BT Tank
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modified: Nov 10, 2012
The BT (Russian: Быстроходный танк, Bystrokhodny tank, Fast Tank, known in Russian service as the Betka or Betushka) was a series of Soviet cruiser tanks. They were produced in the 30s and early 40s. Even though they had light armor, they were well-armed for the time. They also showed superior mobility compared to their counterparts.

BT-7 Model 1937 on parade
BT-7 Model 1937
The BT was assigned to independent tank brigades and cavalry formations. It was based on the American Christie M1930 convertible tank. Tracks of the time had short life-span and were the major cause of mechanical breakdowns. As a result, convertible tanks were widespread during the 1930s. These convertible tanks used road wheels with the tracks removed when traveling on roads. This was done by having a special chain drive that powers the rear road wheels when the tank is in wheel mode. It took about thirty minutes to convert a Christie tank from track to wheel mode.

Two M1930 prototypes were sent to the Soviet Union in early 1931. They were shipped in disguise as agricultural vehicles without their turrets. They arrived at the Kharkov Locomotive Works (Komintern) (KhPZ Nr. 183) and were designated BT-1. On May 23, 1931, even before a prototype was completed, BT-2 was approved for the Red Army. The first three BT-2 prototypes were built in October 1931 without any armament. They participated in the Moscow parade on November 7, 1931. Mass production began in 1932 after trials were conducted. In that year, KhPZ built 396 tanks. The BT-2 Model 1932 had two variants, one mounting a 37 mm Model 1930 gun and the other armed with machine-guns. The latter had two DT machine-guns in addition to the one mounted in a ball socket to the right of the mantlet which was present on both variants. The machine-gun version was not popular and all production efforts were focused on the 37 mm Gun variant.

In 1932, the UMM ordered the design bureaus at the Bolshevik Factory and KhPZ to collaborate their efforts and design a standard turret that has a new ball-mounted 45 mm gun with a coaxial machine-gun. This turret is then can be used on the T-26, BT, and T-35 tanks. KhPZ developed the BT-5 Model 1933 with the new standard turret. The BT-5 wheels were also changed to a simpler convex style. The life of the new turret was very short. Soon after the introduction of the standard turret, OKMO finished developing a better turret for the 45 mm gun. This new turret became the standard for all BT tank production until 1937. The BT-5 production ended in 1935.

There were numerous experiments conducted on the BT series of tanks. The BT-5PKh was equipped with a snorkel and rubber sealing to that it can cross rivers under water. It was first deployed by the 4th Mechanized Regiment of the 4th Don Cossack Division in the 1936 summer Belorussian Military District maneuvres near Slutsk. The commander of this unit was Georgi Zhukov who has not yet achieved his popularity.

BT-2 BT-5 PT-1
Type (Role) Medium Cruiser tank Medium Cruiser tank Amphibious Tank
Origin Soviet Union Soviet Union Soviet Union
Years of production
Weight (Metric tonnes) 10.2 11.5 15.5
Crew 3 3 4
Length, gun forwards (m) 5.58 5.58 6.70
Width (m) 2.23 2.23 3.00
Height (m) 2.20 2.25 2.30
Engine 400hp Liberty gasoline 400hp M-5 gasoline 500hp M-17 gasoline
Operational range on road (km) 300 200
Road Speed forward (km/h) 100 72 80
Fuel capacity (l) 400 360
Armor (mm) 6-13 6-13 10-13
Primary Armament 37mm Model 1930 gun 45mm Model 1932 gun 45mm Model 1932 gun
Secondary Armament 7.62mm DT machine gun 7.62mm DT machine gun 7.62mm DT machine gun

A special OKMO team led by N. Astrov and N. Tsiets looked into less exhaustive methods for crossing rivers. The result was the PT-1 (Plavayushchiy Tank-1: Amphibious Tank-1) prototype completed in 1932. It used several BT components but the hull was made larger to provide sufficient buoyancy. A propeller was mounted under the hull and a rudder was used for steering. Trials that took two years proved that the tank had so many glitches. Therefore improvements were made and PT-1A was developed. The PT-1A lacked side turret machine-guns and had a shorter pitched track among several other refinements. Both PT-1 and PT-1A prototypes were unarmed during trials. Finally, it was agreed that the tank was too complicated for mass-production. However, a small batch of PT-1A amphibious tanks were built for conducting tactical trials.

