 era medium tanks like the Pz.Kpfw. IV, but did not foresee the heavy armor on tanks like the M48 Patton.

Even against contemporary light tanks, like the AMX-13 and M41 Walker Bulldog, the PT-76 was inferior in general combat terms, lacking in firepower, speed, and armor. The PT-76 did excel over its rivals in mobility in rough environments, like swaps, deep muds and snow, and, of course, water bodies.

Further prototypes

The obsolescence of the PT-76 was becoming more and more apparent at the end of the 1950s, with new, and better armored Western tanks appearing. Soviet designers got working on several solutions, fixing fundamental issues in different ways, either armament or size. However, their complexity, price, and the development of the BMP-1 canceled them all.

PT-76M (Object 907)

In 1959, an attempt was made to improve the survivability and mobility of the PT-76 by the designers at STZ. A new welded hull was made with up to 80 mm of armor. It was reshaped, closer to the shape of a boat. The weight increased to 14.87 tonnes, so a new V-6M engine delivering 280 hp was added. Additional fuel tanks were added for an increased range of 400 km. Speed on land remained at 45 km/h and on water at 11.2 km/h. This vehicle was the PT-76M / Object 907 (not to be confused with the medium tank with the same index).

In August of 1959, the one and only prototype was built, but after testing, the new hull actually impaired the floating capabilities. All in all, there were no significant improvements over the standard vehicle and it was canceled.

The PT-76M modernization. Note the angling in the front of the hull and towards the sides. Turret and armament remained identical.
Source: Reco Monkey

PT-85 (Object 906)

Also at STZ in 1960, a project was started with the aim of improving the firepower of the PT-76B. Capital changes were made to the tank. Firstly, and most importantly, was the installation of the 85 mm D-58 rifled gun, fitted with an autoloading system and a highly effective two-plane stabilization system. In addition, an 8D-BM 300 hp diesel engine replaced the previous 240 hp, which allowed for top speeds of 75 km/h on land and 10 km/h on water, despite the 15-tonne weight. Six prototypes were built by 1963 at the now renamed Volgograd Tractor Plant. The military was not particularly interested in the project, as it was expensive and complex, despite the rather obvious advantages over the PT-76B. There was also an Object 906B, which was a low-profile light tank design, meant for scouting and other purposes.

PT-85 or Object 906. Note the completely redesigned turret, with the more powerful 85 mm gun.
Source: Reco Monkey
Object 906B light tank. It never left the drawing board.
Source: Solyankin A.G., Pavlov M.V., Pavlov I.V., Zheltov

Object 8M-904

This peculiar and fascinating vehicle was a 13.5-tonne testbed based on the PT-76 of an armored hovercraft. The turret was removed and, instead, an aircraft engine was installed, delivering 200 hp. Testing proved satisfactory and it proved the viability, or at least, the worthiness of experimenting with armored hovercrafts, or more literally, floating tanks.

Object 8M-904 testbed. Note the additional changes made to the hull, like the heightening the running gear to allow space for the air skirt underneath the hull.
Source: Domestic Armored vehicles 1946-1965

PT-76B with 9M14 Malyutka

In late 1964, tests were carried out for equipping existing Soviet armor with 9M14 Malyutka wire-guided anti-tank missiles. One of these was a PT-76B, which got equipped with a special launcher for said missile. After trials were undertaken at the NIIBIT proving grounds, the PT-76B system was dropped due to its unreliability. It is sometimes referred to as PT-71, however, there is no proof of it being called this officially and is plausibly a confusion.

A PT-76B with the 9M14 Malyutka ATGM.
Source: WT Forums

Object 170

As ATGMs became more prolific and popular in the 1950s, Soviet engineers tried a large variety of self-propelled ATGM vehicles. One of the lesser-known attempts was the Object 170, which used a PT-76 chassis. Its turret was removed, and instead, a turret with two drum missile launchers, equipped with 5 x 100 mm NURS missiles each. In between them, was the mounting for a 140 mm missile. The project was canceled in 1959 due to the complexity of developing a functional missile fire control system.

The Object 170 used a PT-76 hull but moved the entire crew inside the hull.
Source: Source: Domestic Armored vehicles 1946-1965

Object 280

Developed in 1956 to provide support for troops, this variant used two launchers, each with 16 x BM-14 artillery rockets. Getting it ready to fire took 1 to 2 minutes and so did the reload. Allegedly, one prototype was built and passed factory tests, but state trials were unsatisfactory and the project canceled.

PT-57/PT-76E

A more recent attempt to upgrade the PT-76 in Russia was the PT-57, sometimes called PT-76E. Based on the PT-76B, it used a new 57 mm AU-220 autocannon, an improvement of the S-60 AA autocannon, featuring an automatic loading system. It also received a new 300 hp engine, giving the vehicle a top speed of 60 km/h. Allegedly, Russian Marines placed an order of 50 to 60 units in 2006, but it never materialized, likely due to the obsolescence of the chassis, budget cuts, and other, more promising programs.

PT-57 or PT-76E during trials.
Source: Topwar

Muromteplovoz PT-76B Modernization

Another smaller-caliber plan to keep the PT-76B relevant was the modernization made by Muromteplovoz JSC. The updated version replaced the original engine with a 300 hp YaMZ-7601 engine, propelling the vehicle to up to 60 km/h on road and 10.2 km/h in water. General reliability and repairability were also improved, including increasing parts commonality with the MT-LB. The driver controls are smoother, leading to decreased crew fatigue. The most visible change was to the armament, swapping the original turret with an MB2-03 turret (also manufactured by Muromteplovoz) which featured a 30 mm 2A42 automatic cannon, a 7.62 mm PKTM machine gun, and a 30 mm AG-17 automatic grenade launcher. The weapons system was primarily used against soft targets and low-flying aircraft and utilized a two-plane stabilizer and TKN-4GA day-night sight. Elevation angles were between -5 and +70 degrees. All ammunition was stored in the hull of the vehicle. Similar modernizations are also available for vehicles such as the MT-LB, BMP-1, various BTRs, and other vehicles.

The promotional image from Muromteplovoz for their PT-76B modernization.
Source: muromteplovoz.ru

Variants

As the PT-76 offered a light and versatile chassis, specially designed to be easily redesigned for other uses, it branched off into other variants. The main one was the BTR-50, co-designed with the PT-76 from the very start. Later in the ‘50s and ‘60s, as the effectiveness, popularity, and threat of missiles became larger and larger, various close to long-range missiles systems were made based on the PT-76 chassis, like the ballistic missile launchers 2K1 Mars and 2K6 Luna, but also defensive surface-to-air missile systems like the 2K12 Kub. Various conventional systems were also designed, like the short-air defense ZSU-23-4 Shilka, airborne assault gun ASU-85, or GSP mobile ferry.

BTR-50

One cannot mention the PT-76 without raising the BTR-50. Developed alongside the light tank, it became the first Soviet tracked armored personnel carrier. Having the same hull as the PT-76, the fighting compartment was raised, allowing for the transport of troops. Initial variants were open-topped, but later received a roof and were renamed BTR-50PK, among other changes. Well over 6,000 units were built, but was, just like the PT-76, replaced by the BMP-1.

BTR-50PK during a parade. Note the open roof hatches and InfraRed (IR) light. Source: Pinterest

2K1 Mars

As conventional artillery cannons grew heavier and larger in the 1950s, ballistic missiles were developed onto vehicles to make them mobile. The 2K1 Mars was one of the first such systems to enter service within the Soviet military. Based on the chassis of the PT-76, the turret was removed, with the missile launcher placed across the length of the hull, thus creating the SPU 2P2 hull. The launcher could pivot on the spot where the previous turret was. The range of the missile was quite short, between 7 and 18 km. Several problems, like damage to the chassis from the rocket launch were noted. Production started in the mid-1950s, albeit after just 25 units delivered, focus shifted on the more performant 2K6 Luna missile system. It had a loading vehicle also based on the PT-76 called the 2P3.

Despite the limitations of the 2K1, it offered a basis for future Soviet ballistic missile systems.
Source: Militaryrussia.ru

2K6 Luna

The 2K6 Luna was a further development of the 2K1, with more advanced 3R9 (HE) and 3R10 (nuclear) missiles, capable of reaching a distance of 45 km. The launcher itself was the 2P16 chassis, with the index Object 160. The loading vehicle was the 2P17. Production started in late 1959 and the first units were received in 1960 and would remain in service until 1982. It was also exported to Second and Third world nations.

2K6 Luna ballistic missile system, mounted on the 2P16 carrier chassis, in itself based upon the PT-76.
Source: Weaponsystems.net

GSP tracked self-propelled ferry (Izdeliye 55)

The GSP (Rus: Gusenitschnyi Samochdnyi Parom; Eng: Tracked self-propelled ferry) was intended to shorten and simplify the movement of medium and heavier tanks and other equipment over bodies of water. When two units were placed side by side, they would drop a pontoon on either side, thus creating a moving pontoon or ferry. Also based on the PT-76, but its engine was replaced with a much smaller 135 hp YaZ-M204V 2-stroke engine, limiting its top speed to 36 km/h on land and 8 km/h on water.

A single GSP ferry. It would drop the pontoon on one side (in the case of the vehicle in the image above, left) to transport equipment across riverbanks.
Source: Obordow.ru

ASU-85 (Object 573)

The ASU-85 was an airborne assault gun developed in the late 1950s to replace the obsolete ASU-57 for the Soviet Airborne troops. It mounted an 85 mm D-70 2A15 gun in a conventional armored casemate. It was also based on the hull of the PT-76, but it was no longer amphibious and the engine was changed to a YaMZ-206V engine with 210 horsepower, allowing it to reach 45 km/h. However, it quickly became clear that AFVs with hull-mounted armaments were no longer necessary, and it was replaced in the 70s by the much more nimble and amphibious BMD-1 IFV.

Paratrooper’s ASU-85 on parade at the Red Square.
Source: Pinterest

ZSU-23-4 Shilka

One of the most capable SPAAGs of the Cold War, the ZSU-23-4 Shilka was developed after 1957, but only entered service only in 1965. Featuring 4 x ZU-23 23 mm autocannons and equipped with a radar, the weapon system could fire 4,000 rounds per minute. Consequently, the Shilka was an extremely dangerous threat for low flying aircraft, like helicopters. Its chassis was based on the PT-76, named the GM-575, although the upper hull was radically changed. The front lower plate, normally very large on the PT-76, was lowered down, making space for a large superstructure. Another 6,500 systems were produced and exported across the world.

ZSU-23-4 Shilka SPAAG. Note the redesign of the upper hull, for instance, the driver’s hatch. Source: Net-Maquettes

2K12 Kub

Whereas the Shilka excelled at close-range anti-air support, the 2K12 surface-to-air missile system offered protection over a greater area. Equipped with large 3M9 frag-HE missiles, which could reach an altitude of 14,000 m and a range of 24 km, the system was deemed satisfactory for serial production only by 1967, almost 10 years after development started. The 2P25 TEL (Transporter Erector Launcher) was based on the GM-578 while the 1S91 SURN radar vehicle was based on the GM-568, both of which were similar to the chassis for the Shilka, barring smaller details, like hatches. Naturally, other vehicles completed a battery, like a missile transporter. These systems saw widespread use throughout communist states and affiliated, and are still widely in service today.

The 1S91 SURN radar (left) and 2P25 TEL (right), part of the 2K12 Kub air-defense missile system. Source: SimHQ

Shmel class gunboats (Project 1204)

One of the more curious uses of the PT-76, or more precisely, its turret, was on the Shmel-class gunboats. In the 1960s, the Soviet military began the development of a new gunboat that was capable of sailing through narrow and shallow rivers, but also getting closer to the shore for the support of ground troops. Naturally, this meant it was rather small, being only 27.70 meters long, 4.3 meters at beam, having a remarkably shallow draft of 0.8 meters, and a total displacement of about 70 tonnes. Powered by two 1200 hp M-50F-5 diesel engines, it could make up to 26.2 knots (48.5 km/h). However, the main forte of these gunboats was the number of onboard armaments. At the bow, the turret of a PT-76B, including its 76 mm gun and coaxial 7.62 mm machine gun, was mounted, offering both direct and indirect firepower against enemy forces and positions at closer ranges. On later models, a 140 mm BM-14-17 MLRS was mounted near the center of the ship for longer-range barrages. At the stern, either a 2M-6T turret with twin 14.5 mm machine guns or a 2M-3M turret with twin 25 mm autocannons could be fitted, being found on early- and late-production vessels, respectively. Additionally, four 30 mm AGS-17M automatic grenade launchers, all contained within an armored cabin, could be found directly aft of the bridge on later vessels. To top things off, it featured a minelayer with a complement of 10 mines. It entered service in 1967.

Shmel class gunboat, firing its 76 mm D-56TS gun.
Source: Anton Blinov

BMP-1 Development and other light tanks

The PT-76 was undoubtedly the starting point of many light tanks and IFV projects in the 1960s, like the Object 911, 911B, 914, and 914B, just to name a few. The 911 and 914 were APC prototypes, in the competition for a new IFV, the BMP-1. The Object 911 had hydraulic suspension and retractable running gear, similar to a wheel-cum-track system. This allowed it to achieve high speeds both on roads, with the help of tires, but also a good off-road performance from the tracks. In contrast, Object 914 was a much more conventional vehicle, very similar to the PT-76. To boost its firepower, firing ports for the infantry were placed throughout the vehicle, including two in the front, giving it a very unusual look. Both prototypes were built and tested, and now rest at Kubinka tank museum. The Object 911B was a light tank project, focused primarily on having a very low profile. This was done to decrease the probability of being hit, but also minimize the level of armor needed. A low-profile tank is also much harder to hit.

Object 911 IFV prototype. Note the rear entry passage for the infantry.
Source: Pinterest
Object 914 IFV prototype. Note how similar the hull is to that of the PT-76.
Source: Kubinka
The Object 911B had hydraulic suspension and was able to lower its hull, to touch the ground, similar to that of the E-10 German tank destroyer. Here it is in the driving position, next to a PT-76B.
Source: Domestic Armored vehicles 1946-1965

Chinese Type 63

China received a number of the Soviet PT-76 tanks in the mid-1950s and by 1958 decided to build their own light tank, taking ‘inspiration’ from the Soviet design, albeit with various changes made. The driver sat on the left side of the hull, the crew was increased to 4 and the weapon was a more capable 85 mm Type 62 rifled gun. The most remarkable difference, however, is the amphibious propulsion, as the Chinese tank is also able to use its tracks for water propulsion, not just the water jets. It entered production in 1963 and branched off into many variants and modernizations. It is still in service in the PLA and various other nations.

Chinese Type-63 amphibious light tank, heavily inspired by the PT-76, but with significant changes.
Source: Military Today

North Korean M1981

The M1981 is a North Korean light tank developed in the late 1970s; though it takes some inspiration from the Soviet tank, mechanically, it is much closer to North Korea’s own 323 armored personnel carrier. The turret shows clear inspiration from the Soviet design, with a conical shape, but retains completely different hatch designs, and mounts a more powerful 85 mm gun based on a Chinese model. That gun warranted it the nickname of ‘PT-85’, given by Western enthusiasts, which largely overestimates its links with the Soviet tank, which serves as one within several inspirations to North Korea’s vehicles.

North Korean M1981 in 2009. From afar, it looks similar to the Soviet counterpart but is in fact different in every aspect.
Source: massimotessi.altervista.org

Export

The PT-76, like most other Cold War Soviet vehicles, saw substantial export to nations across Eastern Europe, Africa, and Asia. Around 2,000 such tanks were exported by the Soviet Union, out of which 941 were PT-76B models.

Finland

Finland received 12 PT-76B export light tanks from the Soviet Union in 1964 and were used until 1994. Finland also purchased 118 BTR-50s in the same period. After the retirement of the light tanks, a few were transformed into driver training vehicles for the BTR-50s. The main difference was the removal of the main gun and mantlet. In its place, a sheet of plexiglass was bolted over the gap. These were named PT-A and were also retired in 2018, alongside all remaining BTR-50 APCs.

A PT-A driver training vehicle for BTR-50 armored personnel carriers.
Source: yhdistykset-akaa.fi

East Germany

East Germany, or DDR (Deutsches Demokratische Republik), ordered 170 units in 1956, which were delivered between 1957 and 1959. These were used in exercises across the northern coast and even exercises with the Polish army and Soviet naval forces. When East and West Germany were reunited, the light tanks were scrapped or sold off to various countries.

A unique and tragic incident happened on the 24th of August 1965, when the 1st Reconnaissance Battalion, stationed in Groß Behnitz, invited schoolchildren on an amphibious ride across the local Riewend Lake. For the ride, one PT-76 light tank was used, with 21 children and guardians, plus the driver situated in the hull. They were standing across the length of the hull, however, at one point, the children towards the back moved forwards to the bow of the tank, either to get away from the hot engine bay or to hear what the driver was saying. This brought additional weight to the front, which sunk and took water over the top, further sinking the tank. Eventually, the water reached the driver’s hatch, which was open. From there, the sinking of the tank was rapid. Everyone was able to exit, but as the sinking happened in the middle of the lake, getting to shore was hard. The driver and 14 children survived, but 7 boys drowned in the accident. A local diver found the bodies and also uncoupled the tank, entering through the turret hatch. Lastly, he connected the tank with a tow hitch through which the tank was removed and pressed back into military service.

PT-76B carrying children over the Riewend. It is unclear if this was the same time as the incident or a previous date.
Source: Maz-online.de

India

India first ordered 178 PT-76 light tanks from the Soviet Union in 1962 and received them between 1964 and 1965. They first saw combat in the Indo-Pakistani war of 1965 but cemented their success in 1971, first in the Battle of Garibpur, where Indian and Bangladeshi troops, supported by Indian PT-76 tanks, invaded the then Pakistani region of Garibpur. India would continue to fight weeks later in what had now become the 1971 Indo-Pakistani war or the Bangladesh Liberation war. One hundred of the now popular tanks would continue to serve in the Indian army until 2009 when they were finally retired. These were kept in reserve and eventually scrapped, used as targets for the Indian Air Force or in museums and memorials.

An Indian PT-76 from the Battle of Garibpur, with Indian propaganda text.
Source: seniorstoday.in

India even converted an M4 Sherman medium tank with the more potent 76 mm gun from a PT-76, mainly due to the availability and reliability of M4 Sherman components, while the original guns were clearly obsolete and possibly worn out. It is unlikely that it kept the stabilizer.

Indian Sherman with a 76 mm D-56T gun from a PT-76.
Source: FTR

Indonesia

This southeastern Asian nation first ordered PT-76 tanks in 1962 and received them by 1964, but had, at most, 170 such tanks in service. They were ordered for the Cavalry, but most served with the Indonesian marines or Marinr. These first saw combat during the Indonesian-Malaysian border war in 1965, where an Indonesian marine brigade was equipped with the brand new PT-76 tanks, but also BTR-50 APCs and BRDM-2 armored cars. Following the G30S (30th September movement) coup d’etat and political issues that followed in Indonesia, the USSR placed an export embargo on the country, terminating any export of tanks and spare parts for the Indonesian vehicles. This led to the Indonesian marines having to ‘cannibalize’ their tanks to keep them in service. The PT-76 saw further combat, primarily in the invasion of East Timor, where the tanks gave a decisive upper hand in combat against weak opposition.

In the 1990s, despite the embargo, the PT-76 still constituted a large part of the armored fighting force of the Indonesian marines. Thus, a plan to modernize the vehicles started. The main upgrades were giving the tanks a Belgian 90 mm Cockerill Mk.III and a Detroit Diesel V 92, 290 hp engine, increasing the top speed to 58 km/h. This version is sometimes called PT-76M (not to be confused with the Soviet one).

Indonesian marines upgraded PT-76. The easiest way to distinguish between the standard and the upgrade is the new, triple slotted muzzle brake.
Source: VnReview

A curious vehicle is an Indonesian PT-76 with the gun removed and a BM-14-17 MLRS mounted on top of the turret.

The Indonesian prototype with a MLRS on the turret roof.
Source: WT Forums

Poland

Poland was among the first to buy the PT-76 from the Soviets, as early as 1955, with 300 units ordered, which were delivered between 1957 and 1958. These were used both as reconnaissance tanks within tank division subunits but also coastal units, namely the 7th Lusatian Landing division. Poland did conceive its own upgrades for the PT-76. Most notable is the DhSK roof-mounted heavy machine gun, which could be operated by the loader when the hatch was open. This upgrade was not given to all tanks.

A Polish PT-76 with a DhSK roof-mounted machine gun during an exercise by the coast. Note the removed muzzle brake.
Source: Twitter

Vietnam

North Vietnam first ordered the tanks in 1964, buying a total of 500 units, which were delivered from 1965 to 1973. These were second hand and some of these tanks came as aid from the Soviet Union for their efforts against western forces during the Vietnam war. The numbers grew from a single battalion in 1965 to 3 regiments by 1971. Locally, the tanks were called ‘Xe thiết giáp’, meaning ‘Ironclad’, leading to Vietnamese tanks being called as such in western literature. While it was deadly when fighting weakly prepared Laotian troops, it struggled against American troops equipped with anti-tank weapons and heavier medium tanks. After unification in 1976, the PT-76 still remained an important part of the Vietnamese tank force, which still has around 300 in service as of 2020. Vietnam also received a large amount of Chinese Type-62 and Type-63 light tanks and are used together.

