Monday 25 January 2021

Armoured Confusion

Works on Soviet tank building are published with striking regularity. Some are the results of many years of archival research, but many are based on prior works. There is nothing shameful about this, as skillful compilation is an art of no lesser value than writing from scratch. However, an issue with credibility may arise when picking secondary sources, and even primary documents can contain mistakes often caused by a lack of information. As a result, dozens of myths were built around Soviet tank building over the course of decades that live on today. This article will discuss such myths connected to pre-war tank building in the Soviet Union.

An independent first

Even though the first Russian Renault tanks were built in 1920-21, Soviet tank building truly took its first steps closer to the mid-20s. The GUVP Technical Bureau directed by designer S.P. Shukalov was founded on May 6th, 1924. The bureau didn't start from nothing, in fact RVSR order #111/20 issued on January 13th, 1921, formed a special commission within the Main Military Engineering Directorate. Its task was to develop tanks and support their production. Shukalov led this commission.

The GUVP Technical Bureau's first design was the "Regimental support tank" accepted into service on July 6th, 1927, as the T-18 (MS-1). Some claim that this was a tank developed on the bureau's own initiative, but this was not so. The requirements for this tank were issued in 1924. Even though they changes several times before it was finished, the initial requirements still directly influenced the tank's final form.

Drawings of tanks that were considered for the role of the Soviet small support tank. The FIAT-3000 and future MS-1 are among them.

There is a myth that the development of the MS-1 was influenced by the Italian FIAT 3000. Some publications even claim that a FIAT 3000 tank captured from Poland in 1920 was studied by the creators of the MS-1. This information is fabricated. The FIAT 3000 does have some relation to Soviet tank building, but not how it's commonly presented. There was no captured FIAT 3000. This tank first came into the spotlight in 1924. Italy offered a batch of 10 such tanks, but the final deal was for only 3. These tanks arrived in the USSR in November of 1927. As much as they wanted to, the Italians could not have influenced the MS-1's development. However, the FIAT 3000 was considered a reserve option in case development of the MS-1 failed.

A comparison of the FIAT 3000 and MS-1. As you can see, these two tanks have very little in common.

The FIAT 3000 and MS-1 had little in common. The first was that both vehicles were inspired by the Renault FT. The second is both vehicles had a perpendicular engine. This was caused by the same initial requirement: reduction of mass. This is where the similarities ended. The hull, turret, and running gear of the MS-1 were completely original. The French and Italian tanks used truck engines, but a special tank engine was developed for the MS-1. There is another myth associated with this engine: allegedly, it was developed by A.A. Mikulin, a famous Soviet aircraft engine designer. Mikulin first saw the future MS-1's engine on February 26th, 1927, when he was working at NAMI. The engine was already finished and undergoing testing. The layouts of the FIAT 3000 and MS-1's transmissions are radically different. The MS-1 had an engine and transmission assembled in one unit. Additionally, the MS-1 was designed to have a cannon and a machine gun from the start, unlike its foreign analogues. Only a person who understands very little about the design of tanks can claim that the first Soviet mass produced tank was based on the FIAT 3000.

The German sword was forged in the USSR

One of the most popular topics associated with Soviet tank building is the Reichswehr's activity in the USSR, primarily at the OsoAviaKhim Technical Courses (TEKO, known as Kama in German documents). German tankers were trained at these proving grounds and German armoured vehicles were tested there. This is used as the basis of claims that the USSR built Germany's armoured forces and bears fault for its rise.

Diagrams of the T-28 and Grosstraktor Krupp suspensions. As you can see, they have much in common.

