BT-7: Soviet Cavalry Tank

BT-7.

 

The BT-7 was the last of the BT series of Soviet cavalry tanks that were produced in large numbers between 1935 and 1940. It was lightly armored, but reasonably well-armed for the 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.

The BT-7's successor was the famous T-34 medium tank, introduced in 1940, which replaced all of the Soviet fast tanks, infantry tanks, and medium tanks then in service.

Development

The first prototypes of the BT-7 had a distinctive canted-ellipse shaped turret mounting both the main gun and a coaxial machine-gun. The specification also called for the project to allow for the installation of new guns without any significant change to the framework: the 76 mm KT-26 or PS-3 main gun (a short-barreled howitzer) and the 45 mm 20K model 1932/38, a long-barreled, high-velocity gun useful against tanks, but less effective than the 76 mm gun against infantry.

In the rear of the turret, there was a rotating drum-type magazine for 18 45 mm shells or a radio station. The prototype underwent an extensive testing program in the summer and autumn of 1934. As a result of this testing, it was felt that a machine-gun was unnecessary on a tank with a 3-man crew, especially as it made the assembly of the turret more complicated.

Therefore, in early 1935, the tank went into production with a simpler design, incorporating the turret from the BT-5. (However, the idea of a wheeled/tracked vehicle with a 76 mm cannon was not abandoned and the plant was commissioned to develop a new BT-7 turret from the turret of the T-26-4.) In the production model, a cylindrical turret housed a 45 mm 20K gun with a DT machine gun. On some of the tanks, a model 71-TC radio with frame antenna was installed.

The crew consisted of three men: the commander (who also served as the gunner); the loader and the driver. In 1937, the company launched production of the BT-7 with a conical turret. The main armament remained the same, but the ammunition was increased to 44 rounds. All serving tanks now installed the DT machine gun in the rear niche. For the firing of the gun and coaxial machine gun at night, the tank was equipped with two special projector-type headlamps, and a mask placed on the gun. Subsequently, these lights were retrofitted to earlier models of the tank. Improvements were also made to the drive wheels, caterpillar tracks and gearbox by 1938.

In parallel with the main modification, 153 BT-7 (Artillery) tanks were produced between 1936 and 1938. These were fitted with a larger turret and a 76 mm KT-type gun with 50 rounds of ammunition (40 in a tank with a portable radio).

In 1938, four experimental BT-8 tanks mounted with V-2 diesel engines were produced. After comparative tests of the BT-7 and BT-8, the diesel tanks were put into production in 1940 (under the designation BT-7M) with the powerplants being produced in a separate plant of the Voroshilovets factory to ensure supply. The diesel tanks were more fuel efficient, and the petrol-powered tanks were soon placed into reserve.

Several experimental tanks were conceived based on the BT series, for example the wheeled BT-IS, designed by N.F. Tsyganov, a platoon commander in the 4th Armored Regiment of the Ukraine Military District and self-taught designer. The type successfully passed field tests, but was not ordered in bulk. Another Tsyganov design was the SV-2 "Cherepakha" (turtle), with a new design of hull and turret. There was also the command tank KBT-7 with a fixed superstructure, the OT-7 mounting a flamethrower, the KhBT-7 designed to protect from toxic contamination and lay smokescreens, the SBT bridgelayer and the TTBT-7 and Thubten-7 radio-controlled tanks (known at the time as Teletanks). Finland converted 18 captured tanks into BT-42 assault guns.

Shortly before Operation Barbarossa (the German invasion of the Soviet Union), the BT-7 underwent an up-armoring program. In 1940, the Ilyich Iron and Steel Works in Mariupol produced 50 sets of hinged homogeneous armor for the BT-7M, which increased the weight of the test tank to 18 tons. Unfortunately, nothing is known about the installation of these kits to military units.

Between 1935 and 1940, 5753 BT-7 tanks of all modifications were built.

BT-7, BT-7M

Type: Light cavalry tank

Place of origin: Soviet Union

In service: 1935–45

Used by:

Soviet Union

Mongolia

Finland (captured)

Hungary (captured)

Romania (captured)

Nazi Germany (captured)

Wars:

Soviet–Japanese Border Wars

World War II

Winter War

Continuation war

Soviet–Japanese War

Designer: Morozov

Designed: 1935

Manufacturer: KhPZ

Produced: 1935–40

Number built: 5753

Variants:

BT-7 (Artillery)

BT-7M (BT-8)

BT-IS

Specifications (BT-7 Model 1937)

Mass: 13.9 tonnes (13.7 long tons; 15.3 short tons)

Length: 5.66 m (18 ft 7 in)

Width: 2.29 m (7 ft 6 in)

Height: 2.42 m (7 ft 11 in)

Crew: 3 (commander, loader, driver)

