View source for BT-7

{{Redirect|BT-8|the first aircraft designed and built by the Seversky Aircraft Corporation|Seversky SEV-3}}
{{Use dmy dates|date=June 2017}}
{{Infobox weapon
| name = BT-7, BT-7M
| image = Soviet cavalry tank BT-7m.jpg
| image_size = 300
| caption = BT-7M, 1940, with tracks removed from the wheels and carried on the hull
| origin = {{flag|Soviet Union|1936}}
| type = [[Light tank|Light]] [[cavalry tank]]

<!-- Type selection -->
| is_artillery = 
| is_vehicle = yes
| is_UK = no
<!-- Service history -->| service = 1935–45
| used_by = {{flag|Soviet Union|1936}}<br /> {{Flagdeco|Mongolia|1940}} [[Mongolian People's Republic|Mongolia]]<br /> {{Flag|Finland}} (captured)<br /> {{flag|Hungary|1920}} (captured)<br /> {{flag|Romania}} (captured)<br /> {{flag|Nazi Germany}} (captured)
| wars = [[Soviet–Japanese Border Wars]]<br />[[World War II]]<br />[[Winter War]]<br />[[Continuation war]]<br />[[Soviet–Japanese War]]
<!-- Production history -->
| designer = [[Kharkiv Morozov Machine Building Design Bureau|Morozov]]
| design_date = 1935<ref name=v>{{cite web |url=http://www.wwiivehicles.com/ussr/tanks-medium/bt-7.asp |title=BT-7 Bystrochodnij Tankov (Fast Tank) |website=wwiivehicles.com |access-date= 2006-07-25 |archive-url=https://web.archive.org/web/20080514003735/http://www.wwiivehicles.com/ussr/tanks-medium/bt-7.asp |archive-date= 2008-05-14}}</ref>
| manufacturer = [[KhPZ]]
| unit_cost = 
| production_date = 1935–40
| number = 5753 {{efn|4821 BT-7, 779 BT-7M, 153 BT-7 (Artillery)}{{citation needed|date=September 2023}} }}
| variants = BT-7 (Artillery), BT-7M (BT-8), BT-IS<ref name=v />
<!-- General specifications -->
| spec_label = BT-7 model 1937<ref name=v />
| weight = {{convert|13.9|tonne|ton}}
| length = {{convert|5.66|m|ftin|abbr=on}}
| width = {{convert|2.29|m|ftin|abbr=on}}
| height = {{convert|2.42|m|ftin|abbr=on}}
| crew = 3 (commander, loader, driver)
<!-- Vehicle/missile specifications -->
| armour = Hull: 6–40&nbsp;mm<br/>Turret: 10–15&nbsp;mm
| primary_armament = [[45 mm anti-tank gun M1932/38 (20-K)]]
| secondary_armament = 2 x 7.62&nbsp;mm [[DT machine gun]]
| engine = [[Mikulin M-17]]T (V-12) gasoline
| engine_power = {{convert|450| hp|abbr=on}} at 1,750 rpm
| pw_ratio = 32.37&nbsp;hp/tonne
| transmission = [[Chain drive]] (tracks: [[sliding gear]])
| payload_capacity = 
| suspension = [[Christie suspension|Christie]]
| clearance = {{convert|0.305|m|in|abbr=on|sigfig=1}}
| fuel_capacity = {{convert|620|L|USgal}}
| vehicle_range = Road: {{convert|250|km|mi|abbr=on}}<br/>Off-road:  {{convert|120|km|mi|abbr=on}}
| speed = Road: {{convert|72|-|86|km/h|mph|abbr=on}}<br/>Off-road: {{convert|50|km/h|mph|abbr=on}}
| steering = steering stick
}}

The '''BT-7''' {{efn|BT ({{langx|ru|БТ}}) is the Russian abbreviation for ({{langx|ru|Быстроходный танк|translit=Bystrokhodny tank |lit=fast tank |label=none}})}} was the last of the [[BT tank|BT series]] of [[Soviet Union|Soviet]] [[cavalry tank]]s that were produced in large numbers between 1935 and 1940. It was lightly armoured, 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.''<ref>Zaloga 1984, p 74.</ref>

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&nbsp;mm KT-26 or PS-3 main gun (a short-barreled howitzer) and the [[45 mm anti-tank gun M1932/38 (20-K)|45&nbsp;mm 20K model 1932/38]], a long-barreled, high-velocity gun useful against tanks, but less effective than the 76&nbsp;mm gun against infantry.