These claims are a cause for nothing but a sad smile. To start, let us clearly identify the period of Soviet-German military cooperation: 1924-1933. The program was cancelled after the Nazis came to power. In addition, the mere fact of testing German tanks and armoured cars at Kazan is merely a tip of the iceberg. If one digs even a little bit further, any claims of "forging a sword in the East" look silly. All vehicles tested in the USSR were dead ends. The Grosstraktor, Leichttraktor, and Räder-Raupen Kampfwagen m/28 fared poorly in trials, so poorly in fact that their further development lasted for several years and led to nothing of value. It was clear by 1932 that none of these vehicles will be suitable for mass production or even valuable as training vehicles. As a result, German tank designers copied the layout of a Carden-Loyd tractor that was half-legally purchased from the British. The only thing the Germans got from Kama was the need to design new tanks and a few dozen trained men.

The 45 mm tank gun in one mount with a coaxial machine gun and the observation periscope were inspired by the German Leichttraktor.

The opposite side of the story is much more interesting. The USSR gained much from working with the Germans. Supporters of the "German sword" theory don't like to remember this. German influence on Soviet tank building didn't end with Eduard Grotte. To start, putting the MS-1 into mass production without German tools would have been much harder. A portion of the tools used at the Bolshevik factory were purchased in Germany. Nearly all electrical equipment used on Soviet tanks was purchased from Germany as well, for instance Pallas carburetors used on Soviet tanks. Many Soviet pre-war tanks continued this trend and used Bosch electrical equipment. Cooperation with Rheinmetall gave the USSR 37 mm and 45 mm cannons. It was not the USSR that built up the German armoured forces, but the other way around.

The Soviet tank helmet and its predecessor.

The subject of trials at Kama from the Soviet side is also an interesting one. The facility is often described from a German point of view with no thought given to what the USSR gained from it. However, Soviet tank building gained much from this arrangement. The Soviet tank school was at a dead end in the late 1920s and early 1930s. Work on modernizing the MS-1 slowly hit a dead end, the T-24 medium tank turned out to be not what the military wanted, and the TG-1 was a failure. Here is where the "visitors" helped. The Krupp Grosstraktor suspension was used as a starting point in the development of a suspension for the T-28, the most numerous and best interbellum medium tank. The tank's engine also had a German ancestry. The Grosstraktor concept inspired the PT-1 experimental tank, which eventually evolved into the T-29. Soviet designers obtained information on German tanks through Kama. Eight designers passed through the proving grounds, including S.A. Ginzburg, the creator of the T-28 and the man responsible for putting the T-26 into production. The coaxial gun mount on the T-26 was designed based on the one used on the Leichttraktor. Observation periscopes used on German tanks were copied as well. Study of German vehicles significantly sped up Soviet armour welding development. Rail antennas were also first seen here. Finally, the Soviet tank helmet was based on the German design. The Germans met with the consequences of their visit in 1936 in Spain where the Condor Legion faced off against Soviet T-26 tanks that were choc-full of German design concepts.

Convertible drive aggressors

A well known writer once decided to dub Soviet BT tanks "aggressor tanks", allegedly because they were built for good Western European roads. This writer's fans and supporters spread this theory far and wide. According to them, only the USSR built such tanks, which only confirms is fiendish aims. The only reaction to these claims is a smile, as they show a complete ignorance of global tank development in the interbellum period.

Autochenille Saint-Chamond Mle.1921, the first production convertible drive tank.

To understand the cause of convertible drive tanks, we must go back to the late 1910s. Tanks just started their development and faced two major problems. The first was the lifespan of the tracks, which was measured in mere hundreds of kilometers. The second was a very low top speed. This is when American designer John Walter Christie got the idea to create a convertible drive vehicle. Thanks to this invention, the tank could move on wheels at a relatively high speed, but only on decent roads. Christie was unlucky. His tanks and SPGs remained experiments for a very long time, although the concept of a convertible drive tank became popular in other nations.

The first convertible drive tank proposed by Joseph Vollmer.

