Monday 17 October 2022

The Main Soviet Pre-War Tank

There were many cases in tank building history where development programs were restarted almost from scratch. This happened with Soviet tank development at the end of the 1920s and start of the 1930s. By the end of the 20s, the USSR composed requirements for armoured vehicles and created their own tanks. The first such vehicle was the T-18 (MS-1) small support tank accepted into service on July 6th, 1927. This tank was a grand achievement for Soviet industry. It was a very modern tank for the mid-20s and, most importantly, it was mass produced. It was a challenge, but production was fully set up by 1930. The problem was that the tank was already obsolete by then. The Red Army fully understood this. The first solution was to modernise the T-18, but the idea of finding a suitable replacement abroad was also raised.
T-26 tank on display, February 23rd, 2021

The leadership of the UMM (Directorate of Mechanisation and Motorization, formed in November of 1929) worked wisely. They initially only considered the idea of purchasing samples for study, and a commission headed by I.A. Khalepskiy was sent abroad in 1930 for this purpose. By the time the commission left, the idea of organizing production of one of these vehicles was already raised. That is what the USSR ended up doing, since the new generation of infantry support tanks was not coming together. The Vickers Mk.E was among the samples purchased abroad. These two-turreted tanks were not entirely aligned with Soviet requirements, but they were improved by the time of purchase. The tanks were envisioned to have both cannons and machine guns: a cannon in the right turret and a machine gun in the left. The tank was accepted into service with the Red Army as the T-26 on February 13th, 1931. Only 17 units were delivered in the first year of production, but 1032 in 1932. This was more than the total production run of the T-18.

The same tank today.

The T-26 light support tank became the Red Army’s most numerous tank. It came about as a backup plan, but ended up as a symbol of the Soviet armed forces. The BT convertible drive tanks are more famous today, but it was the T-26 that made up the backbone of the Soviet tank forces in the interwar period. Thanks to the work of restoration teams, these tanks are no longer a rarity in museums and can be seen in many places, including the Museum of National Military History. The museum collected a series of these tanks, including the KhT-26 chemical tank and SU-26 SPG, but this article will focus on the T-26 tank with a cylindrical turret, the one with the longest combat career.

Tanks were built like this from 1937 onwards.

The introduction of a tank with one two-man turret was to be expected. The fighting compartment was one of the biggest issues with the Vickers Mk.E, although many Soviet license built copies had this layout anyway. Work on the new turret began in the fall of 1931 after the organisation of T-26 production at the Bolshevik factory was coming to an end. The first variant of the turret was built jointly with the VOAO KB-3 design bureau led by S.A. Ginzburg. This turret was quite reminiscent of the Leichttraktor. Even though it was cylindrical rather than conical, the German influence can be clearly seen. The gun mount and sight clearly came here from the Leichttraktor. The armament initially consisted of a 37 mm B-3 gun with a coaxial DT machine gun, which had an armoured sleeve. This turret was never built, but it gave a direction for further work.

The vehicle has all of its possible equipment.

The turret that went into production is known as the Izhora turret, but that is not where it came from. It was developed at the Kalinin factory (ZIK, later factory #8). The design changed radically. The DT’s sleeve was dropped and the 37 mm B-3 gun was replaced with a 45 mm 20-K. The change of caliber has many explanations, but there is a key one. The Red Army Artillery Directorate stated that the 45 mm HE shell was much more powerful (119 grams of explosives compared to just 22 in the 37 mm shell). The effect of this shell was close to that of the RGD-33 grenade, which made it an effective infantry support weapon. It’s worth mentioning that the 45 mm 19-K gun was used for a lot more than fighting tanks and the caliber was not a new one for Soviet field artillery. Battalion guns with this caliber were built in the 1920s and the 20-K was preceded by the 45 mm model 1930 gun. A DT coaxial machine gun remained, but a periscopic sight was used instead of a telescopic one. An air intake cap appeared on the roof.

The hooks on the back are used for carrying tow chains.

The project was moved to Leningrad after the turret was finished. The design changed here with the introduction of a turret bustle. There was originally only one hatch and the assembly was riveted, although correspondence shows what armour welding was already being introduced on them. The Izhora factory designed a similar turret for the BT-5 tank. Development of T-26 and BT turrets continued in parallel for a long time. T-26 tanks received the first two-man turrets in 1933, but not for long. An improved variant was introduced in the same year. Instead of a box-like bustle, it had a gradual transition, which greatly increased the internal size. This allowed the introduction of a second hatch. The air intake moved to the middle of the roof. These turrets were welded from the very start. The hull also changed. An exhaust fan was added to the rear right corner of the turret platform. If necessary, it could be covered with a cap. The Izhora factory also started introducing welded hulls in 1933, but the process took some time.

The cylindrical turret variant was the most numerous type of T-26 tank.

