The Fast Tank (abbr. БТ, BT), was a series of Soviet 'cruiser tanks' which were produced in large numbers between 1932 and 1941. They were lightly armoured, but reasonably well-armed for their time, and had much better mobility than other contemporary tank designs. The BT tanks were known by the nickname Betka from the acronym, or its diminutive Betushka.
BT tanks saw service in the Spanish Civil War, in the Far East, in the Winter War in Finland, the Polish campaign, and in the early part of World War II. The BT tank design served as a platform for experimentation with artillery support tanks and advanced armour layout, and further development led directly to the famous T-34 tank.
In 1930, Soviet agents at Amtorg, ostensibly a Soviet trade organization, used their New York political contacts to persuade U.S. military and civilian officials to provide plans and specifications on the Christie tank design to the Soviet Union. At least two of Christie's M1931 tanks (without turrets) were later purchased in the United States and sent to the Soviet Union under false documentation in which they were described as 'agricultural tractors'. Both tanks were successfully delivered to the Kharkov Komintern Locomotive Plant (KhPZ). The original Christie tanks were designated fast tanks by the Soviets, abbreviated BT. Based on the Christie prototypes and previously obtained plans, three unarmed BT-2 prototypes were completed in October 1931 and mass production began in 1932. Most BT-2s were equipped with 37 mm gun and one machine gun, but shortages of 37 mm guns led to some early examples being fitted with three machine guns. The BT-3 and later models were equipped with a 45 mm gun. The sloping front armor design of the Christie M1931 prototype was retained in later Soviet tank hull designs, later adopted for side armor as well.
In 1937, a new design team was formed at the KhPZ under Chief designer Mikhail I. Koshkin, to create the next generation of BT tanks. The team built a BT prototype called the A-20, but also built a more heavily armed and armoured derivative, the A-32, a "universal tank" to replace both the T-26 infantry tank and BT line of cruiser tanks. The design was controversial, but concerns about tank performance under the threat of German Blitzkrieg led to the approval for production of a still more heavily-armoured version, the T-34 medium tank.
|weight||10.2 t||11.5 t||14 t||14.5 t||14.7 t|
|length||5.58 m||5.58 m||5.66 m||5.66 m||5.66 m|
|width||2.23 m||2.23 m||2.29 m||2.29 m||2.29 m|
|height||2.20 m||2.25 m||2.42 m||2.52 m||2.42 m|
|armour||6–13 mm||6–13 mm||6–13 mm||6–13 mm||6–22 mm|
| main gun |
| 37 mm |
| 45 mm |
| 45 mm |
| 76.2 mm |
| 45 mm |
|main ammo||96 rds.||115 rds.||146 rds.||50 rds.||146 rds.|
|machine guns||DT MG||DT MG||DT MG||2×DT MG||3×DT MG|
| engine hp |
| 400 hp |
| 400 hp |
| 500 hp |
| 500 hp |
| 450 hp |
|fuel|| 400 l |
| 360 l |
| 620 l |
| 620 l |
| 620+170 l |
|road speed||100 km/h||72 km/h||86 km/h||86 km/h||86 km/h|
|power:weight||39 hp/t||35 hp/t||36 hp/t||34 hp/t||31 hp/t|
|road range||300 km||200 km||250 km||250 km||700 km|
|tactical range||100 km||90 km||120 km||120 km||400 km|
In the Second World War, BT-5s and BT-7s took part in the Soviet occupation of eastern Poland in 1939, and in large numbers in the battles of 1941. Most of these tanks were abandoned or destroyed in the disastrous 1941 campaign. A few continued in use in 1942, but they became quite rare after that time.
The BT series was numerous, forming the 'cavalry tank' arm of the pre-war Red Army, and had much better mobility than other contemporary tank designs. For these reasons, there were many experiments and derivatives of the design, mostly conducted at the KhPZ factory in Kharkov, Soviet Ukraine.
The most important legacy of the BT was the T-34 design, derived in part from the BT. The T-34 had many innovations well beyond the BT, but the lineage is obvious. Along the way, an important technical development was the BT-IS and BT-SW-2 series of testbed vehicles, which demonstrated the construction of vehicles with very heavily-sloped armor. This proof-of-concept led directly to the armor layout of the T-34.
BTs were also used as chassis for engineer support vehicles and mobility testbeds. A bridgelayers variant had a T-38 turret and launched a bridge across small gaps. Standard tanks were fitted as fascine carriers. The RBT-5 hosted a pair of large artillery rocket launchers, one on each side of the turret. Several designs for extremely wide tracks, including, oddly, wooden 'snowshoes' were tried on BTs.
The KBT-7 was a thoroughly modern armored command vehicle that was in the prototype stage when WW2 broke out. The design was not pursued during the war.
In the Kiev maneuvers of 1936, foreign military observers were shown hundreds of BTs rolling by a reviewing stand. In the audience were British Army representatives, who returned home to advocate for use of Christie suspension on British cruiser tanks. The British A-13, Crusader, and Cromwell tanks all used suspension designs derived from the Christie via the BT. Interestingly, the pointed shape of the hull front armor on the BT also influenced the design of the British Matilda tank.