WW2 Soviet SPG Prototypes

T-27 37 mm Projects

Soviet Union (1931)
Experimental Self-Propelled Gun – At Least 2 Prototypes Built, Possibly A Small Production Series

During the 1920s, the Soviet Army was rather poorly armed and equipped. As it was slowly built, the need for armored vehicles, such as tanks, arose. The initial attempt to develop domestic tank design failed, as the Soviets lacked experience in designing such vehicles. For this, a military delegation was dispatched to countries, including the United States and Great Britain, in hope of acquiring a foreign design that was to be built under licenses. From Britain, the license for the Carden-Loyd tankette was acquired. The Soviets further improved this design, which led to the creation of the T-27 tankette. As it was only armed with a machine gun, the Soviets wanted to increase its firepower by adding a 37 mm gun, creating a small series of experimental vehicles.

The experimental T-27 was armed with a 37 mm gun. Source: Svirin M. N. Самоходки Сталина. История советской САУ 1919-1945

The T-27’s Brief History

During the 1920s, the Soviet armored forces were in a process of reorganization and rearmament. Initial Soviet attempts to develop armored vehicles were rather unuseful, and only smaller series were built. The first domestically built tank, the T-18 (MS-1), was adopted in small numbers to service in July 1927. Soviet industry was experiencing constant delays in delivery and poor quality of production. In November 1929, Управление по механизации и моторизации – YMM (English: Department of Mechanization and Motorization – UMM) instructed that the current development situation was unfeasible in the near future. To remedy this situation, YMM was instructed to seek technological help abroad.

On 30th December 1929, a commission led by the head of the UMM, Innokentii Khalepskii, went abroad. The plan was to visit Czechoslovakia, France, Germany, Great Britain, and US in order to purchase technologies and armaments. The negotiation with Great Britain proved most promising, as the Soviets managed to purchase a few different tank designs, including the Vickers Carden-Loyd tankettes, the Vickers-Armstrong 6-ton, and the Mk.II medium tanks.

Vickers Carden-Loyd tankette. Source:

Some of the newly acquired Carden-Loyd Mk.VI tankettes were sent to Zavod No.37, a factory in Moscow. There, an engineering team led by N. Kozyrev examined this vehicle in great detail, in order to be put into production as quickly as possible. The Soviet engineers were generally satisfied with this vehicle, but noted a number of shortcomings. Consequently, they implemented a series of improvements (such as modifications to the suspension, adding a stronger engine, etcetera) before the vehicle under the name T-27 was finally accepted for service.
The T-27 was basically a two-man tankette armed with one DT 7.62 mm machine gun. Its production began in 1931, and by the time the production stopped in 1933, slightly fewer than 3,300 had been built (the precise number differs greatly between sources). Given their obsolescence, the T-27 did not stay long in active service, as it was replaced by much more modern tank designs. The T-27s were allocated for crew training, but during the Axis invasion of the Soviet Union in 1941, many would be put into service. They performed poorly due to their weak armament and armor.

T-27 in Soviet Service. Source: www.worldwarphotos

Improving Firepower

While the T-27 filled the gap of a lack of armored vehicles, its potential combat effectiveness was limited due to its weak armament and its general configuration which lacked a turret. As they were available in great numbers, discarding them was not a proper solution. On the other hand, increasing their overall combat performance by adding new armament was something that the Soviet Army considered doing.

For this reason, in October 1930, an official order was issued that such modification be implemented. The following year, a design team led by K.K. Sirken from the Leningrad Bolshevik, began the first steps to do exactly that. The overall T-27 design was to remain the same, with the exception of the vehicle’s right superstructure, where some modification would be required in order to fit the larger gun. This would lead to the creation of two prototypes. These received slightly different armament rearrangements. In addition, the first prototype used a four-wheel suspension, while the latter used the more common six-wheel suspension. Due to the rather short development time, this project appears to have received no official designation.



The hull of this vehicle could be divided into three compartments or sections. The front-mounted transmission with the drive unit, the central engine compartment, and the two fully enclosed crew positions (opposite of the engine).


The engine from this T-27 modification was unchanged. It was powered by a Ford four-cylinder petrol, water-cooled engine delivering 40 hp @ 2,200 rpm. The T-27’s maximum speed with this engine was around 35 km/h, while the operational range was 110 km and 60 km cross-country. The weight of this vehicle was 2.7 tonnes. The modified versions with the extra added weight likely had slightly worse overall driver performance.