The turret finally came together in 1934 when PT-1 model 1932 periscopic sights, 45 mm model 1934 guns, and radios were installed. The tank itself developed in parallel. Welded hulls became the norm in 1934, although riveted ones continued to pop up until 1936. Radios in tanks also became a widespread phenomenon. Only 20 two-turreted T-26 tanks with radios were delivered in 1933, but a year later the Red Army received 457 single turreted T-26es with radios. Starting in 1935, more tanks had radios than not. Since the tank got heavier, the leaf springs were thickened from 5.5 to 6 mm. ATE factory electric equipment was also installed starting in 1934, although German Bosch and American Scintilla components continued to show up even in later periods.

The tank is fully equipped.

The T-26’s time was coming to an end by the mid-30s. 1936 was supposed to be its last year of production. The T-46-1 tank was accepted into service on February 29th, 1936. It was going to enter production that same year and then become the most common combined arms tank just like its predecessor. However, the replacement tank made a rather poor showing. Factory #174 was hit with a wave of repressions and the T-26 had to remain in production. This tank was also starting to show issues, particularly with the road wheels and engine. The engine troubles deserve a separate telling. Nevertheless, a number of improvements were made in 1936-37. A new track tension mechanism was introduced in late 1936. Road wheels with replaceable tires were introduced, although old wheels with permanently attached tires were installed as late as 1937, as evidenced by the tank at Padikovo. Night fighting spotlights and a P-40 anti-aircraft mount were added in 1937. The instruments layout changed sometime in 1936. Toolboxes were added alongside the turret platform. The engine was thoroughly modernized in 1937 which significantly increased its reliability. An extra fuel tank was also added. A TPU-3 intercom and slip ring were added in 1937 as well as a compass.

The only missing item is a rear machine gun, but not all tanks came with one.

The T-26 was in a way a showcase for the achievements of the Soviet defence industry. When T-26 tanks arrived in China in 1938, it turned out that their British cousin the Vickers Mk.E Type B paled in comparison. This was true for the armament, the armour (British steel was considerably worse than the Soviet one), observation devices, mobility, and reliability. The Soviet tank overtook its ancestor in all categories. 4735 tanks with cylindrical turrets were delivered in total from 1933 to 1937, 2568 of which had a radio. This was the most numerous Soviet tank and the one with the most combat experience. It was used in Spain, China, at Lake Hasan and Khalkhin-Gol, during the Winter War and Soviet campaigns in Poland, the Baltics, and Bessarabia, during the Great Patriotic War and Soviet-Japanese War of 1945, then the Chinese Civil War. Captured T-26 tanks served in Finland until 1960, and in China even longer. Even though the tank was obsolete by 1939, they kept actively fighting even in 1944. For example, T-26 tanks supported the landing on Sioninsaari and Teikarsaari in July of 1944. The T-26 kept fighting in the summer of 1945, including the battles for South Sakhalin.

This tank has early road wheels. Production of new road wheels with removable rubber tires began in late 1936.

The tank displayed at the Museum of National Military History is among those that were not modernised in 1940-41. Modernized tanks received caps to protect the air intake on the roof of the fighting compartment, improved running gear, a modernized engine, and other improvements. This is a typical representation of a 1937 production tank. The only item that’s missing is the rear machine gun, but it was not used on all tanks. The tank was put together from fragments into an authentic vehicle with an original engine and transmission. This tank was displayed on February 23rd of last year, but it was improved since. In part, spotlights for night fighting that were installed in 1937-38 were added.

The location of a horn and a headlight in an armoured casing are signs of a late cylindrical turreted tank.

The T-26 is often criticised out of context, but its shortcomings need to be compared to what was happening abroad. A typical tank of the mid-1930s was a light tank assembled either with bolts or rivets. Welding was a rare phenomenon. In the meantime, the “backwards” USSR was producing thousands of tanks with welded hulls and turrets. This was a high tech achievement in its time. There were still bolts used, but only for parts meant to be removable. The protection of the T-26 was also optimal for its time. The tank’s armour protected it from armour piercing rifle bullets except at maybe 100-200 meters. In Spain it turned out that 15 mm was no longer enough, but that was a problem for everyone. The T-26 remained quite a scary tank to infantry without heavy anti-tank weapons. The T-26 even had bulletproof glass in its vision slits starting in 1934. By 1936 the headlights also received an armoured casing that could fold down in combat. A number of vehicles built in Leningrad (plus the T-35) had this feature. The USSR stopped using it, but the Finns liked it so much that they installed these headlights when refurbishing tanks.

The engine deck was fully used.

The tank’s stowage needs to be mentioned separately. The first single turreted T-26es did not differ much from their two-turreted predecessors, but evolution started quickly. The number of carried items increased to an impressive count by 1937. Some of the pioneer tools moved to the engine deck after toolboxes were introduced. A railway style jack was replaced with a more compact type that had its own spot on the engine deck. A spare leaf spring, track links, and a spare road wheel were carried. Later the number of spare road wheels increased to two. Many museums ignore this detail, but the Museum of National Military History has a different goal. At least the exterior of the tank has to be as authentic as possible here.