The French FAMH company was the first to celebrate success here, albeit a limited one. They built a dozen Autochenille Saint-Chamond Mle.1921 tankettes. Although these tankettes were far from perfect, they were the first convertible drive armoured vehicles to enter production. The British did not progress past experiments. Two German engineers actively worked on these tanks: Joseph Vollmer and Otto Merker. Vollmer built a tank on the Hanomag Z WD-50 tractor chassis that was proposed to the USSR but was of more interest to Czechoslovakia. The result was the Kolohusenka family of convertible drive tanks. The Czechoslovakian military was a big proponent of convertible drive tanks in the early 30s in general. If you follow the conspiracy theorists' logic, president Tomáš Masaryk dreamt of hordes of Kolohusenkas driving down autobahns, subjecting Czechoslovakia's neighbours to Knödel and beer while laughing manically.

KH.50. It's hard to interpret the existence of this vehicle as evidence of Czechoslovakian aggression.

Sweden was another country that actively worked on convertible drive tanks. Sweden also made good use of foreign expertise. Fritz Heigl, better known for his historical work, was the first of them. The talented Austrian engineer developed a tank for the Swedish army that also had a convertible drive variant. Heigl's death in December of 1930 put an end to this project, but the second attempt was a much more successful one. This was the Räder-Raupen Kampfwagen m/28, better known as the Landsverk L-5. This vehicle was developed by Otto Merker and was hardly at all Swedish. Only two of the six tanks were built in Sweden, and even Landsverk itself was under the umbrella of GHH (Gutehoffnungshütte, Aktienverein für Bergbau und Hüttenbetrieb), a German company that also owned MAN. In other words, Landsverk was that very anvil on which the German sword was forged. Work on convertible drive tanks at Landsverk only ended in the end of the 1930s when it turned out that Merker's design was too complex.

Landsverk worked on convertible drive tanks until the end of the 1930s.

In depth study of the issue shows that everyone wanted to build convertible drive tanks, but only Christie managed it, plus 16 Convertible Medium Tanks T4 were built in 1935. Until the arrival of the Medium Tank M2 every American medium tank was convertible. One has to ask: whose highways were they supposed to storm and does this serve as evidence of the USA's aggressive goals? 

On a serious note, the popularity of convertible drive tanks began to fade in the second half of the 1930s. Destruction of road wheel tires was a big issue, plus the advantages over tracked tanks were no longer as pronounced. The USSR held onto it the longest because their convertible drive tanks turned out the best, but by the end of the 1930s even the USSR dropped the idea.

The immortal T-28

Many consider the T-34 tank, accepted into service on December 19th, 1939, to be the best tank of WW2. However, some believe that accepting it into service as a mistake. Proponents of this theory state that the T-34 was a descendant of the convertible drive BT light tank, instead of the main Soviet pre-war medium tank: the T-28. The theory states that the USSR would have been better off with a tank developed out of the T-28 rather than the BT, even providing diagrams to show how the tank could have evolved.

The T-28 was the best pre-war medium tank, but its suspension had its limits.

As mentioned above, the T-28 suspension design descended from that of the  Großtraktor Krupp. The Germans considered this suspension poor and decided to develop the Rheinmetall variant. The USSR decided otherwise, not in the least because of its performance at Kama. It's hard to say that Soviet specialists were wrong. A study of various suspension designs performed at experimental factory #185 showed that the T-28's suspension made for an optimal firing platform. It offered a smooth ride both off-road and on a highway. Issues arose only when crossing obstacles. The suspension behaved poorly at high speed, and especially badly when crossing vertical obstacles at a speed of 15-18 kph. The aforementioned Großtraktor Krupp had an extra road wheel in front to absorb the shock from vertical walls, but the T-28 did not.

The result of driving on difficult terrain. After a 102 km drive at an average speed of 21.8 kph the rubber tires on 20 wheels was destroyed.

Meanwhile, the ABTU only increased requirements for mobility. The mass of the tank also grew, from 25.2 tons to 29. Attempts to increase the top speed had mixed results. The experimental T-28A was indeed much faster, but there were still issues with vertical walls and off-road driving at high speed. The running gear began to take damage at a speed of 15-18 kph even when only facing 0.2-0.3 meter tall obstacles. 

The T-29 was supposed to replace the T-28 in 1936, but this didn't happen for a variety of reasons.

Because of these issues, the ABTU expedited work on a replacement: the T-29 convertible drive tank. Factory #185 also understood the tank's potential by the time work was transferred there in late 1934. The plan was to stop production of the T-28 in 1936 and replace it with the much more promising T-29. The mass of the T-29 caught up with the T-28 during development, but it surpassed its predecessor even on tracks. However, the T-29 had its own problems. One of the biggest was the increasing mass that led to reduced reliability of the running gear. The T-29 also had just a two-man turret. Replacing it with a three-man one like on the T-28 would have made it even heavier.

The price was also far from ideal. The T-28 was hardly a bargain at 250,000 rubles per unit initially and 380,000 by 1938. The T-29 cost 350,000 even by initial estimates, so the cost of the final production vehicle could have reached half a million rubles. To compare: a T-26 tank cost 80,000 rubles, a BT-7 cost 120,000. The T-29 program was closed in August of 1938. As for the T-28, 263 were built in 1938-1940, or almost half of the total production run. However, the ABTU perfectly understood that the tank was obsolete.

One of the variants of the T-115 tank. This breakthrough tank was developed at factory #185 as a replacement for the T-28. The estimated mass ranged from 35 to 40 tons.

Work on medium tanks in Leningrad ended with the T-29. On August 7th, 1938, the Committee of Defense within the Council of Commissars of the USSR issued decree #198ss, establishing that the T-28's successor would be a heavy breakthrough tank. This tank would also replace the T-35. Soviet medium tank development followed the A-20/A-32 line, which started out as light tanks. As for the T-28, it was no longer seen as an example to follow, as it was obsolete back in 1935. The tank was simply too big and too thinly armoured. It's easy to see what happened if you tried to improve it with the T-29CN project: the tank received a torsion bar suspension as well as sloped armour with 50 mm in the front and 30 mm in the sides. The mass of the tank grew to 32.5 tons, it wouldn't be hard to imagine that would happen to the road wheels. Even this tank had just a two-man turret. Turning the T-28 into an alternative historian's dream tank would have increased its mass past 35 tons even before other issues could be addressed.

As a result, a transformation of the T-28 would result in a completely new tank. The closest available development was the T-115: a convertible drive breakthrough tank that was developed at factory #185 in 1938. The tracked variant with 50 mm of armour weighed 35-36 tons. Considering its suitability for mass production, this tank would have cost as much as a T-35 and at best 200-300 per year could be built. There was absolutely no point in developing the T-28 concept further.

This T-28 tank was used as a test lab for the heavy SMK tank's suspension.

As for the T-28 tanks that were used to test T-35 suspension elements and a torsion bar suspension, these were just prototypes. Information about proposed modernizations are a fantasy. These experiments had just one goal: to pick an optimal suspension for the SMK-1 tank. This vehicle was supposed to replace the T-35 and the T-28. A "cut down" variant of this vehicle was adopted later. We know this tank today as the KV-1.

German wonder-armour and bad Soviet shells

One of the most widespread myths concerning WWII is the legend of a Pz.Kpfw.III tank allegedly shot up in 1940. The story claims that a tank was captured in the fall of 1939 by Soviet troops. In trials, only 2 shots out of 5 from 400 meters penetrated the side armour. The German surface hardened 30 mm thick armour was equated to 42-44 mm of Soviet armour, and Soviet 45 mm shells produced in 1938 were so over-hardened that they couldn't penetrated it. These claims are usually used to back up claims that German tanks were nearly invincible against Soviet tank and anti-tank guns.

The Pz.Kpfw.II tank that was tested by NII-48 in 1940. The report stated that the armour is homogeneous and that the side armour shattered when hit at a velocity of over 360 m/s.

