BT tank

BT tank series

Company type	Military vehicle series
Industry	Armored fighting vehicles
Founded	1932
Defunct	1941
Fate	Replaced by T-34 medium tank
Headquarters	Soviet Union
Products	Light tanks (BT-1 to BT-7, prototypes A-20, A-32)

The BT tank (Russian: Быстроходный танк/БТ, romanized: Bystrokhodnyy tank/BT, meaning "fast-moving tank" or "high-speed tank") was a series of Soviet Union light tanks manufactured extensively from 1932 until 1941. Despite their relatively light armor, these tanks were well-armed for their era and exhibited superior mobility compared to other tanks available at the time. Commonly referred to by the nickname Betka, derived from the acronym, or affectionately called Betushka, these vehicles represented a key stage in Soviet armored development. The renowned T-34 medium tank, introduced in 1940, eventually succeeded the BT series, replacing all Soviet fast, infantry, and light tanks in active service.

Design

The defining characteristic of the BT tanks was their "convertible" capability—a concept introduced by J. Walter Christie aimed at minimizing track wear issues common in the 1930s. This system allowed crews to remove the tracks within approximately half an hour and switch to a chain-driven mechanism connected to the rear road wheels on each side, enabling high-speed travel on paved roads. Steering in wheeled mode was achieved by pivoting the front road wheels. Historical Soviet research suggests that this feature might have been incorporated due to Stalin’s requirements for rapid European campaigns employing tactics akin to blitzkrieg. However, practical experience revealed that in the largely unpaved terrain of the Soviet Union, this convertible function offered limited utility while adding unnecessary complexity and weight. Consequently, it was omitted in subsequent Soviet tank designs.

J. Walter Christie, a race car driver and mechanic from New Jersey, had unsuccessfully attempted to persuade the U.S. Army Ordnance Bureau to adopt his innovative tank design known as the Christie tank. In 1930, Soviet agents working through Amtorg, a Soviet trade entity in New York, leveraged political connections to acquire blueprints and technical specifications for Christie's design. Subsequently, at least two of Christie's M1931 tanks—stripped of their turrets—were purchased in the United States under false pretenses labeling them as "agricultural tractors" and shipped covertly to the Soviet Union. These vehicles were delivered to the Kharkov Komintern Locomotive Plant (KhPZ). The Soviets designated these original Christie tanks as "fast tanks," abbreviated as BT (later known as BT-1). Drawing upon these models and earlier obtained plans, three unarmed BT-2 prototypes were completed by October 1931 with full-scale production starting in 1932. Most BT-2 units featured a 37 mm B-3 (5-K) cannon accompanied by a machine gun; however, due to shortages of the 37 mm guns, some early models were outfitted with three machine guns instead. The sloped frontal armor design of Christie's M1931 prototype was retained in later Soviet hull designs and extended to side armor as well. Subsequent variants such as the BT-5 were equipped with more powerful 45 mm guns.

Variants

BT-6

A-32 prototype tested in 1939, featuring a 76.2 mm L-10 gun and five road wheels.

BT-1 through BT-4

• BT-1: Christie design prototype without a turret
• BT-2 Model 1932: powered by the M-5-400 engine, a copy of the U.S. Liberty L-12 engine; produced in three turret variants: armed with a single 37 mm B-3 (5-K) (60 units); equipped with a 37 mm gun plus one DT machine gun (148 units); or fitted with twin DP machine guns replacing the main gun alongside a single DT machine gun (412 units). Late in 1932, it was updated to BT-3 but retained the BT-2 designation during production.
  • BT-2-IS: experimental model featuring a three-axle drive system, ultimately discarded due to its complexity.
• BT-3: identical to the BT-2 but manufactured using metric measurements instead of the Imperial system; officially still referred to as BT-2 in documents.
• BT-4: incorporated a welded hull and minor suspension modifications; three prototypes were built with partially riveted hulls. Note that images labeled as BT-4 with dual machine-gun turrets from early T-26 tanks are fabricated and do not represent an actual variant.

