Categories
WW2 Soviet Prototypes

Object 217, PPG

Soviet Union (1940) Mobile Machine Gun Nest – 1 prototype

The Soviet-Finnish War of 1939-1940, more commonly known in the West as the ‘Winter War’, saw many one-off vehicles being designed to help the Soviet Red Army overcome the determined Finnish defenses. Many of these never made it to the front to be tested under fire.

One example of such a unique design was the Object 217, also known as the Podvizhnoye Pulemyotnoye Gnezdo or mobile machine-gun nest.

Background

As the Soviet Red Army set about reorganizing itself in January 1940 due to its ineffectiveness in the opening month of the conflict, many meetings were held to discuss how best to tackle the various obstacles encountered in Finland.

One complaint was the lack of tank/infantry coordination. More often than not, the Soviet tanks would charge ahead and smash through the Finnish lines. The Finns used this to their advantage by allowing the tanks to pass and then reoccupying their positions soon after and shooting at the following infantry. To help counter this, several designs for infantry shields and tank-drawn armored sleds were produced by the various factories of Leningrad (modern-day St. Petersburg). These allowed for sections of infantry to be towed in relative safety to the Finnish lines in order to secure them before the Finns returned.

Clad in snow-suits and well prepared for the harsh climate a Finnish light machine gun position firing upon advancing Soviet troops at Kollaa. Source:SA-Kuva

However, this was not always successful. Once the Finns understood the method of delivery, they used their valuable anti-tank guns to target the towing tanks, or they adapted their defensive positions in order to provide incoming fire as quickly as possible.

Another solution

Another idea was to design a machine-gun-armed tankette that could support advancing infantry. The already existing T-27 was too tall, too weakly armored, and performed too poorly in the snow. As the fighting was in full swing, a quick, cheap design was needed. The task of designing such a vehicle was given to Special Design Bureau No. 2 of the Leningrad Plant of Experimental Engineering No. 185, also known as the Kirov Plant, under the leadership of Josef Yakovlevich Kotin. Kotin created a team under Leading Engineer L. E. Sychev and given the project designation of ‘Object 217’. It was soon called Podvizhnoye pulemyotnoye gnezdo or mobile machine-gun nest by the team.

The finished Object 217 prototype. Source:- https://i.pinimg.com/

The design team quickly produced technical drawings based around a four-speed motorcycle engine with simple suspension. By the beginning of March, a prototype was ready and sent for factory testing. Another four prototypes were also being constructed for trials. The assessors were initially impressed with the vehicle as it fulfilled all the requirements laid out in the request. Even so, the design had numerous drawbacks that called into question its usefulness.

The two Degtyaryov DT machine guns had limited arcs of fire, the crew positions caused discomfort and fatigue within short periods of time, and the armor was seen as too weak when coupled with the limited mobility. However, none of these deficiencies was the reason for not adopting the machine. On 13th March 1940, the Winter War came to a close and there was no longer a need for such a niche vehicle. As a result, the Armored Directorate of the Red Army canceled the project. All the prototypes were scrapped.

Specifications

Hull

The Object 217 used a single-piece of rolled armored steel to form the main body of the vehicle. To this were welded and riveted the side and rear armor. The designers wanted to minimize the silhouette. To do this, they created an oddly laid out fighting compartment. The two crew members sat with the two access hatches on top of the vehicle open during transportation, but when in combat they would adopt a prone position, lying face down inside. At its maximum height, the Object 217 measured only 55 cm. To allow the crew to see, they were each provided with simple periscope devices that protruded from the roof and covered in an armored box. However, this meant that the two crew members had no visibility to their sides and rear.

The commander was seated on the right side, with the driver on the left side of the vehicle.

A headlight was present on the right-hand side, while a smaller rear light was also present on the left-hand side.

A model of Object 217, showing the layout of the hull. The added side vision slit is not seen in the photo of the real vehicle. Source: https://topwar.ru/

Engine and Transmission

To keep the costs down, a PMZ motorcycle 16 horsepower two-stroke, 2-cylinder, air-cooled petrol engine was used for this vehicle. This allowed for limited self-propulsion which was not an issue, as the deployment of the vehicle involved being towed behind a T-26 until it reached the Finnish defenses and then unhooking itself. The transmission was a three-speed gearbox seated next to the engine. A simple friction clutch system controlled by a set of levers was used to control the movement of the vehicle. The factory tests gave a top road speed of 18.5 km/h and a cross country speed of 7 km/h. Due to the large size of the engine in comparison to the internal space available, it was necessary to create an armored box at the rear of the vehicle with several access panels.

The trials also showed that the Object 217 was capable of climbing 30-35 degree inclines and could clear trenches 1 meter wide. It could also wade through streams and puddles so long as they did not exceed half a meter in depth. How this would have translated to the Karelian Isthmus though is not known. The relatively low ground pressure was ideal for getting across the snow but the varied terrain, especially at the specially selected areas of the Mannerheim Line, would probably be taxing on the vehicle.

The same model, clearly showing the engine box. Source: https://topwar.ru/

Running gear

The Object 217 was given a very simple running gear. This consisted of four large cast spoked road wheels which were fixed to rigid axles. To provide power, a drive wheel, about half the size of the road wheels, was installed at the rear. The front road wheels could also turn like the wheels on a car, bending the track in order to allow the vehicle to steer, in a similar style to the later Light Tank Mk VII Tetrarch. To lower the amount of dust and snow thrown up by the tracks, the front and rear had protruding fenders.

The lack of suspension was one of the biggest drawbacks to the design. It put a considerable strain upon the crew, especially under combat conditions that required them to lie down. After only a short while, the assessors reported fatigue which would only make the combat effectiveness of the vehicle worse.

Armor Protection

For the type of vehicle and time, the Object 217 boasted an acceptable armor layout. The front consisted of a rolled single piece of armored plate measuring 20 mm in thickness. The sides were 10 mm thick rolled single pieces that were mainly welded upon the body, with a few rivets in the rear of the vehicle to help strengthen it. The roof and underside were 8 mm thick rolled armored plates. The advanced use of single rolled pieces of armored plate coupled with a heavy reliance on welding gave it a great amount of protection against small arms and shell fragments.

The assessors did express concern about the armor’s ability to withstand anti-tank gunfire or near hits by artillery but this was less about the armor and more about how the limited mobility meant an overreliance upon the armor for protection.

An original document showing two views of the Object 217 vehicle. The upper photograph is already known, but the lower one shows the hatches open, giving information about the upper part of the vehicles. Source: Radikal.ru

Armament

The original directive stipulated that the vehicle had to be armed with a machine gun. This was due to its main task being to keep the Finnish defenders suppressed. The design team added two Degtyaryov DT machine guns in ball mounts which would be aimed using the attached sights. These allowed for 20 degrees of travel in all directions, but this was limited more due to ergonomics within the hull rather than the installations themselves. The sides of the hull contained racks for 25 pan-type magazines, giving a total ammunition amount of 1,575 rounds per gun. In order to allow the crew to maintain operation without the need to clear spent shell casings, each gun mount had a specially designed bag that connected to the side ejection port.

Analysis of possible use

It is not sure how Object 217 would be deployed but some speculations can be made based upon the tactics used by the Soviets during the second offensive phase of the Winter War.

Possibly, after a heavy artillery bombardment upon a section of the Finnish line, a squadron of 12 T-26s would set off, 2 towing Object 217s and 4 towing Sokolov sleds (each carrying 5 Soviet soldiers). As the tanks neared the line, they detached the tow cables and the soldiers advanced to the trenches. The Object 217s would take positions on the flanks, suppressing the Finnish defenders. With these types of tactics, which were deployed during the second offensive phase, but with T-26s taking the role that the Object 217s would have played, it would allow for more tanks to be pushed into the breakthrough and still have the Infantry secure the position. The vehicles could then use their own power to cross the trenches and be ready for any Finnish counterattack.

Conclusion

The Object 217 was a unique vehicle designed for a unique situation. As the Soviet advance stalled by the indefatigable Finnish defense in December 1939, the Soviet Red Army needed any solution to breakthrough. The solution of an armored machine gun position attached to the infantry was a quick fix as it negated a lengthy rework of the current Soviet tactics. The final vehicle produced, however, was inherently flawed as a design. With such extremely limited visibility and a very uncomfortable fighting position for the crew its combat potential was small. The crew would become rapidly tired and the mobile and adaptable Finns would no doubt have quickly learned of its serious limitation and come up with tactics to exploit its weaknesses using their mobility to get around it. With the end of the Winter War the serious deficiencies of the design were never shown by actual combat but the fact that this design was not repeated again is perhaps the strongest indication that this unique vehicle was not an effective solution to breaching well prepared enemy defences. To do that would rely on a far better use of coordinated operations and flexible vehicles supported by artillery – something the Soviets repeatedly failed to manage during the Winter War.

The very small Object 217 mobile machine gun nest was a very peculiar vehicle, very low, with the engine in a small box at the rear. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.

Sources

Komolyets, Maxim. Tanks in the Winter War: 1939 – 1940 (Operations: Scandinavia 1939) (Leandoer and Ekholm (April 14, 2009))
https://warspot.ru/2973-proekt-217-mobilnaya-ambrazura
https://topwar.ru/105675-podvizhnoe-pulemetnoe-gnezdo-tanketka-obekt-217.html

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 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
Categories
WW2 Soviet Prototypes

SMK

USSR (1939) Heavy Tank – 1 Prototype Built

The More Turrets, the Merrier?

Right from the very beginning of the development of the tank concept, the idea that tanks could have multiple turrets to do multiple tasks at the same time was one that was very popular. Japan, Germany, the USA, and Poland all experimented with multi-turreted tanks, but none so much as the USSR and Great Britain. In the early 1930s, the UK produced the A1E1 Independent, Medium Mark III, Vickers 6 ton, and A.9 Cruiser multi-turreted tanks. The Soviet Union had produced the T-26 (a Vickers 6-ton copy), T-28 (based from the Medium Mark III), and the T-35A multi-turreted heavy tank, perhaps the most impressive multi-turreted vehicle to be manufactured in the Soviet Union.

T-35A chassis number 196-94, after being captured by German forces on June 24th, 1941. This vehicle was a prototype that was given some ‘updates’ to try to improve the longevity of the T-35 series. Source: Francis Pulham Collection.
The T-35A was, on paper, an impressive vehicle, but in reality, the vehicle was seriously flawed. It was too long, leading to major structural and mechanical problems, especially when turning, also being too tall and therefore dangerously overbalanced (during WWII, two T-35s would topple over due to the high center of gravity), and too many turrets which left the commander unable to adequately control the numerous crewmen and guns. It became clear that the T-35A was in desperate need of modernizing. T-35A chassis number 183-5 (the twenty-sixth T-35A manufactured) was taken to the testing grounds at Kubinka, near Moscow in 1936 and extensively trialed. After a year of these trials, it was decided that the T-35A was generally unfit for service. In the short term, the T-35A was moderately ‘updated’, but design bureaus were soon busily at work drawing up the Soviet Union’s new multi-turreted heavy tank.

Shaking up the Red Army

Dmitry Grigoryevich Pavlov was the Soviet commander in Spain during the Spanish Civil War during 1936 and 1937, and his experience fighting the Nationalist forces there had quickly seen him gain power within the Red Army. Eventually, in 1937, he found himself in charge of the ABTU (Armor and Automobile Management Bureau). Pavlov was very important in establishing the groundwork for a total overhaul of the Red Army’s tanks, some of which he had seen to perform poorly during the Spanish Civil War. While the main Soviet tank sent to Spain, the T-26, was highly regarded, it was often knocked out by light guns due to the thickness of its armor. The T-26’s armor plates were no thicker than 12 mm, almost no better than the tanks of World War One. This proved to be a major flaw with not only Soviet tanks but tanks all over the world.
In 1937, Resolution 94ss was passed. This was a general order from Pavlov for a total review of the entirety of Red Army stocks. Factory KhPZ 183 (Kharkov Locomotive and Tractor Works) was ordered to begin prototyping for a new multi-turreted heavy tank to replace the T-35A, and a new fast convertible tank to replace the BT-7. Despite this, KhPZ 183 found itself out of its depth developing two new tanks and was busily focusing on the BT tank replacements, the eventual A-20 and A-32, which led to the T-34.
Due to KhPZ 183’s inability to begin designing a new heavy tank, the project was partly handed over to Factory 185. After this, the Kirov Works was also invited to design a new multi-turreted heavy tank for the Red Army. On paper, three factories were now designing a multi-turreted heavy tank, these being KhPZ 183 (which had still technically had not pulled out of this race), Factory 185, and the Kirov Works.
By May 1939, Factory 185 had drawn up the T-100 heavy tank, and the Kirov Works had named their vehicle the SMK, after Sergey Mironovich Kirov, the short-lived chairmen of the CPSU (Communist Party of the Soviet Union) in 1934, who was assassinated not too long after. Much can be said on the death of Kirov, such as whether it was under the orders of Stalin himself, but nevertheless, after his death, Kirov became a much-celebrated figure in Soviet mythology. KhPZ 183’s project had not begun, and therefore at this stage, it became a two-horse race.

‘We are building a tank, not a department store!’

