BT tank: Encyclopedia - BT tank

BT tank

BT-5 command tank, with horseshoe antenna around the turret top

The Bystrokhodniy Tank (Fast Tank), was a series of Soviet 'cavalry 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 by the diminutive version Betushka.

The BT tanks were 'convertible tanks'. This was a feature designed to reduce wear of the unreliable tank tracks of the 1930s. In about thirty minutes the crew could remove the tracks and engage a chain drive to the road wheels, allowing the tank to travel at very high speeds on roads. In wheeled mode the tank was steered by pivoting the front road wheels.

BT tanks saw service in the Spanish Civil War, in the Far East, in the Winter War in Finland, the annexation of Poland, and in the early part of the Second World War. 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 of World War Two.

BT tank - Production History

In 1931 two experimental M1930 Christie tanks without turrets, designated BT-1, were purchased from the U.S. and delivered to the Kharkov Komintern Locomotive Plant (KhPZ). Based on the Christie prototypes, three unarmed BT-2 prototypes were completed in October 1931 and mass production began in 1932. Most BT-2s were equipped with 37mm gun and one machine gun, but shortages of 37mm guns led to some early examples being fitted with three machine guns. The BT-3 and later models were equipped with a 45mm gun.

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-30, a "universal tank" to replace both the T-26 infantry tank and BT-8 cavalry tank. 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.

Production:

• BT-5: 1,884
• BT-7: 5,328
• BT-8: 706

BT tank - Variants

• BT-1 - Christie prototype.
• BT-2 Model 1932 - 37mm gun, M-5 engine (copy of U.S. Liberty engine).
• BT-5- larger cylindrical turret, 45mm gun, ball-mount MG.
  • BT-5 Model 1933 - new turret with twin hatches, larger bustle and coaxial MG.
  • BT-5PKh - snorkelling variant (prototypes only).
  • BT-5A - artillery support version with 76.2mm howitzer (few made).
  • BT-5 flamethrower tank - (prototypes only)
  • PT-1A - amphibious variant with new hull (few made).
• BT-7 Model 1935 - welded hull, redesigned hull front, new M-17T engine (copy of BMW), enclosed muffler
  • BT-7 Model 1937 - new turret with sloping armour
  • BT-7TU - command version, with whip antenna instead of earlier horseshoe antenna
  • BT-7A - artillery support version with 76.2mm howitzer
  • OP-7 - flame-thrower version with external fuel panniers
• BT-8 (1938, originally called BT-7M) - new V-2 diesel engine (based on Hispano-Suiza 12Y aero engine), two DT machine guns: in P-40 AA mount on roof and in a ball-mount on turret rear
• BT-42 - Finnish assault gun, captured BT-7s were equipped with British 114mm howitzers.
• BT-IS - Prototype/proof-of-concept platform with heavily sloped armor; forerunner of the armor design on the T-34.
• BT-SW-2 Cherepakha ("turtle") – Another prototype, which took the the armour sloping to an extreme.

BT tank - Specifications

BT tank - Combat History

BT tanks were used in combat on several occasions prior to World War II. A battalion of BT-5s saw action on the Republican side in the Spanish Civil War, where their 45mm guns could easily destroy the opposing German and Italian light tanks. In the border skirmishes against Japan in 1939, both BT-5s and BT-7s were used. Again the BT generally outclassed the lightweight enemy tanks. Against Finland during the Winter War (mainly BT-2 and BT-5 models) the BT was less successful. The Finnish forces were well-led, highly motivated and defending very constricted terrain. The thinly-armored BTs were very vulnerable to dug-in Finnish antitank guns.

In the Second World War, BT-5s and BT-7s took part in the Soviet occupation of Poland in 1939, and in large numbers in the battles of 1941. Most of these tanks were abandoned or destroyed in the disasterous 1941 campaign. A few continued in use in 1942, but they became quite rare after that time.

The Red Army planned to replace the BT series with the T-34 and had just begun doing so when the German invasion (Operation Barbarossa) took place.

BT tank - Technical Legacy

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.

See also

• Kharkiv Morozov Machine Building Design Bureau

Adapted from the Wikipedia article "BT tank", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki