Friday, 31 March 2017

Provornov's Light Tank: T-34 in Miniature

Hundreds of tank-themed proposals were sent to the Main Automobile and Armour Directorate of the Red Army during the Great Patriotic War. There was a wide spectrum of ideas and inventors. There were workers, scientists, engineers, ordinary citizens. A significant percentage was made up of military men of all ranks and branches. One of these men was Lieutenant Provornov, who proposed a light tank in July of 1942 with a number of original solutions. It was never built in metal, but fans of World of Tanks know it as LTP.

A Tank from a Tanker

July 5th, 1942, was a pivotal date in Soviet tank building. GKO decree #1958ss "On production of T-34 and T-70 tanks" cancelled the production of small T-60 tanks. They left the stage to make room for the improved T-70. At the same time, factory #264 in Krasnoarmeysk switched to producing hulls for T-34 tanks, which the front needed like the air they breathed.

On the same day, a letter arrived at the Main Automobile and Armour Directorate of the Red Army (GABTU KA) with a design for a tank that could have replaced the T-60. The author of this design was Lieutenant Konstantin Yakovlevich Provornov. Lieutenant Provornov was not involved with inventions until this moment, as he had more important things to do. Provornov entered the Red Army in 1939 and met the start of the Great Patriotic War as a platoon commander in the 98th Tank Regiment of the 49th Tank Division. In late July of 1941, the 49th division was encircled at Uman, the lieutenant was heavily wounded and disappeared. Provornov was listed as MIA until February of 1942, when he was discovered in a hospital.

Cutaway of Provornov's tank. It's not hard to guess what existing design inspired him.

Provornov fought in a T-34 tank, and this was reflected in the light tank design that he proposed to GABTU's Department of Inventions. At the time the lieutenant was only 22 years old, but his light tank was very well designed. This was because the young tanker knew the Red Army's tanks well. As a direct user, he knew the advantages and drawbacks of the tanks he served with.

T-40's Competitor

Before we example Lieutenant Provornov's idea, let's remind ourselves what tanks the Red Army had in the summer of 1942. Mass production of the T-50 tank, which was supposed to become the most numerous representative of its class, failed. The development of light tanks started from turning the small T-40 amphibious reconnaissance tank into the T-60, then T-70. That was the correct decision for the time, but the T-70 had some nuances.

The layout of the T-40, T-60, and T-70 placed the engine to the right of the driver. The turret was also displaced to the left. If a shell hit the engine, fire quickly engulfed the tank. In addition, the layout inherited from the amphibious tank left little room for improvements. The T-80 tank with a two-man turret that appeared in the end of 1942 was the pinnacle of this family. Further evolution was senseless.

Final drive diagram.

Provornov's light tank was much more interesting than the T-70, and especially the T-60. The inventor was familiar with the T-60 at the very least, which can be seen in the design of the engine. He also knew the design of the light T-26 tank. In concept, the tank he proposed was closer to the T-34. The resemblance can be seen in the overall shape. A hull with sloped armour, a familiar turret, rear transmission, all of this came from the T-34. Of course, the tank was not just a copy, as it contained a number of original and interesting ideas.

 Provoronov joined the engines into one unit.

Characteristics of the Design

Provoronov's light tank was an 11 ton three-man fighting vehicle. The hull was only 4 meters long, less than not only the T-70, but the T-60 as well. The hull was also narrower than that of its analogues at 2 meters. The tank's layout within such confining dimension was a difficult task, but Provornov managed to solve it. As mentioned above, because of the T-40's amphibious past, the T-60 and T-70 used their internal volume poorly. This is especially evident in the front, where there was a lot of empty space. Thanks to a T-34-like hull shape, Provornov's tank did not have this drawback.

The driver's position was further forward than on the T-60 or the T-70, which freed up space behind him. The driver used a large T-34-like hatch to get inside, which was equipped with two observation devices. A ball mount with a DT machinegun and a periscopic sight like the ones used on STZ T-34s was installed next to it. An emergency evacuation hatch was installed in the floor.

Fuel system layout. The placement of fuel tanks outside of the fighting compartment was a definite plus.

The rear of the tank also had a lot in common with the T-34. The tank used a pair of GAZ-11 engines, same as the T-40, T-60, and T-70. According to calculations, their combined power of 170 hp could achieve a top speed of 45 kph. The implementation of the pair of engines, however, was novel: both engines were connected to a perpendicular gear system. The engines were also installed on the same frame, shared fuel lines, ignition systems, and electric starter.

The cooling system was also original. The radiators were placed above the engines. The same solution was used on the T-26 tank. The result was a compact assembly that fit into such a small hull. The rear of the tank also fit the 500 L fuel tanks. According to calculations, the range of the tank on a highway was 430 km, and the range on a dirt road was 300 km. The placement of the fuel tanks outside of the fighting compartment was a definite bonus. The transmission was also in the rear. The final drives were the same as on the T-60. Large access hatches could be used to access the engine and transmission compartment, just like on the T-34.

Engine/transmission compartment hatches, inspired by the T-34.

The suspension, combining the solutions from the T-34 and T-60, was also very rational. Provornov's tank used a torsion bar suspension. Unlike the T-60 or T-70, it did not have return rollers. Each side had 4 650 mm road wheels, much larger than on the T-60. The width of the tracks was 300 mm. The tracks of a modernized T-70, which appeared several months after Provornov's proposal, had the same width.

While the hull layout was reasonable, the turret raised some questions. Provornov managed to fit a two-man turret into the tank, despite such a small size and dense layout. The diagrams only give an approximate idea, but the turret ring diameter was the same as on the T-26 and BT-7, which was large enough to comfortably house two men.

The design of the smaller tank's turret was similar to that of the T-34's turret. According to the description, the turret was cast. It inherited a large hatch from the T-34 in addition to the shape, as well as the observation devices. The armament consisted of a 45 mm gun and a coaxial DT machinegun. The ammunition capacity was 150 shells and 75 DT magazines. Considering the size of the tank, the actual amount of ammunition carried would likely have been smaller.

Torsion bar suspension and idler diagram.

Fate of the project and its author

Lieutenant Provornov came up with a light tank that was appropriate for contemporary realities and had a number of original solutions. It was a good replacement for the T-60 and was no worse than the T-70. The amount of thought that went into the design was more than in some actual design bureaus. The issue was that the tank was no longer needed. Production of the T-70 was in full swing, and work on SPGs on its chassis had already begun. Compared to that, the young tanker's work was destined to remain in the archives.

Provornov's light tank turret, based on the T-34 turret.

Thanks to published archive documents, it was possible to discover Provornov's fate. The lieutenant received the position of a platoon commander in the 214th Tank Battalion, 65th Tank Brigade. Provornov participated in Operation Kutuzov, the finale of the Battle of Kursk. According to his award order, Provornov's crew destroyed 2 tanks, 3 guns, and up to 30 enemy soldiers on June 26-27th. For his skilled actions, he was awarded the Order of the Red Star.

Unfortunately, Lieutenant Provornov died on the very next day in battle for the village of Gorki, Orel oblast. He was buried in a mass grave next to the village. Later, the grave was moved to Rzhava, Orel oblast. Who knows what could have happened to Provornov, had he survived the war? Many former officers became notable tank designers. Among them was, for example. Leonid Nikolayevich Kartsev, who had a number of battle medals and later became a leading tank designer.