BT tank


The BT tank was one of a series of Soviet light tanks produced in large numbers between 1932 and 1941. They were lightly armoured, but reasonably well-armed for their time, and had the best mobility of all contemporary tanks. The BT tanks were known by the nickname Betka from the acronym, or by its diminutive Betushka. The successor of the BT tanks was the famous T-34 medium tank, introduced in 1940, which would replace all of the Soviet fast tanks, infantry tanks, and light tanks in service.

Design

The BT tanks were "convertible tanks". This was a feature that was designed by J. Walter Christie 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 rearmost road wheel on each side, allowing the tank to travel at very high speeds on roads. In wheeled mode, the tank was steered by pivoting the front road wheels. According to historical researches, this feature may have been required by Stalin for planned European warfare within a strategy similar to blitzkrieg. However, Soviet tank forces soon found the convertible option of little practical use; in a country with few paved roads, it consumed space and added needless complexity and weight. The feature was dropped from later Soviet designs.
Christie, a race car mechanic and driver from New Jersey had failed to convince the U.S. Army Ordnance Bureau to adopt his Christie tank design. 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 of the Christie tank to the Soviet Union. At least two of Christie's M1931 tanks 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 delivered to the Kharkov Komintern Locomotive Plant. The original Christie tanks were designated fast tanks by the Soviets, abbreviated to BT. Based both on them and on other plans obtained earlier, three unarmed BT-2 prototypes were completed in October 1931 and mass production began in 1932. Most BT-2s were equipped with a 37 mm B-3 gun and a machine gun, but a shortage of 37 mm guns led to some early examples being fitted with three machine guns. The sloping front hull armor design of the Christie M1931 prototype was retained in later Soviet tank hull designs, later adopted for side armor as well. The BT-5 and later models were equipped with 45 mm guns.

Variants

Soviet Union

BT-1 to BT-4

  • BT-1: Christie prototype with no turret
  • BT-2 Model 1932: M-5-400 engine ; three turret versions were produced: with single 37 mm B-3 ; 37 mm gun and one DT machine gun ; twin DP machine guns in place of gun and a single DT machine gun. In late 1932, modified to BT-3 but produced under the same designation.
  • *BT-2-IS: prototype with three-axle drive, rejected due to complexity.
  • BT-3: same as BT-2, produced according to metric system. In official documentation referred to as BT-2.
  • BT-4: was a design with welded hull and minor changes in the suspension. Three prototypes produced. A fake "variant" with two machine gun turrets of early T-26 can be found captioned as BT-4, but it has never existed and images are edited.

    [BT-5]

  • BT-5: larger cylindrical turret, 45 mm 20-K gun, coaxial DT machine gun. Earlier tanks used simpler fully cylindrical bolted turrets with rear bustle welded on.
  • BT-5PKh: snorkelling variant
  • BT-5A: artillery support version with 76.2 mm howitzer
  • RBT-5: rocket launcher artillery version, equipped with two 420 mm tank torpedoes
  • BT-5 flamethrower tank
  • BT-5-IS: prototype with three-axle drive, rejected due to complexity. In 1938 the same prototype was upgraded with sloped side plates, leading to development of BT-SV-2.
  • PT-1A: amphibious variant with new hull
  • TT-BT-5: teletank, remote-radio-controlled tank
  • Tsyganov's BT: a "very fast" version of BT-5 by N. F. Tsyganov, which had a set of 30 wheels connected by a chain. It was supposed to reach up to 105 km/h, but was rejected due to complexity and only one mock-up was built
  • BT-6: BT-5 with fully welded hull, predecessor of BT-7

    [BT-7]

  • BT-7 Model 1935: welded hull, redesigned hull front, new Mikulin M-17T engine, enclosed muffler, new short-pitch tracks
  • BT-7 Model 1937: new turret with sloping armour
  • BT-7TU: command version, with whip antenna instead of earlier frame antenna
  • BT-7A: artillery support version with a 76.2 mm howitzer in larger turret similar to one of T-28. 155 were intended to be made, but of them 21 were finished with normal BT-7 turrets and one lacked a cannon, this particular tank was later used for testing 76.2 mm L-11 and F-32 cannons.
  • OP-7: flame-thrower version with external fuel panniers
  • TT-BT-7: teletank, remote-radio-controlled tank
  • BT-SV-2 Cherepakha : another prototype, this took armour sloping to an extreme
  • BT-7M : new V-2 diesel engine replacing earlier gasoline engines.