The SMK was originally designed with the T-35’s suspension, but this was deemed inadequate. Therefore, testing was conducted with a T-28 that had its suspension replaced by torsion bars. While not a total success, the potential was not lost on the engineers, and it was decided to implement this into the design.
There were now two tanks on the table, and both vehicles had a very similar internal layout. At first glance, the T-100 and SMK looked similar, but there were very different vehicles. The T-100 had coil spring suspension with rubber-tired road wheels, a different engine, turret shape and design, armor thickness, and even main armament in the shape of the L-10 76.2 mm gun.
Both the SMK and T-100 had three turrets. The SMK prototype originally had two small turrets, one forward and one behind a central pedestal. The main turret was perched upon this central pedestal. The smaller turrets had a 45 mm Model 1934 gun, capable of semi-automatic fire (the breach automatically locked when a shell was inserted, and the spent shell casing was automatically ejected once fired) when shooting armor-piercing projectiles, and quarter automatic fire (the breach automatically locked when a shell was inserted, but the spent shell casing had to be manually removed) when firing High Explosive projectiles. The main turret was equipped with an L-11 76.2 mm gun. The three guns were accompanied by coaxial 7.62 mm DT-29 machine guns, and the main turret had a rear ball mount that was given a 12.7 mm DShK machine gun.
The chassis of the original SMK prototype was octagonal, with a substantial overhang of the upper hull over the tracks and running gear, much like the earlier T-24 tank. The forward turret was placed off-center to the right, whereas the rear turret was off-center to the left, with a large armored radiator intake to the right of the rearmost turret.
The tank was powered by an 850 hp GAM-34T liquid-cooled diesel engine housed in the rear portion of the tank. The drive sprocket was also to the rear. The prototype, on paper, had eight road wheels and four return rollers.

Prototype drawings of the three turreted version of the SMK, with the top image featuring T-35 suspension, and the lower depicting torsion bar suspension. Interestingly, the torsion bar version still retains a track tensioning wheel between the idler and the first road wheel, something not seen on the prototype. Source: https://www.dieselpunks.org
On 9th December 1938, the two prototypes were presented to the ABTU, with wooden mock-ups of the two vehicles. Both prototypes were approved, but the design of both vehicles was requested to change, and the rearmost turret was to be removed from both tanks, reducing the turrets to two, one turret with a 76.2 mm weapon, and one with a 45 mm weapon. Some sources claim that Stalin himself requested this, and the mythology of the incident describes Stalin inspecting one of the two wooden mock-ups, and snapping off one of the sub turrets, exclaiming ‘We are trying to build a tank, not a department store!’ This is not verified anywhere and is highly apocryphal of Soviet doctrine at the time. As it was, the Kirov Works was well aware of the limitations of multi-turreted tanks and was already designing a single-turreted version of the SMK.

Prototypes

From this point, the prototype was approved for production. The tank was now to only have two turrets, instead of three, and due to the weight saved from this, the desired 70 mm thick glacis was able to be introduced into the design.
Now that the chassis was shorter, the prototype was given eight cast road wheels with internal shock absorbers and four rubber-rimmed return rollers. An adjustable front idler wheel was provided for the tank.
The frontal armor was 70 mm thick, and the sides and rear plates were 60 mm thick. The floor plate was 30 mm thick, and the hull and turret roofs were 20 mm thick. The hull no longer extended over the tracks, and therefore a fender was placed along the length of the chassis.

The SMK was an imposing tank, however, the design had some flaws, including a dangerously high and exposed turret ring, a flaw that was exploited during the combat trials in Finland. Source: TSAMO via Maxim Kolomiets
The hull was split into three compartments, not including the main turret. These were the forward fighting compartment, the central fighting compartment, and the engine/ transmission compartment. The crew consisted of seven men: driver, engineer/ radio operator, 45mm gunner, 45mm loader, main turret gunner, main turret loader, and, finally, a commander.
The main turret was given a P-40 anti-aircraft mount with a station for a DT-29 7.62 mm machine gun. The radio in the hull was a TK-71-3, standard in all Soviet heavy tanks. This radio had a rage of 15 km on the move, and 30 km when stopped.
The prototype entered the construction stage in spring 1939, but the design team at the Kirov Works was not happy with the outcome. Engineers knew that the tank was too heavy, limiting its combat capability. Due to the height and weight of the SMK, the vehicle was too cumbersome to be an effective fighting machine. Ultimately, the engineers knew that the multi-turreted tank concept was fundamentally flawed. Therefore, under their own initiative, they began working on a single-turreted version of the SMK.

A cutaway of the SMK prototype as produced. The turret displays features of the vehicle when it was deployed in Finland, the rear turret-mounted DsHK 12.7 mm gun has been replaced with a DT-29 7.62 mm machine gun. Source: vesna-info.ru

Kliment Voroshilov

The Kirov Works began to design a new single-turreted version of the SMK, and the tank they designed was similar to the SMK. Instead of two turrets, the smaller turret was removed from the design, and therefore there was no need for a turret pedestal. The turret ring was now flush with the hull roof plate. The new main turret was similar to that of the SMK, with an L-11 76.2 mm gun, but this prototype, named KV-U0, was given a coaxial 45 mm gun, so as not to reduce the firepower compared to the SMK. The engine of this prototype was a 500 hp V2 diesel that had been designed for the BT series. In this case, it was supercharged. The engine was also used in the T-34, known as the V-2-34, and the version used on the KV series was known as the V-2K. The V-2K was seriously strained when powering the KV-1, but it was completely overworked when powering the KV-2, with its much larger and heavier turret.
The new tank was named after Kliment Voroshilov, who at the time was a prominent figure in the Soviet Union, being one of the five Marshals of the Soviet Union. This new KV (Kliment Voroshilov) tank was submitted with the SMK for trials at Kubinka in the late summer of 1939.

The first KV tank prototype, KV-U0 during WWII. The similarities to the SMK are striking, with the main obvious differences being the lack of the smaller turret with a 45 mm gun. Other differences include a shorter chassis, thicker armor and a different engine. Source: Francis Pulham Collection.

Kubinka trials

The T-100, SMK, and KV tanks were all taken to the Kubinka training ground to conduct trials. The SMK had an advantage over the T-100, being three tonnes lighter than the T-100, and having better cross-country capabilities, but itself was at a disadvantage to the KV tank, the surprise entry for the new role.

Front view of the SMK. Notice the off-centered front 45 mm gun turret. This was to allow for an escape hatch for the driver on the hull roof. Notice the fabric on the front fenders hanging down almost to the tracks. This was likely some measure to curb debris being kicked up. Source: TSAMO via Maxim Kolomiets

The rear view of the SMK during Kubinka trials. The engine deck was very high from the ground, with a large air intake hidden under the upper portion of the hull. At the rear of the turret is a 12.7 mm DShK machine gun. During the combat trials in Finland in 1940, this gun was replaced with the standard 7.62 mm DT-29 machine gun. Source: TSAMO via Maxim Kolomiets
The trials did not go smoothly for either the SMK or the T-100. The SMK suffered from transmission failures during the trials, which were one of the major issues that were desired to be eliminated when replacing the T-35A. It did, however, perform marginally better than the T-100. The vehicle was able to ascend an escarpment of 37 degrees and travel at 35.5 km/h.
The tank that performed best during the trials was the KV. The weight and length saved by removing the secondary turret proved most advantageous. Additionally, the commander had a much easier time controlling the actions of the tank. The KV did not completely win over the crowd, however. The V2K engine (the name for the new V2 engine) was working at its absolute limit, and the vehicle had serious trouble crossing a moat.
This testing was done in early September 1939. This was too late for combat trials in Poland, but for the Soviet Union, another conflict was on the horizon that was a prime testing ground for the new vehicles.

The left side of the SMK at Kubinka trials. The swing arms for the road wheels can be clearly seen and was one of the major improvements over earlier Soviet heavy tank designs. The two turrets are conical in shape, with the main turret consisting of four main plates, and a pressed and shaped roof to maximize space inside. Source: TSAMO via Maxim Kolomiets

Opportunity in Finland

The Winter War was a major conflict between the USSR and Finland. The war was caused by Soviet expansionism, as the USSR wanted a bigger land buffer between Leningrad and the Finnish border 20 km to the north. Initially, a peaceful territory renegotiation was held in Moscow, but Finnish diplomats were understandably unwilling to give away Finnish land in exchange for less strategic positions.
Hostilities opened on 30th November 1939, when forces of the USSR began an invasion of Finland across the entire border. However, the greatest concentration was on the Karelian Isthmus, north of Leningrad. Molotov had promised that a peace settlement between the USSR and Finland would be complete by Stalin’s birthday, 12th December. However, this did not happen, as the Finnish defenses and defensive strategy were highly effective against a Red Army that had suffered greatly from the Purges.
As the war dragged on, it became apparent that the new prototype tanks could be used in real combat situations, a real trial by fire. The three tanks, T-100, SMK, and KV, were given to a special experimental tank unit, the 91st Tank Battalion of the 20th Heavy Tank Brigade.
This unit, despite being a heavy tank brigade, was primarily made up of T-28 tanks, with 105 T-28s (which was one-fifth of the total number of T-28s manufactured), but also 21 BT-7 tanks and 8 BT-5 tanks. Additionally, 11 BMH-3 experimental flame-throwing T-26 tanks were deployed with the unit. The BMH-3 was a conversion for a regular T-26 with two turrets, converted to shoot fire from one or both turrets. It had two tanks of kerosene and compressed gas placed onto the engine deck.
The SMK arrived with the brigade after a major overhaul. One of the minor changes was that the rear-mounted DShK was replaced with a DT-29 machine gun.
The crew of the tank was mostly made up of very experienced members. The commander of the SMK was Senior Lieutenant Petin, the main turret gunner was Senior Lieutenant Mogilchenko, and other members were taken from the Kirov Works, and were generally veterans of driving and operating heavy machinery. The driver was I. Ignatiev, the mechanic was A. Kunitsyn, and the transmission specialist attached to the repair team was A. Teterev. The radio operator in the hull was pulled from regular tank units and is not named in sources.
As can be seen, the crew was a very serious roster, all being high ranking or experienced enough to be mentioned in testing reports.

Combat Trials

The 20th Heavy Tank Brigade was deployed on the Karelian Isthmus, which was the most hotly contested portion of the Soviet-Finnish frontline. This piece of land was the primary concession requested by the Soviet government, as they felt that the Finnish border was too close to the strategic port and major industrial hub of Leningrad (nowadays Saint Petersburg). It was on the Karelian Isthmus that the strongest Finnish defenses were organized, which included the famous Mannerheim Line.
The Mannerheim Line was a cleverly designed series of limited fortifications that used the harsh terrain of the Isthmus to force Soviet forces to rely on the few poor roads throughout Karelia. Anti-tank and anti-personnel traps were interwoven with trenches, pillboxes, small forts, and even deep covered ditches to trap tanks trying to cross.
One of these concrete forts was known by the Soviets as ‘Giant’ and, on 17th December, the 91st Tank Battalion, along with other battalions of the 20th Tank Brigade, were committed to the attack.


The only known photographs of the SMK during operations in Finland are these stills from a Soviet propaganda film. The SMK is moving at speed towards the front. Notice that the tank is still 4BO green, but it has had snowfall accumulate on the nose of the tank. Source: Youtube.com
‘Giant’ was in a stony wooded sector of the front, quite unsuited to tank warfare, but the tanks committed themselves to the assault nonetheless. Contrary to standard practice, the KV was separated from the SMK and the T-100, and was assisting a company of T-28 tanks in the assault, following a tree line to the bunker. The T-100 and SMK were ordered to assist the infantry in crossing the stony open ground.
This attack did not go according to plan, and the T-100 and SMK were forced to call off the attack. Conflicting reports claim that the SMK did or did not get hit that first day. One account states that the vehicles were under intense machine-gun fire while supporting the attack, but remarkably did not suffer any hits. Finnish machine gunners were very well trained, and were likely concentrating their fire on the massed infantry accompanying the SMK.
Another combat report from AP Kunitsyn reads: ‘To test the fighting qualities of the new tanks, a rather difficult sector of the front was chosen. The front lines were between Summajärvi Lake and the non-freezing Sunasuo swamp. On the left of the height was an enemy camouflaged pillbox armed with 37-mm Bofors guns and machine guns. BOT (Armored Firing Points) covered two trenches, an anti-tank ditch and several rows of wire obstacles. Granite anti-tank racks stood in four rows. Together with the T-100 and KV tank, the SMK was to attack the enemy fortifications and capture the height at which the observation tower of the ‘Giant’ sat, which apparently served as a command and observation post. The actions of the three experimental tanks were observed by the commander of the North-West Front, commander of the 1st rank, S. K. Tymoshenko, commander of the Leningrad Military District, commander of the 2nd rank, K.A.
The hour of the attack arrived. A series of red rockets soared into the sky. The artillery preparatory bombardment was carried out in such a way as to not only suppress enemy defences, but also to break through passages in anti-tank barriers and minefields. With the last volleys of the artillery, the infantry went on the attack, and soon the tanks received orders to start moving forward. The commander of the SMK and the whole group, Senior Lieutenant Petin, buttoned down the hatch of the turret and, through an intercom, gave a command to the crew: “Forward!”
Ignatiev, the driver, clearly distinguished the road through the viewing gap. The tank, crushing trees and sprawling debris from thick, specially felled trunks, moved forward. Then, it broke through a number of wire barriers, crawled across the ditch and went to the granite dragon teeth.
With slow movements from side to side, Ignatiev began to swing and push the massive granite teeth. Finns methodically fired from anti-tank guns. Inside the tank was a terrible roar. The shells hit the armor with a terribly loud and painful noise, but the crew did not find any holes. The enemy intensified the fire, but not a single shell could penetrate the body of the vehicle.
It was extremely difficult for the commander and driver to control the tank under fire on such a difficult road. Smoke from firing the gun irritated the throats and eyes of the crewmen. But the crew continued to fight and boldly led the tank straight to the height of the enemy pillbox. Using the two turret guns, tankers fired at embrasures, and fired from machine guns.
Mechanic, AP P. Kunitsyn, one of the crew of the SMK recalled ‘The battle was terrible. Our tank, so thick-skinned, completely impenetrable. But we received a dozen and a half slug hits from the bunker, mostly small-caliber artillery.’
The two combat reports suggest that the SMK did in fact see intense action on the first day of fighting, but more was still to come.
The next day, 18th December 1939, the SMK, T-100, and KV were involved in still heavier fighting. This time, however, the SMK was involved in direct fighting. The three vehicles advanced down a road towards the bunker and were engaged directly with Finnish 37 mm Bofors guns. The SMK was hit at least a dozen times by 37 mm rounds, and successfully engaged Finnish positions, firing its main guns in anger. This, however, did not last long, as a shot from one of the 37mm guns jammed the main turret of the SMK, causing the crew of the main turret to become preoccupied with fixing this problem rather than fighting.
As the SMK traveled down the road, what the crew thought to be Finnish stores were stacked to one side of the road, and the SMK proceeded to roll over this equipment. It is claimed by the driver that he did not notice this debris, but the boxes and stores were hiding a Finnish anti-tank mine.
The mine detonated on the tank’s forward left track. The explosion was enormous, and ripped apart the SMK’s track, buckled the chassis, and broke the torsion bar suspension. The blast had also damaged the transmission, shut off electrics to the tank, and part of the floor plate had been knocked downwards.
One crewman, the driver, I.I. Ignatiev, was knocked unconscious by the blast, but was not seriously wounded.
In the T-100, EI Roshchin, a tester from the Kirov Plant, recalled that: ‘Going to the damaged SMK, our tanks (T-100 and KV) covered him with their armor. The T-100 stood in front and to the right, a KV was also in front, but a little to the left, so a triangular armored fortress was formed from three cars. In this configuration, we not only lasted for several hours, but also tried to put the SMK on the course, connecting the broken tracks. We were well-dressed in new coats, felt boots, fur helmets, mittens and the severe frost was easily tolerated, but the damage was too great – except for the tracks, the rollers suffered and the heavy machine could not be moved.’
Attempts were made to recover the SMK, but the track of the T-100 and SMK slipped on the heavy snow, and therefore the vehicle had to be abandoned. The crew of the SMK were evacuated by the T-100, which had more than enough room to accommodate the now 15 strong group in the tank.
Interestingly, D.A. Pavlov had been observing this engagement unfold. Upon the return of the SMK crew, they were personally de-briefed by Pavlov, and were given awards. But the question remained what to do with the wrecked SMK? The Soviets could not simply allow the Finns to capture the USSR’s newest heavy tank prototype.

Fate and Cancelation

On 20th December 1939, special orders were given by Pavlov to remove the SMK, and recover it to the Soviet lines. Seven T-28 tanks, two 45 mm guns, and an infantry battalion were given the task of recovering the SMK. This, however, was not successful. One T-28 was knocked out by artillery fire near the SMK, 43 infantrymen were injured, and two killed. Therefore, the SMK sat in the snow. Soviet crews had left many hatches open to the elements, and snow and water got inside the tank, further damaging the vehicle.
The vehicle sat where it was lost until February 1940. The Finns had shown little interest in the behemoth, though the vehicle was photographed. The T-28 lost near the SMK was harvested for spares, as the Finns had captured a number of T-28s in working condition, and were in the midst of pressing them into Finnish service.
While this was happening, the ABTU was finishing up the job of choosing a successor to the T-35. This was given to the KV tank, which had proved the best of the three vehicles tested. The designers of the T-100, Factory 185, tried for a while longer to have their design accepted, but to no avail. A second KV prototype was ordered in December, and KV-U0 returned to Kirov to have a new, ‘big turret’ fitted to hold a direct fire 152 mm support weapon.
As for the SMK prototype, the vehicle was cut up and scrapped after February 1940. Interestingly, the crew who served in the SMK were very fond of the vehicle, and spoke warmly of its survivability.

The last photograph of the SMK known to have been taken by Finnish authorities. A T-28 can be seen in front of the SMK, one of the vehicles sent to help recover it. Source: Aviarmor.com
The SMK was a vehicle too late to be practical, as its replacement was essentially designed in tandem with it. The flaws in multi-turreted tanks had been adequately displayed. Despite this, the SMK was a fine vehicle, being heavily armed and armored. Strictly following the ABTU’s specifications for a new multi-turreted heavy tank, the SMK was the vehicle the Red Army was looking for, but not the one it actually needed. However, the single-turreted version of the SMK, the KV, became one of the most important and influential vehicles in the history of armored warfare.
Interestingly, despite the flaws in multi-turreted tanks, engineers at the Kirov Plant drew up plans for a future KV tank with multiple turrets. This was the KV-5, with a 107 mm gun in a main turret, and a small sub-turret equipped with a DT-29 machine gun. This vehicle never left the drawing stage.
While the SMK was scrapped, the T-100 was converted into a heavy assault gun and renamed the T-100Y. This vehicle has survived to the present day, and resides at Patriot Park in Moscow. The KV prototype, KV-U0, was deployed on the Western Front (from the Soviet perspective) when the German attack came on 22nd June 1941, and was captured intact by German forces. It was likely scrapped by the Germans.
The Finns took at least one official photograph of the SMK, and handed it over to their allies. One such ally was Germany, which was busy categorizing Soviet tanks (both before and during WWII). The Germans were well aware of the T-35A. German categorisation called the cylindrical-turreted tanks T-35A, the conical-turreted tanks T-35B (though the Soviet T-35B was an entirely different product) and, interestingly, they called the SMK the ‘T-35C’. Despite the tanks having little in common beyond having more than one turret, the Germans thought that there was enough of a similarity to call it a T-35.
The official name for all T-35s was T-35A. This includes conical-turreted tanks. The T-35B was a version of the T-35 with a V2 diesel engine, which was planned but not produced.

The right side view of the SMK. The chassis has eight road wheels and four return rollers. This would be cut down two six road wheels and three return rollers on the KV tank. This was ultimately more successful and less cumbersome than the SMK’s layout. Source: TSAMO via Maxim Kolomiets

Sources

Tanks of the Winter War – Maxim Kolomiets
T-35 Heavy Tank. Land Dreadnought of the Red Army – Maxim Kolomiets
Aviarmor.com

SMK specifications

Dimensions (L-W-H) 8.75 x 3.4 x 3.25 m (28.7 x 11.1 x 10.9 ft)
Total weight, battle-ready 55 tons
Crew 7 – driver, engineer, 45 mm gunner, 45 mm loader, 76.2 mm gunner, 76.2 mm loader, commander
Propulsion GAM-34BT (ГАМ-34БТ) V-shaped 12-cylinder engine, 850 [email protected] rpm
Speed 35.5 km/h (22 mph)
Range 725 km
Armament 76.2 mm L-11 gun
Model 1934 45 mm gun
4 х 7.62 mm DT machine guns
12.7 mm DsHK model of 1938
Armor Frontal: 75 mm (2.95 in)
Side and rear: 55-60 mm (2.16- 2.3 in)
Turret side: 30 mm (1.81 in)
Bottom: 30 mm (1.81 in)
Top: 20 mm (0.7 in)
Production 1 prototype made


Illustration of the SMK Heavy Tank Prototype by Tank Encyclopedia’s own David Bocquelet.

Tanks Encyclopedia Magazine, #2

Tanks Encyclopedia Magazine, #2


The second issue of the Tank Encyclopedia magazine covers the fascinating history of armored fighting vehicles from their beginnings before the First World War up to this day! This issue covers vehicles such as the awe-inspiring rocket-firing German Sturmtiger, the Soviet SMK Heavy Tank, the construction of a replica Italian Fiat 2000 heavy tank and many more. It also contains a modeling section and a feature article from our friends at Plane Encyclopedia cover the Arado Ar 233 amphibious transport plane! All the articles are well researched by our excellent team of writers and are accompanied by beautiful illustrations and period photos. If you love tanks, this is the magazine for you!
Buy this magazine on Payhip!


Categories
WW2 Soviet Prototypes

Dyrenkovs Armored Tractors (D-10, D-11, D-14)

USSR (1931) Armored Tractors – 1 prototype of each built

At the beginning of the 1930s in the USSR, several global interrelated processes were going on. These parallel processes had a severe impact on military effort and procurement.
Firstly, there was a need to re-equip and reform the army, in particular, the armored forces. The armored forces of the USSR mainly consisted of outdated tanks and armored cars, such as the British Mark V and Medium Mark A Whippet tanks or Garford-Putilov armored cars captured during the Civil War, and T-18 (MS-1, Maly Soprovozhdenya) tanks. These vehicles no longer met the needs of the tank units, The Red Army wanted a tank with a more powerful engine, better speed, maneuverability, ergonomics, and installed radios.
Secondly, the country’s leadership realized a serious setback in the industrial field. On July 15, 1929, the program of mechanization and motorization of the Red Army for the next 5 years was approved. By 1933, it was planned to have 3,500 active tanks in the army and another 2,000 in the mobilization reserve. At the same time, the RVS (Revolutsionniy Voenniy Sovet – Revolutionary Military Council, the supreme military authority of the Soviet Union) adopted a new system of auto-armor-tank-tractor armament, which was based on the modern requirements of combat and tactics.
When trying to implement the adopted plans for the development and production of new weapons and military equipment, the industry faced “enormous difficulties.”
Thirdly, both the production and the army suffered from a shortage of qualified personnel. New cadres (specially trained professionals) were not yet ready and did not have enough experience, and a significant part of the old and experienced specialists, for political reasons, were “cut off” from military service and leadership positions.
There were many different causes for rejecting specialists or young recruits “for reasons of political and moral inferiority”, such as affiliation to the “wrong ”class (bourgeoisie, clergy etc.) or professional backgrounds — service in the White Army or administration of the Russian Empire.
The military leadership, however, followed the global trends in the field of armaments and tactics and tried to keep up with them. At this time, new military theories were actively developed.
One of these theories was developed by the Soviet military theoretician and Marshal of the Soviet Union Mikhail Nikolayevich Tukhachevsky. According to that theory, simple and cheap armored tractors could be used as tanks of the 2nd and 3rd echelons (troops and armor of the 2nd and 3rd lines in a formation), even at the expense of reducing important combat characteristics.

“… we need to strive to have military tanks in numbers up to about one-third of the total, to perform special tasks, fight against anti-tank artillery, etc. The remaining tanks, usually advancing in the 2nd and 3rd echelons, can have somewhat lower speed, larger size, etc. And this means that such a tank can be an armored tractor, just as we have armored cars, trains and railcars, which will allow us to field armored tractors in huge masses.”

The Red Army required a large number of inexpensive, easy to manufacture and operate combat vehicles. The latter was especially important due to the acute personnel shortage – Soviet military theorists understood that the skills of the available manpower were not sufficient in the early 30s, and in the event of a major war, they would not have time to train qualified soldiers to man complex military equipment.
The Experimental Design Office of the Department of Mechanization and Motorization of the RKKA (UMM RKKA – Department of Mechanization and Motorization, Upravlenie Mekhanizacii I Motorizacii) was instructed to develop a “tractor tank”, like the American dual-purpose machine, the six-ton tractor Disston.
Most likely, the information about the Disston tanks was obtained from mass-media or during the so-called “Khalepsky Commission” visit to the USA. At that time, Nikolai Ivanovich Dyrenkov, a talented and extremely ambitious self-taught engineer, headed the Department of Mechanization and Motorization of the Red Army. Under his leadership, at the end of 1930, the development of so-called “surrogate tanks,” an infantry transporter and a number of other vehicles, began.

Development

The “Kommunar” tractor, a licensed version of the German tractor Hanomag WD50, was taken as the basis for the D-10 and D-14, and the American Caterpillar-60 tractor was taken as the basis for D-11.
The production of “Caterpillar-60” was planned to start in Chelyabinsk (a city east of the Ural Mountains, which became a very important transport hub and industrial center during 1930s). “Kommunars” were already in production in Kharkov.
The Department of Mechanization and Motorization of the Red Army was charged with building prototypes of so-called “surrogate tanks”: D-10, D-11, APC D-14 (“desantniy tank”). In Russian, the word “desant” is often used for troops which ride into the battle on top or inside the armored vehicles. Thus – “desantniy tank”. The same word is used for airborne troops – “vozdushno desantniye voyska”) and the D-15 “chemical tank”. All vehicles were created in the Moscow MOZEREZ plant (Moscow Railway Repair Plant, Moskovsky Zheleznodorozhny Remontny Zavod). By February 1931, they were ready.

Design

The design of all three vehicles was approximately the same: an engine was located in the front and, behind it, in the middle and aft part of the hull, there was a crew compartment, combined with a fighting compartment or compartment for troops. A fuel tank was also at the back.
On the roof of the fighting compartment there was a fixed commander’s cupola with viewing slots. Neither of the three vehicles had a rotating turret.

