BT-7, BT-7A, BT-7M , BT-7U, BT-7TU and variants, plus BT-1, BT-S and BT-5.
Type: fast tank.
Crew: 3 men.
Armament: a 35 mm M 1935 gun; a coaxial 7.62 mm DT machine gun. (Some vehicles had a second DT 7.62mm machine gun at the rear of the turret and a P.40 machine gun.)
Armour:
minimum 10mm;
maximum 22mm.
Dimensions:
length: 5.66 m;
width: 2.29 m;
height: 2.42 m.
Weight: 13.9 t
Ground pressure: 0.79 kg/cm2.
Power to weight: 36.5 bhp.
Engine: Model M17T 12 cyl. water-cooled gasoline engine, developing 507 hp at 1,650 rpm.
Performance:
road speed: 73 km/h on wheels, 53 km/h on tracks;
autonomy: 730 km on wheels, 430 km on tracks;
vertical obstacle: 0.55 m;
clean cut: 2 m;
slope: 320.
Service time: in the Red Army from 1935 to 1945.
The BT fast tank was after the light infantry support tank T-26, the most widespread armored fighting vehicle in the Red Army during the 1930s. The initials BT stand for “Bistrokhodny Tank” (fast tank). Tank crews called it “Betka”’ (beetle) or even “Tri-Tankista”, alluding to its three-man crew. Unlike most other Soviet vehicles of the time, the BT tank was not derived from a British Vickers model but from an American tank designed by J.W. Christie. Later, the British were also to draw inspiration from this model to create their famous line of "cruiser" tanks, the most famous of which was the Crusader.
In 1930, Soviet officials bought the basic Christie vehicle from America, which, shipped to Russia the same year, was delivered to the Kharkov locomotive factory. After intensive trials on May 23, 1931, the Revolutionary Military Council approved the use of the Christie by the Red Army and ordered it into production. The plans for the BT prototype were sent to the Comintern factory in Kharkov in August 1931.
On September 3, 1931, the first two prototypes, called BT-1, were delivered to the army for testing. This first tank being armed only with machine guns, the military commission in charge of the tests claimed, for the series models, an artillery piece.
Meanwhile, the BT-2 model, still armed with machine guns, was built in limited quantities. However, after the production of a few examples, the BT-2 tank received a 37 mm Model 1930 gun mounted in the original machine gun turret. In 1932, the army requested that the BT tank be equipped with more powerful armament, in this case a 45 mm gun.
After testing various prototypes, the BT- S was accepted. It had a 45mm gun in a turret almost identical to that of the T-26 light tank. A coaxial 7.62 mm DT machine gun completed the armament Command vehicles that received the suffix U or TU (BT-5U or BT-5TU) were equipped with a radio transceiver installed in the overhang of the turret, which required the displacement of part of the 45 mm shells.
Like that of the T-26 command, the turret carried a very characteristic loop antenna. The BT tanks were intended for large autonomous motorized armored units with a long range of action, called "group DD". Their mission was to attack the rear of enemy positions in order to seize their nerve centers such as headquarters, supply bases, airfields, etc.
For this silence, the speed was a primary factor.
One of the characteristics of the tank created by Christie was its ability to move either on its tracks or on its road wheels. He used the tracks when off-road or on bad roads and the wheels for long road trips. It took 10 to 15 minutes to change from one type of bearing to another. This capacity of the tank to move on its wheels was however never exploited operationally by the Soviets. When the tank moved on its wheels, the tracks were attached to the track guards and the driving force was transmitted to the rear wheels. The two front road wheels were steerable to provide vehicle steering for most other tanks, steered by means of two levers, the direction of the BT was controlled by a steering wheel.
The great maneuvers of the Red Army, at the beginning of the 1930s, had shown that the "DD groups" had to be provided, in one way or another, with artillery support which would bring them the support of his fire during offensive maneuvers. So special artillery support tanks were created, which received the suffix A.
The first of them, the BT-5A, appeared in 1935. It had a 76 gun, 2 mm short-barreled in a turret similar to the main turret of the T-28 medium tank. Following the experience acquired in combat, the army requested that the BT be provided with wrought and inclined shielding, so as to increase its protection. Thus was born the BT-7, which constituted considerable progress.
Its ammunition load was 188 45mm shells and 2,142 7.62 mm cartridges. As with the BT-5, a command model was created called the BT-7U or BT-7TU.
The first B T-7s, however, still had the cylindrical turret of the T-26 tank. In 1938, thanks to the experience gained during the fights against the Japanese in Manchuria, the new turret created for the light tank T-26- was also adapted to the BT-7. Of this model, also a command version was built.
In order to provide artillery support, the BT-7A version was created, equipped with the same turret as the BT-5A The BT-7 also featured a more powerful engine and an improved transmission system. The new V-2 diesel engine, created in 1938 especially for tanks, was to be fitted to all BT-7s built thereafter. To distinguish them from earlier models, these were called BT-7M, although they would also have been called BT-8
The new engine developed 507 hp at 1,800 rpm and as it was a diesel, it allowed the “DD groups” to considerably increase their range of action. In addition, the risk of fire was reduced because diesel fuel is less volatile than gasoline.
Several special and experimental vehicles were developed from the BT tank. In 1936, the experimental model BT-IS (“investigator tank”) was created. Provided with a strongly inclined shielding and enveloping this vehicle contributed largely to the development of the tank T-34. In 1937, several BT tanks were equipped with a snorkel that allowed them to cross deep fords. These vehicles were called BT-5PH. As the BT-5 and BT-7 models became more prevalent in the military, earlier BT models were used in the construction of special purpose vehicles, such as the BT Bridgelayer, a Smoke Launcher Tank and a chemical tank.
BT tanks took part in the Spanish Civil War. The BT7M in particular also fought on the occasion of the first exploits of Joukov, during the battles of Khalkhin-Gol, at Lake Khasan, as well as during the Finnish-Soviet war. All BT tanks were engaged in the first battles of 1941 on the Eastern Front