Armor: Hull: 6–40 mm

Turret: 10–15 mm

Main armament: 45 mm anti-tank gun M1932/38 (20-K)

Secondary armament: 2 x 7.62 mm DT machine gun

Engine:

Mikulin M-17T (V-12) gasoline

450 hp (340 kW) at 1,750 rpm

Power/weight: 32.37 hp/tonne

Transmission: Chain drive (tracks: sliding gear)

Suspension: Christie

Ground clearance: 0.305 m (10 in)

Fuel capacity: 620 liters (160 US gal)

Operational range:

Road: 250 km (160 mi)

Off-road: 120 km (75 mi)

Maximum speed:

Road: 72–86 km/h (45–53 mph)

Off-road: 50 km/h (31 mph)

Steering system: steering stick

Combat Experience

In June 1941, at the outset of Barbarossa, the BT-7 was used as the main cavalry tank of the Soviet army. Tank losses were high, with over 2,000 BT-7 series tanks lost in the first 12 months on the Eastern Front. Hundreds more had been immobilized before the invasion by poor maintenance, and these had to be abandoned as the Soviet forces withdrew eastward. The BT-7 continued to be operated by the armored and mechanized forces of the Red Army for almost the entire war, but in greatly-decreased numbers after 1941.

By 1 November 1942, 32 BT-7 tanks were captured by Romanian forces. BT-7 series tanks continued in use by the Soviets in the Far East, against Japanese forces which lacked the heavy tanks of their German allies. BT-7 tanks were employed against Japanese forces in the Battles of Khalkhin Gol in 1939 and the Manchurian Strategic Offensive Operation in 1945.

Survivors

Although many BT-7 tanks were produced, as of early 2018, there is only one known remaining BT-7 that is currently in operational order, located in Belarus.

Organization and Use

The Table of Organization and Equipment for a typical Soviet light tank brigade in 1939 is as follows:

3 tank battalions, each containing:

Three tank companies, each with 17 BT-7 or T-26 tanks;

1 signal platoon;

1 anti-tank platoon with three 45 mm antitank guns;

1 antiaircraft machine gun (AA MG) platoon

1 reserve tank company, with eight BT-7 or T-26 tanks;

1 signal company, with five T-37A tanks;

1 motorized infantry battalion, containing

3 motorized rifle companies;

1 signal platoon;

1 antitank platoon with three 45 mm antitank guns;

1 AA MG platoon

1 additional AA MG platoon in brigade headquarters;

1 motor transport battalion;

1 reconnaissance battalion;

1 pioneer company;

1 medical company;

1 chemical company (flamethrowers)

Further Reading

Milsom, John F. (1971). Russian BT Series. Profile AFV Weapons No. 37.

Mikhail Baryatinskiy, 2006, Russian Armour Volume 2: Light Tank T-27, T-38, BT, T-26, T-40, T-50, T-60, T-70.

Zaloga, Steven J.; Grandsen, James (1984). Soviet Tanks and Combat Vehicles of World War Two. London, UK: Arms & Armour Press.

 

BT-7-1(V) (commander’s version) medium tank was a BT-7 fitted with the turret from the BT-5(V). Seen with tracks removed for travel on paved surfaces.

 

BT-7-2 medium tank with a new conical turret, thicker front armor, all-welded construction, a more powerful aero type engine, ball-mounted machine gun in the turret rear in some vehicles, new gearbox, and extra fuel and ammunition stowage. The BT-7 was the major service type in 1939-41.

 

BT-7s on maneuvers.

 

Late model BT-7s (BT-7-2s) advancing down Gorky Street in Moscow on their way to the front on 7 November 1941. The battles around Moscow were probably the last occasion on which BT tanks were used in large numbers.

 

Russian officer observes from a BT-7(V), the commander’s model which had a frame antenna around the turret.

 

A BT-7 destroyed during the 1941 German offensive. BT-7 Model 1935: welded hull, redesigned hull front, new Mikulin M-17T engine (licensed copy of a BMW engine), enclosed muffler. BT-7 Model 1937: new turret with sloping armor. BT-7TU: command version, with whip antenna instead of earlier frame antenna. BT-7A: artillery support version with 76.2 mm howitzer. OP-7: flame-thrower version with external fuel panniers (prototype only).

 

Soviet BT-7.

 

BT-7M medium tank was based on the BT-7 chassis but with considerable re-design to take a V-2 diesel engine and a full-width sloped front glacis plate instead of the faired nose of earlier BTs, and the turret from the T-28 with two ball-mounted machine guns and a 76.2mm gun. Retained wheel/track running ability. Also called the BT-8. Saw limited production.

 

Destroyed BT-7.