The T-27 was used in two similar suspension configurations. One used the original 4 road wheels placed on a suspension cradle. In addition, there was a front drive sprocket and rear idler. The road wheels were placed in par on bogies which were suspended using simple flat leaf springs. The Soviets were not satisfied with this design, so they improved it by adding another pair of wheels.

The T-27’s suspension consisted of six road wheels, one front drive sprocket, and a rear-positioned idler. There was no return roller, instead, a simple guiding rod was used for the upper track section. Source:

The first prototype armed with the 37 mm gun used a four-wheel suspension. While there is very little information on these vehicles’ overall construction, thanks to surviving photographs, it is possible to identify that some structural changes were made. Given the recoil force of the gun, the integral structure of the suspension had to be strong. The part of the suspension cradle that held the rear idler was reinforced. Lastly, the upper track guiding rod was replaced with two simple return rollers.

The first attempt to modify a T-37 led to the use of a strengthened four-wheel suspension. Two small return rollers were used on this prototype, Source: A.G. Solyankin Отечественные бронированные машины.

This arrangement appears to have been insufficient for this modified vehicle. So, on the second prototype, a six-wheel suspension was used. It also received extensive structural improvement to better cope with the gun’s recoil. Its suspension cradle appears to have been slightly larger than on a standard T-27 vehicle. While the two upper return rollers remained, they appear to have received some kind of leaf spring addition.

The suspension on the second prototype was even further improved, in order to better cope with the new gun installation. Source: Svirin M. N. Самоходки Сталина. История советской САУ 1919-1945
Rear view of the modified T-27. Source:


The superstructure is another part of the vehicle that was heavily modified. Originally, the T-27 had a simple box shape superstructure that covered most parts of the vehicle. The crew’s head (and the engine’s top) were protected by a pyramidal-shaped hatch. In front of the crew compartment, there was a hatch placed on the upper glacis that provided access to their transmission unit. The T-27 was built using simple plates connected using bolts.

The driver and the gunner positions were protected by two pyramidal-shaped hatches Source: www.worldwarphotos

The right part of the superstructure, where the machine gun port was originally located, was redesigned in order to fit the larger gun inside of it. This part was greatly extended forward to provide room for the gun mount. Not much is detailed in the sources about this new superstructure’s design. We can assume though, that due to the T-27’s small size, it would be quite cramped and difficult for the gunner to operate this gun.

To accommodate the gun and provide the gunner with working space, the left side of the vehicle’s superstructure was enlarged. Note the trailer which was used to store additional ammunition. Source:,en/


The initial armament of the T-27 consisted of only one 7.62 mm DT machine gun. This proved to be completely inadequate and was the main reason why this project was initiated. Instead, the Soviet designers wanted to install a 37 mm gun. Two guns were initially considered: the PS-2 and the B-3. Due to delays in production, neither of them was available for use.

As a replacement, a 37 mm Hotchkiss which was in service by the Soviet Army was chosen instead. In the first prototype, this gun was placed in the enlarged gunner position. The overall construction and the general characteristic of this gun mounted on the modified T-27 are not specified in the sources. What is known is that the performance of this vehicle was poor. The chassis became overburdened with the added weight of the gun, ammunition, and extra armor. It was noted that the ammunition for the main gun took up too much space inside the vehicle. As a temporary solution, a trailer was to be used to transport additional ammunition.

The front view of the first prototype. Source:,en/

The second prototype received more modifications in order to provide more working room for the gun. The Soviet engineers were a bit overambitious, as they added a machine gun to this vehicle. For this reason, the main gun was placed in a lower position. Above it, a Degtyaryov 7.62 mm DT machine gun was placed on a ball mount. The machine gun could be operated independently of the main gun. In theory, this would provide armament to deal with the enemy armor and infantry. Realistically, this arrangement proved too much for the small vehicle and cumbersome to use.

The second prototype had its gun placed in the lower position. Above it, a machine gun ball mount was placed. Source:,en/


The crew consisted of only two: the commander/gunner and the driver. The driver’s position was on the left and the gunner was on the other side. This arrangement was not changed on the modified T-27. Interestingly, on the second prototype, the Soviets tested the use of dual controls, meaning that both crew members could drive should the need arise.

The small size of the T-27 is evident here. Source:


Given its slight weight and small size, the T-27 was only lightly protected. The armor thickness of the front armor was 9 mm, the side and rear were 8 mm thick, the bottom was 4 mm, and the top was 6 mm thick. There is no mention in the sources that the armor of the modified T-27 was changed. This level of protection ensured that the vehicle was protected against small arms fire and shell splinters, but little else.