Vietnamese PT-76 tanks during crew training. Note that the tank in the foreground is the earlier model 1952 variant with the D-56T gun. All the models behind are the newer PT-76 with the D-56TM gun, suggesting that the Soviet Union shipped whatever tanks they did not have in service.
Source: Pinterest

Operators list

– Angola: 68 second-hand ordered from USSR in 1975. Likely still in service
– Albania: from Yugoslavia
– Afghanistan: 50 ordered from USSR in 1958. Some likely still in service
– Belarus: from USSR, all retired by 2000
– Benin: 20 second-hand ordered from USSR in 1980
– Bulgaria: 250 ordered in 1959. Withdrawn from service
– Cambodia: 10 second-hand ordered in 1983. Another 10 ordered in 1988
– Republic of Congo: 3 second-hand ordered in 1971
– Croatia: captured from Yugoslavia
– Cuba: 60 bought in 1970
– Czechoslovakia: Tested one unit but never placed orders.
– Egypt: 50 ordered in 1958. Additional 200 ordered in 1970
– Finland: 12 ordered in 1964, Withdrawn from service
– East Germany: 170 ordered in 1956
– Germany: Received after unification with DDR (Deutsches Demokratische Republik), scrapped and sold
– Guinea: 20 ordered in 1977, second hand
– Guinea-Bissau: 10 in service
– Hungary: 100 ordered in 1957, withdrawn from service
– India: 178 ordered in 1962, withdrawn from service in 2009.
– Indonesia: 50 ordered in 1962, with additional orders up to 170 total units. They were later upgraded with Belgian 90 mm guns – and new powerplants.
– Iraq: 45 ordered in 1967 and an additional 200 in 1983, second hand. Withdrawn from service.
– Kingdom of Laos & Laos: 45 ordered in 1961, with an additional 25 captured from the NVA. 25 are in service in Laos.
– Madagascar: 12 ordered in 1983, second hand, with subsequent orders following.
– Mozambique: 16 bought from the DDR.
– Nicaragua: 22 ordered in 1983, second hand. 10 in service
– North Korea: 100 ordered in 1965. Own indigenous design was created; M1981.
– Pakistan: 32 ordered in 1968 from Indonesia, with a number captured from India in 1965.
– Poland: 300 ordered in 1955. Withdrawn from service.
– USSR/Russia: 12,000 produced. By 1991, 1,113 were still in service, some of which went to the separating nations. All have been retired during the 2010s.
– Slovenia: 10 from Yugoslavia used in the Slovenian war of independence. Withdrawn from service.
– Syria: 80 ordered in 1971, second hand.
– Uganda: 50 ordered in 1973, second hand.
– Ukraine: 50 passed on from the USSR and were all retired by 2000.
– USA: Captured units used for training in OPFOR. These were upgraded with new engines.
– North Vietnam and Vietnam: 150 were ordered by the NVA (North Vietnamese Army) in 1964. 100 more ordered in 1971. Total received was 500, some as aid. Vietnam received a large number after unification and still has around 300 in service.
– Yugoslavia: 100 PT-76B bought in 1962.
– Zambia: 50 ordered in 1983 second hand. 30 possibly still in service.

In Combat*

As a consequence of its large export numbers, the PT-76 saw service in a number of conflicts, as early as the Hungarian uprising in 1956, Vietnam War, Laotian Civil War, both Indo-Pakistani Wars, South African Border War, Six-Day War, Invasion of Czechoslovakia, Yom Kippur War, Indonesian Invasion of East Timor, Iran-Iraq War, 1990-1991 Gulf War, Balkan wars, Ten-day War, Second Chechen War and Invasion of Iraq, to name a few. The light tank’s effectiveness has been controversial, with critiques on both sides of the spectrum. On one hand, it has been widely criticized, as it showcased poor performance in battle, as its armor was thin enough to be penetrated by a variety of weapons and its armament ineffective against main battle tanks. It is worth arguing that many such incidents were cases of using the PT-76 as a regular MBT/support tank in unfavorable locations when the tank was designed to undertake amphibious assault roles and end off potential attacks until heavier tanks arrived.

On the other hand, the PT-76 has been praised in countries like India and Indonesia, which used it for a long time after decisive victories, using the excellent amphibious capabilities and the main armament, still capable of dealing with obsolete and lightly armored targets; as often encountered in such parts of the world. The success of the tank in these situations also has to be attributed to good tactics and correct usage of the tanks.

*Note that the following battles and wars will mostly try to cover information relevant to the PT-76, while still offering important information of the action’s timeline and other facts, but are incomplete, and many details are left out.

Hungarian Uprising

In the Hungarian Revolution of 1956 against the Soviet-controlled communist government, Soviet troops stationed within Hungary entered Budapest on 4th November. Sources disagree on how many tanks and AFVs were used by the Soviets, with numbers ranging between 4,000 to as low as 1,100, with the latter being more realistic. Revolutionaries had no weapons to reliably fight off Soviet tanks, many of which were IS-3 or T-55 tanks and a few of the brand new PT-76 tanks. However, due to the narrow streets of central Budapest, Molotov cocktails were used by revolutionaries to set tanks on fire. Around 700 Soviet troops were lost.

A Soviet PT-76 tank during a temporary retreat in Budapest, on Szent István boulevard. Note that it is a 1951 year model.
Source: Fortepan.ru

Vietnam war

One of the most well-known uses of PT-76 light tanks was by the NVA (North Vietnamese Army) in Vietnam. The first use of the ‘ironclads’ (the Vietnamese name for tanks) would appear in the Tet Offensive, in 1968. However, the trial by fire of Vietnamese PT-76 tanks began on 23rd January 1968, one week prior to the mass offensive. Infantry from the 24th Regiment and a company PT-76 from the 198th Armored Battalion were sent to reinforce the 304th Division. These traveled down the famous Ho Chi Minh trail, through opposing Laotian territory.

Things did not go smoothly. The PT-76 tanks often got stuck in the harsh jungle terrain and often remained behind the infantry. To make matters worse, the NVA infantry got caught in combat with the BV-33 Elefant Battalion, consisting of 700 Laotian troops at Bane Houei Sane. It was only after the light tanks had caught up that the poorly equipped Laotian troops were quickly defeated – in only 3 hours. The retreating Laotian troops settled at Lang Vei Special Forces camp. From here, on 6th February, the 24th Regiment and 198th Armored Battalion chased down Laotian troops towards Lang Vei camp, in what would become Battle of Lang Vei. This base was a U.S. Army Special forces base, manned by a detachment of the 5th Special Forces Group.

The camp was defended by around 500 civilian militia, 350 troops from the Elephant Battalion, and 24 US Army Green Berets commanded by Captain Frank Willoughby. At 18:10 hours a combined artillery barrage, consisting of mortars and later, 152 mm howitzers, opened fire at the American, South Vietnamese, and Laotian camp, damaging certain structures. Five hours later at 23:30, a second artillery barrage commenced, this time covering the advancing PT-76 tanks and infantry regiments, alongside Lang Troai road. Willoughby had been alerted that the NVA PT-76s were attacking by Sergeant Nickolas Fragos, who was in an observation tower. At last, the shelling of the camp stopped.

Three PT-76 tanks had been knocked out by a single 106 mm recoilless rifle, manned by Sergeant First Class James W. Holt, but to no avail, as 5 other NVA light tanks crushed the barbed wire and overran the defenders. Willoughby had been continuously trying to request reinforcements, while also focusing artillery fire on the attacking forces. He later also received the support of an AC-119 gunship, which delivered continuous airstrikes over the attackers. Despite the constant bombardment, NVA troops overran the entire eastern portion of the outpost by 01:15 hours the next morning. The tanks just kept on pushing forwards into the camp, destroying bunker after bunker, with the defenders in terror, as there were no weapons to engage them with. Allegedly, the tanks also depressed their guns as low as possible (-4) and engaged infantry in trenches.

On the other side of the camp, another 3 or so PT-76 tanks approached the camp and opened fire with their main guns on the bunkers, forcing the defenders to retreat towards the center of the camp, essentially squishing together the surviving forces.

Two destroyed PT-76 tanks at Lang Vei.
Source: Alchetron

At 02:30 hours, the PT-76 tanks had entered the inner defense perimeter of the camp and infantry reached the underground bunker where Willoughby, 7 other Americans, and 29 South Vietnamese and CIDG soldiers were hiding. These would stay there until later in the day, with the Vietnamese soldiers being shot when attempting to surrender (or after surrendering, or perhaps not at all, depending on the various and conflicting sources) and the US forces escaped later, being covered by artillery and airstrikes.

The camp did have, as aforementioned, only two M40 106 mm recoilless rifles, but these were not enough to stop the attack. The US troops referred to their single-shot anti-tank M72 66 mm Light Antitank Weapon (LAW) unguided rockets, but with even worse results. They often misfired, missed, or did not set off, with one source claiming that 9 such rockets were launched (and hit) at a PT-76 without doing any damage. One of the last tanks destroyed in the battle was set on fire by a direct hit with an M72 to the engine.

The battle ended in a clear NVA victory, with failed attempts at recapturing the base, like the famous one conducted by Medal of Honor recipient Eugene Ashley Jr. who died trying to recapture Lang Vei camp. Casualties were heavy on both sides. The NVA lost a number of tanks, with estimates as low as 4 to as high as 13 (some sources even state that 13 tanks were used altogether in the assault).

The battle proved once again how a well-planned attack, using the PT-76’s good cross country capabilities to maneuver through the terrain and jungle against an enemy force lacking AT weapons, can be more than enough. It was the NVA’s first major tank usage, alluding towards a promising future. However, human casualties were high. Between 90 to 167 men killed and 220 wounded. On the opposite side, 132 – 309 South Vietnamese were killed, 64 wounded and 119 captured. Seven Americans were killed, 11 injured, and 3 captured.

In an encounter of tanks against mostly inadequately equipped infantry, it is unsurprising when the tanks win, bringing to memory the old aged saying, any tank is better than no tank. A more fair comparison is the encounters with the M48 Patton main battle tank, which outclassed the Soviet light tanks in virtually every category. Allegedly, the first encounter was a bit odd. Three months after Lang Vei, a US observation plane spotted a PT-76 being washed by its crew in the Beng Hai river. Its position was sent to the US Marine 3rd Armored Battalion. One of their M48 tanks then fired indirectly, elevating its barrel into the air. It apparently only fired three shots, with the third hitting the tank and destroying it. M48 Pattons had been used for indirect fire throughout the Vietnam war, but probably not very often against another tank, considering their small size.

One of the PT-76 destroyed at Ben Het in 1969. This is the most famous example for showcasing the PT-76’s weakness. More angles and images of the same tank are available online.
Source: Steelbeasts.com

On 3rd March in 1969, the North Vietnamese, consisting of the 66th Regiment and 202nd Armored Regiment, attacked the Ben Het special forces camp in the darkness. Three M48 Pattons from the 69th Armored Regiment, alongside two M42 Duster SPAAG vehicles, were entrenched and protected with sandbags. As the PT-76 tanks attacked, leading the charge of the infantry, one struck a landmine, alerting the defenders to their exact position and illuminating the other tanks. With the help of their xenon searchlights, the M48s blinded their opponents. A ferocious exchange of fire started, with a PT-76, using the muzzle flash of an M48 as a target, hit its turret, killing two and injuring another two of the crew, although it was allegedly replaced with a new crew, and the tank put back into action. An M48 used the same tactic, knocking out a PT-76, on just its second shot, meanwhile, another M48 ran out of AP ammunition, having to switch to HE.

Second PT-76 (or BTR-50PK) destroyed at Ben Het.
Source: Steelbeasts.com

Eventually, a platoon of 3 more M48s came to help the US forces, dissipating the attackers. The following morning, US troops counted two destroyed PT-76 and one BTR-50PK.

On 9th May 1972, the North Vietnamese launched another attack on Ben Het. This time, however, South Vietnamese Rangers, equipped with UH-1B Huey helicopters mounting advanced BGM-71 TOW guided missile launchers, were on station. These could far better exploit the air superiority that US and ARVN (Army of the Republic of Vietnam) forces enjoyed, as these direct missiles did not pose a threat of harming friendly troops, like conventional airstrikes and artillery fire did. The NVA often came close to enemy positions with their tanks in order to stop them from using artillery. Nonetheless, the new system proved devastating for those on the receiving end. The helicopters destroyed 3 PT-76 tanks, forcing the remaining NVA forces to retreat, and allegedly destroying another 11 or so tanks after the initial attack. The Hueys would go on and destroy 5 more PT-76 tanks, in the same manner, a handful of days later.

The PT-76 would be used again in battles of Lac Ninh and An Loc and final campaigns leading up to the fall of Saigon.

The PT-76 was also used in the Laotian civil war and Cambodian-Vietnamese war.

Indo-Pakistani Wars – When PT-76s sunk ships

The Indo-Pakistani wars of 1965 saw a full-scale attack of Indian troops, as a response to the Pakistani Operation Gibraltar, which involved instigating the local populations from Kashmir and Jammu against the Indian government. While tanks were used by both sides, mainly M4 Shermans, M36 Jacksons, and M24 Chaffees but also newer Patton tanks. India, on the other hand, used British Centurion tanks, M4 Shermans, and the brand new PT-76 tanks. Nonetheless, both sides were not very experienced with the use of AFVs in combat. For example, the 7th Light Cavalry, which was the first Indian unit to receive the tanks, only got them, in late August 1965. In September, crew instructions commenced, headed by 3 officers which were trained in the USSR. However, in the same month, they were ordered to intercept advancing Pakistani troops. The issue here was that Indian crews had just begun training and had little familiarization with the vehicles. In fact, the day they were to sight in their guns was the same day they were sent off to attack. Reportedly, the new tanks also caused confusion among other Indian troops, who mistook the tanks as Pattons or Pakistani tanks.

On 17th September, C squadron, detached from the 7th Cavalry, was advancing towards Chattanwala, when 7 PT tanks got bogged down. The unit commander’s tank had to be abandoned and was destroyed to avoid capture. The Pakistani East Bengal Rifles took the remains as a souvenir, but Indian troops recovered them in 1971.

Four days later, on the 21st, C Squadron encountered Pakistani M4 Sherman tanks and Pattons, near the village of Thathi Jaimal Singh, until Indian Centurions backed the light tanks up. The tanks engaged at close ranges of around 600 meters, but only one Indian PT-76 and two Pakistani tanks, an M4 and Patton were damaged, showing the poor usage and inexperience on both sides.

Pakistan captured a number of PT-76 tanks from India during the 1965 war, which ended inconclusively. Both sides more or less claimed victory, with a return to the state prior to the war, but with tensions at an all-time high.

Inevitably, war broke out again in 1971, after the Pakistani ‘Operation Searchlight’, a military operation that sought to crank down on the East Pakistan nationalistic movements, and resulted in the Bangladeshi Genocide. As a response, India stationed troops and military hardware near the border, including the 45th Cavalry Regiment and 69th Armored Regiment, both armed with PT-76 tanks. The border was separated by the rivers of the Ganges delta, making the PT-76 ideal for the location.

Consequently, on 21st November of the same year, in what is now known as the Battle of Garibpur, the 14th Punjab Battalion, consisting of 800 men, alongside 14 PT-76 light tanks belonging to the 45th Cavalry Regiment, entered areas of Garibpur (East Pakistani territory), with the mission of seizing and securing a road leading towards Jessore. Prior to the mobilization, there had been fights amongst the two nations’ border patrols, thus alerting to India’s plans. This allowed Pakistani forces to mobilize their military towards the respective areas, including an infantry battalion, and/or 107th Infantry Brigade for a total of 2,000 men, the 24th Independent Armored Squadron, 3rd Armored Squadron, and 3 additional armored squadrons equipped with M24 Chaffee light tanks. These tanks, while comparable in armor to the PT-76, were from the Second World War, and had worn out barrels and other components.

Major Daljit Singh Narag, commander of the C Squadron, part of the 45th Cavalry Regiment. He was killed by enemy machine-gun fire in his PT-76 hatch and awarded the Maha Vir Chakra.
Source: Honourpoint.in

The Indian PT-76 tanks were used to intercept the Pakistani counterattack, which began early in the day. They were able to gather intelligence on the Pakistani attack, allowing them to dig in the PT-76 tanks, recoilless rifles, and other equipment in the ground, for better protection, but seem to have left their positions to spearhead a counterattack against the Pakistani tanks. Despite being outnumbered 3 to 1 (though this claim might be exaggerated), the Indian tanks took advantage of the fog with the battle, seeing the incoming Pakistani forces from a mere 30 to 50 meters away. The Indian tanks were commanded by Major Daljit Singh Narag from his PT-76. He managed to destroy 2 Indian tanks before being killed by a fusillade of machine-gun fire when he was outside the hatch commanding his troops. He was awarded posthumously the Maha Vir Chakra, the second-highest military award in India.

Indian propaganda photograph showing a knocked out Pakistani PT-76. It is not entirely out of the question that this particular tank was actually Indian, as it has been misrepresented as a Chaffee.
Source: Seniorsday.in

In terms of losses, the sources conflict, claiming between 8 to 10 to even 14 Pakistani Chaffee tanks were destroyed and 3 captured (according to one source. in running condition) by Indian forces. Additionally, 300 Pakistani soldiers were killed and wounded. In terms of Indian losses, 28 were killed, 42 wounded, and 4 PT-76 tanks were lost.

Important to note is that the Battle of Garibpur happened before the war was even officially declared, and the Indian victory greatly boosted the confidence of Indian troops and decreased Pakistani morale. This disparity in morale is often said to be an important factor in following battles when the 1971 Indian-Pakistani war officially started.

In subsequent engagements in December of 1971, Pakistani troops had entrenched themselves in towns and cities. To combat this, the advancing Indian troops relied on Mi-4 Transport helicopters and PT-76 tanks to transport troops and equipment over the swampy delta, filled with bodies of water. However, in some instances, the PT-76 of the 5th Squadron bogged down, falling behind the infantry, and when attempting to cross a river, the hull sealings leaked, forcing them to go around on land.

Indian PT-76 tanks crossing a stream. Note the infantry hitching a ride.
Source: Medium.com

On 4th December, PT-76 tanks from the 1st Squadron defeated an infantry battalion defending the town of Mian Bazar. However, at this point, the thin armor proved inefficient against proper anti-tank equipment, losing 4 tanks to 106 mm recoilless rifles. On 9th December, the same unit overtook the docks in Chandpur, with Nepalese Gurkhas on top of the tanks. However, during the battle, three Pakistani gunboats engaged the amphibious tanks on the Meghna river. After a series of volleys and exchange of fire, all three boats were sunk and 180 sailors were rescued, out of the 540. Just two days later on 11th December, the tanks encountered another gunboat, which grounded itself, after being fired at with 54 shells from the main gun of the tanks. The tanks were then used as ferries, transporting troops and materiel to and from across the river, but there were instances where the engines overheated and required towing by nearby civilian boats. Note that the Meghna river is very large, and can be up to 1.5 km wide.

Simultaneously, on 9th December, tanks of A Squadron, 45th Cavalry attempted to occupy the town of Kushtia, however, were met by two platoons of M24’s, commanded by Major Sher Ur Rahman and an infantry company. They had used the raised terrain to cover themselves and offer a good overlook over the otherwise flat terrain. The Indian tanks pushed through the field until the Pakistani tanks opened fire. Two to four PT-76s returned fire, knocking out a Chaffee, but were, in turn, destroyed themselves. The lead tank (or last, depending on the source) started a full-throttle retreat, confusing and scaring the surrounding Indian infantry, who were using the tanks as cover, both physically and morally. However, the crews of the two tanks that had remained to fight were found shot dead with their limbs tied.

Two days later, the Indian troops were ready for a second attempt at taking over the town, but to their relief, Pakistani troops had retreated.

Indian PT-76 tanks on their way towards Dacca, the capital of East Pakistan.
Source: Medium.com

However, at times during the war, the PT-76 redeemed themselves, showing their worthiness when properly used. An example was when Indian advances were halted at Gobindaganj by well-positioned Pakistani troops, tanks, and artillery. To aid the troops, the 63rd Battalion used their PT-76 in a 55 km detour to flank the defending forces. This terrain was in no way forgiving, filled with bogs, swamps, and rivers, but the not-so-little PT’s were in their element. Exploiting the Soviet design, 12 Gurkha Nepalese troops were riding atop the tanks. The flanking maneuver was extremely successful, catching the Pakistani’s by surprise, knocking out one M24 Chaffee, a battery of 105 mm howitzers, and a detachment even set up a roadblock ambush for retreating forces, virtually encircling them.

The 45th Cavalry Regiment also continued their operations, swimming upstream the Bhairab (this is questionable, modern maps show this as geographically impossible unless a confusion in names or change of names) River, where they would intercept a ferry at Shyamganj, where around 3,700 fleeing Pakistani troops were captured. When the Regiment’s A Squadron crossed the Madhumati River, on the night of 14th December, 393 more prisoners were taken.

Two days later, on 16th December, the Pakistani forces surrendered, leading to the creation of the state of Bangladesh. While the PT-76 mostly met the very obsolete and worn out M24 Chaffee tanks, their correct use and full exploitation of its good amphibious capabilities, allowed the Indian military to fulfill tasks that no other vehicle could have done. A total of 30 such tanks were lost during the short war.

Prague Spring

The Prague Spring began in January of 1968 after Alexander Dubček was elected as First Secretary in the Communist Party of Czechoslovakia. He strived for decentralization from the Soviet Union, and encouraged more democratic reforms, loosening controls and restrictions on the media or freedom of speech. The main reform was the splitting of Czechoslovakia into the Czech Socialist Republic and the Slovak Socialist Republic.

Naturally, the Soviets were not too happy about these reforms, and during the night of the 20th and 21st August, invaded the ČSSR, with help from other Warsaw Pact nations – Poland, Hungary, and Bulgaria. It is worth noting that there were attempts by the USSR to reverse the reforms by Dubček, diplomatically, but to no avail. Around 200,000 troops alongside 2,000 AFVs invaded the country, according to the Washington Post. Despite the quick occupation, civilian sabotage and resistance continued for nearly 8 months, leading to around 137 dead and 500 wounded.

Two PT-76 Model 1952 on Na Poříčí street in Prague. Note the white stripes across the length of the hull and the width of the turrets.

Naturally, there were several PT-76 tanks present, but like other historians have noticed, documentation is scarce. All tanks, including PT-76 tanks, were painted with white stripes, one going across the hull and one, perpendicular to the previous, across the turret, forming a cross shape on the turret roof. This was done for aerial recognition in cities because, during the Battle of Berlin, many Allied aircraft mistook Soviet armor for German and shot them.

Arab-Israeli Wars

The Soviet light tank saw combat in the Middle East as well, with one of the better-documented conflicts being those between Israel and Arab nations, Syria and Egypt. Egypt first purchased PT-76 tanks in 1958, buying 50, followed in 1966 by another 50. Between 1970 and 1972, another 200 were bought. Egypt first used them during the Six-Day War, where they lost 29 such tanks.