In the rear of the turret, there was a rotating drum-type magazine for 18 45&nbsp;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&nbsp;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&nbsp;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&nbsp;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 [[Diesel model V-2|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 Armoured 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'', черепаха)'', 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 [[Armoured vehicle-launched bridge|bridgelayer]] and the TTBT-7 and Thubten-7 radio-controlled tanks (known at the time as [[Teletank]]s). Finland converted 18 captured tanks into [[BT-42]] assault guns.<ref>[http://www.jaegerplatoon.net/TANKS5.htm BT-5, BT-7, and T-50 Tanks] "Finnish Army 1918-1945"</ref>

Shortly before [[Operation Barbarossa]] (the German invasion of the Soviet Union), the BT-7 underwent an up-armoring program. In 1940, the [[Illich Steel and Iron Works|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.

== Combat experience ==
[[File:Niemiecko - radziecka linia demarkacyjna (2-4233).jpg|thumb|German infantry and Soviet armoured forces meet along the agreed-upon demarcation line after the 1939 [[Invasion of Poland]].]]

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 (World War II)|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.<ref>Mark Axworthy, Cornel I. Scafeș, Cristian Crăciunoiu, ''Third Axis, Fourth Ally: Romanian Armed Forces in the European War, 1941–1945'', p. 220</ref> 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 in operational order, in Belarus.<ref>{{Cite web |last=Vorobei |first=Marina |date=1 July 2020 |title=The salvagers who raise World War Two tanks from the dead |url=http://www.bbc.com/future/story/20180312-the-salvagers-who-raise-world-war-two-tanks-from-the-dead |website=BBC Future}}</ref>

== Organization and use ==

The [[Table of organization and equipment|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 tank]]s;
**1 [[Military communications|signal]] platoon;
**1 anti-tank platoon with three 45&nbsp;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 tank]]s;
*1 [[motorized infantry]] battalion, containing
**3 motorized rifle companies;
**1 signal platoon;
**1 antitank platoon with three 45&nbsp;mm antitank guns;
**1 AA MG platoon
*1 additional AA MG platoon in brigade headquarters;
*1 motor transport battalion;
*1 reconnaissance battalion;
*1 [[Pioneer (military)|pioneer]] company;
*1 medical company;
*1 chemical company (flamethrowers).<ref>{{cite web |url=http://www.wwiivehicles.com/soviet-union/organization/table-of-organization/1939-11-light-tank-brigade.png |title=Soviet light tank brigade November 1939 | archive-url= https://web.archive.org/web/20160304101537/https://www.wwiivehicles.com/soviet-union/organization/table-of-organization/1939-11-light-tank-brigade.png |archive-date= 2016-03-04 |website=wwiivehicles.com |format=png}}</ref>

== References ==

=== Notes ===
{{notelist}}

=== Citations ===
{{Reflist}}

==Further reading==
*{{cite book |first=John F. |last=Milsom |date= 1971 |series=Profile AFV Weapons No. 37 |title= Russian BT Series }}
*Mikhail Baryatinskiy, 2006, ''Russian Armour Volume 2: Light Tank T-27, T-38, BT, T-26, T-40, T-50, T-60, T-70'',
*{{cite book |last1=Zaloga |first1=Steven J. |author-link=Steven Zaloga  |last2=Grandsen |first2=James  |title=Soviet Tanks and Combat Vehicles of World War Two |date=1984 |location=London, UK |publisher=Arms & Armour Press |isbn=0-85368-606-8}}

==External links==
{{Commons category}}
* [https://web.archive.org/web/20120425052218/http://english.battlefield.ru/bt-7.html BT-7 Tank] at the Russian Battlefield
* [https://www.youtube.com/watch?v=RAgROdZd5gs BT-7 "test drive" (video)]
* [http://www.wwiivehicles.com/soviet-union/vehicle/medium-tank/bt-7-fast-tank.asp BT-7 at wwiivehicles.com (updated link)]

{{WWIISovietAFVs}}
{{Interwar tanks}}
{{Authority control}}

[[Category:Light tanks of the Soviet Union]]
[[Category:Cavalry tanks]]
[[Category:Interwar tanks of the Soviet Union]]
[[Category:World War II tanks of the Soviet Union]]
[[Category:Military vehicles introduced in the 1930s]]
[[Category:Malyshev Factory products]]