Armament

The D-10 and D-11 surrogate tanks were equipped with a 76.2 mm cannon on a pedestal mount as a primary weapon and two 7.62mm DT (Degtyaryov Tankovy) machine guns in the front and aft armor plates, as an auxiliary armament. Two more spare DT machine guns were stowed in the fighting compartment. There were two ball mounts for additional machine guns on each side armor plate. Worth noting is that the main gun mount was placed in the aft of the tank. In fact, this solution was the same as that of the Garford Putilov armored vehicles.
In the case of the Garford-Putilov, this decision was reasonable because the armored car had two driver positions and often went into battle ‘backwards’, but it was a significant flaw for the armored tractor, since it has to be turned around to fire the main gun.
According to some records, the ammunition did not fit into the tank and it was supposed to be carried on a towed trailer, but there is no information about the trailer itself. The D-14 APC was armed with two DT machine guns – one in the bow and one in the aft ball mounts.

Crew

The D-10 and D-11 tanks had a crew of 3 men – commander, driver, and gunner. D-14 APC had a crew of 2 men – driver and commander.
It is difficult to imagine how the engineers behind the design saw the distribution of crew duties between just two people. It can be assumed that firing was possible only after the vehicle stopped, so the driver or commander could take gunner positions.

Armored Hull

All three vehicles had riveted hulls made of rolled armor plates. The D-14 had three doors on each side of the hull used for the entrance and exit of the crew and dismounts. The D-10 had one door on each side; on the left side, the door was closer to the stern, on the right, to the aft. The D-11 had one door in the middle of each side.
A distinctive feature of all three armored vehicles was a massive armored engine in the front, which blocked visibility for the driver and made it difficult to fire a machine gun.

Engine

Propulsion was provided by a water-cooled four-cylinder, four-stroke engine with a carburetor and a vertical arrangement of cylinders. Kommunar 9GU and Kommunar 9EU had a 75 hp (55 kW) 4-cylinder petrol engine, and Caterpillar-60 had a 60 hp (45 kW) 4-cylinder gasoline engine.

Chassis and Suspension

All 3 vehicles used reinforced tractor chassis’ used as a basis with minimal changes. Transmissions were the same as on the original tractors. The D-10 and D-14 had a spring suspension with two springs for each bogie. The D-11 had a semi-rigid suspension.

Trials and Results

In 1931, all three vehicles were tested at the NIABT Test Site (Nauchno Ispytatelny Avtobronetankovy Poligon, Scientific armored vehicle proving ground in Kubinka, also NIABP). Most likely, the tests of all three vehicles (D-10, D-11 and D-14) were conducted in May-June 1931. This fact is confirmed by the document with the preliminary test results dated July 1931.
On July 18, 1931, the Scientific-Technical Committee of the UMM RKKA considered a report on the testing of three vehicles: a “Kommunar 9GU” armored tractor (D-10 tank), a “Kommunar 9EU” armored tractor-infantry carrier (D-14 APC) and an armored tractor “Caterpillar 60” (D-11 tank).

D-10 Tank

The total weight of the tank exceeded by 1.5 tonnes the original projection. As a result, the average speed and mobility decreased. Instead of the estimated speed of 7-8.5 km/h on roads and 5-6 km/h off-road, the tractor-tank showed 6-6.2 km/h on roads and only 3.2 km/h off-road. When the outside air temperature was above 15 °C and the radiator was closed, the water boiled after 1-1.5 hours of the engine being in use.
Obstacle overcoming tests were unsatisfactory. The tractor-tank coped with a 1.25 m wide and 1 m deep trench dug in sandy soil, which was no worse than MS-1 tank. But the vehicle did not cope with a 1.5 m wide trench. D-10 could cross, tear or crush barbed wire barriers only if the stakes did not fall between the tracks, because the bottom of the tank was not protected by armor.
The report also mentioned the fact that the engine could not be started from inside the tank and the absence of a vacuum apparatus for supplying fuel, both considered to be further negative aspects of the armored tractor. The D-10 had a ‘gravity fuel feed’, so if the tank got in an unfavorable position, for example, when crossing the trench, the fuel supply to the engine would be interrupted and the armored tractor would stop. It should be noted that the problem was old, and known since the days of the British Mark I Tank.
The following two problems were distinctive for most Soviet armored vehicles of the 1930s-40s. First, the tests showed difficulties with visibility due to the inconvenient location of the viewing slits. This applied, in particular, to the driver’s position. Secondly, it was noted that there was a lack of ventilation in the crew compartment.

Front view of a D-10 with the D-11 in the background. Source: RGVA

Right side view of the D-10. Source: Domestic armored vehicles. XX century

Left side of the D-10. Source: Domestic armored vehicles. XX century

D-14 Troop Carrier

The weight of the tank, as in the case of the D-10, was exceeded, this time by 2 tonnes. Due to the increased length of the hull, the load on the rear bogies was also increased; as a result, these bogies collapsed during the tests. Problems with the visibility and fuel supply were similar to those of the D-10.
There was also a problem with ventilation, although, in the case of an infantry carrier, it was more acute. According to the designer’s idea, the transporter was supposed to fit 18 riflemen (dismounts) with weapons, plus the crew, since the compartments for crew and dismounts were combined.
Poor ventilation made the conditions inside the APC such that after a few hours of being inside the vehicle, the soldiers and crew would be unable to perform their duties due to heat, cramped space and noise.
The engineer who designed the D-14 placed the doors for entering and exiting the armored tractor on the sides of the hull, with 3 on each side. The doors opened backward in relation to the nose of the vehicle. There were no hatches or doors in the stern. This decision made exiting the vehicle quite dangerous, as soldiers could not hide behind either the doors or the hull of the APC and would be exposed to enemy fire.
Subsequently, the number of troops carried decreased. Later Soviet experimental armored personnel carriers were designed for 14 (TR-1) and 15 riflemen (TR-4). For comparison, the crew of the French Lorraine 38L consisted of 12; driver, commander and 10 infantrymen – four in the troop compartment and another 6 in the armored trailer. It is noteworthy that the exit of the troops through the side hatches or doors returned to the Soviet APCs in the 60-70s, namely the BTR-60P and BTR-70.

Front view of the D-14. Source: Domestic armored vehicles. XX century

D-14 Prototype. Side doors and engine starting handle are clearly visible. Source: RGVA

Rear view of the D-14. Source: Domestic armored vehicles. XX century


Illustration of the D-10 Tank (armored tractor) based on the “Kommunar 9GU” tractor.


Illustration of the D-11 Tank (armored tractor) based on the “Caterpillar 60” tractor.


Illustration of the D-14 Troop Carrier (armored tractor) based on the “Kommunar 9EU” tractor.

These illustrations were produced by Andrei ‘Octo10’ Kirushkin, funded by our Patreon Campaign


D-11 Tank

As in the case with the D-10 and D-14, the weight of the vehicle was exceeded by 2.7 tonnes with similar consequences. The speed dropped to 4.7 km/h on roads and 3.9 km/h off-road. In addition to the familiar problems of D-10 and D-14 with fuel supply and engine overheating, the D-11 had its own unique ones.
According to test engineers, the armored hull was attached to the chassis extremely poorly. Firstly, the hull blocked access to the most important parts of the tractor, such as rear axle and gearbox. Secondly, during the tests, the armored hull of the tank tore off the bolts that attached it to the tractor and fell on the tracks.
Additional problems were reported: poor ventilation – during movement, “dust filled the crew compartment”. When trying to cross a trench, the tractor-tank “sticks the nose into the ground”.
It is not known whether this was a distinctive feature of this particular machine (which was the one based on the Caterpillar 60), or if it was also the case on the machines based on the “Kommunars”. In addition, D-11 has a reduced off-road capability in comparison with D-10 and D-14, because of the shorter base. The report noted a reduced cross-country capability and reduced mobility of this vehicle compared to the D-10 and D-14.

Left side view of the D-11. Source: Domestic armored vehicles. XX century

Test Results and Recommendations

On August 6, 1931, the test results were confirmed in another document, where conclusions and recommendations were presented.
General conclusions were as follows:

  1. “Surrogate tanks” were not suitable for clearing barbed wire fences due to unarmored bottom. Adding armor to the bottom meant increasing the weight, which means a decrease in the combat performance of already heavy and slow vehicles. In the second document, the general conclusion was much harsher: “nullifies the combat use of this type of armored vehicle”;
  2. The speed and maneuverability were considered insufficient, even for tanks of the 2nd to 3rd echelons. The chairman of the Scientific and Technological Committee UMM, Ivan Andrianovich Lebedev, noted that the average speed being “less than 4 km/h”;
  3. Suspension elements were destroyed or worn out due to the excessive weight of the vehicles;
  4. The artillery armament with which it was equipped was deemed unsatisfactory;

There was another important point that influenced the decision. It was considered that the “Kommunar” tractors surpassed the “Caterpillar-60” capabilities. But, firstly, “Kommunars” were produced by the KhPZ factory (Kharkov Locomotive Factory) in quantities that barely met the needs of the army in tractors for towage of artillery and other weapons. Secondly, the production at KhPZ was, in fact, custom-made. There was no exchangeability of parts even within the same series of machines.
The conclusion for Dyrenkov was disappointing: according to Lebedev, the main purpose of these tractors was towing artillery, therefore it was recommended to remove the armored hulls and convert the surrogate tanks D-10 and D-11 into self-propelled guns and test them.
In the case of the infantry transporter D-14, the UMM committee decided to retest it in order to “obtain more detailed data, both from the technical and from the tactical side.” Alterations included reduction of the troop compartment to 12 soldiers instead of 18. The rear part of the armored hull had to be partly cut off in order to reduce the load on the rear rollers.
In general, it was recommended to reduce the weight of the machine to 10 tons. To achieve this, it was proposed to remove or lighten individual armor plates. And, finally, to install an additional fuel tank, with the ability to pump fuel from the main fuel tank. Lebedev noted that “it is not possible to get a surrogate tank, even with reduced combat capabilities, without a major overhaul of the design.” In fact, it was easier to design a new tank.

Conclusion

Dyrenkov managed to create in 1931 armored vehicles that had the flaws of tanks of the Great War. The Red Army quit experiments with armored tractors but returned to them as an emergency measure in early 1941.
There was a plan to charge the faculty of mechanization and motorization of the Red Army to develop a personnel carrier on the chassis of the tank MM-1 (aka TMM-1, based on the Vickers Mk. E), as it was one of the most robust and common tanks of the Red Army. Further experiments with armored personnel carriers continued and the next attempt was the TR-1 (TR-26) transporter based on the T-26 tank. Nevertheless, the Red Army entered World War Two without any indigenous APC.
As for Dyrenkov and Tukhachevsky, they were both arrested and executed in 1937 during the “Great Purge”.

Specifications (D-10)

Total weight, battle ready ~ 12,000 Kg
Crew 3
Propulsion 4-cyl petrol, 75 hp (55 kW)
Maximum speed 6-6.2 km/h forward, 3.2 km/h reverse
Range 120 km on road
Armament 1 x 76-mm gun M1913 on Garford mount;
1 x 7.62-mm DT machine gun
Armor Front – 16 mm; Back – 16 mm; Sides – 11 mm, Top – 6 mm
Production 1

Specifications (D-14)

Total weight, battle ready ~ 12,500 Kg
Crew 2 + 18 passengers
Propulsion 75 hp (55 kW) engine
Maximum speed 6 km/h forward
Range 120 km on road
Armament 2 x 7.62-mm DT machine gun
Armor Front – 11 mm; Back – 11 mm; Sides – 11 mm, Top – 6 mm
Production 1

Specifications (D-11)

Total weight, battle ready ~ 13,250 Kg
Crew 3
Propulsion 60 hp engine
Maximum speed 4.7 km/h forward, 3.9 km/h background
Range 100 km on road
Armament 1 x 76-mm gun M1913 on Garford mount;
2 x 7.62-mm DT machine gun
Armor Front – 16 mm; Back – 11 mm; Sides – 11 mm, Top – 6 mm
Production 1

Sources

RGVA f. 31811 (Russian State Military Archive (Rossiiskii Gosudarstvenni Voennyi Arkhiv- RGVA)
Domestic armored vehicles. XX century: Scientific publication: In 4 volumes / Solyankin A.G., Pavlov M.V., Pavlov I.V., Zheltov I.G. / Vol 1. Domestic armored vehicles. 1905-1941 – M .: Exprint Publishing Center, LLC, 2002. – 344 pp. Ill., P. 61, pp. 88-89
Domestic Armored Vehicles 20th Century Vol 1 1905-1941 (Solyankin 2002)
Tukhachevsky / Boris Sokolov. – M: Molodaya Gvardiya, 2008. – 447 [1] s: il. – (Life of remarkable people: ser. Biogr .; issue. 1104)
Kirindas A.M. “Artillery tractor“ Comintern””, – Moscow: Yauza-Catalog, 2017
A.Bezugolny. “The Source of additional power of the Red Army …”, Moscow: ROSSPEN, 2016

Categories
WW2 Soviet Prototypes

T-35 Prototypes

USSR (1932)
Heavy Tank – 2 Prototype

The T-35A tank is one of history’s strangest tanks – often seen crawling across the Soviet inter-war era parade squares. This tank grabbed the hearts, souls, and imaginations of the Soviet people and foreign military attachés alike. It was one of the many proud achievements of Soviet industrialisation – its image appeared on posters, films, and even medals and awards!