Additionally, the IDF also captured 9 Egyptian PT-76 and some BTR-50 APCs and pressed them into service. The vehicles underwent some changes and modernizations, like the addition of a 4th crewmember, rearwards opening hatches, new radios, and roof-mounted machine guns. For some reason, these are often called PT-71, but that does not make much sense.

On 18th June 1969, the Israeli 88th Don Lavan unit was created, with PT-76 and BTR-50 tanks. However, the main issue was spare ammunition for the PT-76 tanks – only 1,950 rounds. These were used, for example during the War of Attrition. Then, on the night of 25th and 26th May 1970, 6 PT-76 and 7 BTR-50s attempted to cross the Timsah lake and attack the Egyptian place on the western shore. Even before entering the water, Egyptian forces spotted the Israelis, because 3 tanks got bogged down in the sandy shore, canceling the operation.

The PT-76 tanks were potentially used again during Operation Raviv, but that has yet to be confirmed. However, it is not entirely unlikely, as BTR-50 APCs had been used.

In 1971, the unit was moved to the reserves, with 9 PT-76 and 15 BTR-50 and 280 men, but was recalled in action at the start of the Yom Kippur war.

Egypt was to use the tanks again in 1973, this time vast numbers to cross the Suez Canal, as part of Operation Badr, in what would become the Yom Kippur war. Tensions had been building up for a long period of time, with Egypt rearming itself with state-of-the-art military equipment bought from the Soviet Union. Israel had intelligence that Egypt was rearming itself for war, but some Israeli officials considered it unlikely. Nevertheless, both Israel and Egypt conducted large-scale military exercises on either side of the canal. The attack was carried out between 6th and 9th October, while Syrian troops performed a simultaneous attack at the Golan Heights, also using PT-76 tanks.

Sources vary, claiming that Egypt assaulted with 90,000 to 100,000 troops, and 1,000 to 1,280 tanks, and 2,000 artillery. Meanwhile, Egypt carried out a heavy artillery bombardment against the Israeli bank. At 14:00, on 6th October 1973, 20 PT-76 tanks escorted 1,000 marine troops, riding inside BTR-50s. By 02:40 hours the next morning, the Egyptian troops were clearing minefields. The IDF only had 450 troops placed across the length of the canal, from the Jerusalem Brigade, backed up by only 1 armored brigade.

The Israeli tanks launched a counterattack but were beaten back by Egyptians who were equipped with RPGs and Sagger anti-tank missiles, which knocked out two tanks and 3 APCs. The Egyptian armored brigade then went on drive-by attacks against the Bir El Thamada air base and radar stations. The 603rd Marine Battalion, part of the brigade, then occupied Fort Putzer on the 9th.

The 602nd Battalion, consisting of 10 PT-76, was pushing eastwards, deeper into Israeli territory, when a battalion of 35 Israeli Patton tanks encountered them in the middle of the night. The Patton tanks used their xenon lights to effectively blind the Egyptian crews, wreaking havoc. Whatever tanks survived returned back.

When the Egyptian forces invaded, the 88th Don Lavan unit was flown to Sharm el-Sheikh, from where they had moved in position to engage Egyptian troops at Et-Tour. These were ordered to push forwards towards the Great Bitter Lake, but because they had to cross water bodies, they arrived late, at dawn on 16th October. They combined forces with a company of Magach tanks from the 79th Battalion and some infantry. The task was to intercept the Egyptian 25th Armored Brigade, towards the north of the lake. Later, another company of Magach tanks joined, also from the 79th Battalion. The PT-76 and Magach tanks offered a distraction, allowing for troops and tanks to flank the Egyptian tanks, annihilating them.

Israeli modified PT-76 tank, passing by a disabled Magach tank, Yom Kippur war.

On 14th October, the 88th and 14th Brigades, bringing with them 7 PT-76s and 8 BTR-50s, crossed into Egyptian territory, on the western bank of the Suez canal using pontoon bridges. Similar to the tactics employed during Operation Raviv, the tanks were painted in Egyptian colors and crews could speak Arabic. There, the units would participate in Operation Knights of Heart on the 15th of October. The main goal was to establish a bridgehead in the Egyptian territory, allowing for more troops to come in and turn the fighting from a defensive into an offensive campaign.

By the end of the war, the 88th was south of Ismailia. In June of 1974, the unit was disbanded. Many of their vehicles are now on display.

Chechen war

The Chechen war is one of the last conflicts where the PT-76 saw combat and were used from the very beginning. The tanks were mostly used in front of the infantry, protecting them from enemy fire. Likewise, they were also used in defense of roadblocks, strategic checkpoints, and various escorting missions. As an example, a PT-76 was seen near the Grozny Presidential palace.

Unit 3723 (one of the units known to have used PT-76 as a spearhead for infantry) is proof that the light tanks were also used in populated areas against Chechen militants. The unit was from Nalchik, and in December of 1994, entered Chechnya.

One of the few known photos showing a Russian PT-76B in the Chechen war.

On the 18th of April, 1995, Unit 3723 entered the town of Bamut. At least one PT-76 participated in the assault, commanded by Lieutenant Sergei Golubev. He made his way through all the way to the center of the town, alongside a T-72, commanded by Vyacheslav Kubynin. The battle lasted over two hours. Golubev’s PT-76 was quickly immobilized, while the T-72 was set on fire. Yet Golubev managed to extirpate one of the heavy machine gun nests situated in a building, thus covering the retreating Russian troops (the attack was unsuccessful). His tank was eventually destroyed, killing Golubev and his crew.

It was only after the battle it was remarked that, after an inspection of Golubev’s PT-76, the tank withstood 2 hits from RPGs and destroyed 3 enemy positions.

After the assault on Bamut, the unit commander, Alexander Korshunov, and Warrant Officer Alexander Maximov, recalled:

“We’re here from the very beginning of the Chechnya (campaign). Started at Chervlennaya, Vinogradnaya, Grozny. On February 18th, we left, returned, then came back again. Now Gudermes, Argun, Samashki and now – Bamut. (…)”
Korshunov, posthumously, was originally intended to be presented with the Order of Russia, but was awarded Order of Courage instead.

Two years after the end of the first Chechen war, in September of 1998, a PT-76 light tank battalion from the 8th Independent Brigade was dispatched to the city of Nalchik. These saw service in the second Chechen war, where crews, acknowledging the poor armor and vulnerability to RPGs, would add on improvised armor, like spare track links and rubber panels. Despite their obsolescence, their mere presence must have improved the morale of their own soldiers and frustrated the opponents.

PT-76 in the autumn (November likely) of 1999. Note the add on armor. These worked together with T-62 tanks.
Source: Armorama

One riot police officer recalled November 1999:

“With a tank, even though it’s light, you feel much more confident, than say, in a BTR of BRDM. After all, a 76 mm gun is much more hefty than a machine gun, even a heavy one. With suppressing (harassing) fire from the tanks, there were no attacks on us.”

A list made out of official reports covers around 50 to 60% of the official losses of Russian tanks during the wars, link to report here. Only one PT-76 is mentioned. This report is of exactly the PT-76 and T-72 from the assault of Bamut. There is also a possibility of a third tank, but that is unconfirmed. A video from the opposing militants from the 26th of April shows the two tanks. Aside from confirming the information above, it brings up the possibility that the T-72 was hit by an RPG from a school building and it caught fire.

The reports also give more information on the PT-76: After receiving two hits, it caught fire, disabling the gun. The tank then drove towards a mosque and rammed a tower, possibly a minaret, crashing the structure down. The commander, Golubev died under the rubble. However, according to Associated Press, the tank was close to the T-72 in an open area with no debris surrounding it. In the end, the entire crew died, consisting of Commander and gunner Lieutenant Sergei Golubev, loader Private A. Klimchuk and driver Private A. Kudryavtsev.

In the memoirs of K. Masalev, it is recounted how, during the retaking of Bamut, a PT-76 was found abandoned on a hill, clearly left by the Chechen forces. It is possible that it was Golubev’s tank, as there were no other PT-76 tanks used in the vicinity. It was blown up.

End of production and service

The light tank enjoyed a lengthy production run, starting in 1952 and ending in 1967, with a total of around 12,000 units built, out of which 2,000 were exported. Out of these, 4,172 were PT-76Bs, with 941 in turn, for export. In November 1990, there were still 602 PT-76 light tanks still in service in the European side of the USSR alone. After the dismantling of the USSR in 1991, a large portion of them went to the newly independent states. PT-76s would still see service as late as the Chechen wars in the 1990s, but so far, none in the war in Donbas.

With the start of production of the BMP-1, the PT-76 was redundant for the Soviets. Just as mobile and amphibious, with a new gun and most importantly, able to transport troops, this vehicle also made the PT-76’s brother, BTR-50, redundant.

After Russian equipment was withdrawn from Chechnya, in 2006, PT-76 tanks were all placed in the reserves of the Russian Defence Ministry, officially ending their active service in Russia.

Conclusion

The PT-76 was one of the many post-war tanks that were designed with WWII battles in mind, for a war that never happened. Yet it still is a more controversial tank than many others. On one hand, its obsolescence from the day it left the factories has been seen as its weakest side, with an outdated gun and paper-thin armor. On the other hand, its great water crossing capabilities and lower price compared to medium tanks or MBTs launched it into mass production and export success, with nations such as Syria buying them. Its practicality and design prompted the Chinese and North Koreans to produce tanks very similar to it. While it was not as high tech or capable of some of its contemporary Soviet vehicles, it proved that, when used as intended by its designers and Soviet doctrine, it was quite not as poor as it seemed.

Special thanks to Sebastien A. Robin for providing sources, Marisa Belhote for the segment on the M1981, and Hugo Yu for the section on the Muromteplovoz upgrade section.

PT-76
PT-76 model 1951, soviet naval infantry, in amphibious configuration, 1955.
East German PT-76
East German PT-76 model 1951, early 1960s
Finnish PT-76
Finnish PT-76B, 1960s.
NVA PT-76A
North Vietnamese PT-76A, battle of Ben Het 1969.
PT-71 PTRS Malyutka
PT-76 9M14 testing the Malyutka wire-guided missile system, 1970s.
PT-76
Polish Naval infantry PT-76B, 1980s.
PT-76
Indian PT-76B, Indo-Pakistani war of 1965, as displayed in Barhat war museum.
Egyptian PT-76
Egyptian PT-76B, war of 1967.
Syrian PT-76B
Syrian PT-76B of a reco unit, Golan heights, Yom Kippour 1973
Syrian PT-76B
A Syrian or possibly Egyptian PT-76B on display at Yad-La-Shiron museum, with the elevated trim vane.
IDF PT-76B
IDF PT-76B, fall 1970s.
North korean PT-76
Indonesian PT-76B.
PT-76
PT-76B from a Soviet naval infantry brigade, Yemen 1980.
Cuban PT-76B
Cuban PT-76B, Angola, 1980s.
Indonesia PT76B
Indonesian marine\’s PT-76B, 1990s
Iraqi 1990
Iraqi PT-76 B in 1990.
Croat PT-76 Slovenia
Croat P-76B.
Soviet Marines 1990
Late PT-76B, Soviet Marines, 1990s
PT-76B 1990
PT-76B Russian naval infantry, Baltic fleet 1990.
Russian Marines, Baltic fleet 1992
PT-76B, Russian naval infantry, Baltic fleet 1992.

Sources

PT-76B manual
PT-76 Light Tank They All Float | Medium
Tankograd: PT-76 (thesovietarmourblog.blogspot.com)
수륙양용 전차 PT-76 (1) : 네이버 블로그 (naver.com)
«Объект 907» и «Объект 906». Проекты развития ПТ-76 (topwar.ru)
https://www.history.com/this-day-in-history/soviets-put-brutal-end-to-hungarian-revolution
ARMOR: July – August 2012
Aresdifesa.it
Domestic Armored vehicles 1946-1965
Armor in Vietnam, Jim Mesko
PT-76 amphibious tank, Mikhail Borisovich Baryatinsky
Otvaga2004.ru
Kubinka tank museum
PT-76 light tank and variants, Christopher F. Foss
PT-76 tank | soldat.pro – military experts. unites the best!
Stories about weapons. The floating tank PT-76 outside and inside (topwar.ru)
India’s Armored Cavalry Rolled — And Swam — Into Bangladesh | by Sebastien A. Roblin | War Is Boring | Medium
PT-76 Light Amphibious Tank (enemyforces.net)
ArtOfWar. Понамарчук Евгений. Танковые потери федеральных сил в Первой чеченской войне
ОТЕЧЕСТВЕННЫЕ БРОНИРОВАННЫЕ МАШИНЫ 1945–1965 гг. (VI) « « Военно-патриотический сайт «Отвага» Военно-патриотический сайт «Отвага» (otvaga2004.ru)
As far as I know, PT-76E or PT-57 has never made it to serial production, only a few prototypes… | by Sergey Chernyshov | Medium
Военная продукция (muromteplovoz.ru)
Tactical missile system 2K1 “Mars” (topwar.ru)
M41 Walker Bulldog in combat – Mike’s Research
When Tanks Overran the Green Berets: The Battle of Lang Vei (warhistoryonline.com)
Танки ПТ-76 в боях на Северном Кавказе (vestnik-rm.ru)
Vor über 50 Jahren: Tödliche Spritztour auf dem Riewendsee (maz-online.de)
PT-76 – Kisah Tank Amfibi Tua TNI-AL (indomiliter.com)
Stockholm International Peace Research Institute (Sipri, Trade Registers)
ArtOfWar. Понамарчук Евгений. Танковые потери федеральных сил в Первой чеченской войне
Major Daljit Singh Narag MVC | Honourpoint
Battle of Garibpur: How did Indian PT-76 tank defeat American tanks in Pakistan? – Defence View
Не стреляйте в белых медведей. – Пещера злобного Буквоеда — LiveJournal
Last Stand At Lang Vei (Part One) | SOFREPs
PT-76 MLRS: Prototipe Tank MLRS Amfibi Marinir yang Terlupakan (indomiliter.com)
http://muromteplovoz.ru/en/product/mil_mod_pt76.php
Defense Intelligence Agency’s Soviet Navy Surface Ship Identification Guide (September 1982) DDB-1210-13-82
Советские мониторы, канонерские лодки и бронекатера by А. Платонов

Specifications PT-76*
*These details might vary depending on the production model year, check specific production model

Dimensions (L-W-H) 7,625 x 3,140 x 2,195 (prior 1957, 2,255 after 1957) m
Total Weight, Battle Ready 14.48 tonnes tonnes
Crew 3; driver, commander & loader
Propulsion V-6, 6 cylinder in-line, 4-stroke, water-cooled diesel, outputting 240 hp (179 kW) at 1800 rpm
Speed 44 km/h (27 mph) on road

10/11 km/h (6.2/6.8 mph) on water

Range X km
Armament 76.2 mm D-56T gun, later D-56TM or D-56TS

Coaxial 7.62 mm SGMT mg, later PKT

Armor 15 mm front turret & sides
8 mm upper hull¨front
13 mm lower hull front
15 to 13 mm on sides
6 mm rear
Total Production Circa 12,200
Categories
Cold War Soviet APCs

BTR-50

USSR (1954-1970) Amphibious Armored Personnel Carrier – 6500+ built

Introduction

The BTR-50 was the first mass-produced tracked and amphibious Soviet-built armored personnel carrier (APC). It was developed from the desperate need of a more mobile APC, capable of keeping up with tanks in rough terrain and be able to operate in the difficult terrain of eastern and central Europe. Despite not having any weapons and being very vulnerable to enemy fire, it served for a long period of time within the Soviet and later Russian armed forces, but also in many other countries.

Development – The Need for an Armored Personnel Carrier

All throughout the Second World War, or the Great Patriotic War for the Soviets, the massive Soviet Army felt the need for a domestic armored vehicle capable of transporting troops to the front and into battle in a safe fashion. The BA-64 and BA-10 armored cars simply did not have enough space to carry any additional troops, neither were they designed for this, despite attempts at such projects. Soviet trucks and half-tracks were not armored and thus could not be used for frontline combat transportation in the way the German Sd.Kfz. 251 half-tracks were used.

The Soviets did receive copious amounts of M2, M3, M5, and M9 half-tracks and Universal Carriers from the USA and UK through the Lend-Lease program during the war. Yet, once the war was over and tensions with the West grew, a domestic APC was needed. The need for a designated APC was accentuated by the practices of Soviet military doctrine – Deep Operation, which relied on armored penetrations deep into enemy territory, fast mobilization of infantry, and multiple waves of combined arms attacks. The lack of an armored personnel carrier was a considerable setback on a modern battlefield.

Shortly after the end of WWII, the BTR-152 was developed. It was an attempt to quickly (and cheaply) motorize the vast Soviet Army by building on the chassis of the ZiL-151 truck, which was a formidable platform. Yet, as a modern APC, the BTR-152 fell short. Primarily, the mobility of the BTR-152 was limited, as it simply could not keep up with tanks off-road. Additionally, it was not amphibious, which was seen as something crucial for fighting in eastern and central Europe. Thus, the need for a tracked, amphibious APC became apparent.

BTR-152 in Yerevan, Armenia.
Source: Wikipedia

In 1948, the GABTU (Main Directorate of Armored Forces) [Rus. Главное автобронетанковое управление] requested the development of two types of Armored Fighting Vehicles (AFV); an amphibious light tank and an amphibious APC. The two were to share as many components as possible, be able to be converted into many versions, and have versatile hulls for the development of future AFV designs. These vehicles were to have the ability to cross bodies of calm water with no prior preparation. Another requirement specific to the APC was that it had to be able to carry 2,000 kg (4,400 pounds) of equipment on water. Development had begun through a collaboration between the Sormovo factory No.112, the Chelyabinsk factory (ChTZ), and the VNII-100 research institute of the Kirov plant, Leningrad. The project manager was the famous Josef Kotin, a renowned AFV designer, having designed tanks from the KV and IS series of heavy tanks.

Josef Kotin, the chief engineer of the BTR-50 and PT-76 program.
Source: kpi.ua

First Prototypes

The Sormovo No.122 plant was tasked with the design of the first prototypes in 1948. By 1949, these were ready and were documented as the ‘Object 101’ (R-39 light tank) and ‘Object 102’ (R-40 APC). They, however, failed the factory tests. The reliability and strength of certain components were poor and the vehicles did not even reach the desired speeds of 10 to 12 km/h (6 – 7 mph) over water. They were as well underpowered on land, not reaching the desired top speeds of 50 km/h (31 mph). On the second prototype, to fix the slow speed, the propellers were mounted externally and were supposed to be lifted onto the engine deck when not used, causing them to be vulnerable to enemy fire and overall damage. The second round of testing was done at VNII-100 institute in Leningrad, but they failed those too. The poor performances led to the Sormovo No.112 factory being removed from the program. After this disappointment (the program was supervised by Stalin himself), some of the heads of No.112 factory, alongside certain engineers, were removed from their offices and held accountable.

Object 102, also known as BTR R-40, from the No.112 factory. Source: Rulit.me

The Council of Ministers of the USSR decided on 15th August 1949 that the VNI-100 research institute in Leningrad should restart the development of the two vehicles, with testing to be started in 1950.

Object 750

Work started immediately on the new combat vehicles on the 15th of August, 1949 and the blueprints were ready by the 1st of September. The project was moved entirely to the Chelyabinsk factory, receiving the GABTU designation ‘Object 750’ for the APC and ‘Object 740’ for the light tank. In ChTZ, there were four different systems proposed for the steering and propelling of the light tank (Object 740) in water. These were:

    • propellers in water tunnels
    • conventionally mounted propellers on hinges
    • water-jets
    • tracked propulsion.

Engineers Kotin and L.Troyanov wanted to implement hinged propellers, as they had worked on vehicles with the same propulsion before, however, Nikolai Shashmurin (the famous Soviet tank designer behind the IS-7 and others), who was also involved in the project, wanted to implement water jets. Shashmurin went to the Minister of Medium Machine building, Viacheslav Malyshev, to get his idea materialized. Malyashev agreed, and this meant that all alternative propulsion system projects were terminated, focusing entirely on a vehicle with two waterjet engines. The first Object 750 prototype was completed in April 1950.

The reasoning behind why the water propulsion system was first designed as part of the light tank was that, because the light tank was expected to weigh more than the APC (in reality, they were almost identical), whatever system would work on the tank would surely work on the APC.

The first prototype of the Object 750. The holes in the rear of the hull are for the reverse water jets. These would throw out water forwards, at high pressure, allowing the vehicle to go backward. Source: http://btvt.info/1inservice/btr-50.htm

Rivals; K-75 & K-78

The R-39 and R-40 were not the only competitors for the new amphibious light tank and APC. The Central Design Institute D.M. Karbyshev, Moscow, headed by A.F. Kravtsev, was also in this competition. Kravtsev understood the difficulties of supplying parts in remote areas or on the frontline, so he and his team wanted to use as many automotive and readily available parts. Truck engines and retired light tanks, such as the T-60, were a great source. They came up with a series of vehicles using these parts, the APCs were the K-75 and K-78. The K-75 had a very low profile and was cheap, yet the small engine and lack of designated water propulsion system made it swim with hope and prayers, rather than waterjets. It was also considered too small. Nonetheless, it still somehow managed to pass the requirements set by the Chief of Engineering forces in 1948, but it was not ordered into production, likely because of the superiority of the R-39 and R-40 designs. The K-78 was developed simultaneously with the K-90 light tank, a competitor for the PT-76. While the K-78 did have two propellers and rudders, it was deemed to be too slow on both land and water, despite the boat-shaped hull. Additionally, the crew compartment was still too small. Both failed prototypes survive today in Kubinka.