    A-20/A-32

  • ' : prototype for a new BT tank, with 20 mm extremely sloped armour inspired by BT-SV-2 prototype, 45 mm 20-K gun, model V-2 diesel engine. Lost out in trials to the tracked-only A-32. The only built prototype is known to have participated in the Battle of Moscow. In 1941, as the Germans neared Moscow, the situation was so desperate that everything battle-worthy was put into service by the Soviets. The A-20 prototype, which at that time was at Kubinka army proving ground near Moscow for evaluation trials, was immediately put into service together with other prototypes of tanks present here, which were organized into a separate company led by Captain Semenov. Later on, the tank was included in the 22nd Tank Brigade organic, together with its predecessors and successors, BT-7 and T-34 tanks. On 1 December 1941, during fighting, the tank was seriously damaged and sent to the rear for repairs. Three days later, it re-entered service with the 22nd Tank Brigade until mid-December, when the tank was again damaged and evacuated to the rear. After these events, its fate is unknown.
  • ' : initially known as the A-20G and then renamed to A-32, it was the competitor to the A-20. The wheels-and-tracks system was removed for the first time from the BT tanks series, making the tank design and production easier, more reliable and, especially, lighter; in fact, armor was increased to 30 mm, hull was enlarged, 5th road wheel was fitted in for better ground-pressure distribution and the 45 mm 20-K gun was replaced by the 76.2 mm L-10 gun, but the weight increased by only 1 ton. Trials in 1939 showed that the tank armor could be upgraded and thus a request for increase to 45 mm was made. A second prototype was specially created for the purpose, this time equipped with turret and 45 mm armament from the A-20 and with additional weights placed on special brackets welded on the hull and turret to simulate mass of the up-armored tank. After satisfactory tests, other requests were made, for example to improve the visibility from inside the tank and to adopt the newer F-32 gun, which finally lead to the A-34, serial produced as the famous T-34.

    Foreign variants

  • BT-42: Finnish assault gun; captured BT-7s were equipped with British QF 4.5-inch howitzers. The co-axial DT gun was removed and turret re-designed to accommodate the new gun. Only 18 were made.
  • BT-43: Finnish armoured personnel carrier; captured BT-7 equipped with troop accommodation. Only one prototype was made.

    Specifications

Combat history

BT tanks saw service in the Second Sino-Japanese War, Spanish Civil War, Battles of Khalkhin Gol, the Winter War in Finland, and in World War II.

Spanish Civil War

In the Spanish Civil War, a regiment of 50 BT-5's fought on the Republican side. They were manned by the members International Brigades trained in USSR and by some Soviet tankists. Their first combat on 13 October 1937 during the Zaragoza Offensive was disastrous: 19 of the 48 tanks, and one third of their crews were killed or wounded, due to bad planning by the Spanish Second Republic.Later, 12 more were lost from December 1937 to February 1938 during the Battle of Teruel. A few captured BT-5s were also used by the Nationalist side.

Chinese service

The Chinese Nationalist Army had four BT-5s which fought against the Imperial Japanese Army during the Second Sino-Japanese War.

Battles of Khalkin Gol

During the Battles of Khalkhin Gol, which lasted from May to September in 1939, BT tanks were easily attacked by Japanese "close quarter" teams which were – in lieu of anti-tank weapons – armed with petrol bottles. The BT-5s and BT-7s, operating in temperatures greater than on the Mongolian plains, easily caught fire when a Molotov cocktail ignited their gasoline engines. General Georgy Zhukov made it one of his "points" when briefing Joseph Stalin, that his "...BT tanks were a bit fireprone...." Conversely, many Japanese tank crews held the Soviet 45mm gun of the BT-5 and BT-7 in high esteem, noting, "...no sooner did they see the flash from a Russian gun, than they'd notice a hole in their tank, adding that the Soviet gunners were accurate too!"
After the Battles of Khalkhin Gol, the Soviet military broke into two camps; one side was represented by Spanish Civil War veterans General Pavel Rychagov of the Soviet Air Force, Soviet armour expert General Dimitry Pavlov, and Stalin's favorite, Marshal Grigory Kulik, Chief of Artillery Administration. The other side consisted of the Khalkhin Gol veterans led by Generals Zhukov and Grigory Kravchenko of the Soviet Air Force. The lessons of Russia's "first real war on a massive scale using tanks, artillery, and airplanes" at Khalkhin Gol went unheeded.