The second fuel tank cap can be seen to the right of the mallet.

The museum’s tank belongs to the late production series. The only missing improvement is the new road wheels. The second fuel tank is already present. It increased fuel capacity from 182 to 292 L and range from 120 to 225 km. The tank was added to the front right part of the engine compartment. A second fuel tank cap was also added.

The cylindrical turret was welded from the very start.

The turret developed in 1932-33 was truly revolutionary for its time. The Vickers Mk.E Type B turret appeared earlier, but the Soviet one was much better. The T-34’s turret grew out of a very similar turret that was initially developed for the BT-5 in Leningrad. The BT turret evolved into a conical shape that had a sudden offshoot. The turret of the Japanese Shinhoto Chi-Ha tank and its descendants evolved from the BT-7 turret. As for completely original analogues, the turret of the Czechoslovakian tanks was the most similar. They had better vision thanks to the commander’s cupola, but they were assembled with rivets and the crew had no seats.

Night fighting spotlights.

An item was added to the tank late last year that was a Soviet specialty: night fighting spotlights. Special attachments focused the beam of light. Factory #174 documents indicate that they were only installed from 1937 to 1938. Interestingly enough, these lights made a comeback on foreign vehicles many years later.

Scale modellers take note. Components made from composite epoxy and synthetic resin insulation were not painted.

One of the characteristic features of Soviet tanks of the era was the rail antenna. Few original antennas remain. The museum tank’s antenna was rebuilt from fragments of original ones. This antenna came to the USSR via the Germans. With the exception of the Nb.Fz., the Germans kept their rail antennae on the hull of the tank. Soviet designers moved it to the sides of the turret. The body was composed of either a copper rod or a tube. It was attached to the turret via metal cups welded to the sides of the turret that held epoxy rods. The contacts were covered with a layer of cardboard soaked in synthetic resin. The epoxy and resin parts were not painted since paint can conduct electricity.

Overall layout of the rail antenna.

The antenna formed a rail that wrapped around the sides and rear of the turret, but grabbing on to it would be a mistake. A copper wire connected the antenna to a cup-shaped connector on the turret roof. This design also allowed for a whip antenna to be installed. The rail antennae were later cut off since their made radio-equipped tanks very distinctive and whip antennae were much better to use.

The P-40 was the best AA machine gun mount of the pre-war period.

In addition to the night fighting lights, typical late model cylindrical turret tanks had the P-40 anti-aircraft machine gun mount. This was one of P.N. Syatchinov’s only designs that actually worked, and even that needed work. Instructions also mention the 56-322B mount, but this was essentially the same P-40. Presumably, 56-322B refers to early mounts and P-40 refers to the late ones. The P-40 mount deserves a separate article, but suffice it to say that this was the best pre-war anti-aircraft machine gun mount. It was installed on a number of tanks, the last of which was the KV-1.

A plug is installed on the right side, but a PT-K periscope could be installed here.

The location of items on top of the turret was typical for Soviet tanks. A PT-1 periscopic sight was located on the left. It was covered with a cap during travel. There was a plug on the right side, but not always. Command tanks had a PT-K commander’s periscope here. It was very similar to the PT-1. A ventilation “mushroom” was located between the periscopes. If necessary, it could be flipped open. The T-34, T-28, and KV had the same turret layouts.

Inside the fighting compartment.

The T-26’s fighting compartment might seem cramped now, but it was quite roomy for the time. Most tanks were much more cramped even if there was only one person in the turret. The fighting compartment is laid out very well and everything that’s necessary is right on hand. This tank has an empty turret bustle for the time being. In the future, a 71-TK radio will be placed here. In tanks without radios, the turret bustle contained two ammunition racks.

The main ammunition rack was located under the gunner’s seat.

The tank offered a rare comfort for its time. In many tanks, the turret crew stood up, but in Soviet tanks the gunner and loader had a seat. The ammunition was carried in the left side of the fighting compartment to use up the leftover space. It wasn’t that easy to get to it, but the ready rack was located elsewhere. Tanks without a radio carried 147 rounds of ammunition, tanks with a radio had 107. To compare, the Vickers Mk.E carried 60 rounds and the Polish 7TP had 80.

Exhaust fan.

As mentioned above, the tanks were equipped with exhaust fans starting in 1933. An electric fan with the MV-12 motor was used. This model turned out to be quite successful and even the IS-2 still had the MV-12. Since the fan was not always in use, it was covered up with a cap. When the fan was in use, the cap would open. Few light tanks at the time had ventilation fans.

Driver’s station.

The T-26 was a quite successful vehicle for its time. It was not without drawbacks, but the sum total of its characteristics made it one of the best vehicles in its class. The problem was that it stuck around for too long. Many of its competitors were in the same boat. For example, the German Pz.Kpfw.II was a direct analogue to the T-26, and it’s not hard to see which tank is better.

Original article by Yuri Pasholok

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