 

BT-1S medium tank prototype was the final development of the BT series. Based on the BT-7M but with sloped side armor as well as the sloping glacis plate, retaining the conical turret of the BT-7-2 and had removable side skirts. This was a important development vehicle in the evolution of the T-34 medium tank.

 

A German infantryman walks toward the body of a killed Soviet soldier and a burning BT-7 light tank in the southern Soviet Union in 1941, during the early days of Operation Barbarossa.

 

Snow-covered Soviet BT-7. They remained standing after the summer 1941 fighting

 

German Feldgendarmerie with an abandoned BT-7. The Feldgendarmerie were the primary military police units of the German Army (Wehrmacht) during World War II. Highly trained and invested with broad police powers, they were responsible for maintaining troop discipline, controlling traffic, securing rear areas, and managing prisoners of war across occupied territories.

 

Abandoned BT-7 and BT-5 of the 34th Tank Brigade, March 1940.

 

BT-7 tanks of the Soviet 24th Light Brigade enter Lviv.

 

German troops pose on a BT-7.

 

Abandoned BT-7 tanks, 1941.

 

Abandoned BT-7 tank.

 

Finnish soldiers examines a BT-7 destroyed from an internal explosion.

 

German infantry and Soviet armored forces BT-7 tanks meet along the agreed-upon demarcation line after the 1939 invasion of Poland.

 

Two BT-7 tanks in a ditch. The tank in the background appears to have been abandoned when it got stuck in the ditch. The tank in the foreground appears to have suffered an internal explosion, blowing off the turret and the resultant fire has burned the rubber off the roadwheels.

 

As German troops march past on the road in the background, several soldiers investigate the abandoned BT-7 tank. Note the shell hole in the hull side.

 

The BT-7 in the foreground has been knocked out, while the BT-7 in the background was abandoned.

 

German troops examine an abandoned BT-7 tank.

 

A column of captured Soviet tanks in Finnish army service. The first and last tanks are BT-7s. The middle tank is a T-26 which is being towed by the first BT-7.

 

BT-7 tank knocked out and pushed over into the ditch to clear the road. Smolensk.

 

Knocked out BT-7 at right and a T-26 at left in Volkhov, Aug 1941.

 

German soldier examines an abandoned BT-7 tank.

 

Two captured turretless Soviet BT-7 tanks converted into munitionspanzers (?). Note the lead vehicle is towing a Soviet 45mm anti-tank gun M1937 (53-K) — transporting the gun for delivery to a frontline unit (?). A Panzer 38(T) is in the background.

  

Whitewashed BT-7 tanks parked at the edge of a wooded area.

 

German troops examine a destroyed BT-7 tank. The tank caught fire and all the rubber has been burned off the rear roadwheel while only partially burned off the third roadwheel. 

 

BT-7 tank.

 

BT-7M Cavalry Tank.

 

Knocked out BT-7 "271", 1941. Note the numerous small caliber shell holes on the side of the hull.

 

BT-7 tanks in the background prior to the offensive at Khalkhyn Gol in 1939.

 

Three abandoned KV-2 heavy tanks and a BT-7, June 1941.

 

A horse-mechanized group supported by a BT-7 tank advances to break through the German defenses. May 1942.

 

A knocked-out and burning BT-7 tank, June 1941.

 

Soviet tanks, including BT-7s, at Khalkhin Gol in 1939.

 

BT-7 Model 1935, 1943.

 

Destroyed BT-7 tank during the German advance to the Dniester, Jul 1941.

 

Destroyed BT-7 tank on a bridge in Riga, Latvia, 21 Jun 1941.

 

BT-7 tank in Rakaŭ in the Minsk Region of Belarus, 17 Sep 1939.

 

 

 Soviet occupation of Bessarabia and Northern Bukovina. BT-7 tanks participate in a military parade in Kishinev on 4 Jul 1940.

 

Soviet tanks cross the Khalkhin Gol river in Aug 1939.

 

A BT-7 tank with a truck and troops in the center of Riga, 1940.

 

 Soviet tanks at the Khalkhin Gol, 1939.

 

BT-7 knocked out and burned (note rubber on roadwheels has been burned off). In the background is the church of the Nativity of the Virgin Mary, 22 Jul 1941.

 

BT-42 assault gun with the turret facing the rear of the vehicle. The BT-42 was a Finnish assault gun, constructed during the Continuation War. It was constructed from captured Soviet BT-7 light tanks and British 4.5-inch howitzers (114 mm-caliber light howitzer, model 1908) from 1918, which had been donated during the Winter War. Eighteen vehicles were constructed, yet only one survives to this day, housed at the Parola Tank Museum.

 

BT-7M tank, 1942.

 

Tanks produced at Plant No. 183 in 1941. From left to right: A-8 (BT-7M), A-20, T-34 Model 1940 (L-11 gun), T-34 Model 1941 (F-34 gun).