Many authors, including this one, attempted to track down this report. It was never found, although it was established that the claim that a Pz.Kpfw.III tank was captured is an exaggeration. A raid by the 24th Light Tank Brigade carried out at Tomaszow Lubelski returned with two dozen tanks and tractors including two German ones: a Pz.Kpfw.II Ausf.B and an Ausf.C. One of these tanks was indeed shot up, but its armour was penetrated without issues and it was considered very brittle. A Pz.Kpfw.III did indeed end up in the USSR, but this was a Pz.Kpfw.III Ausf.G officially purchased from Germany. There is a separate article detailing the study of this tank, but suffice it to say no penetration trials of the hull were held. Nobody would even dream of shooting up a tank that contained so many valuable secrets for Soviet tank designers.

A study of the Pz.Kpfw.III's armour carried out by NII-48. They did not find surface hardened side armour, and such armour could never exist in the first place.

The tank's armour was indeed seriously studied. In 1942 NII-48 prepared a report on the armour of foreign tanks where the Pz.Kpfw.III Ausf.G purchased in 1940 played a key role. This report casts doubt on the claims of high quality surface hardened armour. First of all, NII-48 didn't find any surface hardening on the sides. It was only used on the front armour, as it is reasonable to expect the front armour to take the most hits.

The first hit to a German armour plate shattered it. An identical part made of Soviet armour steel hit by the same shells at the same range can be seen on the right.

This is where the most interesting part begins. The tank's side armour was indeed tested, but not quite as claimed. NII-48 took off a side hatch, replacing it with an identical domestically produced component. The hatch was used for penetration testing. The first first hit from a 45 mm round shattered the plate. The 45 mm gun was not used in trials again after that. There were suspicions that the hardening could have been harmed by heat (the plate was cut in half prior to trials), so an identical part was produced from Soviet FD 5634 steel that was cut in half just as the German one was. Two shots were made at the limit of penetration (525.4 and 564.2 m/s). The plate was not penetrated, only two dents were made. The result is clear: a 30 mm German plate that was penetrated and a 30 mm Soviet plate that resisted two hits. The same shells were used. The reality is the opposite of the claim.

Penetration of the side of a StuG III with the same "defective" 1938 production shells.

These trials were far from the only ones. Trials of the 45 mm gun model 1937 were held in October of 1940. The showed that the 45 mm armour piercing shell penetrated 30 mm of armour at a 30 degree slope from 1000 meters. There was no mention of defective shells. The only issue was that when the armour grew to 40 mm the range of penetration fell significantly. Analogous trials were carried out later. There were plenty of German tanks to test by 1942, and it just so happened that a StuG III Ausf.B was shot at by AP shells produced in 1938. The 50 mm thick front armour was not penetrated, as expected. However, the side was penetrated from 850 meters. The same results were obtained when shooting at a Pz.Kpfw.III Ausf.H. The author eagerly awaits the discovery of this report on surface hardened armour and over-hardened shells.

Original article by Yuri Pasholok.


  1. "It turned out that the hatch made made from high carbon steel that was different from the type used in main armour and hull plates."
    FD-5634 NI 2.2-2.6 MO 0.3-0.4 CR 1.2-1.7
    Compare a hatch door plate with SOV high quality plate

    Is it comparable?

    1. What makes you think that the hatch was made out of lower quality than normal steel while the Soviet plate was made out of higher quality than normal steel?

    2. Watertown Arsenal Laboratory Reports
      The hatch door plate steel components is different from the main plate
      The Izhora factory considered this result incomplete, since the other parts of the tank were made from different steel. However, trials of the rest of the hull were not possible at the time.

  2. Once got into a convo where that "aggressor tank" claim came up. Besides the points made in this article I further pointed out late-model BTs abandoned the conversion outright as no longer necessary, and the geographical detail that the USSR had an awful lot of open plains and long stretches of nothing between points of military interest where the wheels oughta have come in pretty handy...

    Eventually the other party started spouting stuff I could readily recognise as Suvorovian Bullshit™ at which point I judged further exchange pointless.