Prototypes

In the late 1920s and early 1930s, the USSR was desperate for a modern army. After hard fighting during the Civil War (1918-1920), the vehicles of the Red Army were worn out and obsolete. These consisted mostly of obsolete Mark V heavy tanks and Medium Mark A Whippets.
Designing and mass-producing a new vehicle would help the fledgling Red Army set foot on the international stage again. It would also give Soviet engineering a fantastic opportunity to put its skills to the test, which were comparatively primitive to those of the USA and Great Britain in the late 1920s.
However, as Soviet engineering was still in its early stages of modernization, and as Soviet engineers had little to no experience designing tanks, it was decided to outsource Soviet tank designing to foreign sources. This came in three different types. The USSR would either pay for engineers to come to the Soviet Union and help build tanks, buy blueprints from foreign powers and visit tank factories or outright purchase foreign tanks wholesale and begin local manufacture.
In the heavy tank department, the German engineer Ernst Grotte was brought in from Germany, a country banned from tank development. Between 1929 and 1931, his design team came up with the TG tank. Grotte was assigned to the Leningrad AVO-5 design bureau.

TG Tank

The TG tank was a large tank with two independent tiers of armament. The lower elliptical turret was equipped with an A-19 76.2mm (3 inch) gun, and a rotating turret mounted on top of the first one which was fitted with a 37mm (1.46 inch) PS-2 gun. The suspension consisted of coiled springs, and each side of the vehicle had five large diameter road wheels.
The TG tank also had three water-cooled 7.62mm (0.3 inches) Maxim machine guns, one on either side of the hull and one at the rear of the machine. The vehicle weighed 20 tonnes, The tank was powered by the M-6 Aero-engine and could reach a maximum of 35 kilometers per hour (22 mph). The TG had a crew of 5.
null
The TG Tank during trials. The turret ring for the main turret broke, therefore tests were conducted with the turret permanently facing forward. Source: Military Images
The vehicle was tested in April 1931 and was quite successful, displaying good cross-country capabilities, relatively good speed, and reliability. A noted flaw though, was that the fighting compartment of the vehicle was very cramped.
However, the TG project was dropped, not due to the vehicle’s performance, as this was better than other Soviet prototypes at the same time, but rather due to costs. It would cost almost 1,500,000 roubles to manufacture a single such tank, money better spent on manufacturing up to twenty-five BT-2 fast tanks.
null
The TG tank incorporated many modern ideas, however, it was an inherently flawed vehicle. Source: panzernet
null
The TG tank in 1940. Nothing more than a display piece at the Polygon near moscow. Source: panzernet

Unrelated to the Independent

Some allege that the T-35 was inspired by the British A1E1 Independent tank, but Soviet-era sources claim that the A1E1 had no influence on the design, despite Soviet knowledge of the vehicle. Indeed, apart from the layout of the turrets, the T-35 and A1E1 are very different machines.

The British A1E1 independent tank. Even a quick inspection will reveal that the machine is vastly different to even the prototype T-35-1 and T-35-2. Illustration by David Bocquelet.
Soviet engineers were given the opportunity to inspect the A1E1 Independent tank when advisors from the USSR visited the Vickers factory in 1930. However, they found the same flaws in the machine as the British did, i.e. that the tank was too long and too thin, and the tank’s sides were prone to warping under the tension of the tracks.

T-35 specification

Dimensions (L-w-h) Unknown
Total weight, battle ready 35 Tons
Crew 9
Propulsion M-6/ M-17L Aero engine
Armament 1x Ps-3 76.2mm, 2x Ps-1 37mm, 4x 7.62mm
Total production 2

Links, Resources & Further Reading

Fallen Giants: The Combat Debut of the T-35A Tank – Francis Pulham
Land Battleship: The Russian T-35 Heavy Tank – Maxim Kolomiets & Jim Kinnear
aviarmour.ru
ww2 soviet armour
ww2 Soviet Tanks Poster

T-35-1 and T-35-2

A new heavy tank prototype was designed in early 1932, designated ‘T-35-1’. It was produced at the Kharkov Locomotive and Tractor Works (KhTZ). This first prototype had six pairs of road wheels arranged with two pairs of road wheels per bogie. Each bogie was fitted with coiled spring suspension comprised of two pairs of springs. The name T-35 comes from the Red Army requirement for a 35-ton tank.
null
Both the T-35-1 and T-35-2 were paraded in 1933 on palace square. Notice the round turret roof of the T-35-1. Source: pinimg.com
All the sub-turrets of the prototype were of the same design and shape regardless of armaments. Two of the turrets were equipped with the 37 mm PS-2 guns and the other two having DT-29 machine guns. When facing forward and aft of the tank, the 37 mm turrets were on the right, while the machine gun turrets were on the left. The main turret was fitted with a 76.2 mm PS-3 gun and another machine-gun in a ball-mount to the right of the gun. It was welded with distinctive curved roof and rested on an armored pedestal.
The tank had two armored skirts on either side to protect the suspension. However, rather foolishly, the skirts of the first prototype had no access ports and there was no way to access the suspension without pulling the skirts apart. The tank was powered by the M-6 aircraft engine, with the drive wheel at the rear. The tracks ran on top of 6 return rollers that were almost two meters above the ground.
null
The T-35-1 turret was removed at some point when the tank was dismantled. Here it sits at the Polygon in 1940. Source: Sergey Lotarev
The prototypes had crews of 9, a driver, engineer/ hull machine gunner, a single crew member in each of the four small turrets, and three crew in the main turret. The driver and engineer were equipped with dome-type escape hatches on the front hull roof.
This prototype was evaluated in mid-1932 before a second prototype was ordered. The second prototype was outwardly similar, with the exception of the addition of access ports in the skirts. These were square shaped and gave all-important access to the bogies for maintenance. In addition, the main turret relinquished the round roof.
null
The T-35-2 can be harder to distinguish from production T-35s, however inspection of the drivers compartment with the hull machine gun and the escape hatches clearly reveals its origin. Source: www.battlefield.ru
The powerplant of the second prototype was changed to the new M-17L Aero Engine. This was the Soviet copy of the BMW VI Aero engine. Accordingly, this prototype was called the ‘T-35-2’.
These T-35 prototypes were both evaluated but were not accepted for Red Army service. This was due to a new design buro designing a similar, yet superior machine.
The OKMO of Kharkov, in parallel with the T-35-2, had designed the T-35A prototype. Similarly to how the T-37 and T-37A were different vehicles with similar names, the two tanks shared similarities but were, by and large, different vehicles.

Visual Identification Guide

The two T-35 prototypes are discernable from production T-35A tanks through a multitude of factors. The main way of identification is by the placement of the exhaust pipes lengthwise on the rearmost fenders. Production T-35As had their exhaust lying sideways on the central hull, and in later tanks, this was moved under armor.
The turrets too are different. The main turret of the T-35-1 had a distinctive round roof, and the T-35-2 is missing much of the exterior detail that production T-35As had. The main gun in the main turret was also a PS-3 76.2mm gun rather than the KT-28 76.2mm gun of production tanks.
null
The front of the T-35-1. Notice the two driver’s positions. Source: Land Battleship T-35
The sub turrets on the two prototype tanks were all identical to each other, whereas production T-35s 45mm gun turrets were larger than the machine gun turrets, and were cylindrical in shape.
Hulls too were very different, with the prototype T-35-1 and T-35-2 having only six road wheels per side, whereas production tanks had eight road wheels. The entire nose of the vehicle was different, with the two prototypes having round bulbous escape hatches for the driver and engineer. Additionally, there was a hull-mounted machine gun position on the prototypes absent from production tanks.
null
One of the production T-35A’s. Notice the vast differences between this machine and the prototypes. Source: Land Battleship T-35

Conclusion

The two T-35 prototypes, while sharing the name and basic layout with the T-35A, was, in reality, an entirely different machine. It is clear inspecting the dimensions and the armaments that the prototypes were inferior in almost every way to the production T-35As.
While a useful jumping-off point, these prototypes were technical failures. The production tanks heavily differed from these prototypes, so much so that pre-Glasnost western sources called these prototypes “T-32”. This is, of course, wrong.


T-22 Tank Grotte prototype


T-35-1 prototype
Both Illustrations by Tank Encyclopedia’s own David Bocquelet

Combat Debut T35A
Fallen Giants: The Combat Debut of the T-35A Tank

By Francis Pulham

The Soviet T-35A is the only five-turreted tank in history to enter production. With a long and proud service history on Soviet parade grounds, the T-35A was forced to adapt to the modern battlefield when the Second World War broke out. Outclassed and outdated, the T-35A tried to hold its own against the German invaders to no avail. For the first time, actual battlefield photographs have been cross-referenced with maps and documents to bring about the most complete look at the T-35A in the Second World War to date.

Buy this book on Amazon!

Categories
WW2 Soviet Prototypes

ISU High Power Gun Projects

Soviet Union USSR (1944-1945)
Heavy Tank Destroyers – 5 prototypes

Dedicated Beast Slayers

In mid-1944, the Red Army recognized that it might need tanks that could consistently and reliably destroy the Wehrmacht’s most well-armored tanks. The Red Army fielded few tanks that could destroy the King Tiger, Elefant, and Jagdtiger reliably from medium-long ranges. Although it is true that the ISU-122, ISU-122s, ISU-152, and IS-2 were capable of destroying German heavy tanks, their combat results were not consistent enough. As a result, starting in June of 1944, five “BM” (“High Power” – Russian: “высокой мощности”) guns were developed for the ISU chassis. The resulting vehicles were: Object 243 (ISU-122-1 with the 122mm BL-9 gun), Object 246 (ISU-152-1 with the 152mm BL-8 gun), Object 247 (ISU-152-2 with the 152mm BL-10 gun), Object 250 (ISU-130 with the 130mm S-26 gun), and Object 251 (ISU-122-3 with the 122mm S-26-1 gun). More gun projects were being developed at this time, but no others appeared to be mounted onto a chassis. The guns proved capable, on paper, of destroying tanks such as the Jagdtiger, but testing showed that they were simply not practical. Moreover, these projects took well over a year to refine, and seeing as though the war ended before they were complete, they were all dropped.

A table with comparative statistics is provided at the bottom of the article.

Context: Soviet guns against German armor

Mythbusting: The SU-152 and ISU-152 were “Beast Killers”
Soviet wartime propaganda suggested that the SU-152 and ISU-152 (SU being based on the KV chassis, ISU being based on the IS chassis) were “Beast-Killers” because they could destroy Panthers, Tigers, and Elefants. The ISU-152’s 152mm ML-20S howitzer was, indeed, capable of destroying heavy German armor, but this required a direct hit with a High Explosive (HE) shell. Such a direct hit could do one of three things to disable the tank: destroy the vehicle’s drive systems, kill its crew, or blow the turret / casemate / hull open (or even clean off, in the case of turrets). Armor Piercing (AP) and Concrete Piercing shells were developed, but these were expensive and complicated to make, hardly more effective than HE rounds, and thus were scarcely supplied – even at Kursk! However, the ISU-152 was not a dedicated tank destroyer – it was an assault gun designed for bunker busting and indirect fire. Needless to say, using an assault gun as a tank destroyer was risky business.
Firstly, the gun would need to be fired at short ranges against enemy tanks. This is because the ML-20S was a fairly low velocity howitzer, which would simply not be accurate enough to engage tanks from distances. Consider also that the vehicle had a maximum of 90 mm of armor, which meant that it whilst it was adequately protected from some German guns at long ranges, it simply was not thick enough to protect the vehicle in the short ranges it would need to operate in as a tank destroyer. For example, the 7.5 cm KwK 40 L/48, as mounted on StuGs, Panzer IVs, and Jagdpanzers, could penetrate 97 mm of armor at 500 m, and 87 mm of armor at 1000 m, at 30 degrees (the ISU-152 casemate was barely sloped at all). Also consider that the vehicle was simply not mobile enough to be engaging more nimble German tanks, and could probably be outmaneuvered anyway.
Yet another major issue of using the ISU-152 as a tank destroyer was that it could only manage 1-3 rounds per minute (depending if it had one or two loaders, and how experienced they were). This meant that in any type of ‘duel’, the ISU-152 would not only need to fire first, but also guarantee a hit, or practically any opposing German tank could get numerous shots off against it – as mentioned early, likely knock-out blows. Having said this, it did not seem to be a consideration taken into account when making the “BM” projects, as the guns all had equally as poor rates of fire.
In conclusion, the ISU-152 did not live up to its legendary name. Other Soviet field guns and tank destroyers had somewhat better results compared to the ISU-152, although the results were still not quite satisfactory.
Mythbusting: The 122 mm A-19S and D-25T / S were sufficient
It is a commonly held belief that the 122 mm D-25T / S and A-19S were sufficient at destroying the heaviest German armor. This belief is somewhat problematic, given the weight of the evidence.
According to a Wa Preuf 1 (a Wehrmacht weapons research facility) report from October 5th, 1944, the 122mm A-19 (the A-19S being used on the ISU-122, the latest Soviet SPG at that time) could not penetrate the upper glacis of a Panther. However, it could penetrate the lower glacis from a distance of up to 100 m, the mantlet from 500 m, and the side of the turret from 1500m. This was still somewhat wanting, as the Red Army would prefer to engage such tanks from longer ranges, to prevent heavy losses of their own tanks.
The improved 122mm D-25T (which was used on the IS-2, the D-25S was essentially the same, and was used on the ISU-122S) seems to have fared much better against German armor. Testing of the gun on the IS-2 platform in Kubinka in 1944 suggests that a King Tiger’s turret (likely the side) could be penetrated from up to 1000-1500m. The welds of front hull seams could also be penetrated from 500-600m. Whilst these penetration statistics might make the D-25T sound more promising, they must be taken with some caveats.
Firstly, to score such hits would require a very skilled and very experienced gunner – especially to score a hit on the turret from a range of up to 1500m. Secondly, similar to the ML-20S, the D-25T could only manage up to 3 rounds per minute. Thirdly, the validity of these statistics has been called into question, because they come from Soviet sources. In the past, these statistics were often exaggerated for propaganda purposes. Finally, the very fact that the ISU “BM” projects were put into production suggests that the Soviets knew that the D-25T would not give consistently reliable results in AT duties.
Whilst, indeed, the D-25T was, in theory, capable of destroying the heaviest German armor, it was perhaps not as reliable as it needed to be in the field. Of course, it is true that penetrations were not required to disable the tank or kill the crew (both in the case of the ML-20S and D-25T), but one could not simply rely on non-penetrating hits to, in some manner, disable the tank.
As a result of these relatively unsatisfactory Soviet AT capabilities against the Wehrmacht’s heaviest tanks, in June 1944, Zavod Nr. 100 began developing new, high velocity 122 mm, 130 mm, and 152 mm guns to be mounted on the ISU (and perhaps IS and KV) chassis.