The K-75 prototype in Kubinka.
Source: Tumbral
The K-78, like the K-91 hull it shared, used a boat-shaped hull and large propellers with a rudder each to boost speed and maneuverability in water. It today stands in Kubinka.
Source: Encyclopedia of Safety

Trials

During June and July of 1950, factory testing of the first Object 750 prototype began. Allegedly, it flawlessly passed the tests, one of which was to drive for 1,500 km. Another trial was testing the buoyancy of the vehicle with the specified 2,000 kg payload. After the first swim, the vehicle showed no problems, deeming the first test as successful. However, due to the good performance on the first test, the trialing manager decided to repeat it, this time with 20 men aboard. As soon as the vehicle entered water, it began to flood and, by the time it was in the middle of the basin, it had sunk. Fortunately, the body of water used was very shallow and those who stood on the engine compartment “only” had water to their knees. The crew itself also climbed onto the deck of the vehicle. It was only after the transporter was pulled ashore, that they found out that screws and drain plugs for the hull hatches had not been mounted back onto the APC after the first swim.

Object 750 prototype during swimming trials. Note the frontal water guard (or ‘trim vane’), offering stability and preventing water from reaching and entering into the driver’s hatches. Source: http://btvt.info/1inservice/btr-50.htm

Shortly after, two more Object 750s were built and, in August 1950, presented to state officials. State trials of these two prototypes were undertaken between 4th and 29th September in Brovary, Kiev. However, the prototypes failed the mileage testing and, according to the Council of Ministers of the USSR, on 31st December 1950, VNII-100 and ChTZ were required to fix the issues by 1st May 1951.

The new prototypes were delivered in July and state trials began in August 1951. They passed trials and three more vehicles were ordered and delivered by August 1952. Testing was carried out between September and October of 1952. One of the tests was firing the 57 mm ZiS-2 and 85 mm D-44 field guns mounted on top of the BTR while afloat! This was done out of the factory engineers’ own will, as the state requirement was to transport the guns, in no way whatsoever to be able to fire them. Regardless, the tests went well. The BTR sustained no damage and stability while firing was acceptable. The Object 750 did not capsize or flood, thanks to the vehicle’s long and wide body. Weirdly, it did not pass firing tests with a 12.7 mm DShK heavy machine gun, which was mounted on a ring around the commander’s hatch, probably because the roof was too thin. Instead, a 7.62 mm SGMB machine gun was mounted.

One of the later Objet 750 prototypes with the 12.7 mm DShK heavy machine gun. Source: http://btvt.info/1inservice/btr-50.htm

On 30th January 1954, after decisions made by the Council of Ministers of the USSR, the BTR was put in service and and additional 10 new vehicles were ordered under the name BTR-750P (BroneTransporteR Russian: Бронетранспортер, meaning Armored Personnel Carrier). The Volgograd Tractor Plant (VgTZ) was selected for their production. By 1955, the name was changed to BTR-50P and mass production was in full swing. It would be unveiled to the public for the first time in November 1957.

Design and technical data

The BTR-50’s lower hull was identical to that of the PT-76, a wide and spacious body for good stability and buoyancy in water, and a heavily sloped front to give better fording capabilities. A large lightly armored box was mounted over the front of the vehicle. The driver sat in the middle and the commander was on the left, with three TNP-B periscopes to look out from. The driver had a small hatch right in front of him which could be opened in non-combat environments, however, it could not be used for entering or exiting. On the other hand, he did have an emergency exit port on the floor of the vehicle, which was not recommended to be used while in water.

The driver’s workstation. He controlled the tracks with two tillers and had three periscopes to see out from.
Source: btvt.narod.ru

The compartiment where the 12 troops sat on benches running across the width of the APC was open-topped and had no side hatches. This meant that the soldiers had to climb over the sides of the vehicle and sit in the open air. This issue was fixed in later versions. The main engine was a V-6, being a 6 cylinder in-line, 4-stroke, water-cooled diesel capable of delivering 240 hp (179 kW) at 1800 rpm, giving the 14.5 tonne (32,000 lbs) APC a top speed of 44 km/h (27 mph) on roads, a power to weight ratio of 16.6 hp per tonne and a range of 400 km from three 400 liter fuel tanks (two in front of the engine compartment and one at the rear of the vehicle). Tests also showed it could run along 30° side slopes, climb 60° gradients, climb 1.1 m high vertical obstacles, and negotiate trenches up to 2.8 m wide. The engine cooling system had a pre-heater to start at extremely low temperatures. The manual shaft-type transmission had 5-gears (4 forward/1 reverse), similar to the T-34-85 system. The side clutch helped the driver for turning, assisted by a mechanical transmission and a band-brake. Taking the harsh Russian weather conditions into consideration, it could operate in a range between -40 C° to 40 C° (-40° to 104° Fahrenheit). The radio was a 10 RT-26E and for internal communication, a TPU-47 tank intercom was used.

The V-6, a 6 cylinder in-line diesel engine, found on the BTR-50 and PT-76.
Source: Bemil.chosum.com

The running gear had 6 wheels per side with no return rollers. These wheels were hollow and helped with the buoyancy of the APC. Additionally, the wheels used simple torsion bar suspension. This layout proved to be very reliable, with countless Soviet vehicles using similar running gear and tracks, such as the MT-LB and BMP-1. This goes to show that the original GABTU request of making the PT-76 and BTR-50 hull very modular and interchangeable truly paid off.

The armor of the vehicle was very thin and was designed to only protect from shrapnel. It was made out of cold-rolled homogeneous steel sheets welded together. In the front, the armor was 13 mm (0.5 inches) thick, 10 mm on the sides and just 7 mm in the rear (0.3 inch). For later versions that had a 10 mm (0.4 inches) thick roof.

Propulsion in water was done through two main jets with openings in the floor of the APC. Water would be pumped up and propelled out the back of the vehicle through two holes, creating thrust. To steer, either one of the holes was shut. For example, to turn to the right, the right whole was closed while the left was still running. Closing the ports to the jets forced the water to exit under pressure through the ports on the side, forcing the water forwards. When reversing, both rear jet holes were shut, redirecting the water to the two smaller ports on the side of the vehicle. This system was designed by Nikolai Konowalow and was identical to that of the PT-76.

Diagram showing steering of PT-76 in water. The system on the BTR-50 was identical. Source: m.blog.naver

As mentioned earlier, the BTR-50 was supposed to be able to carry 2,000 kg over water. The reasoning behind this rather high carrying capacity was to transport a large variety of equipment over water. This included towed weapons and cannons, such as 57 mm, 76 mm, 85 mm guns, 107 mm recoilless rifle, 120 mm mortars, and even GAZ-69 cars. This would have sped up crossing rivers considerably, and having an APC that could transport both the troops and their weapons was a massive upside to the design. Engineers experimented with two different types of mounting systems for the equipment, either an electric crane or a winch with a simple ramp. The crane, run by the main engine, would lift the equipment over the sides and onto a bed. This option was deemed too mechanically and operationally complex, added weight, and, most importantly, expensive. As a result, the winch and ramp alternative was chosen. The winch was mounted underneath the hull, meaning that the cable was running through the center of the fighting compartiment. The winch had a lifting power of 1,500 kg. The system was only used on the BTR-50P and was eventually dropped, as designated amphibious transporters were developed, such as the PTS.

The ramp/winch system of the Object 750 showing loading and transportation of a 85 mm D-44
anti-tank gun. Source: Weaponews.com
A BTR-50 with a ZiS-2 gun undergoing firing trials.
Source: Reddit
While the BTR-50P is often shown carrying smaller guns, it was able to carry guns up to 85 mm in caliber. In the image above, the steps necessary for mounting a towed field gun are shown.
Source: army.lv

BTR-50P

The BTR-50P was the first production version to be accepted into service in 1952. It was very rudimentary, with no roof over the crew compartment. The crew and soldiers had to climb over the sides to enter and exit. Likewise, it had no firing ports for the soldiers inside, but considering the vehicle was designed to drive the troops to battle, from where they go off by foot, it was deemed as acceptable. Inside the troop compartment, 12 soldiers could sit on three benches.

Because it had no roof, it completely lacked NBC (Nuclear, Biological & Chemical) protection, which was a large problem considering the military and political environment of the 1950s and 60s. This was also the version with the ramps for transporting material. A similar version, the BTR-50PA, had a 14.5 mm KPV heavy machine gun instead of the DShK machine gun which was mounted on some vehicles. It also lacked the loading ramps and winch system.

As aforementioned, the BTR-50P had the ability to carry a variety of equipment while afloat thanks to its winch and ramp system. These were:

    • 3x 82 mm D-10 recoilless rifles with 24 rounds (6 boxes), spare parts (6 boxes) and individual gun crews, each crew consisting of 4 men.
  • 3x 82 mm M1937 mortars with 120 projectiles (12 boxes), spare parts (3 boxes) and individual gun crews, each crew consisting of 4 men.
  • 1x 107 mm D-11 recoilless rifle with ammunition, spare parts and 5 man crew.
  • 1x 120 mm gun with 32 projectiles (16 boxes), spare parts and 6 man crew.
  • 1x 57 mm or 76 mm gun with 25 rounds (5 boxes), spare parts and 5 man crew.
  • 1x 85 mm gun and two gun crews.
  • GAZ-69 light utility car.
BTR-50P APCs at the Red Square on 7th November 1961. Note the folding ramps and extra fuel tanks which were removed in later versions. Source: Topwar.ru

BTR-50PK

During the Hungarian Revolution in 1956, the Soviet Army experienced considerable BTR-50 losses. The lack of a roof meant that Molotov cocktails and grenades could be dropped into the crew compartment. Thus, an armored roof with two large hatches for exit/entrance for the troops and a round hatch for the commander were added. Considering this additional weight, a torsion bar was added that prevented injuries when closing the door. The roof also allowed for NBC protection for the crew. When the engine was on, air was distributed into the compartment by a supercharger. When the engine was turned off, a ventilator was used.

The troops sat behind the crew’s compartment that ran along the entire width of the vehicle. There was no separator of any sort in between the two spaces, so communication between the crew and troops was simple. Now that the roof was closed, two gun ports were added on each side wall through which the troops could fire.

Other changes were made, such as the addition of a TVN-2B night vision device for the driver, a P-113 radio, and an automatic carbon-dioxide fire protection system. A new fuel tank was installed, extending the range with 150 km (93 miles). It entered service on 27th October 1958 and was the largest upgrade for the BTR-50 during its service life within the USSR. It received the codename Object 750PK. Many BTR-50Ps were converted to the PK standard.

BTR-50PK during a parade. Note the open roof hatches and InfraRed (IR) light. Source: Pinterest
Top view of the BTR-50PK
Cutout side view of the BTR-50PK. Various details, such as the driver’s position and controls, machine gun ports for the troops and transmission are well shown. The large tube in the rear is the water jet. Source: Btvt.info
All three hatches open on the crew compartment in the BTR-50PK. Interesting to note are the driver’s position and commander’s seat in front of the benches for the troops. Source: BTR-50 – Modimio Collections
BTR-50PK troop compartment, view from commander’s position. Note the three, longitudinally-mounted benches.
Source: Source: army.lv

BTR-50PU

This was the most produced and exported version of the BTR-50. In addition to being a conventional troop transporter, the PU version was a command version of the BTR. These had new radios, an auxiliary power supply, a new ‘cupola’ in the front with three additional TNP-B periscopes, four antennas, and lacked weapons. A TVN-2B night vision device was also added for the driver. A third crew member was also added, responsible for navigation. He sat to the right of the driver. For communication between the crew members, an R-120 intercom system was used.

This version was heavily exported to many nations. Poland and Czechoslovakia produced this version under the name OT-62 and had an entire array of other versions. There was also a marine version with an elongated ‘nose’. Three other versions were the BTR-50PU-2 with R-123 and the R-130M radios and a portable generator, the modernized BTR-50PUM with an AMU telescopic antenna mast and R-123 (3x), R-130, R-326, R-405D, and T-218 radios, and the BTR-50PUM-2 with a reduced crew of 8 and the same equipment as in the BTR-60 R-145BM. Both M versions were converted between 1972 and 1980.

BTR-50PU. The new antennae and new sponson with TNP-B periscopes on the front can be seen. Source: Flickr
BTR-50PU crew compartment from the vehicle manual. Note the addition of the third crewmember location, to the right. Source: BTR-50PU manual
BTR-50PU command version working space. Source: BTR-50PU manual
BTR-50PU schemes. The changes and detail of the command version become apparent. Note that it does not have the second bulge for the navigator. Source: BTR-50PU manual
BTR-50PU top view. Referring back to the similar image of the BTR-50PK, the differences become clear, such as the larger, rounder exit hatches. Source: BTR-50PU manual

Soviet variants

Given the versatility, huge production, and reliability of the BTR-50, many versions were produced within the USSR.

UR-67

The UR-67 (Ustanovka Razminirovaniya Eng: Mine clearer) is a mine-clearing vehicle equipped with a UR-67 rocket launcher system, with extra UZP-67 or UZR-3 explosive tubes stored inside the hull. This innovative system launches a rocket and an explosive charge. The charge detonates mines, thus clearing a path wide enough for tanks and other vehicles to pass.

UR-67 in the Togliatti Technical Museum, Russia. Source: survincity.com

MTP-1

The MTP (Mashina Tekhnicheskoj Pomoshchi, Eng: Technical Assistance Machine) was an armored technical assistance vehicle built on the base of the BTR-50PK, featuring an electrically operated crane mounted on the left side of the vehicle. For easier transportation, the crane was stored on the side of the vehicle, and when needed, it was lifted and mounted into place. To provide better comfort and more working space for the crew, the hull was raised significantly.

MTP with the crane in operation. The upper hull was extended, making the vehicle much taller.
Source: Topwar.ru

Object 209 ‘Penguin’

This peculiar vehicle was born in 1957 when M.M. Somov from the Soviet Academy of Sciences addressed Kotin from the Kirov plant for the need for a new vehicle to be used in the explorations of Antarctica. Due to the short time for development and strict requirements, a proven platform was needed, thus the BTR-50 chassis was used. The vehicles were very reliable, transporting over 15,000 tonnes of material during the Antarctic expeditions. Thanks to the large, insulated interior compartment, work could be done inside of the vehicle without any need for thick clothes, despite the temperatures being as low as -50°C outside of the vehicle. There was also the Object 210, for the Northern Fleet, but was fundamentally the same vehicle.

Object 209 before transportation to Antarctica. Note the enlarged interior compartment, external fuel tanks, and wider tracks.
Source: Topwar.ru
Model of the Object 209, note the smooth wheels, as opposed to the stamped wheels. This was a mistake or omission in the model, the real vehicle had standard wheels.
Source: Saint-Petersburg.com

Prototypes

While the BTR-50 itself did not serve as a chassis for many derivatives (thanks to the use of the PT-76), there were attempts to mount anti-aircraft guns on top of the troop compartment of a BTR-50P in 1955. These were the ZTPU-2 (BTR-50P2) and ZTPU-4 (BTR-50P4). The first had two 14.5 mm KPVT machine guns while the latter had four. The effective range was around 600 meters. They fell short because of the conception of the ZSU-23-4 Shilka in 1957, based on the PT-76 chassis.

ZTPU-4 with the 4x 14.5 mm KPVT heavy machine guns, a distant relative of the ZSU-23-4 Shilka SPAAG.
Source: Kubinka tank museum

Object 211 (BTR-50 with GTD-350 engine)

In the 1960s, engineer J.Y. Kotin got together with the head of the Klimovsk plant, S. P. Izotov to work together on a gas-turbine engine for the Object 288 tank. They used the GTD-350 helicopter engine found on the Mil Mi-2. They placed the engine into a K-700 tractor and a BTR-50 to study the possibility of using such an engine in a ground vehicle. The engineers noted that it offered pros in terms of mass and size and did not need liquid-cooling, however at the cost of poor efficiency and fuel consumption, plus lack of engine braking.

Object 211 during trials. Note the superstructure was made taller to fit the engine.
Source: Tив

Muromteplovoz upgrade

Russian company OJSC Muromteplovoz offered an upgrade package for the BTR-50 in the 2000s, replacing the engine with a turbocharged 300 hp YMZ-7601, elevating the top speed to 63 km/h. The main addition is the new turret, similar to that on the BTR-80A, it has a 30 mm 2A42 autocannon, automatic smoke grenade launchers and a PKT machine gun. The company claims that this upgrade could extend the service life of a BTR-50 by 15 years.

The Muromteplovoz upgrade, with the new turret.
Source: Muromteplovoz.ru

Exports

Like many Soviet vehicles of the era, the BTR-50 was exported in massive numbers in various nations across the world. Exporting military hardware was one of the ways the superpowers of the Cold War era attempted to keep or bring states into their spheres of influence. It is thus not surprising that a large number of the states which received BTR-50s were communists or socialists. Keeping track of the exact versions and names can be difficult, as each nation has its own modifications, own designations, etcetera. There are also many private companies offering their own upgrade packages for BTR-50s.

Belarus

After the dissolution of the Soviet Union, Belarus inherited a large number of BTR-50PKs. An upgrade package has been developed, but Belarus no longer has BTR-50s in service. The upgrade, BTR-50PKM, had new brakes, steering, transmission and a new engine; the UTD-20, giving 300 hp. An ARV (Armored Recovery Vehicle) upgrade package is also available. The upgrades are carried out by Minotor Service in Minsk.

Belarussian BTR-50PKM. Source: Minotor Service

Czechoslovakia & Poland

The OT-62 TOPAS (Obrněný Transportér vzor 62 – Eng: Armored Personnel Carrier model 62) was a joint development between Czechoslovakia and Poland in the 60s. These were based on the BTR-50PK and were built into a variety of different designs and variants, such as ARVs and SPAAGs. Unlike their Soviet counterparts, they often had machine gun turrets to give the vehicle better protection against enemy infantry, an issue with the BTR-50.

OT-62 TOPAS at the Wojska Polskieg Museum in Poland. The vehicle is a Polish version armed with a 14.5 mm KPVT heavy machine gun and a 7.62 mm SGMT coaxial machine gun. Note the side exit hatch, a feature missing on Soviet-designed BTRs.
Source: Wikipedia

East Germany (DDR)

East Germany produced and imported a large number of BTR-50s and built many specialized versions. The Soviet-built BTR-50Ps were named SPW-50P (Schützenpanzerwagen Eng: Armored Personnel Carrier). Many variations were built, including reconnaissance, ARV, air defense observation unit, minesweeper, command vehicles, and many more. After the unification of Germany, the BTR-50s were scrapped or sold.

SPW-50PK of the DDR. Source: Pinterest

One of the more interesting East German variants of the SPW-50 was the Minenräumfahrzeug (MRF) mine-clearing vehicle. Using a similar basis as the UR-67, it used two ‘coffin’ shaped containers containing the explosive charges and the rocket. These were able to create a 100 meter (328 feet) long alley inside a minefield. Two slides were mounted on either side of the engine deck for loading the containers.

The East German SPW-50 MRF. The rocket and explosive charge are located inside the transport containers. Note the angled slide on the engine deck.
Source: Panzer der NVA 1956-1990

Finland

Finland bought 118 BTR-50s from the USSR between 1964 and 1969 and has converted them into command versions and upgraded APCs. These were withdrawn from service in 2018.

A Finnish BTR-50YVI with modern Finnish camo. Source: Deviantart

Indonesia

In 1997, Indonesia purchased 34 BTR-50s from Ukraine, with subsequent orders in later years. These were upgraded with new engines, brakes, radios etcetera. They are used by their Marines. Another version used by the Indonesian Marines is the PAL-AFV, which is a local modernization of the BTR-50. Two large issues had been identified by the Indonesian Marines with the standard BTR-50, the first being water entering into the radiator. The water pumps tasked with removing the water can fail in powerful currents. The second issue was that the engine deck was too low, which can be problematic in a high-rise, powerful waters. To fix this, the entire engine deck was elevated.

Indonesian BTR-50PK. Note the smoke grenade launchers.
Source: IndoMiliter
PAL-AFV in a parade. The much taller engine deck can be seen.
Source: Indonesia Defence

Iran

There are still a number of BTR-50s left in Iran, after they purchased around 270 in 1966 from the USSR. A heavily modified BTR-50, known as the ‘Makran’, was unveiled in 2020, with additional armor and a new turret. This conversion was made by the Iran Islamic Revolution Guard Corps (IRGC).

Surprisingly, the Makran maintains its amphibious capabilities, courtesy of the original Soviet design. The entire front and sides have been up-armored. The turret is armed with a 30 mm autocannon and is unmanned.
Source: Tasnim News

Iraq

Iraq ordered around 250 units in 1968 from the USSR and they have been used in the Iran-Iraq War and Gulf War. More recently, some have been converted with large armored turrets, housing ZU-23-2 AA guns. The Iraqis have also converted OT-62s with, amongst others, Cascavel turrets.

As recently as 2019, Iraqi BTR-50s have been modified with 23 mm ZU-23-2 guns, with more being salvaged from graveyards.
Source: IraqBasic
Older Iraqi conversion, with a different turret.
Source: Bukoved.Livejournal

Serbia

Serbia still has 12 BTR-50s in service in addition to 28 in reserve it inherited from Yugoslavia. Yugoimport offers an upgrade package, the BTR-50S, fitted with an M91 E turret with a 20 mm M-55 autocannon, 7.62 mm coaxial machine gun, 9M14 Malytuka ATGM, and smoke grenade launchers.

BTR-50S with the M91 E turret in 2011.
Source: Wikimedia Commons

Other operators

– Afghanistan (total of 660 vehicles from 1963 to 1988; large amount most likely destroyed). First 100 ordered from the USSR in 1963, delivered between 1965-66.
– Albania (200 BTR-50s, withdrawn from service)
– Algeria (130 BTR-50s, withdrawn from service)
– Angola
– Bangladesh (withdrawn from service)
– Republic of the Congo
– Croatia (26 BTR-50s, replaced by Patria AMV)
– Cuba (200)
– Egypt (500 BTR-50s upgraded to BTR-50PKM in 2014)
– Guinea
– Germany (Passed over from DDR, sold/scrapped)
– Hungary (150 ordered in 1959. 20 BTR-50PU-2 still in service)
– India (200 BTR-50s in service)
– Indonesia (70 in service)
– Iran (150 in service)
– Iraq (Various rudimentary conversions, such as a turret equipped with ZU-23-2 AA gun).
– Israel (captured from Egypt and Syria, now withdrawn from service)
– Kazakhstan (inherited from former USSR)
– Liberia
– Libya (many still in service)
– Nicaragua
– North Korea
– Romania (withdrawn from service)
– Russia (withdrawn from service)
– Serbia (12 are active and 28 in reserve)
– Slovenia
– Somalia
– Somaliland
– Sudan
– Syria
– Ukraine (none in service; BTR-50M upgrade package available under the name BTR-50M).
– Vietnam
– Yemen
– Zimbabwe

Type 77

The Chinese APC, Type 77, has many visual similarities to the BTR-50. However, it is a completely independent design, based on the Type 63-I, itself derived from the PT-76, ironically coming back full circle. It was produced by Norinco into the mid-1980s and entered service in 1978. The Type 77 was not exported and was declined into four versions, a gun carrier, ammunition carrier, ambulance, and command vehicle.