Ultimate Fate

After a series of examinations, it quickly became obvious that this concept was flawed. The gun was simply too heavy for the chassis. The use of machine gun placed above the gun was difficult to operate. The added weight led to engine overheating problems. As a result, the project was rather quickly terminated. It is not clear if any additional vehicles were built beside the two already mentioned prototypes. Some sources, such as D. Nešić (Naoružanje Drugog Svetsko Rata-SSSR) mention that a small production run was made.

Despite the cancellation of this project, the experimenting with stronger armament on the T-27 continued. An installation of a recoilless gun on the right side of the vehicle was tested. In addition, a modified version with a 76.2 cm gun installed to the vehicle’s rear was also built. None of these entered productions and any further work on improving the armament of the T-27 was discontinued.

A prototype armed with a recoilless gun. Source:
Mounting an infantry support gun on the T-27 also proved futile. Source:


While the whole concept of rearming the older design with a stronger gun was sound, in reality, this was impossible to achieve. The T-27’s chassis was simply too small and weak. The 37 mm armed T-27 project was essentially doomed from the start. The gun weight and its recoil were probably too much for the small chassis. In addition, the working space inside it was quite limited to effectively operate this gun. This ultimately led to the cancellation of this project, but at least, it offered some experience to the Soviet tank engineers.

The first modified T-37 used a strengthened four-wheel suspension. Illustration made by Godzila.
T-27 37 mm second prototype The suspension was further improved, in order to better cope with the new gun installation. In addition, an installation of a machine gun was tested.  Illustration made by Godzila.

T-27 with the 37 mm gun Technical specification

Crew Commander/Gunner, and Driver
Weight over 2.7 tonnes
Dimensions Length 2.65 m, Width 1.83 m, Height 1.47 m
Engine 44 hp Ford petrol engine
Speed 45 km/h
Primary Armament 37 mm gun
Secondary Armament One 7.62 mm DT machine gun (second prototype)
Armor 6 to 9 mm


S. J. Zaloga and J. Grandsen (1984) Soviet Tanks and Combat Vehicle of World War Two, Lionel Leventhal
T. Bean and W. Fowler (2002) Russian Tanks Of World War II MBI Publishing Company
Svirin M. N. (2008) Самоходки Сталина. История советской САУ 1919-1945, Эксмо
A.G. Solyankin (2002) Отечественные бронированные машины. XX век Том 1, Цейхгауз
D. Nešić, (2008), Naoružanje Drugog Svetsko Rata-SSSR, Beograd,en/

4 replies on “T-27 37 mm Projects”

In the “Armorment” section, it states that it was armed with a 7.62 cm machine gun instead of a 7.62 mm machine gun.

I reckon a AA MG conversion may have worked, or using it like the original concept as a small tractor or ammo carrier.

I’m afraid I don’t quiet agree.
While indeed T-27s were used to tow field guns, they simply fall short compared to the T-20 (1936 multi-purpose tankette) and other logistic options available from the late 1930s and onwards.

As for the AA MG version, well… I’ve yet to find a concept for it and at the top of my head, I cannot recall any dedicated AA-tankettes.
I don’t include things like the TKS-series which were able to mount an external MG for additional coverfire or AA defense.
I cannot really see any method to convert it to a dedicated SPAAG without compromising the armour protection, specially due to the large and shaped hatches when compared to the TK-3s.
Even if so, you now have a tiny tracked vehicle with maybe a DP/DT-28 on top, perhaps a DShK if you wait till 1938.
You’re not going to mount anything heavier, and while it would be enough for the Winter War perhaps, you’re not going to deter a Messerschmitt and the role is better left, as it historically was, to various ZiS and GAZ trucks with a couple of sandbags for good measure.
You see armoured SPAAGs in the USSR such as the T-90, the ZSU-37, the SU-6 (T-26 based), the ZiS-43, SU-11 and the ZUT-37 but most of those are prototypes or never saw real service.

The best you “could realistically do” as a what-if scenario, would be to re-equip some of them on a platoon level with DShK HMGs or perhaps even PTRS-41s to give them a fighting chance with only “so much modification” to the vehicles and transfer the DT-28s to other vehicles.
If it wasn’t because they weren’t already so badly outdated by the time those weapons became available.

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