Object 243 (ISU-122-1)

Object 243 (ISU-122-1) with the 122mm BL-9
Object 243 (ISU-122-1) with the 122 mm BL-9. This vehicle is distinguishable as its gun has no muzzle brake, and looks like an elongated A-19S. However, the gun replicator has been angled (see the rectangular plate on the mantlet below the gun), unlike a regular ISU-122.

  • The Object 243 featured the 122 mm BL-9 gun – one of the infamous BL guns made at OKB-172. The vehicle can be distinguished by its gun and mantlet. The gun essentially looked like a longer version of the A-19S. The mantlet also had some tweaking to fit the longer and heavier gun – most notably, the tip of the gun replicator has been angled to one side (just below the gun).
  • It could penetrate 204 mm of armor at 1000 m, with 2 rounds per minute.
  • The gun’s muzzle velocity was 950 m/s with an 11.9kg AP shell.
  • It had a range of 10,700 m, compared to the 6000 m range of the 152 mm ML-20S of the ISU-152 and SU-152.
  • It could carry 20 AP rounds, the same as the ISU-152.
  • Like the other “BM” guns, the BL-9 was likely too powerful for its mountings, which caused mechanical issues.

Object 246 (ISU-152-1)

Object 246 (ISU-152-1) with the 152 mm BL-8
Object 246 (ISU-152-1) with the 152 mm BL-8. This vehicle is distinguishable by its slightly longer gun than the Object 247 (15 cm, or 5.9 inches), but the same muzzle brake, and its unchanged gun replicator.

  • The Object 246 featured the 152 mm BL-8 gun. This vehicle can be distinguished by its distinctive muzzle brake, and unaltered gun replicator.
  • It could reportedly penetrate 203 mm of armor at 90 degrees from up to 2000 m away (dubious) 1, with 3 rounds per minute.
  • The gun had a muzzle velocity of 850 m/s with a 43.56 kg HE shell.
  • It had a maximum range of 18,500 m.
  • It could carry 21 rounds.
  • Whilst these results sound excellent, trials in December 1944 showed that the crew found operating the gun difficult, the muzzle brake and breech block were unreliable, and the barrel strength and angle of horizontal guidance were unsatisfactory. Consider also that the very long gun would limit the maneuverability of the vehicle, much like the D-25S on the ISU-122S limited its maneuverability. As a result, the 152mm BL-10 was developed…

Object 247 (ISU-152-2)

Object 247 (ISU-152-2) with the 152 mm BL-10
Object 247 (ISU-152-2) with the 152 mm BL-10. This vehicle is distinguishable by the length of its barrel (it was slightly shorter compared to the BL-8), its muzzle brake, and its altered gun replicator.

  • The Object 247 fitted the 152 mm BL-10 gun, an improvement of the BL-8. This vehicle can be distinguished by its muzzle brake and slightly altered gun mantlet, whereby the rectangular tip of the gun replicating system had been angled, unlike the original ISU mantlet.
  • It could penetrate 205 mm of armor from 1000 m.
  • The gun had a muzzle velocity of 851 m/s with a 43.56 kg HE shell.
  • It had a maximum range of 17,000 m.
  • It could carry 20 HE shells.
  • Testing revealed that barrel integrity and angle of horizontal guidance were poor.
  • It was eventually deemed that there was no need for this work to continue, mostly because the war was over, and there was no need to combat heavily armored German vehicles.
  • Consider also, that whilst the barrel length was a little shorter than the BL-8, it, too, would still suffer from maneuverability issues as a result.

Object 250 (ISU-130)

Object 250 (ISU-130) with the 130 mm S-26
Object 250 (ISU-130) with the 130 mm S-26. This vehicle is distinguishable by its unique muzzle brake.

  • The Object 250 (ISU-130) was built in autumn, 1944 and featured a 130 mm (5.12 in) S-26 gun. This gun is sometimes referred to as a naval gun, but this is not entirely accurate – the S-26 derived from a naval gun and featured a rectangular muzzle brake and horizontal wedges.
  • It could penetrate 196 mm of armor from 1000 m.
  • It had a muzzle velocity of 702 m/s, firing a 33.4kg HE shell, with 1.5-2.5 rounds per minute.
  • It had a range of 15,000 m.
  • It could carry 25 shells, which were smaller than 152mm shells, meaning that it provided similar ballistic results to the 152mm BM guns, but could carry more shells.
  • In October 1944, the ISU-130 underwent factory trials, and the following month, trials were held at the Polygon.
  • A major concern came from the caliber – 130mm. The issue was that the army would have to make special arrangements for the 130mm naval shells to be supplied to the army, and thus it was decided that a gun using current army-issue 122mm or 152mm would be preferable.
  • Testing of the ISU-130 ended in 1945, and the gun was sent to the TaSKB for completion, but the war was over, and the project was disbanded.
  • The ISU-130 is currently preserved at the Kubinka Tank Museum.

The ISU-130 preserved at Kubinka.
The ISU-130 preserved at Kubinka.

Object 251 (ISU-122-3)

Object 251 (ISU-122-3) with the 122 mm S-26-1.
Object 251 (ISU-122-3) with the 122 mm S-26-1. This vehicle is distinguishable by its round gun mantlet and its unique cylindrical muzzle brake.

  • The Object 251 was derived from the ISU-130. It featured essentially a 122 mm version of the 130 mm S-26, which was designated the S-26-1. It had a round muzzle brake, different components, but the mantlet was the same shape.
  • It could penetrate 204 mm of armor from 1000 m.
  • It had very similar ballistics to the BL-9, but had a muzzle velocity of 1000 m/s, firing a 25kg shell.
  • It could fire a disappointing 1.5-1.8 rounds per minute.
  • It underwent field tests in November 1944, but according to sources, something (probably the mantlet and / or gun mechanism), was simply not strong enough to withstand firing the gun.
  • The gun project was totally completed in June 1945, but was abandoned due to the war’s end.
  • (Note that the ISU-122-2 was the ISU-122S with the 122 mm D-25S, hence the skip from ISU-122-1 to ISU-122-3).

Conclusion

The “ISU High Powered Gun Projects” were, in many respects, a failure. True, the guns were incredibly potent, particularly in the case of the S-26-1, which could penetrate 204 mm from 1000 m. They also had a very long range, only limited by the elevation of the ISU mantlet. However, they were simply not practical and mechanically reliable enough for their intended purpose, which was to knock out the thickest armored Wehrmacht tanks consistently, and from long ranges.
Even if the vehicles were put into serial production, how often these tanks would face off with the most heavily armored vehicles of the Wehrmacht is questionable. With Jagdtigers, King Tigers, and Ferdinands being so rare, the war was more likely to have ended before the ISU High Powered Projects saw combat with the vehicles they were designed to destroy. What had ultimately put the nail in the coffin for these guns was that the war had ended, and they were no longer necessary.

Sidenote: Designations and identification through photos

In the writing of this article, it has been exceptionally difficult to pin down which photos correspond to which project. Indeed, some sources only mention four (in some cases, only three) High Powered Gun Project vehicles. It has been the author’s conclusion that there were five such High Powered Gun Projects mounted onto ISU chassis, as outlined in Solyankin’s book “Советские тяжелые самоходные артиллерийские установки 1941-45″. Most online sources, particularly non-Russian language sources, are incredibly inaccurate. Gun statistics were mostly provided by a Soviet data set as provided by Tankarchives.blogspot. However, these statistics sometimes differ with Solyankin.

Notes:

1 – Note 1 – Most data has been obtained from this Soviet data set. However, certain statistics have not been given and have been obtained from alternative (potentially dubious) sources. Where necessary, statistics provided by Solyankin have been used, but these are questionable.
2 – Note 2 – Experienced crews were able to load much faster. Consider that the BM guns were likely tested by experts in test ground conditions, thus likely making their rounds per minute data higher than would be in the field, by more typical tank crews.
3 – Note 3 – Obtaining the ISU-122S’ ammo capacity has been difficult. It is reported that with a crew of four, instead of five (IE, one loader instead of two), then ammo capacity was increased, but the only given figure is 30, presumably with two loaders.
Sources:
Germany’s Panther Tank: The Quest for Combat Supremacy”, by Thomas Jentz
Sturmgeschutz & Its Variants”, by Walter J. Spielberger
“Советские тяжелые самоходные артиллерийские установки 1941-45”, by A.G. Solyankin
battlefield.ru
battlefield.ru (second page)
forum.axishistory.com
tankarchives.blogspot
tankarchives.blogspot (second page)
tankarchives.blogspot (third page)
armchairgeneral.com forums
WW2 AT Penetrations.pdf
alternatewars.com
alternatewars.com (second page)
ftr.wot-news.com
3.bp.blogspot

BL-9

BL-8

BL-10

S-26

S-26-1

ML-20S

D-25S

12.8cm PaK 44 L/55

Chassis Object 243 Object 246 Object 247 Object 250 Object 251 ISU-152, SU-152 ISU-122S Jagdtiger
Caliber 122 mm 152 mm 152 mm 130 mm 122 mm 152 mm 122 mm 128 mm
[email protected] deg 204 mm from 1000 m
157 mm from 1500 m
155 mm from 2000 m
203 mm1
from 2000 m (Dubious)
205 mm from 1000 m
202 mm from 1500 m
160 mm from 2000 m
196 mm from 1000 m
184 mm from 1500 m
156 mm from 2000 m
204 mm from 1000 m
157 mm from 1500 m
156 mm from 2000 m
125 mm from 500 m 147 mm from 500 m
138 mm from 1000 m
and 129 mm from 2000 m
200 mm from 1000 m
30 degree angle
PzGr.43 shell
Rounds per Minute 2 3 1 No data 1 1.5-2.25 1.5-1.8 1-3 2
(crew dependent)
1-3 2,3
(crew dependent)
2
Muzzle velocity 950m/s1(AP)
700 m/s (HE)
850 m/s (presumably HE) 1 826 m/s (AP)
851 m/s (HE)
898 m/s (AP)
702 m/s (HE)
1000 m/s (AP and HE) 600 m/s (HE) 800 m/s (HE) 950 m/s (AP)
Range 10,700 m 18,500 m 1 17,000 m 15,000 m 1 15,000 m 1 6000 m 5000 m 24,410 m
Shell Weight and Type 11.9kg AP 43.56kg HE 43.56kg HE 33.4kg HE 25kg HE 43.56kg HE 25kg HE 28kg HE
28.3kg AP
Ammo Capacity 20 21 1 20 25 24 20
(ISU-152)
30 1, 3 38-40
Overall length, chassis included 11.15 m (36.58 ft) 11.82 m (38.78 ft) 11.67 m (38.29 ft) 11.42 m (37.47 ft) 11.26 m (36.94 ft) 9.18 m (30.12 ft) 9.85 m (32.32 ft) 10.65 m (34.94 ft)


Illustration of the Object 247/ISU-152-2 armed with the 152mm BL-10 gun by Tank Encyclopedia’s own David Bocquelet

Categories
WW2 Soviet Prototypes

Matilda II Mk.IV with ZiS-5 76mm

USSR (1941)
Infantry Tank – 1 Prototype Built

In the early stages of WWII, Great Britain started a lend-lease relationship with the Soviet Union. Along with the Churchill III, Tetrarch, Valentine and Universal Carrier, the famous Queen of the Desert Matilda II soon found itself in the USSR.

Between 1941 and 1943, some 1084 Matildas were shipped to the Soviet Union. Only 918 were ever received by the Red Army, however. It is suggested that the others never made it to the end of the famous Arctic Convoys. This is one-third of the entire 2987 vehicle production run of the Matilda.