Chinese Type 77 APC
Source: Military Today

In Combat

Due to the large export numbers, BTR-50s have seen plenty of combat in recent history, however, being an unarmed APC, there are not many notable combat stories and scenarios, as opposed to battle tanks. Used as early as the Vietnam War, they also saw action in the Middle East. Both Egypt and Syria used them during the Six-Day War in 1967, leading to a handful being captured by Israel. The Syrian armored units consisted of 31 MBTs (T-55s/T-62s/T-72Ms), 2 BTR-50s/BTR-60s, and 10 trucks. They were also used in the War of Attrition by both sides.

BTR-50s were used again by all sides during the Yom Kippur War, in October 1973. BTR-50s have and are being used in the Hungarian Revolution 1954, Prague Spring 1968, Iran-Iraq War (1989-1988), and as recently as the War in Donbas (2014-present).

Likewise, they have been used in the war in Syria by various factions with many homemade adaptations. The lack of armor and the Soviet doctrinal design of the BTR-50 makes it a poor IFV/tank, in the way that it has been used by rebels and fighters in Syria.

Hungarian Uprising

In the Hungarian Revolution of 1956 against the Soviet-controlled communist government, Soviet troops stationed within Hungary entered Budapest on 4th November. Sources disagree on how many tanks and AFVs were used by the Soviets, with numbers ranging between 4,000 to as low as 1,100, with the latter being more realistic. Revolutionaries had no weapons to reliably fight off Soviet tanks, many of which were IS-3 or T-55 tanks. However, due to the narrow streets of central Budapest, Molotov cocktails were used by revolutionaries to set tanks on fire. This posed huge dangers to the open-topped APCs then in service, such as the BTR-40, BTR-152, and BTR-50. Around 700 Soviet troops were lost.

A burning BTR-152 during the Budapest Uprising. The lack of a roof and unseparated internal crew and troop sections made it very vulnerable from Molotov cocktails thrown from the buildings. The BTR-50 suffered from the same issues.
Source: The Budapest Beacon

Prague Spring

The Prague Spring began in January of 1968 after Alexander Dubček was elected as First Secretary in the Communist Party of Czechoslovakia. He strived for decentralization from the Soviet Union, and encouraged more democratic reforms, loosening control and restriction on media or freedom of speech. The main reform was the splitting of Czechoslovakia into the Czech Socialist Republic and the Slovak Socialist Republic.

Naturally, the Soviets were not too happy about these reforms, and, in the night between 20th and 21st August, invaded the ČSSR, with help from other Warsaw Pact nations – Poland, Hungary, and Bulgaria. It is worth noting that there were attempts by the USSR to reverse the reforms by Dubček, diplomatically, but to no avail. Around 200,000 troops alongside 2,000 AFVs invaded the country, according to the Washington Post. Despite the quick occupation, civilian sabotages and resistance continued for nearly 8 months, leading to around 137 dead and 500 wounded.

BTR-50PK (left) and BTR-60PA in Prague, 1968. Note they have canvases with white aerial markings.
Source: Pinterest

BTR-50 in Israeli use

Israel first captured around 240 BTR-50s and OT-62s from Egypt in the Six-Day War in 1967. The IDF used them extensively until the 1980s when they were sold off/retired in favor of M113s which were first delivered in 1971. Some BTRs were assigned to the 88th Battalion and 440th Reserve Tank Division, which consisted of only captured equipment.

Captured BTR-50 used by the IDF in the Yom-Kippur War. Note the additional machine guns mounted.
Source: Indomiliter

BTR-50s were also used by the IDF in the Ten Hour War, also known as Operation Raviv. Operation Raviv was an Israeli armored raid into the western bank of the Gulf of Suez, on 9th September 1969. Under the cover of darkness, six T-55s and three BTR-50s painted in Egyptian colors landed south of Ain Sokhna just after 0330 hours, north of their main objective; an Egyptian radar installation located at Abu-Dareg. Without stopping, the armored raiding party drove approximately 45 km south along the coast, raiding Egyptian outposts and attacking the thoroughly surprised Egyptian forces along the way. Infantry forces, consisting of elements of the 7th Armored Brigade’s reconnaissance company and Arab-speaking special forces members, fought while mounted in order to maintain momentum and prevent a protracted battle with Egyptian forces. After nine hours of operating in Egyptian territory, the armored force was withdrawn just after 1200 hours via ship north of Zaafarana, having suffered only light casualties and no known vehicle losses.

Two Israeli T-54s and a BTR-50 painted in Egyptian colors during Operation Raviv.
Source: archives.mod.gov.i

BTR-50 in VPA service & Vietnam War

By 1965, the People’s Army of Vietnam (VPA) had received 50 PT-76 light tanks and 50 BTR-50 APCs from the Soviet Union. While the PT-76 was used successfully in the south, the BTR-50 was deemed obsolete and vulnerable at close range and to airborne attacks. One thing remains certain, that even the North Vietnamese found the lack of firepower of the APC a drawback, limiting the effectiveness and versatility of the APC. It is important to note that the Vietnamese landscape is not what the BTR-50 was designed for, being rather the opposite of the plains of eastern and central Europe. Nonetheless, at least three BTR-50s were converted into SPAAGs, with two ZPU 14.5 AA heavy machine guns mounted. These belonged to the 202 Motorized Infantry Regiment and were named BTR-50 ‘phòng không’, meaning anti-air. They saw combat in Quang Tri in 1973 and 1975. Starting in 2014, Vietnamese BTR-50s were upgraded using the Belarusian Minotor upgrade package.

BTR-50 number 609 was converted with a 14.5 mm ZPU machine gun in the crew compartment and one in an armored turret on the engine deck. This particular vehicle was captured by US forces at My Chanh in May of 1973. There are photos of a BTR-50 with different turrets and dual ZPU guns.
Source: Reddit

Iran-Iraq War

By the time of the First Battle of Al-Faw, the Iran-Iraq War had been a stalemate for years. Iran’s lack of resources and spare parts meant that a lot of equipment was lost and unretrievable, having relied on human wave attacks. However, Iran had to focus more on surprise attacks to be able to break the stalemate. One of these was Operation Dawn 8, which consisted of an amphibious landing on the Al-Faw peninsula and occupying it, leaving Iraq landlocked.

Between 100,000 to 150,000 Iranian troops attacked on 9th February 1986. Human wave attacks were sustained on the north of the peninsula while, at the south, amphibious armored assaults were made. The Iranian forces used torrential rain to their advantage, taking the Iraqi forces by surprise, additionally not allowing them to use their vastly superior air force and artillery.

Amphibious ships and BTR-50s, amongst others, were used to transport troops across the Persian Gulf and Shat al-Arab River, until Iranian engineers were able to build bridges to continue the flow of troops and equipment. In the end, Iran captured the Al-Faw peninsula. The entire operation decreased the morale of Iraqi troops and population, also cutting them off from the Persian Gulf.

Iranian BTR-50 during landings on Al-Faw peninsula, February 1986.
Source: military-photo.com
While the Soviets never really used the BTR-50s capability of carrying heavy weapons, in the Iran-Iraq War, it was used in very creative manners. Here, a recoilless rifle is mounted on a BTR-50. The lack of AFVs meant that even a vehicle like the BTR-50, usually with little value in firefights, could be upgunned in many creative ways.
Source: Pinterest

Replacement

The BTR-50 was slowly replaced by the BMP-1 as a frontline mechanized brigade APC. The BMP-1 was also able to engage enemy targets, as it was an IFV. Radio and command BTR-50s and BTR-50PUs were replaced by MT-LBu after their introduction in the 1970s. The MT-LBu was much more versatile and spacious, better suited for equipping a variety of systems.

MT-LBu amphibious multi-purpose vehicle equipped, in this case, with a 1L112 radar.
Source: Vitaly Kuzmin

While most BTR-50s had been retired from active use by 2003, the Russian Armed Forces still possessed large stocks of these vehicles. Potential upgrade plans were met with mixed feelings, some considering them as certified death traps due to the poor armor, while others saw the upgrade potential of such a vehicle, similar to the M113’s long list of upgrades.

The BTR BT-3F is a modern Russian amphibious APC based on the BMP-3F IFV. While it uses modern technology, including a RCWS (Remote Controlled Weapon Station) equipped with a 7.62 mm machine gun, the BT-3F is, at heart, a BTR-50. Intended to replace the MT-LBs and naval infantry’s BTR-82As (which have entirely replaced the BTR-80s), the BT-3F is able to carry troops and provide moderate support during amphibious maneuvers. Unlike the BTR-50, it has adequate protection, STANAG level 4, and a rear entry and exit door for the infantry.

BTR BT-3F was first shown in 2010. As of 2020, the BT-3F still has not entered service in the Russian armed forces, although Russia did sign a contract with Indonesia to replace their BTR-50s.
Source: Ensamma Vargen

Conclusion

The BTR-50 served as a formidable starting point for future Soviet IFV and APC designs. Thanks to its low price, reliability, versatility, and high production, it still serves in a lot of countries to this day, embedding itself as one of the most influential and well-known APCs in AFV history. Although later BTRs were wheeled for higher speeds and reduced maintenance costs, the BTR-50 chassis still served as a basis for other tracked transporters, like the MT-LB.

Due to its high production numbers and exports, it has seen service in many conflicts around the world, from as early as the Hungarian Revolution to the Iran-Iraq War or Operation Desert Storm. Although their combat value was very limited in these scenarios, as the war they were intended to fight in never took place, ingenious adaptations and armaments made it work.

Like many other Soviet vehicles, many countries have produced their own versions, such as the Polish/Czechoslovak OT-62 or the Chinese Type 77. Even today, private companies offer upgrade packages for the BTR-50, as there are still countries that use them. The BTR-50’s story has ended in Russia, being replaced by more capable transporters, and is nearing an end globally, as the nations that still use them seek to replace them. Nonetheless, the almost 70-year long service of the BTR-50 is surely something to be impressed by.

BTR-50P on parade durin the 1950s. Note the fuel tanks and gun loading ramps.
BTR-50
Soviet BTR-50P, the first version, with an open-air compartment for the troops (1954).
DDR BTR-50PK
East German BTR-50PK, the standard enclosed version (1958).
Hungarian BTR-50PU
Hungarian BTR-50PU (1959), the second command version.
BTR-50
Soviet marines BTR-50PK in the 1970s.
Czech OTAS-62
Czech TOPAS-62 in the 1960s
BTR-50
Iraqi BTR-50PK, Iran-Iraq war of 1985-87.
BTR-50
Egyptian BTR-50PK, war of 1967.
Indonesian marines BTR-50PK
Indonesian Marines BTR-50PK, with some modifications like the smoke dischargers.
Croatian BTR-50PK
Croatian BTR-50PK.
BTR-50
Soviet UR-67 rocket-assisted mine-clearing vehicle.
Romanian BTR-50 PU
Romanian BTR-50PU.
Cuban BTR-50PK
Cuban or Nicaraguaian BTR-50PK modified with ball-mounted and two pintle-mounted LMGs.

Sources

Soviet/Russian Armor and Artillery Design Practices: 1945-1995, MCIA
topwar.ru
BTR handbook, the universal APC, CTID
Obrněný transportér OT-62 TOPAS: historie, takticko-technická data, modifikace, Frýba Jiří
soldat.pro
Btvt.info
Weaponews.com
PT-76 amphibious tank, Mikhail Borisovich Baryatinsky
Otvaga2004.ru
Kubinka tank museum
T-54/5 To IDF Tiran 4/5: The Birth Of A Bastard Tank – Ma’or Levy
ARMOR: July – August 2012
Aresdifesa.it
Domestic Armored vehicles 1946-1965
Armor in Vietnam, Jim Mesko
Panzer der NVA 1956-1990
http://army.lv/ru/btr-50/2054/3827
http://btvt.narod.ru/5/btr50/btr50.htm
http://www.opoccuu.com/btr-50.htm
http://army.lv/ru/pt-76/2054/3834
http://www.military-today.com/apc/bt_3f.htm
https://www.history.com/this-day-in-history/soviets-put-brutal-end-to-hungarian-revolution
Военная продукция (muromteplovoz.ru)

BTR-50 specifications

Dimensions BTR-50PK (L-W-H) 7.07 x 3.14 x 2.03 m
Dimensions BTR-50PU (L-W-H) 7.07 x 3.14 x 2.05 m
Total Weight, Battle Ready 14.5 tonnes
(32,000 lbs)
Crew 2; driver & commander + 12 to 20 passengers)
Propulsion V-6, 6 cylinder in-line, 4-stroke, water-cooled diesel, outputting 240 hp (179 kW) at 1800 rpm
Speed 44 km/h (27 mph) on road
10.2 km/h (6.2/6.8 mph) on water
Range 240-260km on land
60-70km on water
Armament 7.62 mm SGMB machine gun, 1250 rounds on BTR-50P
14.5 mm KPV heavy machine gun on BTR-50PA
Armor 13 mm in the front (0.5 inches)
10 mm on the sides and roof (0.4 inches)
7 mm in the rear (0.3 inches)
Total Production circa 6500+
Categories
WW2 Soviet Prototypes

GAZ-68 / KSP-76

Soviet Union (1943-1944)
Experimental wheeled infantry support gun (1 built)

The SU-76 remains, to this day, one of the most well-known Soviet self-propelled guns of the Second World War. Yet, at the start of its production, it was plagued by unreliability and mechanical issues caused by its drivetrain. Thus, production was halted at only 560 units in order to remedy these problems. Solutions came with the SU-76M in 1943, but in between this period, another vehicle was designed, not to replace the SU-76, but rather supplement it. This was the GAZ-68 (also later referred to as KSP-76). Meant as a desperate and ultimately unsuccessful attempt to bolster tactical mobility, it was meant to provide close support artillery for rifle and cavalry units through direct fire. The GAZ-68 was based on a truck chassis, and the main gun would still be the famous ZiS-3 field gun.

SU-76M in what seems like Berlin, 1945. The SU-76M was an attempt to fix some problems with the SU-76. The GAZ-68 was a different vehicle in its role but would have functioned alongside the SU-76s.
Source: Pinterest

Why?

Throughout the early stages of the Second World War, the Soviet military found itself in a dire need of a fast vehicle, with good firepower, able to take on German Panzers but also other targets. Mainly, it would assist the infantry units in dealing with armored and unarmored targets, but also have the capability of responding quickly, moving and penetrating deep into enemy lines, accompanied by infantry attacks. Until 1943 and ‘44, the RKKA had no designated infantry support vehicle, relying entirely on towed artillery. Using a wheeled chassis as a basis, would allow much greater on-road speed, while also, theoretically, keeping production and maintenance costs down. On paper, a vehicle like the GAZ-68 was just what the Red Army needed, but in reality, it was the complete opposite, a consequence of the Soviet war and industrial struggle. Contrary to popular conceptions, this vehicle was not meant for artillery units for indirect fire or ‘shoot and scoot’ purposes, rather just an infantry support gun.

Front of the GAZ-68 as it is preserved at Kubinka, Moscow.
Source: A. Tarasov’s personal collection

Development

Shortly after the battle of Kursk (July – August 1943), where the use of mobile defenses and counter-attacks (plus numerical superiority) proved key for the Soviet victory, the mobility of artillery and self-propelled guns proved crucial. Thus, the Gorky Automobile Plant (Gorkovsky Avtomobilny Zavod, GAZ) started the development of a wheeled infantry support gun with the approval of the head of GAZ, V.A. Grachev, who was head designer of the project, while N. Astrov was head of the project. Already in August of 1943, the design office and plant management approved the idea. Grachev, a lesser-known name within western literature, was the chief designer at GAZ between 1941 and 1944 when he created many vehicles, most notably the GAZ-64 and BA-64. Post-war, he continued his career at ZiL, where he created, among others, the famous ZiL-157 and BTR-152.

The first ideas involved mounting a ZiS-3 gun on a 1½ tonne truck chassis, with only minor modifications. Clearly, the main goal here was to get a mobile vehicle for as little money as humanly possible.

Drawings for the installation of a ZiS-3 76 mm gun on a truck chassis, which has been stripped down to the bare minimum, missing even an enclosed driving cabin. For obvious reasons, the combat value of such a creation would be extremely limited.
Source: Солянкин А.Г., Павлов М.В., Павлов И.В., Желтов И.Т. Отечественные бронированные машины. XX век. Том 2. 1941-1945

The idea of a wheeled infantry support gun interested the Soviet military, leading to a go-ahead to the project from the People’s Commissariat (Ministry) of Medium Machine Building and the Main Armored Directorate of the Red Army (GABTU). Previously, all self-propelled artillery projects were under the command of GAU (Main Artillery Directorate), until all the SPGs were re-subordinated to GABTU as Stalin personally was outraged that the GAU adopted SU-12 (SU-76) in an unsatisfactory condition. Thus, the Directorate of the Self-Propelled Artillery of the GABTU was established on the 21st of May 1943.

Work started in October of 1943 under the name ‘Izdelie 68-SU’, but this was changed to GAZ-68. By December, a wooden mockup was already completed and documentation on the vehicle from GAZ was sent to the GABTU in mid-December. The GABTU approved the project for further development. On the 7th of February, 1944, the GABTU gave a green light for the production of a prototype. It was around this time that the name ‘KSP-76’ appeared, most likely a product from GABTU to remove the GAZ factory name. It stands for Wheeled Self-Propelled Gun with a 76 mm gun (‘Kolyosnaya Samokhodnaya Pushka’, KSP).

An experimental model of the wheeled self-propelled gun KPS-76.
Curiously that the name in the document is КПС-76 (KPS-76), not KSP-76.
Source: TsAMO

Following the approval for a prototype, the design bureau quickly sent the plans and documents to the workshops, which meant that, by April, the armored hull was completed. This was designed by Y. N. Sorochkin and A. N. Kirilov and was to protect from small arms fire and splinters. To keep weight down, the top was left open. On the 4th of May, the prototype was already completed.

An important part of this quick development and production process was the use of an already tried and tested chassis (not that this meant much for the Soviets, as there were plenty of prototypes in all fields made pre-war, but in this case, it did help boost development). The GAZ-68 was based on the GAZ-63 truck, however, it needs to be pointed out that the production of the GAZ-63 began only in 1948. Rather, the GAZ-68 was based on the experimental GAZ-63 developed in 1939. Essentially this was an all-wheel-drive GAZ-51, which itself was made to replace the aging GAZ-MM. Ironically, a GAZ-MM superstructure was used for the prototype. A Dodge D5 Diesel engine was used, outputting 76 horsepower, coupled to a 4-speed transmission. These trucks were tested at Kubinka in 1940, with good results. Mass production was to begin in 1942, but the start of the Great Patriotic War (as WW2 is called in Russia) meant that all projects were canceled.

The GAZ-63 model 1939. Not to be confused with the GAZ-63 model 1948.
Source: Rus-texnika.ru

Grachev, very sensibly so, claimed that using this already finished and tested chassis would greatly increase the development speed and trials. The advantages of a wheeled vehicle over a tracked one are also clear, with cheaper maintenance and higher speeds on roads. The designers wanted to use as many readily available components as possible for reliability and production purposes. This idea was, however, the one that led to the GAZ-68’s demise.

Design

The GAZ-68 was surely an unorthodox vehicle, especially by Soviet standards. However, at its core, it was essentially a SU-76 on wheels, albeit 69 cm narrower, 65 cm lower, and 135 cm longer.

The superstructure was thinly armored, made from a simple box, and no roof. The gun was mounted slightly behind the front wheel axle. The driver was located to the right of the gun, and with the gunner to the left. Ammunition was stowed to the sides of the casemate and behind. Thanks to the long wheelbase, the vehicle was very low to the ground, ideal for ambushes and camouflage, but also offered good stability. The engine was located at the back, over the rear axles. The design was rudimentary and simple, allowing for a very cheap vehicle to manufacture if the situation of Soviet truck plants was not as disastrous as it was. The top could be covered with a tarpaulin to protect from precipitation and wind. Two large fenders would protect the front wheels. As a result of the lack of resources, automotive plants were forced to take shortcuts during production, such as fitting just a single headlamp. On the GAZ-68 it was placed on the left side fender, to not further impair the view of the driver. Coupled with the low-mounted gun, these give the GAZ-68 its iconic look.

The very low profile of the GAZ-68/KSP-76 can be seen here. It was only 155 cm tall, 54 cm shorter than the SU-76. This would have made it a smaller target, crucial for a vehicle with such little armor.
Source: Maximonline.ru

Crew

The vehicle had a crew of only 3, a gunner (who also served as a commander and radio operator), a driver, and a loader. The gunner was responsible for aiming and firing the main gun. He had two vision slits through which he could see, plus the scope of the ZiS-3 gun, extending above the frontal shield. If in doubt, he could just stick his head up to get a clear 360° view using a pair of binoculars. The gunner also had a panoramic sight at his disposal.

Overloading the gunner/commander with so many tasks is unusual for the Soviets, especially in a late 1943 design and it is noteworthy that there was also enough space in the vehicle to put a fourth crew member, although test reports claim other crew positions were cramped. It is also worth mentioning that the Soviets had already suffered catastrophic losses, especially in specialized troops, such as tankmen. This might have been a deciding factor.