The BT-5A was an artillery tank built on the BT-5 chassis. It had a turret derived from that of the T-28 with a 76.2 mm regimental howitzer. It was more successful than the T-26A and a small batch were manufactured. BT-5 flamethrower tanks were also built. But unlike their T-26 counterparts, the flame-projector was carried in the hull which allowed for the main gun to be kept. However, this design made the turret extremely crowded that it was very difficult to service the main gun. Because of this problem, no mass production of the BT-5 flamethrower variant ensued.

Other BT derivatives included fascine carriers to bridge gaps and anti-tank ditches, bridge-layer tanks, and tanks with 'supplementary track' for poor terrains. All of the derivatives were built only in few trial batches.

The Far East fighting in 1934 and 1935 showed the vulnerability of riveted tank design. As a result it was decided to redesign the BT-5 tank with welded construction. The BT-5 also had power-train problems with its M-5 engine. In 1935, A. Morozov in Kharkov finished a new clutch system and professor V. Zaslavskiy in Moscow built a new braking system. The clutch and braking system were combined with the new M-17T engine and the new tank was designated the BT-7 Model 1935. It is similar to the BT-5 Model 1934 except for the wholly redesigned hull front, the fully enclosed muffler, and the new short-pitch track. The hull was entirely welded and provided a place for exterior fuel panniers. The BT-7 Model 1935 was produced until 1937 when it was replaced by the BT-7 Model 1937. This variant had a sloping armor for better ballistic protection.

BT-7 BT-7A BT-8
Type (Role) Medium Cruiser tank Medium Cruiser tank Medium Cruiser tank
Origin Soviet Union Soviet Union Soviet Union
Years of production
Weight (Metric tonnes) 14 14.5 14.7
Crew 3 3 3
Length, gun forwards (m) 5.66 5.66 5.66
Width (m) 2.29 2.29 2.29
Height (m) 2.42 2.52 2.42
Engine 500hp M-17T 500hp M-17T 450hp V-2 diesel
Operational range on road (km) 250 250 700
Road Speed forward (km/h) 86 86 86
Fuel capacity (l) 620 620 620 (+170)
Armor (mm) 6-13 6-13 6-22
Primary Armament 45mm Model 1935 gun 76.2mm Model 27/32 gun 45mm Model 1938 gun
Secondary Armament 7.62mm DT machine gun 2x 7.62mm DT machine gun 3x 7.62mm DT machine gun

The command version of the BT-7 Model 1937, the BT-7TU Model 1937 used whip antennae instead of the horseshoe antenna used by the BT-5TU and the BT-7TU Model 1935.

The last version of the BT series was introduced in 1938. It was designated the BT-7M in Red Army service. It is also sometimes called BT-8 due to its experimental designator A-8. It contained the new V-2 diesel engine and a ball-mounted machine gun in the turret rear. The roof hatches were redesigned to allow a P-40 anti-aircraft machine gun. BT-8 production started in 1939. In 1940, 706 BT-8 tanks were built and production was terminated in 1941. There was a proposal to build an artillery tank version of the BT-8 designated the BT-8A but none were produced.

Support variants of the BT-7 include the BT-7A. It was the only artillery support variant of the BT-7 to be mass-produced. The BT-7A was armed with a 76.2 mm regimental howitzer in a larger turret. Another support variant was the OP-7. It was the flame-thrower version of the BT-7 Model 1937. To prevent the tank from being overcrowded like the BT-5 flame-thrower version, the OP-7 mounted the fuel cell for the flame-gun in an exterior armored pannier on the right side of the hull. In all, a total of about seven thousand BT tanks were built.

References: STCV, T34MT