The Matilda equipped with the 76mm ZiS-5 gun . Photo: pinterest

Fighting Under the Red Flag

The Matilda IIs that found their way to the USSR were mostly Mk.IIIs and Mk.IVs, with Leyland diesel engines. Diesel being the preferred fuel of the Soviets. The Soviets identified the Matilda as the “British Mk.2”. The 170th and 171st Tank Battalions of the South-Western and Kalininsk fronts were the first units to receive the tank. At the time of the Battle of Moscow, their first action under the Soviet flag, only 145 Matildas had been received. Along with the Valentine, the Matildas only made up 2 percent of all Soviet armor used. The 170th only had 13 of them at the time.

Matilda’s tanks of the Soviet 5th Mechanized Corps, 68th Army. Photo: Osprey Publishing

Soviet crews fell in love with the Matilda, however, and up until 1942 they deemed it “the toughest tank on the western front”. To the Soviets, of course, the German front was the “Western” front. The only thing they didn’t like were the tracks, that were ill-suited to icy conditions. The tank fought on several fronts under Soviet use, mostly on Western Front, but also at North Caucasian Front and Bryansk Front until at least early 1944. In December 1943, the 5th Mechanized Corps of the 68th Army, fighting on the Western front, still had 79 fully operational Matildas.

Soviet Modification

The Red Army soon realized that the standard 40mm 2 pounder cannon of the Matilda was becoming less and less effective against German armor. As such, in December 1941 at design office number 92, Vasiliy Grabin, the famous designer of the ZiS-3 gun, made plans to mount the Soviet’s own 76mm tank gun M1941 ZiS-5 (76-мм танковая пушка обр. 1941 г. ЗиС-5), on the Matilda.

The ZiS-5/F-96 gun used on the Matilda. Photo: warspot.ru

This was the same gun found on early war KV-1s. It was re-designated as F-96 for the project. The weapon was a substantial improvement over the 40mm/2-pounder. The 76mm shell could penetrate up to 61mm of armor at 1,000 meters and could fire numerous types of ammunition including HE-F (High Explosive – Fragmentation), APCR (Armor Piercing Composite Rigid) and APHE (Armor Piercing High Explosive). The gun could elevate to roughly 20 degrees, but could only depress 2 degrees. 120 guns were originally put-by for the project, however this was later cut down to only 40.

Cramped

Just one Matilda, still having its British War Department (W.D) numeral markings, was experimented on. Extensive modifications of the turret were implemented to allow the larger gun to fit, requiring a complete redesign of the mantlet. The new mantlet was based on the KV-1’s, and to grant a little extra room inside the turret, a gasket roughly an inch thick was placed in-between the mantlet and turret face.

The turret of the Matilda was cramped to begin with, so one can only imagine how much more uncomfortable it would’ve been with the 76mm inserted. It is unknown as to whether this Matilda would’ve kept the same amount of crew as the stanard tank. If so, the loading and general operating of the gun would likely have been an awkward task.

Another view from the front shows how disproportionate the mantlet looks to the rest of the Vehicle. Phot: ftr.wot-news.com

Fate

In January of 1942, the modified tank was sent to Moscow for testing. Come March 1943, the Commissar for Tank Industry, V. Malysheva and Commissar for weapons D. Ustinovu contacted the design team in a letter basically telling them the project was canceled as the guns were needed for the USSR’s own tanks, which were rolling off the assembly line by the battalion load. Because of this, the project was canceled with just the one prototype built. The prototype was likely scrapped soon after. It is possible that the component parts were put back into circulation. The guns may have been re-installed on their respective vehicles with the F-96 going back to a KV, and the 2-Pounder going back onto the Matilda hull.

There is, however, and unverified German intelligence report that the 36th and 37th Tank Brigade were equipped with 76mm armed Matildas. There is no concrete evidence to back this up though. It may be that the tanks were mistaken for Matilda CS versions, of which there was 130 sent to the Soviets.

This image shows the gun at maximum elevation. Photo: warspot.ru

The Soviets were not the first to attempt an up-gunning of the vehicle. As well as the experiments on using the Littlejohn adapter for the 2-pounder, the British army attempted mounting the QF 6 pounder gun in a new turret taken from the A27 Cromwell. Like the Russian concept, this too was scrapped with one prototype built.



The ZiS-5 armed Matilda. This illustration was produced by Tank Encyclopedia’s own by David Bocquelet.

Matilda II specifications

Dimensions 18 ft 9.4 in x 8 ft 3 in x 8 ft 7 in (5.72 x 2.51 x 2.61 m)
Total weight, loaded 25.5 tons (25.6 tonnes)
Crew 4 (driver, gunner, loader, commander)
Propulsion 2x Leyland E148 & E149 straight 6-cylinder water cooled diesel 95 hp engine
Max. Road Speed 15 mph (24.1 km/h)
Operational Road Range 50 miles (807 km)
Armament 76mm ZiS-5 Gun
Armor 15 mm to 78 mm (0.59-3.14 in)
Total production 1 prototype
Data source Infantry Tank Mark II Specifications, by J.S. DODD The Vulcan Foundry Ltd, Locomotive Works, August 1940

Sources

Infantry Tank Mark IIA* Specifications, The Vulcan Foundary Ltd by designer Sir John Dodd August 1940
Infantry Tank Mark II manual, War Department
Osprey Publishing, New Vanguard #8, Matilda Infantry Tank 1938-45

Soviet Matildas on FTR
Matilda Mk.IV on Panzernet.net (Czech)
A live journal entry on the Matilda IV (Russian).
An article by Yuri Pasholok on Warspot.ru.
Osprey Publishing, New Vanguard #247: Soviet Lend-Lease Tanks of World War II


Categories
WW2 Soviet Prototypes

T-45

Soviet Union USSR (1942) Light tank – 1 prototype built

Introduction

Excellent frontal view of the T-45 - Credit: warspot.ru
Excellent frontal view of the T-45 – Credit: warspot.ru
The T-45 was a Soviet WWII light tank project, meant as a stop-gap measure until the T-70 could enter production. It was based on the lesser T-60, but with a new gun, turret and engine. While the T-45 didn’t have any glaring deficiencies and was superior to the T-60, it was nevertheless inferior to the T-70 in a number of aspects. However, there was no competition between the two, and the order to switch to T-70 production reduced the T-45 to a footnote in AFV history.

Background history

The NKTP found that Factory #37, based in Sverdlovsk, Ukraine, was unable to completely master T-70 production. This was an apparent issue from March 9, 1942 to late August, 1942. Another issue became apparent. Engines became a problem at Factory #37. They lacked GAZ-202 engines for their T-60s. The Gorky Automobile Plant (now known as GAZ) sent less engines than what was needed in the 1st quarter of 1942. This, in turn, delayed T-60 production. This sparked the theoretical idea of adding a ZIS-5 and/or ZIS-16 engine to T-60s produced by Factory #37.
Factory #37’s design bureau, headed by N.A. Popov, was tasked with designing the new vehicle. The design bureau was mostly made up of engineers who worked for Department #22 until their evacuation to Sverdlovsk. Department #22 worked on many tank projects and N.A. Popov, who also evacuated to Sverdlovsk, was the senior designer of the T-40 amphibious light tank.
The ZIS-16 (which came from a bus of the same name) was chosen as the new engine. The ZIS-16 engine received a new designation as the ZIS-60 for the tank version. This modified T-60 had an engine compartment which was easier to access, was less noisy, and had a top speed of 40.5 km/h which is one 1 km/h gained from the T-60 with the GAZ-202 engine installed. However, the engine had cooling problems. It also had modified final drives and a redesigned exhaust system. 5 of these new T-60s were ordered.
Factory #37’s military engineer 1st class, S.A.A. Afonin, mentioned this to the NKTP (People’s Commissariat of Tank Industry) during a meeting on May 14, 1942. He also conveyed the idea of adding a 45mm gun and increasing the armor to 35mm, which started the idea of the T-45. To Factory #37’s disappointment, these modifications and proposals were seen negatively by the NKTP.  With this combination, this T-60 variant was still inferior to the T-70 in terms of armor, engine power, and mobility. Since this would increase the weight of the vehicle, the engine, transmission, and suspension would suffer from further stress. The NKTP would not recommend this T-60 variant.
By the end of the meeting, Factory #37 was told to perform a trial of 200 km. After this task was completed, the results were to be sent to the Main Directorate of Armored Forces (GABTU) for evaluation. In the meantime, no more prototypes were allowed to be constructed.
It seems like Factory #37 started from scratch during or shortly after the meeting. This time they would actually install the 45mm gun, a new turret, and increase the armor thickness of the hull. This became known as the T-45.
T-45 prototype sitting in the yard of Factory #37 in 1942 - Credits: warspot.ru
T-45 prototype sitting in the yard of Factory #37 in 1942 – Credits: warspot.ru
S.A. Ginzburg, lead designer of the T-50 light tank and deputy director of the NKTP, joined the factory’s design team around April, 1942. Ginzburg sought to produce a light SPG based on the T-60 chassis, which matched the Factory #37’s goal. However, the T-45 was mostly complete by then.

Motivation behind the T-45

Upon the T-70s entry into mass-production, the Gorky Automobile Plant would have to produce twice as many engines GAZ-202 engines, as the new light tank used two of them. However, the factory was already having problems supplying them, and this in turn caused delay to the delivery of the tanks to the Red Army.
The T-70 required 1440 new types of parts, the creation of 545 new dies (basically a stamping tool), 825 new devices and 2300 new tools to start production. The T-45 required 224 new parts, 104 new dies, 175 new devices, and 255 tools. However, the T-45 borrowed 132 parts. 85 dies. 149 devices, and 433 tools from the T-70.
This meant that tank production wouldn’t be significantly disturbed by the introduction of the vehicle, which was superior to the T-60 on which it was based. The T-45 offered superior weaponry, and armor compared to the T-60, and it would have used an engine that was easier to obtain, as the factory which produced it was closer.

Protection

Compared to the T-60, the T-45’s hull armor was mostly the same with the exception of the sloping of the upper front plate, that had 25mm of armor instead of 15mm. If it was ever needed, the flat front plate could be up-armored from 35mm to 45mm. The increase of armor made the protection almost on par with the T-70. The armor thickness of the side of the T-45’s turret was 35mm. The driver’s hatch now swiveled to the side in a similar fashion to the Panther’s cupola. The T-45’s side plates was also riveted opposed to being welded (it is highly likely that this would’ve changed during production).
The T-45's 45 mm gun can be easily seen when the hatch is open - Credits: warspot.ru
The T-45’s 45 mm gun can be easily seen when the hatch is open – Credits: warspot.ru

Firepower

The T-45 was armed with a 45mm 20K Model 1938 and a coaxial DT machine gun. This setup was very common among Soviet light tanks, as well as on the T-70.
The first trials were held on May 20th, 1942. The firepower was tested. The T-45 achieved 7-8 shells per minute when standing still and 3 shells per minute when on the move. The turret tended to sink inside the hull due to its weight. Despite the sinking turret, it allegedly managed to hit all 25 of its shells at the target at an unknown range.
The TMPF sight was planned to be replaced with the standard TOP 45mm sight.

T-45
Illustration of the T-45

Mobility

The T-45 received the inferior, but common ZIS-5 engine (the engine already traveled 12,000 km) which was ripped from a truck. The ZIS-16 engine was in short supply as they only had one left. Unfortunately, the top speed decreased to 37.2 km/h. It also received final drives and steering clutches from the T-70. New, strengthened torsion bars were added alleviate the added weight (weight 7 tonnes).
Driving trials were performed for seven days, from the 6th to the 13th of June. In total, it traveled 1505 km; 189 km on asphalt roads, 805 km on gravel, 410 km on rubble, and 110 km on dirt roads. The trials revealed several defects, such as the cooling fans malfunctioning twice, the engine working at high RPMs (which increases the chances of it breaking down), tires occasionally slipping off the wheel, and the track links breaking several times. The quality of the track links reflected on Factory #183, which manufactured them, and not Factory #37. The trials were successful otherwise with the exception of a few complaints that were listed earlier, especially given the old ZIS-5 engine that already had 12,000 km on it.
Upon successful termination of the trials and if the GABTU gave its blessing, the Miass factory, based in Miass, Chelyabinsk Oblast, Russia, would’ve produced the T-45’s ZIS-5 engine along with the transmission. The ZIS-16 engine would probably replaced the ZIS-5 once it’s production would have been properly set-up. However, since the T-45 was never placed into service, production of the engine and the transmission never occurred.
The T-45's riveted side armor is clearly seen - Credits: warspot.ru
The T-45’s riveted side armor is clearly seen – Credits: warspot.ru

Conclusion

The data of the trial was sent to GABTU by the end of June, 1942. This data included both the T-45 and the T-60 with the ZIS-16 engine.
Factory #37 already struggled at producing T-60s. 321 semi-completed T-60s were produced in June, but only 109 were fully complete in June. The rest lacked tracks and armaments. The goal at the factory was supposed to be 200 complete T-60s.
Central Command’s new rule named #1958ss “Regarding T-34 and T-70 Tank Production” forced Factory #37 to cancel all T-60 production and to switch to the T-70.  Prior to this, Factory #37 only built 10 T-60s in July. After they switched, scarcity of parts became more and more obvious. This sealed the fate of the T-45 project.
The T-45 didn’t suffer from any condemning defects and some of the characteristics were largely on par with the T-70.
Whatever small advantages the T-45 could bring to the table could not convince the Soviet command to add yet another light tank into service. This would have complicated both maintenance and production in a moment when the Soviets needed as many tanks as possible as fast as possible.
Ultimately, the T-45 was born and quietly faded in the shadow of the T-70, without having a chance of proving itself.’
The remaining prototype was sent into battle where it was most likely destroyed.