BT-5

• BT-5: introduced a larger cylindrical turret mounting a 45 mm 20-K gun along with a coaxial DT machine gun. Earlier versions featured simpler fully cylindrical bolted turrets with rear bustle welds.
• BT-5PKh: snorkel-equipped variant (prototype stage only)
• BT-5A: artillery support model fitted with a 76.2 mm howitzer (prototype stage only)
• RBT-5: rocket artillery variant armed with two 420 mm tank torpedoes (prototype stage only)
• BT-5 flamethrower tank (prototype stage only)
• BT-5-IS: experimental three-axle drive version rejected for its complexity; upgraded in 1938 with sloped side armor, leading to the development of the BT-SV-2.
• PT-1A: amphibious model featuring an updated hull design (prototype stage only)
• TT-BT-5: teletank, remotely operated via radio control (prototype stage only)
• Tsyganov's BT: an exceptionally fast BT-5 version designed by N. F. Tsyganov, utilizing 30 wheels linked by a chain aiming for speeds up to 105 km/h; rejected due to mechanical complexity after only one mock-up was completed
• BT-6: prototype combining the BT-5 with a fully welded hull, serving as the forerunner to the BT-7

BT-7

• BT-7 Model 1935: featured a welded hull with redesigned frontal armor, equipped with the new Mikulin M-17T engine (a licensed BMW copy), enclosed muffler, and short-pitch track design
• BT-7 Model 1937: introduced a turret with sloped armor plating
• BT-7TU: command tank variant fitted with a whip antenna replacing the older frame antenna
• BT-7A: artillery support version mounting a 76.2 mm howitzer within a larger turret similar to that of the T-28. Although 155 units were planned, 21 were completed with standard BT-7 turrets and one lacked armament; this particular vehicle was later used for testing 76.2 mm L-11 and F-32 guns.
• OP-7: flame thrower version equipped with external fuel tanks (prototype only)
• TT-BT-7: teletank, radio-controlled remote vehicle (prototype only)
• BT-SV-2 Cherepakha ("turtle"): experimental model emphasizing extreme armor sloping
• BT-7M (1938 prototypes designated A-8; occasionally called BT-8): powered by the new V-2 diesel engine developed by Kharkiv, replacing previous gasoline engines

A-20/A-32

• Template:Visanc (also referred to as Template:Visanc): served as a prototype intended to replace the BT series, featuring highly angled 20 mm armor inspired by the BT-SV-2 experimental model, armed with a 45 mm 20-K cannon, and powered by a V-2 diesel engine. It was ultimately outperformed in evaluations by the fully tracked A-32 model. The sole prototype constructed is documented to have taken part in the Battle of Moscow. In 1941, as German forces approached Moscow, the Soviet command mobilized all operational vehicles for combat. At that time, the A-20 was undergoing tests at the Kubinka military proving ground near Moscow and was promptly deployed alongside other prototype tanks stationed there, forming a distinct company under Captain Semenov’s command. Subsequently, this tank became part of the 22nd Tank Brigade’s roster, operating alongside its predecessors and successors, including BT-7 and T-34 models. On 1 December 1941, it sustained severe damage during combat and was withdrawn for repairs. After three days, it returned to active duty with the 22nd Tank Brigade until mid-December when it was again damaged and removed from the front lines. Its status following these incidents remains unknown.
• Template:Visanc (originally designated as Template:Visanc, with "G" indicating tracked): this model competed directly against the A-20. It marked the first removal of the wheels-and-tracks hybrid system characteristic of BT tanks, simplifying design and manufacturing processes while enhancing reliability and reducing weight. Armor thickness increased to 30 mm, the hull dimensions were expanded, and a fifth road wheel was added to better distribute ground pressure. The 45 mm 20-K gun was replaced by a 76.2 mm L-10 cannon; despite these enhancements, the tank’s weight rose by only one ton (from 18 tons in the A-20 to 19 tons in the A-32). Testing conducted in 1939 indicated potential for further armor improvements, prompting a request to increase protection to 45 mm. To evaluate this upgrade, a second prototype was built incorporating the turret and 45 mm armament from the A-20, with added weights attached via brackets on both hull and turret to simulate the heavier armor mass. After successful trials, additional modifications were proposed, including improved internal visibility and adoption of newer weaponry such as the F-32 gun (which eventually evolved into the L-11 and F-34 used on later prototypes and production units). These developments culminated in the creation of the A-34, which entered serial production as the renowned T-34.

Foreign adaptations

• BT-42: A Finnish assault vehicle created by mounting British QF 4.5-inch howitzers onto captured BT-7 chassis. The original co-axial DT machine gun was removed, and the turret was modified to fit the new artillery piece. Production was limited to 18 units.
• BT-43: Finnish armored personnel carrier variant developed from a captured BT-7, redesigned to transport infantry. Only a single prototype was constructed.

