Bizarre armor projects of the ’40s. BT tanks with a rocket twist

Seb: I am super busy until Wednesday when I can finally rest and focus on TAP. I will try to post everything I can tonight too. Sorry for inactivity and for just posting the „basic” stuff. I will make up for it.

Time for another historical article translated by Vladimir:

In the ’30s and ’40s, military engineers tried to solve a non-standard task – to provide a light tank with significant firepower. The light BT-5 tank served as an object for experimentation.

For its’ time, this tank was well armed and protected, but still quite ordinary. In 1933, the chief of the mechanization and motorization department of the Red Army I.A. Halepsky issued the task to turn the “private” into a highly destructive combat vehicle. The aim of the engineers was to “create a torpedo-carrying tank, armed with 250kg torpedoes, intended to destroy enemy resistance pockets…”

One and a half centners of heavenly thunder

The tank torpedoes for the BT were two shell hulls of streamlined form containing 130kg of TNT and equipped with four stabilizers. A light tank carrying at least two of these shells turned into a machine of collosal destructive power. The tank rocket torpedoes 250-TT were designed for usage against heavily fortified positions, pillboxes, railway junctions etc. With their help, the BT could also destroy heavy armor of the enemy.

The designers had many questions on this topic. For example: if a BT-5 turret is equipped with 400kg on each side, can it still rotate? Will the launchers be powerful enough? How will be the range and precision of the torpedoes? None of these questions could be answered in theory, experiments had to be conducted.

Firstly, the engineers tested how durable the hulls of the torpedoes themselves were. They put 95 gunpowder charges inside and lit them up – the hull withstood this. The time had come for firing tests.

The experimenters took six torpedoes – two were filled with wet sand, the other four with TNT. They launched them. The experiment showed that “the flight of all six bombs is correct, stable, the range at an elevation angle of 50° is about 1450-1500 meters”. The four craters in the ground were measured – they were about 10 meters in diameter and 4 in depth.

Not good enough

The time had come to shoot some torpedoes from the tank itself. On the 19th July 1936 a BT-5 arrived at the shooting range of the station “Podsolnechnaya” with torpedo launchers mounted at the sides of the turret. To protect the radiator lattices at the back of the tank from jet streams, the designers provided it with special shields.

The elevation angles were set manually, with a difference of 10°. The first round was fired with closed hatches, the second with open ones to test how the gases of the reactive exhaust would affect the crew.

The flight of the torpedoes was again correct and stable. They landed with a distance of about 100 meters between them, depending on the elevation angles, The exhaust gases were reflected by the tank’s hull, not harming it at all. The turret of the BT-5 was turning smoothly. Everything seemed all right… but not everything was.

To solve the problem of aiming the torpedoes and compile tables with this data, many tests were required. Reloading the torpedo armament was connected to a huge risk for the crew, which had to leave the tank during combat. To solve this problem, the engineers proposed to design a special “reloading tank”.

All in all, the tests continued until November 1936. On their basis, a list of shortcomings of the torpedo tank was compiled:
“a) the size of the armament;
b) the decrease of the tank’s combat capabilities;
c) small number of torpedo shells;
d) impossibility to reload without the crew leaving the tank;
e) exposure of the torpedoes to small arms fire;
f) small range of the shells;
g) small initial speed;”

Due to these results, work on the project stopped, the documentation was archived. The torpedo BT did not enter battle. But six years later, a gunnery instructor from the city of Miass proposed to arm the tank in a more serious way.

Rocket BT of a humble artilleryman

The report of military instructor A.P. Konstantinov arrived at the headquarters of the guards’ mortar units in November 1942. The inventor wrote that he “developed a downsized mounting for M-8 rockets on the BT tank”. Bluntly speaking, Konstantinov wanted to cross the tank and the “Katyusha”.

The design was firstly intended for the T-34, which the inventor already submitted to the design department at the Kirov plant in Chelyabinsk. But their experts noticed a number of shortcomings in the project and advised to finalize it for the BT-7 tanks. Konstantinov didn’t know whether these tanks were still produced, and hesitated to write to the GABTU directly since he “didn’t know anybody there”. The report arrived there after being in the hands of the guards’ mortarmen for a short time.

The document contained drawings and a description of the system. Konstantinov proposed to equip all BT-7 tanks which were in service with it. turning them into special-purpose tanks. A company of these tanks should, according to the author, be attached to every tank brigade to complete the following tasks: “During attacks of our heavy and medium tanks, they halt at our furthest line of defense. On our heavy and medium tanks’ movement, the enemy will show their AT armament… The special-purpose tanks would suppress them. Destroy the retreating enemy. Elimination of enemy counterattacks”.

The modernization of the BT-7 according to Konstantinov’s project consisted of installing mountings for 24 82mm rockets at the back of the tank – two packages for 12 rockets. During marches, the packages would be covered by armor plates for safety. This enlarged the tank’s silhouette, but allowed to transport a few men.

In combat, the packets were readied by moving them to the left and right so they were positioned at the sides of the tank. Horizontal aiming was conducted by moving the hull, vertical by an elevating mechanism located in the turret of the BT-7.

Konstantinov finished his letter as follows: “The M-8 rocket, having a range of up to 1000m, has a similar destructive effect as a high-explosive 122mm grenade, which I will explain in a following letter”. However, no other letters from the inventor arrived.

Was Konstantinov’s project promising? This is unlikely. A year before his report, in the fall of 1941, experts already tried to mount the M-8 system, not on a BT, but on the small T-40 tank. The shooting tests showed a too wide dispersion on medium elevation angles. Thus, the “rocket T-40” was scrapped.

The logical idea of arming a fast-moving combat vehicle with high-power armament was hard to implement. But the absence of torpedoes and rockets didn’t hinder the BT tanks to go through the whole war and finish it among other combat vehicles.

Author – Yuri Bachurin

Source: Central archive of the Ministry of Defense of the Russian Federation (ZAMO RF)