Sources

“T-60 and Related Vehicles” by Yuri Pasholok
Article on the T-45 by Yuri Pasholok
Special thanks for Yuri Pasholok for helping us out and to Nikita Nikitenko for translating!

T-45 specifications

Dimensions 4.12 x 2.34 x 1.8 m (14’24” x 7’68” x 5’9” ft)
Total weight, battle ready 7 tons
Crew 2 (driver and commander)
Propulsion 73-76 hp ZIS-5 engine or 85mm ZIS-16 engine (theoretical)
Suspension torsion bar
Speed (road)  37.2 km/h (23 mph)
Armament 45mm 20K Model 1938
Armor 25mm upper sloped plate
35mm or 45mm (theoretical) flat front plate
35mm turret side
Total production 1 prototype

T-45 schematic - Credits: Dmitry Shuvalov
T-45 schematic – Credits: Dmitry Shuvalov
Pilot standing beside the T-45 - Credits: warspot.ru
Pilot standing beside the T-45 – Credits: warspot.ru
ww2 soviet armour
ww2 Soviet Tanks Poster

Categories
WW2 Soviet Prototypes

T-46

Soviet Union
Light tank (1933-1936) – 4 + Various Prototypes

The BT meets the T-26

The T-46 was an attempt to fix the low mobility of the T-26 by adapting the design to include the BT’s Christie suspension. However, there were many problems – with thin armor, huge production costs, and little overall benefits over the BT series, it was deemed a failure, and the project was canceled.
The OKMO experimental design bureau was eventually broken up by 1939, but the story of the T-46 does not end there, as some T-46s apparently saw service in 1940 against Finland and possibly Germany, as static bunkers. Information on both the T-46 is incredibly scarce and often unverified. This article may include some inaccurate information, but at no point will unverified information be presented as anything other than that.
T-46 prototype in 1936
T-46, shown here using wheeled drive. Note the hang-rail antenna on the turret. This version has the lamp housing in the center of the upper glacis.

Design process

In mid 1930’s the Soviet military elite believed that the Christie suspension used on the BT series of tanks was the most ideal system for a fast “cruiser” tank, and the ability to remove the tracks and drive on road wheels was equally desirable.
The BT-7, for example, could drive as fast as 72 km/h (45 mph) without tracks, while the most common tank in the Soviet forces at the time, T-26, could only achieve a measly 31 km/h (19 mph) on pavement, and about half that off-road. So it is not surprising that in 1932 VAMM (Military Mechanization Academy) was tasked with developing a version of T-26 with Christie suspension and wheeled (track-less) drive. The academy soon produced a prototype named KT-26 (K for Kolesnyi, or wheeled).
A rare clear image of the T-46 tank
A rare clear image of the Soviet T-46 tank.
However, the suspension improvements increased the weight of the tank as well, and seeing how it still used the 90 hp engine of the T-26, it produced a disappointing 40 km/h (25 mph). Only a scale model was built and the project was stopped. But the Soviet government was not about to give up on the idea.
In 1933 the same task was given to the Department of Experimental Vehicles, or OKMO, at Leningrad Factory #174. OKMO was soon moved to Leningrad Factory #185 (a.k.a. Kirov Plant) where by 1935 the first prototype was ready, by then given the designation T-46. It too was not perfect: while designing the new hull and turret, larger than those of T-26, the weight of the tank increased to 14-15 tonnes. As the gearbox and the final drive gears were designed with a 10-tonne tank in mind, the weight placed unacceptable stress on the mechanisms, and even the new 200 hp engine, planned in gasoline and diesel variants, could not solve this issue.
Three plans of improvement were proposed, designated 46-1, 46-2, and 46-3. The latter of those, 46-3, was chosen, and received official designation of T-46-1. The original prototype was redesigned with the extra weight in mind, which now approached 17.5 tonnes. To improve mobility the new MT-5 (sources differ, Svirin: 300 hp, Solyankin: 330 hp) gasoline engine was installed. A prototype performed admirably during trials.
This version was accepted for production and the factory received an order to produce 50 vehicles. However, the large number of technological improvements turned the cheap T-26 into a prohibitively expensive machine, and a senior official was quoted equating the cost of a T-46-1 to the triple-turreted T-28. According to several sources, only 4 serial vehicles were built in November-December of 1936.

Layout

The layout of T-46-1 is similar to that of a T-26 with many improvements. The most obvious was the replacement of T-26 twin-bogie suspension with Christie suspension, with 4 wheels on each side. The tracks could be removed and the tank driven on wheels. During wheeled drive the rear-most pair of wheels drove the tank, and the front-most steered using a differential. The tank featured levers for tracked mode and a steering wheel for wheeled mode.
Its 390 mm wide tracks were an improvement over the 260 mm T-26 tracks. A noted feature of the new powerful engine was that it required only grade 2 (low-octane) gasoline, as opposed to the high-octane fuel needed for T-26.

Both the hull and the turret were enlarged. The design intended for the tank to be welded, but all images show riveted construction. 15 mm armor plates were used for vertical surfaces, and 8 mm elsewhere. The larger turret was designed to accept either the widely used 45 mm 20K gun or the short-barreled 76 mm PS-3 gun. The latter gun would turn T-46 into an artillery support tank similar to a BT-7A. However, there are no records of this gun ever being installed on T-46.

The tank carried three DT-29 machine guns: one was coaxial to the main gun, the second installed in the rear of the turret, and the third MG stowed for anti-aircraft use. A KS-45 flamethrower was installed to the immediate right of the main gun, although on some images the flamethrower port is covered with a metal cover. The enlarged turret bustle now housed a radio set (71-TK-1), and some pictures of T-46-1 show the “hang-rail” turret antenna.

Further development and variants

Please keep in mind that the information on improvements and variants comes largely from a single source, that being either “Soviet Light Tanks, 1920-1941” or “Soviet Flame and Chemical Tanks, 1929-1945”, both by the same team of writers featuring A.G. Solyankin, M.V. Pavlov, I.V. Pavlov, and E.G. Zheltov.
According to these sources, the first improved modification was designated T-46-2 and would feature various armor improvements, a conical turret, gun stabilizer, and improved transmission and tracks. A major improvement in the next version, designated T-46-3, was the addition of sloped armor. One hull was built and subjected to testing at the Izhora Factory range. Solyankin provides a blueprint of this project, as well as a photograph of the hull.
blueprint for a T-46-3 tank
Solyankin provides a blueprint for a T-46-3 tank, according to him, a further improvement of T-46-1 tank with sloped armor.
Other projects apparently included a chemical (dedicated flamethrower) tank called KhT-46, with increased range and 500 liters of flamethrower fuel, compared to the 50 liters on the regular T-46. Also in development were a command tank (T-46-4) and a self-propelled support tank with the 76.2 mm PS-3 cannon (AT-2). There is no substantial evidence that any of these vehicles existed. One version that did exist, however, was T-46-5, also known as T-111, a tank with much better protection but having little in common with T-46-1, besides the name.
In summary, the T-46 was expensive and did not offer many benefits over the rival BT series. But it is possible that T-46 provided Soviet engineers with experience that led to work on other prototypes, such as T-126, T-127, BT-IS, BT-SV, A-20 and A-32, eventually leading to the legendary T-34.

Operational History

This is where the history of the T-46 becomes very murky. In “Tough Armor: History of Soviet Tanks” Svirin notes that the production vehicles went to combat trials, where they remained for around a year and proved themselves as “very good” vehicles, even outperforming the BT in wheeled performance. What happened next is unknown. Years later it became known that at least two vehicles were used as dug-in emplacements.
One of those vehicles was restored by Russian Defense Ministry in 2004 and is now displayed at Central Museum of the Great Patriotic War 1941 – 1945 in Moscow, missing its tracks, wheels, and suspension but otherwise seemingly intact. The plaque next to the exhibit states that it was found on by the association ‘Vysota’ in the Karelia Isthmus near the village of Sosnovo, Leningrad Oblast.
Another T-46-1 is a partial hull donated to Kubinka in June 2013. The latter, according to an article by Komsomolskaya Pravda, was found at a scrap metal collection point – information which the source says is unconfirmed. It was then purchased by a third foreign party, until Dmitriy Bushkakov, an antique store owner, bought it from them for the museum. It does show that there may be more undiscovered T-46 tanks buried in an old hill somewhere. One can hope, at least.
T-46 tank turret bunker
A T-46 is being used somewhere as a dug-in emplacement, probably somewhere along the Soviet-Finnish border. The hang-rail antenna (if it had been installed) is gone, and so are the two periscopes. The gun, like in every image of T-46, is a 45 mm 20K.
An article by DrTankMan
Sources:
Tough Armor: History of the Soviet Tank 1919-1937” Mikhail Svirin / “Броня крепка: История советского танка 1919-1937” Михаил Свирин.
Soviet Light Tanks 1920-1941” A.G. Solyankin, M.V. Pavlov, I.V. Pavlov, E.G. Zheltov / “Советские легкие танки 1920-1941. А.Г. Солянкин“, М.В. Павлов, И.В. Павлов, Е. Г. Желтов.
Soviet Flame and Chemical Tanks 1929-1945”  A.G. Solyankin, M.V. Pavlov, I.V. Pavlov, E.G. Zheltov / “Советские огнеметные и химические танки 1929-1945” А.Г. Солянкин, М.В. Павлов, И.В. Павлов, Е. Г. Желтов.
Russian Tanks and Armored Vehicles 1917-1945 – an illustrated reference” by Wolfgang Fleischer.
The T-46 on Russian Wikipedia
aviarmor.net
kp.ru
dogswar.ru
mihalchuk-1974.livejournal.com
alternathistory.com

T-46-1 estimated specification

Dimensions (L-w-h) 5.7m x 2.7m x 2.4m (19ft x 9ft x 8ft)
Total weight, battle ready 17.5 tonnes
Crew 3
Propulsion MT-5 330 hp petrol engine
Speed (road) Tracks: 58 km/h (36 mph), Wheels: 80 km/h (50 mph)
Range Road, tracks: 220 km (137 mi) Road, wheels: 400 km (249 mi)
Armament Main: 45 mm 20K cannon (101 rounds)
Secondary: 3 x DT-29 7.62 mm machine guns and KS-45 flamethrower.
Armor 15mm
Total production Four, plus prototypes

Tanks Encyclopedia's rendition of the Soviet T-46 tank
Tanks Encyclopedia’s rendition of the Soviet T-46 light tank.
t-46-1_11
T-46-1, the “production” version of which 4 total were probably produced. The caption (from Solyankin’s “Soviet Flame and Chemical Tanks”) labels it as a “flamethrower tank”, but its flamethrower capability was limited to 12-13 shots. Svirin labels the same image in his book as “T-46A”.T-46 rear
The rear of the T-46-1. Notice the rear mounted DT machine gun.
T-46 side
Side-view of the T-46-1.
T-46 Tank karelian isthmus
A more modern image of a T-46-1. According to the image author, it was taken at Karelian Isthmus. This one reportedly ended up in the museum at Poklonnaya Gora. No antenna or periscopes. The removed barrel was probably that of a 45 mm 20K.
T-46-1 tank at Karelian Isthmus being pulled from the ground
The T-46-1 from the image above, being pulled from the ground. There is a Japanese website hosting a number of close-up images of this particular tank before it was restored can be found

Surviving T-46

T-46 on display
This Surviving T-46 is now on display at the Central Museum of the Great Patriotic War 1941 – 1945. Photo credit
This one has the antenna and the periscopes, but they were likely mock parts fitted during restoration, as they look different from the original photographs.
T-46 on display rear
A rear view of the restored T-46-1. It is the same tank as in previous image. It is unknown whether the number is historical. The rear-facing MG is visible, but the turret door looks different from previous images. It is likely a restoration replacement since it was seen missing on a previous image.
recovered hul kubinka
The other recovered hull in Kubinka, after being saved from a scrap yard (presented at the museum as T-46/1). The hull and the turret are facing forward. This hull is missing its upper glacis, the driver’s box, and the gun mantlet. A display to the left of the tank tells the story of its retrieval; however, there does not seem to be a high-resolution image of the display available online.
Soviet Light Tanks 1920-1941 T-46-3
Another image from Solyankin’s “Soviet Light Tanks 1920-1941”. According to the book, one hull of T-46-3 was completed and tested at Izhora Factory range.
The T-46-5 or T-111 was a related prototype which was developed alongside the T-46.
The T-46-5 or T-111 was a related prototype which was developed alongside the T-46. It was built in 1938, but was deemed unsatisfactory. It was one of the precursors to the T-34.
Russian Tanks and Armored Vehicles 1917-1945 T-46-1
This image appears in “Russian Tanks and Armored Vehicles 1917-1945 – an Illustrated Reference” by Wolfgang Fleischer, where it is labeled as a T-46-1 tank. While vaguely resembling a T-46-1, it has a few differences: the turret appears conical, the main armament is a strange unidentified gun and not the usual 45 mm 20K, and the driver is armed with a machine gun. Either this is an image of one of the prototypes, or the illustrator did not have a good reference image for the T-46-1.
ww2 soviet armour
ww2 Soviet Tanks Poster