Specifications

Comparison among BT-2, BT-5, BT-7, BT-7A, and BT-7M (BT-8)

	BT-2	BT-5	BT-7	BT-7A	BT-7M (BT-8)
production quantity	620	2,108 or 5,000	4,965 or 2,000	154	790
crew size	3	3	3	3	3
combat weight	10.2 t	11.5 t	14 t	14.5 t	14.7 t
length overall	5.58 m	5.58 m	5.66 m	5.66 m	5.66 m
width overall	2.23 m	2.23 m	2.29 m	2.29 m	2.29 m
height overall	2.20 m	2.25 m	2.42 m	2.52 m	2.42 m
armor thickness	6–13 mm	6–13 mm	6–13 mm	6–13 mm	6–22 mm
primary armament	37 mm Model 30	45 mm Model 32	45 mm Model 34	76.2 mm Model 27/32	45 mm Model 32/38
main gun ammunition capacity	96 rounds	115 rounds	146 rounds	50 rounds	146 rounds
machine guns installed	DT	DT	DT	2×DT	3×DT
engine output and type	400 hp M-5	400 hp M-5	500 hp M-17T	500 hp M-17T	450 hp V-2
fuel capacity and type	400 L gasoline	360 L gasoline	620 L gasoline	620 L gasoline	620+170 L diesel
maximum road speed (wheels)	"100 km/h (62 mph)" or 72 km/h (45 mph)	"72 km/h"	"86 km/h (53 mph)"	"86 km/h"	"86 km/h"

! maximum road speed (tracks) |"52 km/h (32 mph)" |"52 km/h" |"52 km/h"

|"62 km/h (38.5 mph)" |} ! power-to-weight ratio |"39 hp/t" |"35 hp/t" |"36 hp/t" |"34 hp/t" |"31 hp/t" |} ! operational road range |"300 km" |"200 km" |"250 km" |"250 km" |"400 km" |} ! tactical range |"100 km" |"90 km" |"120 km" |"120 km" |"230 km" |}

Combat record

BT series tanks were deployed in multiple conflicts, including the Second Sino-Japanese War, the Spanish Civil War, the Battles of Khalkhin Gol (also referred to as the Nomohan Incident), the Winter War in Finland, and throughout World War II.

Spanish Civil War

During the Spanish Civil War (1936–1939), a unit consisting of 50 BT-5 tanks operated on the side of the Republicans. These vehicles were crewed by members of the International Brigades trained in the USSR, alongside some Soviet tank operators. Their initial engagement on 13 October 1937, during the Zaragoza Offensive, ended disastrously: 19 out of 48 tanks were lost, and approximately one-third of their crews suffered casualties due to poor operational planning by the Spanish Second Republic. From December 1937 to February 1938, an additional 12 tanks were destroyed in the course of the Battle of Teruel. Notably, a number of captured BT-5 tanks were also utilized by forces aligned with the Nationalists.

Chinese service

The Chinese Nationalist Army fielded four BT-5 tanks which saw action against the invading Imperial Japanese Army during the Second Sino-Japanese War (1937–1945).

Battles of Khalkhin Gol

BT-7 tanks engaged in combat at Khalkhin Gol

In the course of the Battles of Khalkhin Gol (also known as the Nomonhan Incident), spanning May to September 1939, BT tanks faced significant vulnerability to Japanese "close combat" squads armed not with conventional anti-tank weapons but with petrol-filled bottles, later termed "Molotov cocktails." Operating under temperatures exceeding 100 °F (38 °C) on the Mongolian steppe, BT-5 and BT-7 tanks were highly susceptible to ignition when these incendiary devices struck their gasoline-powered engines. General Georgy Zhukov highlighted this vulnerability during briefings with Joseph Stalin, noting that his "...BT tanks were somewhat prone to catching fire...." Conversely, many Japanese tank crews respected the accuracy and effectiveness of the Soviet 45mm guns mounted on BT-5 and BT-7 tanks, remarking that upon witnessing a Russian gun flash, they would soon find a hole in their own armor.

Following Khalkhin Gol, Soviet military leadership divided into two factions: one led by Spanish Civil War veterans including General Pavel Rychagov from the Soviet Air Force, armor specialist General Dimitry Pavlov, and Marshal Grigory Kulik, Stalin’s favored Chief of Artillery Administration. The opposing group comprised veterans from Khalkhin Gol itself, headed by Generals Zhukov and Grigory Kravchenko of the Soviet Air Force. Despite being Russia’s first extensive conflict involving combined arms such as tanks, artillery, and aircraft, many lessons from Khalkhin Gol were ultimately disregarded.

Winter War

In the 1939–1940 Winter War against Finland, the BT-2, BT-5, and BT-7 tanks did not achieve the same level of effectiveness against Finnish forces as they had demonstrated earlier in combat against the Japanese at Khalkin Gol.