Commander/Gunner’s location. Radio and equipment have been removed, but the sight is still there.
Source: svsm.org

As mentioned previously, the driver sat on the right. He had a slightly larger viewport to view out of compared to that of the commander. Oddly, the large steering wheel went above the viewport, which could have been inconvenient for taller drivers.

Driver’s position. Most of the electronics and dials have been removed, but there probably were not many to begin with. Note the large viewport.
Source: svsm.org

The loader was seated behind the gunner, on a foldable seat. He had a ready rack behind him, incorporated into the engine compartment and in front of the fuel tank, which was not very safe, but considering the overall protection, or lack thereof, it did not matter. Forty-one rounds were stored here, in a horizontal position. 13 more rounds were stored on the other side, vertically, behind the driver. The crew also had 2 PPSh submachine guns for self-defense, with 12 magazines (852 rounds).

View from the front of the rear of the fighting compartment. Note the foldable loader’s chair on the right. The rack is right behind him, but is, in this picture, almost obscured by the cover. On the left, the other rack can be seen, and other storage spots.
Source: svsm.org

Armament

The armament of the GAZ-68 was the trusty 76 mm M1942 ZiS-3 divisional gun, one of the most common guns within the Red Army at the time, and also the main weapon of the SU-76. The field gun was capable of both direct and indirect fire (once mounted on the GAZ-68 it was not). Over 100,000 units were produced by the end of the war and saw service post-war with many nations. It had a range of above 10 km and could use a variety of shells.

The KSP-76 would have most likely used AP and HE shells, but there were AP, APHE, HE, HEAT, Fragmentation, and other shells available. Most shells weighed around 6 kg and had a muzzle velocity between 680 and 700 m/s. On the KSP-76, 54 rounds were stored in total. The position of the gun in such a low profile vehicle affected its ergonomics compared to a regular field gun mount. The gun could only be elevated to +15° and depressed to -3° and had a horizontal traverse of 37°, 18.5° to both left and right sides of the gun.

The gun was supported by a travel lock mounted on the edge of the frontal slope. Despite the rather large compartment, the estimated rate of fire was 8 rounds per minute (one round in 7.5 seconds). The ergonomically well-placed ammo rack could have allowed an experienced loader to shorten the reload time even more.

The vehicle lacked any secondary armament, which was a common defect in Soviet SPGs, making them extremely vulnerable in close range combat with infantry, exactly the type of engagements the KSP-76 was meant to tackle.

View of the vertical breech and aiming system to the left.
Source: svsm.org
The iconic recoil system of the ZiS-3 mounted on the KSP-76.
Source: svsm.org

Armor

The armor of the vehicle was thin, only being able to withstand rifle fire and shrapnel. The GAZ-68 was never meant to be well armored in order to keep costs and weight down, plus its low silhouette would have played a big role in improving its survivability. The frontal plate was initially 10 mm thick, later increased to 16 mm. The top of the sides was 7 mm and the inwards angled bottom side plates 4 mm. This was not even bulletproof but would provide some protection against shell splinters and ricochets. The roof of the engine compartment was 5 mm thick but there was no protection over the heads of the crew apart from their own helmets leaving them, and some of the ammunition dangerously exposed. The cutting of corners and economy made in this aspect of the vehicle made it have a low unit production cost but would have clearly made it vulnerable to even rifle rounds from the side. The tires were bulletproof, filled with an elastic substance.

External view of the front corner, driver’s side. Note the thinness of the welded front and side plates. There were small covers for the viewports, but these seem to have vanished.
Source: svsm.org

Engine and Chassis

The chassis was, as previously stated, that of the GAZ-63 model 1939 truck. The engine and transmission were changed from the truck to a single GAZ-202 (some sources state that the engine was a GAZ-202, but the TsAMO document states that it was a GAZ-203), engine outputting 85 hp, mounted in the rear compartment, offset by 276 mm to the right. To the left of the gun, a 140 liter insulated fuel tank was placed. In front of this, the 41 round ammo rack was placed. A very scary thought, considering the armor was only a few millimeters thick! An upwards-facing cooling grille was placed in the back. The transmission was a 5-speed manual (4 forwards, 1 reverse) coupled to both axles. However, the rear axles could be disconnected from the drive when not needed such as on a long road march. The suspension was standard and common to the truck consisted of simple leaf springs and shock absorbers.

Rear top view of the prototype. The rear compartment housed the engine, transmission, fuel tank, and ammunition, with only 4-7 millimeters of protection.
Source: Topwar.ru

Trials and Fate

As soon as the prototype was finished, it began factory testing around May 1944 and had finished tests by autumn of the same year. From the Gorky factory, the GAZ-68 went to the Kubinka test range. Allegedly, it traveled under its own power and with an impressive speed of 60 km/h. Again, this information has to be taken with a grain of salt.

In September-December 1944 the experimental SPG was tested at Kubinka proving grounds and Gorokhovetskii artillery range. During a 2,528 km test drive, it is claimed to have reached a top speed of 77 km/h on-road, but this seems hardly possible in regular conditions. Even if it was true, the limited view of the driver would make such a speed hazardous, to say the least. The vehicle only had an 85 horsepower engine and weighed 5,430 kg battle-ready. During firing trials, 409 shots were fired of unspecified type at the Gorokhovetskii artillery range.

However, testing was not all going to plan for the Soviets. The original chassis took a hard beating and broke down frequently, putting into question the validity of the tests made at Kubinka of the GAZ-63. The driveshafts, gearbox, leaf springs, and frontal axle suffered some form of damage. To be fair, the GAZ-68 did weigh over 2 tonnes more, with different weight distribution. It was also noted that the crew compartment was too small and uncomfortable for some of the crew, especially the driver, who was cramped up by the gun and steering wheel.

The small silhouette and profile of the vehicle were deemed as a plus. However, there were significant issues with accuracy, thanks to the chassis and the suspension, which made the ride very bouncy. This also caused the sight and barrel to become misaligned after driving. Off-road tests were a mixed bag. On one hand, the GAZ-68 proved satisfactory, on the other, it was far inferior to what a tracked vehicle was capable of. Testing was finished by the 24th of December. The Military Council of the Armored and Mechanized forces of the Red Army (Военный Совет БТ и МВ КА, Voennii Sovet Bronetankovyh i Mekhanizirovannyh Voisk Krasnoi Armii), proposed to GOKO (State Committee on Defence) to produce the initial test batch of 10 units at the GAZ factory and undergo army tests. However, this was not achieved and, instead, the project was terminated altogether.

The situation of the war in mid-1944 was very different than that of a year earlier. The Red Army had been on the offensive for almost a year, pushing the Axis almost back to the pre-war borders, and the Allies had just landed in Normandy, sealing the fate of the war. The implementation of the GAZ-68 made even less sense now than it did before, and the questionable combat value it would have brought would far outweigh the industrial strain, despite the seemingly cheap production price.

Doomed from the start

Even before starting prototype production, the fate of the GAZ-68 was predetermined. The straightforward fact that it was based on a truck chassis, which for the designers certainly seemed like an advantage, but the industrial capabilities and resources of the USSR could not deliver. The Soviet industry could not keep up production of ZiS-5 and GAZ-AA simple flatbed trucks, even with help through the Lend-Lease program, let alone the mass-production of an even more complicated truck designed in 1939 and canceled because of the German invasion.

Automotive factories could not start assembly of a new, complex, and relatively new design, in the conditions that they could not even keep up with simple production models. It is important to note, both of these truck models were standard commercial trucks, with little to no improvements for off-roading or any sort of military specialization. Before the war, the Red Army only had the GAZ-M1 and no off-road trucks.

Side view of the prototype showing off the impressively low profile to a good extent. Note the tarpaulin and muzzle cleaning rod.
Source: Topwar.ru

The GAZ-68/KSP-76 was also doomed through its design. The use of wheels would have given it faster speeds on good terrain, but most of the western Russian terrain was flat plains and forest, with poor road connections. This is not to take into account the harsh conditions of thick winter snow or deep muds, where even tracked vehicles could struggle. The supply of tires before and during the war was also a big issue for the Red Army. While the situation to some extent improved during the war, they still relied on imported tires for around 33% of their needs.

In modern eyes, a wheeled vehicle might seem superior, as we now have many roads and good infrastructure, plus more advanced technologies, but this was Russia in 1943. The GAZ-68 was simply not compatible with Soviet military doctrine, industrial capabilities, and the terrain of Eastern Europe.

Compared to the SU-76, the GAZ-68 was far cheaper to build and maintain, was 54 cm lower, but with similar protection levels and firepower, in addition to the pros and cons of a wheeled chassis. Whether the KSP-76 was an improvement over the SU-76 is up to debate, but it clearly was not enough to justify the changing of truck production lines to a new vehicle this late into the war.

GAZ-68/KSP-76 illustrated by Pavel Alexe, funded through our Patreon Campaign

GAZ-68 / KSP-76 specifications (Source: TsAMO)

Dimensions (L-W-H) mm 6,350 / 2,050 / 1,550
Total Weight, Battle Ready 5.39 tonnes
Crew 3 (Commander, Driver and loader)
Propulsion X
Speed X km/h
Range X km
Armament 76 mm gun ZiS-3 M1942 Regimental gun (662 m/s muzzle velocity)
Ammunition count 54
Maximum speed, km/h 62.5
Average speed on a paved road, km/h 49.3
Average speed on an unpaved road, km/h 21.2
Engine GAZ-203 (with an aluminum head) outputting 85 hp
Fuel type and range KB-70 or B-70 fuel,
140 liters for 430 km range
Armor (frontal hull, fighting compartment), 7-16 mm
(Sides, rear hull and fighting compartment), 4-7 mm
Total Production 1 prototype

Sources:

https://topwar.ru/51030-kolesnaya-sau-gaz-68-ksp-76.html
S. Lopovok, Inventor and Rationalizer, No 12,
Zaloga, Steven J., James Grandsen Soviet Tanks and Combat Vehicles of World War Two
https://rus-texnika.ru/gaz-62-obrazca-1939-goda.html
A.V. Karpenko. Part 1. Light self-propelled artillery installations  Domestic self-propelled artillery and anti-aircraft installations
https://rus-texnika.ru/gaz-63-obrazca-1939-goda.html
https://tech.wikireading.ru/9308
Солянкин А.Г., Павлов М.В., Павлов И.В., Желтов И.Т. Отечественные бронированные машины. XX век. Том 2. 1941-1945
TsAMO & GABTU archives (from A. Tarasov)

Red Army Auxiliary Armoured Vehicles, 1930–1945 (Images of War)

Red Army Auxiliary Armoured Vehicles, 1930–1945 (Images of War), by Alex Tarasov

If you ever wanted to learn about probably the most obscure parts of the Soviet tank forces during the Interwar and WW2 – this book is for you.

The book tells the story of the Soviet auxiliary armor, from the conceptual and doctrinal developments of the 1930s to the fierce battles of the Great Patriotic War.

The author not only pays attention to the technical side, but also examines organizational and doctrinal questions, as well as the role and place of the auxiliary armor, as it was seen by the Soviet pioneers of armored warfare Mikhail Tukhachevsky, Vladimir Triandafillov and Konstantin Kalinovsky.

A significant part of the book is dedicated to real battlefield experiences taken from Soviet combat reports. The author analyses the question of how the lack of auxiliary armor affected the combat efficacy of the Soviet tank troops during the most significant operations of the Great Patriotic War, including:

– the South-Western Front, January 1942
– the 3rd Guards Tank Army in the battles for Kharkov in December 1942–March 1943
– the 2nd Tank Army in January–February 1944, during the battles of the Zhitomir–Berdichev offensive
– the 6th Guards Tank Army in the Manchurian operation in August–September 1945

The book also explores the question of engineering support from 1930 to the Battle of Berlin. The research is based mainly on archival documents never published before and it will be very useful for scholars and researchers.
Buy this book on Amazon!


Categories
Cold War Soviet Prototypes WW2 Soviet Prototypes

Object 704

USSR (1945)
Heavy Self-Propelled gun – 1 prototype built

The SU-152 and ISU-152 were, and still are, well known for their massive guns and impressive claimed capabilities against German tanks such as the Tiger and Panther. That is how they got their nickname “Zveroboy”, meaning beast killer. However, that was more related to propaganda than their actual usefulness as tank destroyers. Their massive 152 mm guns, while very effective if they hit the target, were rather inaccurate at long range, slow to aim and to reload, and limited in traverse by their mounting in a superstructure. These guns were not well suited for a tank destroyer. The SU-152 and ISU-152 were not, in fact, tank destroyers, but assault guns, meant to help Soviet attacks break down enemy defenses and strongpoints. Yet, for assault guns, their protection was more often than not, quite lacking. With the start of production of the Kirovets-1 (Object 703, or better known as IS-3), the opportunity arose to improve the “Beast Killers”, now focusing on protection. This vehicle was to become the Object 704 or Kirovets-2. It is also called ISU-152 model 1945 in Russian literature, however, it is likely that the Object 704 was never referred to as such in the short life it had, and could be a modern name, possibly invented at Kubinka, according to Russian historian Yuri Pasholok.

Despite the success of the ISU-152, its weak armor, tall silhouette, and inconvenient muzzle blast made the Soviets seek a replacement. Ironically, they never got one and the ISU-152 served decades after WWII. Source: Pinterest

Development

Due to the problems of the ISU-152, proposals came as early as 1944 from GABTU (Main Directorate of Armed forces) to the SKB-2 plant to upgrade the vehicle, however, little materialized. Then, work started on a new IS tank- the Kirovets 1 (IS-3).

There were also plans to modernize the gun on the ISU-152 as well. In 1943, the GABTU Artillery section stated that the 152.4 mm ML-20S howitzer was not suited for use on a self-propelled gun. The issues on the ML-20 naturally reflected on the battle performance of the ISU-152. An example was the TsAKB slotted muzzle brake kicking up a lot of dust, almost blinding the gunner after firing, and more importantly, revealing the vehicle’s position.

Thus, the GABTU put out a series of requirements for the modernization of the weapon. Firstly, this included the removal of the muzzle brake, changes to the breech, and improvements to the recoil system. OKB-172 was assigned to develop the upgrade by the 13th of January, 1944, headed by M. Tsirulnikov. The new gun was to be named ML-20SM, M standing for modernized. Blueprints were ready by the 1st of March of the same year and, by the 10th of March, the prototype was built in Factory No.172. The very next day, firing trials were undertaken, but after the 33rd shot, testing was halted due to poor operation of the new breech. Further tests were made through March until the 14th of April when it passed the test for rapid consecutive firing of 60 shots, which it fired in 39 minutes. While that might seem like a lot, the initial firing time estimation for them was 60 minutes (1 round per minute), the gun averaging 1.5 rounds per minute. Testing continued into May, the gun firing a total of 249 rounds, out of which 196 were with high explosive charges (for direct firing). The average rate of fire over the entire testing period was an impressive 2.9 rounds per minute. Factory testing of this gun continued until September 1944. Due to the high rate of fire and no muzzle brake, it was decided on the 2nd of October to mount the gun inside an ISU-152. Consequently, the gun was shipped off to Chelyabinsk, but, when it arrived in the middle of October 1944, it was unfinished! At the end of 1944, the GABTU stated that the gun needed urgent work and that factory No.172 workers should be sent to ChKZ. This only happened by mid-February 1945, when the battlefield was different and the IS-3 was approaching mass production, making the ISU-152 chassis archaic.

The massive muzzle blast made concealing the vehicle virtually impossible after firing. It also blinded the crew, so following the shot and keeping track of the target was a challenge. Source: Weapons of Victory

In fact, ChKZ had started working on an SPG based on the Kirovets-1 at the beginning of 1945. It received the name Kirovets-2. The chief engineer and designer was L.S. Trojanov.

A letter from Engineer-Lieutenant Colonel Markin, a representative of the GABTU in ChKZ, was sent to GABTU chief Engineer-Lieutenant Colonel Blagonravov on this topic. It stated that the Kirov factory (SKB-2 to be precise) was working on a Kirovets-1 based SPG, stating its armor thickness level and other features, namely that it used the same transmission, running gear and engine as the Kirovets-1. Most interesting is that, according to the letter, work on the prototype started on the 1st of February, 1945. The letter was sent 10th of February, 1945.

The Kirovets-2, later named Object 704, was an attempt to fix the main issues with the ISU-152, yet created more problems and was plagued by bureaucratic wrangling. Source: Topwar.ru

ChKZ also announced S.P. Gurenko, chief designer of Factory No. 172, saying that SKB-2 was working on such a vehicle. This led to engineers from No. 172 coming over to Chelyabinsk between the 14th and 20th of February. During this time, SKB-2 had sent the blueprints of the Kirovets-2 over to Factory No. 200 as well. Also in mid-February, the hull of the SPG was ready in ChKZ.

On the 3rd of March, a meeting was held on the topic of improving the Kirovets-2. The main issue brought up was fitting the ML-20SM, originally built for the ISU-152, into the Kirovets-2. The gun had been sitting for quite a few months in a hall somewhere in ChKZ. Other points discussed were further increasing the armor and thickening it from 100 to 150 mm (3.9 – 5.9 inches) and replacing the panoramic sight with a Hertz sight from a 76 mm Mod. 1943 ZiS-3 gun, as it was smaller. The telescopic sight was also changed for a smaller TSh-17. The traverse mechanism was altered and, most importantly, it was decided to give the Kirovets-2 a co-axial DShK heavy machine gun, mounted on the right side of the main gun.

The hull of the Kirovets-2 was ready in spring, but the gun was not mounted until halfway through June 1945. This delay was caused by bureaucratic disputes regarding the serial production of the ML-20SM gun. The tank became the Object 704, yet the Kirovets-2 name stuck with factory workers.

Layout and Design

The design of the Kirovets-2 was unique, having little resemblance to previous Soviet heavy SPGs. It still had a frontal mounted casemate, where the turret and pike nose of the IS-3 used to be. Due to the aim to improve the armor protection to the same level as the IS-3, the armor plates were thickened and angled throughout the casemate. On the ISU-152, the gun mantlet was a large frontal weak spot, yet on the Object 704, it was the thickest part of the tank. Interesting to add is that the bottom of the side casemate angled inwards a lot more than it appears to. The almost flat triangle shape part of the side superstructure is actually just a thin sheet of metal.

Although the IS-3 chassis was used, there were still some changes made. Namely, the engine plate was different and the exhaust pipe layout was the same as on the Object 701. It is unclear if this was done to save pieces for the production of the IS-3 or it was intentionally designed as such. An additional small construction detail is the use of several track types, satisfactory for a prototype built in a short period of time. There were 86 tracks per side, each track was 650 mm wide and they were connected by a single pin. The engine was the same V-2-IS engine, producing 520 hp, and the running gear and transmission were kept the same. The transmission was a multi-disc dry friction clutch. The gearbox was a 4+1 dual stage (high/low) manual, for a total of 8 gears forwards and 2 in reverse. The brakes were still planetary rotation mechanisms.

The hull is often said to be identical to that of the IS-3, but the exhausts and engine plate design are different. Note the thinness of the triangular-shaped side plates on the hull can be discerned here. Source: Yuri Pasholok

Despite the external differences, inside, the Object 704 was very similar to the ISU-152. It still had a crew of five; driver, gunner, commander, loader, and breech operator. The heavily angled sidewalls caused major internal ergonomic problems, namely storage for the huge two-part ammunition, which weighed 48.78 kg (107 lb) for the AP and 43.56 kg (96 lb) for the HE, no easy task to load in a tight space. Sacrificing crew comfort and ergonomics for protection was quite common in the late war and post-war Soviet tank doctrine.

Object-704 during testing. The extreme angles of the fighting compartment can be seen. Source: Pinterest

The vehicle’s silhouette was much shorter than that of the ISU-152, now being only 2,240 mm (88 inches) tall, but kept the same width.

Main Armament

The modernized ML-20SM lacked a muzzle brake, which improved the visibility and kicked-up less dust after firing. However, the recoil grew considerably, namely by 900 mm, so a recoil brake was added. The gun had +18° of gun elevation and a shockingly poor -1.45° of depression. The horizontal traverse was not much better at a very limited total of just 11° (5.5° on each side). The new gun fired the same two-part HE weighing 43.56 kg (96 lb) and AP ammunition, weighing 48.78 kg (107 lb), and had very similar ballistics to the standard ML-20S. The HE rounds had a muzzle velocity of 655 m/s, while the AP had 600 m/s. The gun could hit a 2.5 to 3-meter tall target reliably from 800 to 1,000 meters (874 to 1,093 yards), but had a direct fire range of 3.8 km (2.36 miles) and an indirect fire range was 13 km (8 miles).

When conducting indirect firing, the Hertz panoramic scope was taken out through the gunner’s hatch. The practical rate of fire is contradicting and ranges from one to a bit under three rounds a minute. A quick reload was not necessary for such a self-propelled gun, especially considering the terrible ammunition count inside the Kirovets-2; just 20 (19 according to the trial report, although the extra round could be loaded to be 19 +1)) rounds. These were placed on both sidewalls of the fighting compartment, and the charges were placed on the right wall and underneath the breech.

View of the breech of the ML-20SM. Note part of the loader’s tray to the bottom left and the coaxial DShK machine gun to the right of the gun. The manual traverse can also be seen, which was to be operated by the breech operator. Source: Yuri Pasholok

Secondary Armament

The vehicle was equipped with two 12.7 mm DShK heavy machine guns, one coaxially mounted and one on the roof, with 300 spare rounds of ammunition inside (600 according to Kubinka). There was a chute for the ammunition belt to slide over the main gun and into the machine gun.

The roof-mounted DShK was for anti-aircraft use and was mounted on a rotating ring over the loader’s hatch. The ring could swivel over and next to the hatch. The machine gun itself could also pivot on its mount. A collimating K-10T sight was mounted on the gun for easier aiming against aircraft.

For the defense of the 5 crew members, they were equipped with PPSh or PPS submachine guns. Some F-1 grenades could also be mounted on the sidewall, between the commander and breech operator.

Crew

The Object 704 had a crew of 5; driver, commander, gunner, loader, and breech operator. They would communicate with each other with a TPU-4F intercom, having a headset and a microphone. This was essential, as the crew sat quite far away from each other and communication was key in coordinating aiming and directions. Every crew member had his own entry and exit hatch on the roof of the vehicle.