World War II

A destroyed Soviet BT-7 model 1935 during the 1941 German offensive

Throughout the European theater of World War II, BT-5 and BT-7 tanks were deployed during the 1939 Soviet invasion of Poland. The Red Army had initiated plans to phase out the BT tank series in favor of the T-34 and had just begun this transition when Operation Barbarossa, the German assault on the Soviet Union, commenced on 22 June 1941. In the ensuing battles of 1941, large numbers of BT-series tanks were engaged, with thousands being abandoned or destroyed. Although a limited number remained operational into 1942, they seldom encountered German forces in combat after that period.Template:Fix/category

In August 1945, during the concluding phase of World War II, a considerable contingent of BT-7 tanks participated in the Soviet invasion of Manchuria, engaging Japanese occupation troops in Northeast China. This marked the final combat deployment of BT tanks.Template:Fix/category

Operators

• Template:Country data Soviet Union – principal user
• Template:Country data Kingdom of AfghanistanTemplate:Fix/category
• Template:Country data Republic of China – operated 30 BT-5 units
• Template:Flagdeco People's Republic of China
• Finland – operated captured vehicles
• Romania – utilized captured BT-2 and BT-7 tanks
• Hungary – employed captured units
• Template:Country data Nazi Germany – used captured tanks
• Template:Flagdeco Mongolian People's Republic – possessed 15 BT-7 tanks
• Template:Country data Spanish Republic – acquired 50 BT-5 tanks in late 1937 for use during the Spanish Civil War
• Template:Country data Spanish State – operated vehicles seized from the Spanish Republic

Technical legacy

The BT tank family was produced in large quantities and served as the Red Army’s cavalry tank force throughout the 1930s, offering superior mobility compared to other tank models of that era. This advantage led to numerous experiments and derivative designs, primarily developed at the KhPZ factory in Kharkov.

The most significant outcome stemming from the BT series was the development of the T-34 medium tank. In 1937, KhPZ assembled a new design team tasked with creating an advanced successor to the BT tanks. Initially led by chief designer Mikhail Koshkin, and following his passing by Morozov, this team produced two prototypes: a lighter model named A-20 and a more heavily armed and armored variant called A-32. The A-32 was envisioned as a "universal tank" intended to replace all existing T-26 infantry tanks, BT cavalry tanks, and T-28 medium tanks. Although this consolidation plan was contentious, apprehensions regarding tank performance under potential German blitzkrieg tactics resulted in approval for manufacturing an even more heavily armored model—the T-34 medium tank.

During this development process, important technical advancements were made with test vehicles such as the BT-IS and BT-SW-2, which focused on implementing sloped armour. These innovations directly influenced the armor configuration used on the T-34. Additionally, chassis from BT tanks served as platforms for various engineering support and mobility test vehicles. For example, a bridgelayer variant equipped with a T-38 turret could deploy bridges over small gaps. Some standard models were adapted to carry fascine bundles. The RBT-5 featured twin large artillery rocket launchers mounted on either side of its turret. Experiments with extremely wide tracks included unconventional options like wooden 'snowshoes'.

The KBT-7 represented a modern armored command vehicle prototype that was under development when World War II began but was not pursued further during wartime.

During the Kiev manoeuvres of 1936, hundreds of BT tanks paraded before an audience that included British military observers. These officials returned to Britain advocating for adoption of Christie suspension technology in British cruiser tanks—a feature incorporated starting with the Cruiser Mk III. Moreover, the sharply angled hull front armor design seen on BT tanks influenced aspects of British designs such as the Matilda tank.Template:Fix/category

Sources

• Chamberlain, Peter; Ellis, Chris (1972). Global Tanks Overview. London: Cassell. ISBN 978-0-304-36141-0.
• Coox, Alvin (1985). Nomonhan; The 1939 Conflict Between Japan and Russia. 2 volumes. Stanford, CA: Stanford University Press. ISBN 978-0-8047-1160-9.
• Goldman, Stuart D. (2012). Nomonhan, 1939; How the Red Army's Triumph Influenced World War II. Annapolis, MD: Naval Institute Press. ISBN 978-1-59114-329-1.
• Zaloga, Steven J.; Grandsen, James (1984). Soviet Armored Vehicles and Tanks of WWII. London: Arms and Armour Press. ISBN 978-0-85368-606-4.
• Zaloga, Steven J. (25 August 2016). BT Fast Tank: The Red Army's Cavalry Tank 1931–45. New Vanguard 237. ISBN 9781472810656.

External links

• BT-2 Tank Archived 28 December 2018 at the Wayback Machine on Russian Battlefield
• BT-5 Tank Archived 13 September 2019 at the Wayback Machine at Russian Battlefield
• BT-7 Tank Archived 20 December 2016 at the Wayback Machine hosted by Russian Battlefield
• BT tanks and their variants Archived 14 June 2007 at the Wayback Machine at Henk of Holland website
• Recovery of BT-7 tank from the Neva river
• BT tanks, exhibits in museums and monuments featuring BT tanks
• Comprehensive article on early BT tank development translated from Russian