The driver was located higher up in the hull than in the ISU-152, by 600 to 700 mm. Consequently, he did not have his own hatch in the front plate, instead, his vision relied on the single movable MK-4 periscope in his hatch, on the roof. As could be anticipated by such an arrangement, this was not enough, giving the driver rather poor vision when buttoned up. He was, however, also able to open the hatch (by sliding it to the side) and stick his head out in non-lethal environments. To control the tank, he had two mechanical tillers. To his right was the gearshift and the shift for the high/low gear ranges. On a good note, the driver no longer sat next to a large fuel tank, like on the ISU-152, which was good for morale.

The gunner sat behind and to the right of the driver, on a seat attached directly to the gun. There, he had the elevation control hand crank, as well as the trigger, his Hertz panoramic sight, and the 2.5x (other sources claim 4x) magnification TSh-17 sights. This sight was adequate for firing up to 1500 meters (0.93 miles). As previously mentioned, for indirect firing, the gunner’s hatch had to be opened and the sight raised through it. Both sights were illuminated for conducting nocturnal firing. Directly under the breech block was a floor-mounted escape hatch, for a total of six hatches.

The commander was on the opposite side of the driver, also having just one MK-4 periscope for external vision. He was responsible for the radio, placed right in front of him, on the frontal armor plate. This radio was a 10PK-26 radio, connected to the 24 volts onboard power transmitter. The frequency was 3.75 Mhz to 6 Mhz, with a wavelength varying between 50 to 80 meters. While stationary, the range was between 20 to 25 km, and it decreased slightly while on the move. The radio also allowed for communication on two fixed frequencies, simultaneously. The coaxial machine gun was also his responsibility, most likely having to fire it as well. Yet the traverse of the main gun was controlled by the breech operator and elevation by the gunner, so aiming would have been a coordination challenge.

Handling the massive shells was done by the loader. The shells were stacked on the side walls. He was also assigned operation of the anti-air DShK on top of his hatch. To aid him in loading, he had a loading tray, attached to the gun. A round would be rested on it until it was ready to load again. This meant that the loader did not have to hold the round until the breech was open again, a little but crucial detail considering the round’s weight. There were 12 rounds on the wall next to him, while the other 7 were on the other side, by the breech operator, and were a challenge to extract.

Perhaps the most curious crew member position is the breech operator. It is important to note that the breech design was quite ancient and could not open automatically. The breech operator would open the breech while the loader was manhandling the rounds into the gun. Then he would close it. He could assist the loader with charge amounts as well. This was done to decrease the strain on the loader, as it was no easy feat.

While testing reports were quite satisfied with the positions of the crew, a few issues were brought up. The angled sidewalls made storage of ammunition complex and accessing them was cumbersome. Let alone moving them out and into the gun, considering their weight. The elevation of the driver’s position also brought drawbacks, namely, he would bounce around when the tank was moving on poor terrain. This was strenuous on the driver. To boost morale and improve living conditions, two fans were placed behind the gun, to ventilate and remove toxic fumes, as well as a couple of dome lights.

Engine

As aforementioned, the engine was a V-2-IS outputting 520 horsepower. An ST-700 electrical motor, outputting 15 hp (11 kW), was used for starting the main engine. In cold winters, two compressed air cylinders were used to start the engine. These were located by the driver’s feet. An NK-1 diesel fuel pump was used, with an RNA-1 regulator and carburetor. Air filtering was done by a multicyclone air filter. There was also a heater, used to heat the engine in cold winters, but also the fighting compartment. A total of three fuel tanks were in the vehicle, two in the fighting compartment and one in the engine bay, for a total of 540 liters (143 gallons). Two (90 liters each) external fuel tanks were on the engine deck. These were not connected to the fuel system and were meant to be dismounted when entering battle. The engine allowed the tank to reach a top speed of 37 to 40 km/h (23 to 25 mph). The fuel range was around 180 km (112 miles).

The rear of the Object 704, where differences in the engine plate compared to the IS-3 can be seen, such as the tow hook placement. Source: Warspot

Armor

Protection was one of the main focuses of the Object 704 project. All armored plates were welded with heavy sloping all around the casemate. The front plate was 120 mm thick, angled at 50°. The lower plate was 100 mm (or 120, sources are conflicting or might imply there might have been different thicknesses proposed) angled at -55°. The mantlet had two layers of rounded 100 mm cast armor. The side was 90 mm angled at 15° from the side. Even the rear casemate armor was 80 mm at 21°. The tank was immune from the front to the 88 mm PaK 43 L/71 gun of the Tiger II, which it never got to fight. Despite this thick armor, the vehicle still had an acceptable weight of 47.3 tonnes (52 US tons).

This was a very well protected vehicle. The thin (3 mm) sheets “hiding” the heavily sloped lower casemate armor can be seen. Source: Soviet Heavy SPGs, 1941-1945 page 38.

Test results

The SPG was finished by mid-June of 1945. It was sent to Moscow Factory No.37, from where it was taken to the state proving grounds at Kubinka. Originally, testers noted that the fighting compartment was cramped but later changed to praises for the commander’s and driver’s stations and their placement. The People’s Commissariat of Armaments asked to move the Object 704 to the Leningrad Artillery Research Experiment Range, to test the gun and artillery capabilities. Despite this, the vehicle was still sitting in Kubinka. A test program letter for the ML-20SM was also sent in July 1945. It was only in August when tests were approved but only began by September because Factory No.172 engineers did not arrive at the testing grounds. They finally arrived by the 24th of September, only to leave a few days later, leaving behind only an engineer which did not have authorization for any testing work! This outright comical timeline of bureaucracy delayed the testing of the Object 704 by six months. By the 13th of November, Kuznetsov and chief designer Nazarov finally arrived from plant No. 172. Testing was done from October until the 13th of November, through which 65 shots were fired for indirect fire and 244 shots for direct fire.

A letter summarising the results and opinions after tests was published.

  • Loading tray: No complaints other than the corners should be rounded, to make passing between the loader’s station and the breech operator easier.
  • Sights: The TSh-17 was comfortable and in a good position in relation to the gunner’s eye. The offset of the sight was negligible after 40 shots (it is safe to assume after more shots, the offset would be noticeable).

Fighting compartment notes

Several interesting remarks were made in relation to the superstructure and the design of the fighting compartment.
– The gun mantlet had no access port for the much-needed recoil brake. This meant that measuring the hydraulic fluid and releasing air was impossible.
– The hole below the gun mantlet (for depression of the gun) accumulated water.
– The sloping on the side walls made stowing ammunition difficult and complicated. Making the walls vertical was suggested.
– The headlight was mounted on a solid mount. Because of this, it shattered during firing trials. A movable spring stand was recommended.
– The commander’s position was praised, it was put facing forwards and the new hatch made battlefield observation easier and more effective.
– Both the gunner’s and driver’s stations were praised and deemed as an improvement over previous heavy SPGs.
– The loader’s position was actually considered spacious. The report stated that taking out the 12 rounds next to him could be done with ease. However, the 7 rounds on the opposite wall were noted to be hard to reach and load.
– In contrast, the breech operator’s station was noted to be cramped, especially when the gun was traversed to the left, bringing the breech to the right. Extracting the 16 propellant charges to the right side of the tank was not ideal due to the tight space. The other 4 charges beneath the gun were impossible to take out in combat conditions.

Other conclusions were:
– Wear on the barrel and muzzle velocity drop was typical, considering the caliber of the gun. After 309 rounds (244 of which with maximum charge), muzzle velocity dropped by 0.8%.
– The muzzle brake simplifies production and improves observation of the target after firing.
– Recoil brake performance is satisfactory, but the problems with access to it still stand.
– No unexpected wear or deformation occurred on the gun.
The gun had no malfunctions with the exception of failure to extract shell casings that had been used several times (as much as 10 shots).

Conclusion and fate

The Object 704 had clear advantages over the ISU-152. These included the lack of a muzzle brake, improved protection, and position of the driver and commander. The issues that were found, could, and most likely would have been addressed, if it would have entered production. The tank’s entry in service was hindered by bureaucracy and failure to get it to testing. The loss of time meant that the IS-4 was nearing serial production, making the IS-3 and a SPG based on it obsolete. With hindsight, the story of the IS-4 is, arguably, even worse. Another heavy self-propelled gun would not be built until the Object 268, based on the T-10, which had a similar fate to the Object 704.

The single prototype built survives today at Kubinka, where it was brought for testing in 1945. Source: World War II Wiki

You can also watch a walk around of the exterior and interior of the vehicle, made by “The Chieftain”, Nicholas Moran, here 

Illustration of the Object 704 by Pavel Alexe, based on work by David Bocquelet, funded through our Patreon campaign.

Sources:

Tankmuseum.ru
Heavy SPGs 1941-1945, Soliankin, Pavlov, Palov, Zheltov
Zveroboy, Mikhail Baryatinsky
Warspot.ru
Tankarchives.ca
Topwar.ru
Heavy SPG, A.V. Karpenko

Categories
WW2 Soviet Prototypes

Object 257

USSR (1945) Heavy tank – none built

The IS-7 (Object 260) is one of the most well-known tanks developed by the USSR, in part due to its massive size and weight, placing it with the likes of Tiger II. However, few know about its lengthy and intricate development process, consisting of many years of work and prototypes, with a total of seven different prototypes sharing the name IS-7. One of these was the Object 257, the bridging in between the failed IS-6 and the renowned IS-7.

‘Baby’ IS-7

In February of 1945, a replacement program for the Object 701 (IS-4), which had just started development seven months earlier, was requested by the GABTU (Main Directorate of Armored Forces). The SKB-2 factory, which designed the Object 701, was too busy with it and was working on its production. This left a window of opportunity for Factory No.100 to take over and begin work on the IS-4 replacement. Factory No.100 had just lost to SKB-2, as the Object 252 and 253 (IS-6) were deemed inferior in many ways to the Object 701. An upgrade to the Object 252, known as the Object 252U, was made in November of 1944, using pike-shaped angled armor with help of engineers from NII-48 research institute. However, the changes were not able to revive the already canceled IS-6. Despite its failure, it served as a good basis for the upcoming heavy tank.

Illustration of Object 252U, on which Object 257 was largely based. Illustration by Pavel Alexe.

On 7th April 1945, requirements for a 122 mm tank gun with a muzzle velocity of 1,000 m/s (3,280 fps), two-part ammunition, and a rate of fire of four rounds per minute (15 seconds reload) were issued. Factory No.100 had already done work with OKB-172 on the BL-13 gun which was used on the late alterations of the Object 252 and 252U. Earlier prototypes of the IS-6 had the D-30. This new gun was called BL-13-1 and featured improvements over the BL-13, such as a mechanical gun rammer, increasing its rate of fire to a whopping 8-10 rpm. Even a mechanical autoloader was tested, but, despite its claimed solid reliability, it was sluggish and was not worth losing a crew member on. It also decreased the rate of fire to 7-8 rounds per minute at a higher price tag. Nonetheless, the idea was never fully dropped, as the final IS-7 prototype used a loading assistant, using a conveyor belt. The shells were however larger, as the gun had a 130 mm caliber.

Work started on the new heavy tank in May 1945 with P. P. Isakov, who had previously worked on the Object 252U and IS-2U projects, as chief designer. The turret was taken directly from the Object 252U, and so was the pike-nose design. The engine and transmission, rather interestingly, were taken from the Object 253, the IS-6 variant which used a mechanical-electrical transmission, which caught fire during trials, was expensive and unreliable. The biggest change was made to the lower hull and suspension. This project would get the designation Object 257 and was the first design to get the name IS-7.

Design

As mentioned earlier, many elements from the IS-6 program were used in Object 257. The turret and pike nose came from the Object 252U and the engine and transmission from the Object 253. However, one of the main focuses of the Object 257 project was sturdier protection. The same principle applied on the pike nose, which was implemented on the side of the hull as well. The previously flat hull sides were now angled inwards at an extreme angle, forming a diamond shape silhouette from the front and rear. On the downside, this caused huge internal problems. Primarily, torsion bars could no longer be used, since the hull was too narrow, meaning that the suspension had to be moved on the outside of the hull. For the suspension, four volute springs were mounted on each bogie, with two wheels per bogie, a very similar design to that of the American M4 Sherman. This made the Object 257 one of the most unique looking Soviet heavy tanks of the post-war era, as this was the first time a Soviet tank used volute spring suspensions.

The turret was identical to that of the Object 252U, being heptagonal and of a low profile. Inside, the gunner was seated to the left of the gun, with the commander behind him. The loader was located to the right of the gun. A coaxial machine gun was also mounted to the right of the gun, and could be fired by the gunner. It is unclear if it was a 7.62 mm SGMT machine gun or a 12.7 mm DShk heavy machine gun. The loader was responsible for loading this weapon as well.

Cutout line drawing of the Object 257. The pike nose armor can be seen. The problems created by the armor layout and low profile are clear. The gun has little room to depress and the driver is very cramped. 5th June 1945. Source: Yuri Pasholok

Crew

As the Object 257 focused mainly on protection, crew comfort and overall ergonomics of the tank had to be sacrificed. The pike-like front end of the vehicle decreased the amount of space available for the driver. As shown in the drawing, the driver’s pedals would be located high up, his feet being on the same level as his torso. This would have been uncomfortable, especially when driving for longer periods of time. The driver had an entry and exit hatch on top of him, however, it was directly under the gun, meaning that entering and exiting would have been frustrating when the barrel was over the hatch. To add to his misery, he only had one periscope, relying more on the commander for command.

The gunner and commander could sit on chairs mounted to the floor through a long arm. Even for them, the conditions were not great. The low turret profile gave them very little headroom, not to mention it restricted the main gun from depressing more than a few degrees. The commander’s position lacked a cupola, and only had one periscope facing forwards and one backward. This further limited his visibility.

Cutout front and rear view of the Object 257. Many interesting details are made clear here, such as the Y-shaped seat support and interesting ammunition placement. Source: Yuri Pasholok

The loader was to the right of the gun, having to push the shells in with his left arm, a rather large inconvenience, considering the size and weight of a 122 mm shell. In addition, the ammunition was made out of two parts, the shell and the cartridge. In a turret bustle at the back, 30 rounds were stored, protected by an armored case. The cartridges were stored along the sides of the hull, diagonally, meaning that if one cartridge was taken out, another could possibly slide down. This, however, is only speculation. The average loader could load the gun in around 15 seconds. More warheads were stored in the hull, behind the driver. All this meant that the loader could easily load in the warheads, but had to bend down to grab a cartridge. As indicated earlier, an autoloader system was designed, however, despite its reliability, it was slow. If an autoloader was used, it is unknown if the loader would have been dropped or he would have had other tasks.

Armor

One of the most interesting aspects of this tank is the armor layout. The pike nose was an increasingly common feature in Soviet heavy tanks of the time. It was 150 mm (6 inches) thick, angled at 28° from the side. Yet the lower hull was completely new. Instead of flat plates, like on the IS-6, the plates were angled inwards, forming the same effect as a pike nose. This would have helped immensely against incoming rounds, deflecting them into the ground. The top parts were 150 mm (6 inches) thick and angled at 30°. The bottom plates were 85 mm (3.3 inches) thick angled at 23°. This thickness was not maintained all the way to the bottom of the hull. Halfway in, the armor was thinned down to only 20 mm (0.8 inches) yet kept at the same angle. This was most likely done to save weight, as the chances of enemy fire hitting this area were rather low, with the large suspensions being in front. The new side armor was impenetrable to the German 105 mm Flak 39 and the front was even strong enough that the BL-13-1 gun could not penetrate it at point-blank range. The turret armor was thick as well. The sides, although tinner in some areas, since they were curved, were 150 mm (6 inches) thick, angled at 45° degrees. Of course, this came at a cost. The weight of the hull increased to 23 tonnes (25.3 tonnes) over the IS-6’s 21 tonnes (23 tonnes).

Side armor comparison of various Soviet heavy tanks of the time. The newly introduced IS-3 was rather small compared to the Object 257. Consider that, at that stage, the Object 257 was still called IS-7 (ИC-7). To the right, the Object 701 (IS-4) hull can be seen, which was, at the time, the most heavily armored Soviet tank. The IS-6 (ИC-6), on which the Object 257 is based, is in the top right. Source: Yuri Pasholok

Suspension

If there is something that makes the Object 257 stand out, it is the suspension. As previously stated, the lack of room in the hull meant that the suspension had to be moved on the outside. Curiously, a bogie with four volute springs per wheel was used. These were very similar to the M4 Sherman medium tank, and it is entirely possible the design was derived from it. The wheels were mounted on opposite sides of the bogie and had arms on either side. These arms would then be attached to two volute springs that compressed when the wheel moved upwards.

M4 Sherman in Soviet service. The Russians used American equipment throughout the war. This was likely the inspiration source for the suspension on the 257.
Source: The Sherman Tank Site

Engine

As the weight had been increased up to 55 tonnes (60 US ton) on paper, a new engine was needed. Since 1944, Factory no.77 had been working on a new engine, based on the V-2, called V-16F. It was coupled to a similar (if not the same) electric transmission used on the Object 253. However, this engine was deemed very poor. Trials took place between March and May of 1945 and it was found to be unreliable. Even supercharging the engine to 600 or 750 hp that the IS-6 and IS-4 had would have put a huge strain on the engine, and failures occurred. Even at 520 hp, the engine was faulty. However, an engine this underpowered would have been disastrous if mounted on a 55 tonnes heavy tank, considering a 50 km/h (31 mph) speed was wanted. Further development was done on the V-16F, however, efforts were abandoned, and improved V-12 engines were used on the further IS-7 project.

The unreliable and weak V-16F engine initially proposed for the Object 257. Considering its many issues, it was left behind and V-12 engines were re-used in the IS-7 program.
Source: Yuri Pasholok

New German heavies and Conclusion

After the discovery of the Maus and Jagdtiger and their analysis, the armor on the Object 257 was deemed insufficient. The 128 mm KwK 44 guns of the Jagdtiger and Maus would have pierced the hull. Likewise, the armor on the Maus and Jagdtiger was too strong for the BL-13. All this meant that the Object 257 needed to be reworked significantly. In addition, on 11th June 1945, the requirements of a new heavy tank were set by the GABTU. The weight increased to 60 tonnes (66 US tonnes) and the new armament was to be an S-26 130 mm gun. Lastly, torsion bar suspension was required. The Object 257 clearly was not adequate, leaving factory No.100 to start work on a new heavy tank. Nonetheless, work was not in vain, as the experience gained and armor features of the Object 257 were passed on. Many other tanks were designed, until the final Object 260 was made, the IS-7 we know today.

Illustration of the Object 257 by Pavel Alexe. The similarity to the suspension of the M4 Sherman can be seen.

Sources

https://warspot.ru/2793-elektrostalin-6
https://warspot.net/9-object-257-the-first-is-7
http://www.tankarchives.ca/2019/03/modernization-on-paper.html

Object 257 specifications

Dimensions (L-W-H) 7.375 x 2.430 x 3.390 meters
(24 x 9 x 11 feet
Total Weight, Battle Ready 55 tonnes (60 US tons)
Crew 4 (Commander, Gunner, Loader and Driver)
Propulsion V-16F engine and electrical transmission
Speed 50 km/h (31 mph)
Armament 122 mm BL-13-1 2-part ammunition gun
co-axial 7.62 mm SGMT machine gun
Armor Hull armor
Front top plate: 150 mm at 28°
Front bottom plate: 150 mm at 40°
Side top plate: 150 mm at 30°
Side bottom plate: 85 mm & 20 mmTurret armor
Front: 150 mm
Side: 150 – 120 mm
Rear: 100 mm
Top: 30 mm
Total Production 0; blueprint only
Categories
WW2 French Prototypes

ARL 37 ‘Char de Rupture’

France(1937)
Heavy tank – none built

The 1930s was a period of rapid re-armament and tank development. Many European nations were focusing on developing and improving their own tank forces, leading to more and more specialized and advanced fighting vehicles. France was not to be left behind, reorganizing part of its defense industry and starting new tank projects. The need for a new French heavy tank was amplified with the start of the construction of the German Siegfried Line, a defensive wall running across the German border with France, vis-a-vis the Maginot line.

This prompted the French Conseil Consultatif de l’Armement (Armaments Advisory Council) on 4th May, 1936, to start a new heavy tank program. The technical requirements for the new tank, named “Char de Rupture 1937” (roughly translating to breakthrough tank), were released on 12th November 1936. The Conseil Consultatif de l’Armement stated the following:

“Char lourd, très protégé et très armé, propre en particulier à être utilisé défensivement et offensivement dans la guerre en région fortifiée”.
(Eng: “A heavy tank, well armored and well-armed, suitable for both defensive and offensive purposes in fortified battlefields.”)

The main focus was the armor and armament. In Char B1 fashion, there were two main armaments, one in the hull and one in a fully rotating turret. The armor was to be able to resist anti-tank cannon fire from as close as 200 meters (220 yards). In addition, the top speed was requested at 30 km/h (18 mph) and a range of 200 km (125 miles) or 10 hours. The total weight was to not exceed 45 tonnes (49.6 short tons)

In the spring of 1937, three French companies presented their designs: AMX, FCM and ARL.

Ateliers des constructions de Rueil

ARL was the only company that had not designed tanks before. In 1935, the Docks de Rueil, originally part of APX (Ateliers des constructions Puteaux) were renamed to Ateliers des constructions de Rueil (abv. A.R.L.) after nationalization. It was also then that the design bureau was created. Located in the suburbs of Paris, the workshop became more famous post-war, with the construction of the ARL 44, yet participated in the design of many other French tanks.

Triplets

Unlike its competitors, which presented the AMX 37 and FCM F4, ARL presented three designs simultaneously, the Variant C, Variant S and Variant V. Every version had different turrets, armaments and layout. It is important to note that blueprints of the rear of the hull do not exist. It is unknown if they were ever made or potentially lost, however, all the existing blueprints are on the armament layout, showing that they were supposed to use the same hull. Ultimately, the engine used and similar details are unknown. All three variants were, speculatively, based on the same hexagonal-shaped hull, with large tracks running over side skirts, similar to the Char B1. In addition, all versions had a flamethrower mounted in the hull, on the right side, to compensate for potential blind spots.

75 mm APX howitzer model 1929

The gun used inside the hull was the 75 mm APX howitzer mle 1929. Originally made for the Maginot Line as a static defense, it was developed from the infamous Model 1897 75 mm howitzer. It was later adapted for use in armored fighting vehicles and used in the later ARL V39 prototype. This gun was also used by the other competitors, FCM and AMX.

Side view plans of the gun mount in the ARL 37 (in this case, Variant C). The driver was also the gunner, as he had to traverse the entire tank to aim the gun, since it only had 5° of traverse. This arrangement was also present on the Char B1. Elevation and depression were better, at +18°/-15°.

Variant C

The most simple (from a mechanical and design perspective) out of the three, Variant C, was very similar to a Char B1 Bis. Besides the hull-mounted gun, a 1-man turret was mounted on the left side of the hull roof. The turret was very similar to the APX-1 turret on the Somua S35 and Char B1 Bis, however, the armor was greatly improved, at approximately 100 mm (4 inches) all around. Inside the turret, a 47 mm SA35 gun was mounted, the same gun as on the Char B1 Bis and Somua S35. The ammunition used would have most likely been the same Obus de Rupture Mle 1935 (AP model 1935) weighing 1.62 kg (3.6 pounds). The entire shell was 325 mm long (13 inches) while the projectile was 145 mm long (5.7 inches) and the case was 193 mm long (7.6 inches). On the Char B1 Bis, the muzzle velocity of the SA35 was 660 to 680 m/s (22 feet per second) with a penetration of 40 mm angled at 30° at 400 m. Variant C carried 106 rounds of ammunition for the 47 mm, 98 in the hull, and 8 in the turret.

It had a crew of four, a driver, responsible for driving the tank, but also aiming and firing the 75 mm gun. Behind him in the hull was the loader of the 75 mm gun. In the turret was the commander, responsible for commanding the tank, spotting targets, loading, and firing the 47 mm gun. This was a common feature of French tanks of the period. At the end of the crew compartment, a mechanic was seated. Quite common on WWI tanks, this position was archaic by 1937 standards. In practice, he would have been in charge of passing ammo up to the commander and fulfilling other, smaller tasks. He would have also been in charge of the radio, of unknown type, yet it is likely to have been the ER-53, used on Char B1s.

Side views of a SA35 gun from a B1 Bis tank. Source: Warspot
Side view of the crew compartment of the ARL 37 Variant C. The thick armor and crew layout can be seen.
Source: Chars Francais
Top view of the ARL 37 Variant C. The similarity to the Char B1 Bis is discernible.
Source: Chars Francais

Variant S

The second design proposed was more complex than the previous, and the plans available are even more scarce. The small turret was replaced with a larger, three-man turret. However, this increased the crew to six men. The turret was cast into a large octagon, still with 100 mm thick sides. In contrast to Variant C, it was equipped with a 47 mm mle 1934 gun, which was also designed for use on the Maginot Line. It fired APX mle 1936 Obus de Rupture (Armor-Piercing High-Explosive, APHE) shells, with a muzzle velocity of 880 m/s and could penetrate 77 mm (3 inch) of armor angled at 30° at 500 m (547 yards) and 56 mm (2.2 inch) of armor at 1,000 m (1,094 yards). The shell weighed 1.670 kg (mock warhead, translation from the French “fausse ogive”) and the charge weighed 610 g. It is hard to tell why two different guns were chosen for different designs.

The main turret had a smaller, rotating pseudo-turret or cupola for the commander. This was equipped with two machine guns, most likely 7.5 mm MAC 31, however it lost the machine gun mounted parallel to the main gun, like in the Variant C. The commander would now stand in this cupola and be able to more effectively scan the environments and engage infantry.

As the crew expanded to six men, the layout changed. The turret now had a designated commander, gunner, and loader. Meanwhile, inside the tank, the driver, loader, and mechanic were the same. The designated gunner and loader would have vastly increased the efficiency of the tank. However, these changes would have made Variant S vastly more expensive compared to Variant C.

Side cutout view of the Variant S turret. While the majority of the turret was still 100 mm thick, the cupola was thinner.
Source: Chars Francais
Top view of the Variant S turret. The much larger size of the turret is obvious, most likely taking much of the space on the hull roof.
Source: Chars Francais

Variant V

The most complex and interesting of the three designs was Variant V. The turret was now unmanned and was equipped with a 47 mm SA35 (same as on Variant C) and two 7.5 mm MAC machine guns mounted coaxially, on each side of the gun. As it was unmanned, it was made much smaller. To aim and fire it, a device was created by Lorfeuvre, that would allow the commander to aim and fire the guns in the turret, and even the 75 mm in the hull, from a dome-like casemate to the right of the 47 mm turret. To cover up the blindspot that was created by the casemate, an additional 7.5 machine gun was added, facing the rear.

The crew was now five men. There was a driver (it is unclear if the 75 mm howitzer could be aimed and fired by both the driver and the commander) and two loaders, one of which was also designated as a mechanic. They shared the task of loading the 47 mm and 75 mm. Despite being unmanned, the turret did not have an autoloader, the technology did not exist in 1937. Rather, the loader was underneath the turret and loaded from there. The commander was located in the dome-shaped casemate and the radio operator was on the right of the tank, “inside” the side skirt in between the tracks.

Cutout side view of Version V. The small unmanned turret and large, dome shaped casemate can be seen. Note the gas canister for the flamethrower in the bottom right.
Source: Chars Francais
Top view of Version V. The crew positions are clear, however how the two loaders (the two men sitting in line behind the driver) operated is hard to tell. Most likely, one passed on the ammunition, while the other loaded. Yet the interior seems roomy, so they could move around more in combat. The location of the radio operator, inside the track side skirts, gives information on the mysterious hull design. Since there was enough space to fit a man inside, it means the suspension most likely used leaf springs. Coil springs would be too large, like in the AMX 37, where the coils took up the whole height of the sideskrit.
Source: Chars Francais

Version V was a very unorthodox design, clearly being expensive and more complex than the other variants. The ARL 37 would have been extremely expensive no matter what, its undoubtedly large size, thick armor, and need for a massive engine would have made this program very expensive, let alone the complex devices needed on the Version V.

Hull

The largest mystery with the ARL designs remains the hull. Since no complete blueprints exist, it is hard to tell how it looked. From the existing blueprints above, we do get a clear image of how the front looked, and that it had small, leaf spring suspension, like many other French tanks of the time. The rear of the hull was never designed, as it included the engine, transmission, and other parts that did not exist and would be subject to change. Nonetheless, the ARL V39, a tank destroyer built by ARL in 1939, is clearly based on the ARL 37 and is a good clue to how the ARL 37 may have looked like.

Yet the ARL V39 was 25 tonnes lighter, had only 50 mm of armor, and used 190/240 hp engines, completely different from the heavy tank. The ARL designs, and the FCM and AMX proposals all “used” non-existent engines. The FCM and AMX designs weighed over 50 tonnes and required two V12 engines of unknown power.

The ARL V39 self-propelled gun prototype. Despite being a good 25 tonnes lighter than the AMX 37, it was inspired from the designs of the AMX 37 and would be a good indicator of how the ARL 37 looked like.
Source: Pinterest

Conclusion

Each variant of the ARL proposal tried to fix larger, underlying issues. Variant C was the “standard” French design, akin to the Char B1 Bis. However, the overworked commander and gunner/driver would have been a huge drawback, as proven on the B1. Variant S tried to fix this, by having a larger, three-man turret. Yet the larger turret proved to be very wide and it did not fix the overworked driver issue. Variant V eased out the work for the driver, however, now the commander had to aim two guns, and still relied on the driver to traverse the tank when aiming the 75 mm howitzer. All in all, it proved that multi-gunned tanks were not a good idea.

Just like the other competitor’s designs, the ARL variants failed. The entire project was deemed too expensive and the tanks could only be produced in small numbers. Logistical and reliability issues might have appeared when building such a large vehicle with engines made from scrap. The weight and size of the ARL variants are unknown, however, they most certainly went over the 45 tonnes mark. A final blow came when the Conseil Supérieur de la Guerre (Eng: Superior War Council) decided on 26th March, 1937 that a much smaller, cheaper yet heavily armored tank would be designed instead. This in turn went south as well, when the Section de l’Armement et des Études Techniques (Eng: Section for Technical and Armaments Studies) made a study which showed that a tank fulfilling those criterias was already under development, and there would not be a need of a new program. This tank was the Char G1.

The ARL 37 would continue to influence the ARL V39 Self-propelled assault gun, and in February of 1938. the requirements of a heavy breakthrough tank changed. Most importantly, the weight restriction was removed. This led to the development of the ARL 39 (or Char de Fortresse) and ARL Tracteur C super heavy tanks.

ARL 37 Variant C. Note that the appearance of hull is mostly speculative.
ARL 37 Variant S. The significant difference between the SA35 and Model 1934 gun is clear. Observe the cupola with 7.5 mm MGs.
ARL 37 Variant V. The odd dome shaped casemate and the small unmanned turret are what made Variant V such an unusual design.

Sources:

Chars-francais.net
DGA Châtellerault
TNT number 11
Chars De France, Jean-Gabriel Jeudy
Memoiredeshommes.sga.defense.gouv.fr
Wikimaginot.eu
Modernfirearms.net

ARL 37 specifications

Variants C S V
Dimensions (L-H) 7.52 x 2.86 meters 7.52 x Unknown 7.52 x 3.12 meters
Total Weight, Battle Ready 45+ tonnes*

 

Crew 4 5 6
Propulsion Unknown; its competitors used 2x V12 engines
Speed 30 km/h*
Range 200 km*
Suspension Leaf Spring
Armament 1x 75mm model 1929 (11+ rounds)

1x 47mm CA-35 (106 rounds, 98 in hull and 8 in turret.

1x 7.5mm MAC

1x 75mm model 1929 (11+ rounds)

1x 47mm Mle 1934

2x 7.5mm MAC

1x 75mm model 1929 (136 rounds)

1x 47mm CA-35 (114 rounds)

3x 7.5mm MAC (5400 rounds)

Armor 100 mm (4 inch) all around
Total Production 0; partial blueprints only
Categories
WW2 Soviet Prototypes

Object 252 Improved, ‘Object 252U’

USSR (1944) Heavy tank – none built

The Last breath of the IS-6

In the later years of the Second World War (‘The Great Patriotic War’ to the Soviets), there was a quest to develop a replacement for the IS-2 heavy tank. The development process resulted in the IS-6 (Object 252/Object 253) and IS-4 (Object 701). This program was as secret as it was ambitious, with two rival factories working on their designs in absolute secrecy in fear of leaking information to one another.

On paper, the IS-6 seemed superior to any Panzer in Germany’s arsenal at the time. However, due to its mechanical issues and overall poor performance, it lost to its competitor, the IS-4, which would go on to enter service in 1946. Despite this, a last ditch effort to revamp the IS-6 was made, with limited success. This renewed vehicle would become known as the Object 252 November improvement – more commonly known as the Object 252U.

Name

The Object 252 upgrade from November 1944 might have never gotten an official designation. Yet modern historians and video game company Wargaming have called it Object 252U, with the ‘U’ probably coming from the romanized Russian word ‘улучшенный’ (uluchshennyy). For simplicity’s sake, we will refer to it as Object 252U for the rest of the article.

Development

After the battlefront experiences of 1943, with the appearance of the new German heavy tanks and tank destroyers such as the Ferdinand, the Soviet Union quickly realised that a new heavy tank was needed. Thus, in November of 1943, the GABTU (Main Directorate of the Armed Forces) requested the development of a 55 tonnes (61 tons) heavy tank.

Two factories of the same organization (ChKZ) and the same city, Chelyabinsk, were assigned this task.

1. SKB-2, which was headed by Nikolai Dukhov, who had taken part in the development of the IS tank, and would later become the assistant of the chief designer of the Soviet atomic bomb plan. SKB-2 designed the Object 701, which was a planned upgrade of the IS-2 and later became the IS-4.

2. Experimental Factory No. 100, which was headed by Josef Kotin, who previously had done work on countless Soviet tanks. In contrast to their ‘opponents’, they developed a completely new tank, the Object 252 and 253.

From June to October 1944, Factory No.100’s Object 252 and Object 253 (IS-6) failed in comparison to the SKB-2 design. The armor was much thinner than that of the Object 701, yet it was still heavy, weighing over 50 tonnes (55 tons). The mechanical problems in the suspension and mobility were worse compared to its heavier counterpart. Kotin managed to get the IS-6 to Moscow, where it got tested against the Object 701, but to no avail. In late November of the same year, an upgrade attempt was made with the help of the NII-48 institute using a heavily angled pike-nose design for the armor and a new turret. Despite it being a dead-end when it came to the development of the IS-6, it was a turning point for future heavy tank designs. This is now known as the Object 252U.

Outline of the November, 1944 Object 252 upgrade, commonly known as Object 252U. The U comes from the romanized Russian word улучшенный, meaning ‘improved’. It is hard to tell if this is an original name or a modern designation. Despite the improved armor effectiveness, the IS-6 boat had sailed, and the IS-4 was chosen for mass production.
Source: Warspot.ru
Object 252U frontal view. The low profile of the tank is even more clear from this view. Source: Stalin Supertanks IS-7

Design

Naturally, the design of the 252U was similar to that of the Object 252, as it was based on the same hull. Unmistakable are the large stamped steel wheels with a 750 mm (30 inches) diameter. These were first tested on the Object 244 (an IS-2 upgrade) to be used on the Object 252. The Object 253, although also an ‘IS-6’, used regular IS style wheels. The engine and the rear and side of the hull were untouched on the November improvement. The torsion bars suspension would remain the same too.

The engine would most likely have been the same as on the Object 252, a V12U diesel engine producing 750 hp at 2,100 rpm. The internal fuel tanks had a capacity of 650 liters (172 US gallons) but, in typical Soviet fashion, there would have been 4x 100 liter (26 US gallons) external fuel tanks on the sides.

Interesting to add is that the early designs for the IS-6 actually had a rounded frontal hull, similar to that of the much later Object 279, yet having a similar effectiveness to the Object 252U. The actual prototypes had a hull made of angled flat plates, probably because it was much easier and cheaper to produce compared to a large casting.

Early drawings of the IS-6 with a UFO-like shape, akin to the much later Object-279
Early drawings of the IS-6, by that time considered as an “IS-2 upgrade”. The curved hull that transpired onto the Object 252U is somewhat apparent.
Source: Stalin Supertanks IS-7
Factory No.100 IS-2 upgrade proposals. In the middle is the IS-2, while to the left is the rounded hull version and to the right is the flat plates version. This latter one would then become the IS-6.
Source: Warspot.ru
Object 252 with its larger road wheels. These large roadwheels, designed by N.F. Shashmurin proved to be faulty on the IS-6 – needing replacements every 200 to 300 km. In fact, 14 of these wheels were replaced during its 825 km testing. Note the BL-30T gun, which was to be replaced by the BL-13T. However, this idea never left the drawing board.
Source: Bron Pancerna, Flickr

The most notable changes appeared in the hull and turret. The NII-48 institute strongly suggested that, in order to improve the protection yet not increase the weight, a pike-nose design should be used. This meant two diagonal plates were welded in the front, creating a pike-like shape and greatly improving the effective armor on the front of the vehicle from threats directly in front of the vehicle. This was designed by engineers V. I. Takarov and G. N. Moskvin, which went on to later design the Object 257 as well.

Previously, the Object 252 and 253 used the D-30T 122 mm gun. This offered very little improvement over the standard D-25T from the IS-2, yet the price was almost doubled. As a result, a new gun was planned to be added to the Object 252, although it ended up never being fitted. The new gun was the BL-13 122 mm, developed in December of 1943 by OKB-172 and was a combination between the D-25T and the BL-9 gun barrel. Further work was done between Factory No.100 and OKB-172, with the gun being ready by July 1944. The capabilities of this weapon are unknown. A ready rack for the massive projectiles was located in the rear of the turret, covered by a thin protective casing, an overall design similar to modern MBTs. A total of 18 warheads were stored here. The casing with explosive material was stored within the hull, on the exact opposite side. This made loading the warheads relatively easy, however, the placement of the cases required the loader to bend down, and manhandle them up into the breech.

The new turret and BL-13T gun that was to be mounted on the IS-6. The tiny space between the top of the breech and the roof of the turret indicates extremely poor gun depression.
Source: Weaponsandwarfare.com

Crew

As the Object 252U was, for the most part, very similar to the IS-6, the crew compartment was mostly identical. It had a crew of four, a commander, gunner, loader and driver. The gunner sat to the left of the gun with the commander behind him. They seem to have shared the same entry and exit hatch, which could be fatal for the gunner in case of a need to evacuate quickly, as he would have to wait for the commander to exit first. The commander had no cupola to look out from, rather just two periscopes (one pointing forwards and the other backward) on top of his hatch. This would have made the commander almost blind when buttoned up. The commander was also in charge of the radio. The loader, as discussed above, had a tough time when loading the main gun. As the cases for the rounds were in the hull, he would have needed to get off his chair and lift them up. Since the turret had no basket, the crew members in the turret could either sit on seats attached to the turret or stand on the hull floor. The loader seems to also have been tasked with the operation of the 12.7 x 108 AA DhSK heavy machine gun. To operate it, the loader had to expose himself, by partially climbing out of his hatch. It is also entirely possible that he was also responsible for loading the co-axial machine gun, a 7.62 mm SGMT. The driver was located in the hull, with the hatch directly underneath the gun, potentially making it very difficult to exit, if the gun was pointing forward.

Since the Object 252U put such a large emphasis on protection, crew comfort and ergonomics were sacrificed. The angling of the hull armor plates made storing ammunition and overall life inside cramped and claustrophobic. An awful thought for many western tankers, Soviet tank design doctrine often sacrificed crew comfort for protection or a low silhouette.

If the IS-6 or Object 252U would have entered service, it would have most likely received a series of upgrades to fix the problems mentioned above, like the periscopes. The Object 701 had its periscopes altered and more added several times until full scale production. However, the armor profile and no turret basket were still features of future Soviet heavy tanks.

Armor

It was regarding armor that the IS-6 struggled the most in comparison with the IS-4. The front was one 100 mm (4 inches) thick flat plate angled at 65°. The lower front plate was 120 mm (4.7 inches) thick, yet only angled at 52°. The side armor at the thickest, was 100 mm. Testing was done in Kubinka, Moscow with captured German 88 mm and 105 mm guns, which could not penetrate the upper frontal plate from 50 m (55 yards). The 120 mm lower plate, being less angled, was penetrated from a “shorter distance”. These results, while being better than the IS-2 and IS-3, fell short of the protection offered by the IS-4. In this regard, the new pike nose design of the Object 252U came into play, as the lower plate was still 120 mm thick, but more sharply angled at 28°. The two upper plates forming the pike nose were 100 mm thick, yet angled at 16° from the side. This increased the effectiveness of the armor significantly. The rest of the hull remained the same as that of the regular IS-6.

Testbed of an IS-6 hull after firing tests possibly using German guns. Despite being well angled, the protection was not deemed strong enough, considering its weight. Note the heavy interlocking plates. It might come apparent that there is no access hatch for the driver. This, however, was a simplified and shorter mockup, purely designed to test the effectiveness of the angled armor. Having a full-size hull, with hatches and other components would have been too costly and time consuming for this purpose.
Source: Stalin Supertanks IS-7
Testbed of the IS-6 hull after firing tests, view from the side.
Source: Stalin Supertanks IS-7

IS-2U

With the help of NII-48, Factory No.100 also designed the IS-2U simultaneously with the Object 252U, making an IS-2 with a pike-like front hull. An improved version of the IS-2, it featured a new gun, and the pike-nose frontal armor. Like the Object 252, it was rejected, in favor of SKB-2’s Kirovets-1, which later became the IS-3.

Blueprints of the IS-2U, sometimes erroneously used to show Chinese heavy tanks. Although the program itself was different to the Object 252U, the pike-nose armor was designed by the same engineers, Tarotko and Moskvin.
Source: Warspot.ru

Fate and Conclusion

The Object 252 November upgrade never went past the blueprint stage, as the fate of the IS-6 had already been sealed. Yet, despite being unsuccessful, the design was not in vain. Instead, it served as a basis for the Object 257, which in turn led to the IS-7 heavy tank, the heaviest Soviet tank ever built. More importantly, it was one the first Soviet designs to implement the pike-nose design, which became famous with the IS-3, and was implemented in the majority of Soviet heavy tanks until their discontinuation.

Illustration of Object 252U by Pavel Alexe, funded through our Patreon campaign.

Sources

Supetanki Stalina IS-7
https://warspot.ru/2793-elektrostalin-6
https://warspot.net/9-object-257-the-first-is-7
http://www.tankarchives.ca/2019/03/modernization-on-paper.html

Object 252U specifications

Dimensions (L-W-H) 7.50 x 2.4 x 3.3 meters
(25 x 7.8 x 10.8 feet)
Total Weight, Battle Ready 50+ tonnes
(55 tons)
Crew 4 (Commander, Gunner, Driver & Loader)
Propulsion V12U diesel engine, 750 hp at 2,100 rpm
Speed 35 – 50 km/h (hypothetical)
(21 – 31 mph)
Range 400km
(249 miles)
Armament 122 mm D-13 2-part ammunition gun
12.7 x 108 mm DShK heavy machine gun on roof
co-axial 7.62 mm SGMT machine gun
Armor Hull armor
Frontal plates: 100 mm forming pike nose at 16°
Lower plate: 120 mm angled at 38°
Upper side plates: 100 mm angled at 45°
Lower side plates: 100 mm at 90°
Upper rear armor: 60 mm at 60°
Lower rear armor: 60 mm at 30°
Upper hull armor: 30 mm
Floor armor: 20 mmTurret armor
Front: 150 mm
Side: 150 – 120 mm
Rear: 100 mm
Top: 30 mm
Total Production Blueprint only