A revolutionary design
BT means Bystrochodnij Tankov (Fast Tank). It was indeed a new class of its own, originally invented and refined in the USA, as the brainchild of American Engineer Walter J. Christie, which had a tremendous influence in tank design during the thirties. Christie has observed WWI tanks in action and the beginnings of US tank postwar development at home. He had realized how deep was the gap between the fast armored cars, but with poor off-road capabilities, and the slow, but all-terrain proved tracked tanks. He devised new ways to cope with this problem, revolving around power-to-weight ratio and new suspension designs. His first prototype was ready in 1923, but was rejected by the US Army.
A good side shot of the hull of the Christie M1931
He then developed even faster tanks, equipped with powerful radial aircraft engines and the acclaimed “Christie” suspension, as well as the concept of removable tracks. The idea was that, with this new suspension and the combination of very large rubberized wheels and huge vertical coils, his model remained operational even after its tracks were disabled, excessively worn or broken. The tank was also capable to reach the battlefield by itself, on roads, with its tracks stored on the mudguards, rather than to be carried by rail. It was displayed on impressive shows and quickly dubbed by the press “the race tank”. However, the Army only ordered a single prototype for evaluation by the cavalry corps, the Christie model 1931, but further orders were cancelled.
The fastest tank on earth
Due to this setback at home, Christie turned to the international market. His tank was displayed before scores of foreign governments. Among these was a Soviet commission, impressed by the stunning aerial performances of this model and the conversion, in 30 minutes, into a wheeled vehicle. They found it suitable both for the new tactics which were then in gestation back in USSR (the “deep battle” concept) and the bad roads and wide expanses of the Russian territory. However, since the US government had forbade such a purchase, the commission managed to ship them as “agricultural tractors”, turretless and without any armament.
Once in the USSR, they were sent to the Kharkov Komintern Locomotive Plant (KhPZ) and, compared to formerly acquired plans. The design bureau managed to replicate several prototypes, called BT-2. The original Christie tanks were designated BT-1. The three BT-2 prototypes, delivered in October 1931, were still unarmed and turretless, but served as chassis test beds throughout 1932 and, during the fall of that year, mass production began. This was the first of a successful and unique lineage which lasted for a decade, including the BT-5 (1935) and BT-7 (1938-41), the ultimate offspring being the T-32 and the T-34.
The Bystrochodnij Tankov design
The KhPZ design bureau headed by Morozov barely changed any features of the original BT-1 chassis and Christie design, concentrating instead on the engine, transmission, turret and weaponry. The turret was of the simple “barrel type”, a cylinder made of several layers of steel, 5-6 mm (0.2-0.24 in) in all, which was designed to house a 37 mm (1.46 in) long barrel, high velocity AT gun. It was not ready for production at the time and was later in chronically short supply. Because of this, many BT-2s were delivered with a mixed armament of DP-DT machines guns only or a 37 mm (1.46 in) gun with or without a single coaxial DT machine-gun.
The standard configuration included the gun and a coaxial DT machine-gun mounted in an oblique fixed position, in the Japanese style. Its traverse depended on the turret. The “full machine gun” version consisted of a single coaxial DT machine-gun and a twin DP-28 (Degtyaryov model 1928) light machine gun mount replacing the gun. The other important point was the engine. The Soviets imported a licence for the American Liberty L12, a water-cooled 45° V-12 aircraft aircraft engine capable of 400 hp (300 kW), built as the M5-400. This first model, although powerful and light, was also found difficult to maintain and capricious. The power-to-weight ratio meant awesome performance, although less impressive than the original Christie M1931, mostly because of the added weight of the turret and all the military equipment.
Production by KhPZ (Kharkov)
The first run and trials of the BT-2 were successful and showcased a road speed of 100 km/h (62 mph), with an off-road speed of 60-70 km/h (37-43.5 mph) depending of the terrain. They were largely showcased for propaganda purposes and featured in movies throughout the thirties. In 1933, it was a completely new and unrivaled concept in the world, allowing “true” cavalry tactics built on speed, mostly for breakthrough exploitation and advanced reconnaissance missions. This emphasis on speed over protection also reflected the confidence in the naval “battlecruiser” concept, traduced in land warfare. The speed acted like an active protection on its own, since a target moving so fast was more difficult to hit.
The M5 engine gave a 39 hp/t power-to-weight ratio and a 400 liter tank allowed a 300 km (186 mi) range at cruising road speed, with a tactical range of just 100 km (62 mi). This was impressive for the time, giving that it was at an average off-road 60 km/h (37 mph). The Kharkov Komintern Locomotive Plant delivered 620 BT-2 until 1935. Most were equipped with the 37 mm (1.46 in) model 30 gun, provisioned with 96 rounds. Some also received a radio “horseshoe” antenna fixed on the turret. The latter had only two side small vision slits. The gun mantlet also varied slightly in shape during the production run. Another external modification included the front mudguards, not mounted on the earliest model, and headlights.
The BT-3 and BT-4
Before the production came to an end, the BT-3 was built according to Soviet specifications. These were virtually identical to the “regular” BT-2s, only differing by the use of the metric system for their construction instead of the old Imperial one. However, this was only a factory designation, the army still registered them as BT-2s.
The BT-4 was a true upgraded version, with a partially welded hull and a modified suspension. Three prototypes were built in 1935. These plans were altered for the upcoming, upgunned BT-5.
The BT-2 in action
The BT-2 “fast tanks” saw endless exercises in ruthless conditions, which prematurely wore off their already sensitive, even fragile engines. The 37 mm (1.46 in) gun proved accurate, but lacked penetrating power compared to the new 45 mm (1.77 in) already used by the T-26. Thus came the idea of an upgunned version, later materialized as the BT-5. The BT-2s formed the backbone of cavalry units and were superseded in this role by the new BT-5s and BT-7s after 1936. BT-2s were found in July-August 1939 at the Nomonah plateau and played a major part in the Battle of Khalkhin Gol, alongside better armed BT-5s.
A BT-2 armed only with machine-guns
By 1940, veterans of both campaigns argued to make their tactical vision adopted, but the faction of the Nomonah veterans, led by Zukhov, came into favor only in the aftermath of the disastrous Winter campaign. Bad coordination between the air force, tanks and infantry, combined with a Finnish resolute defense, led to crippling losses, and the BT-2s were no exception. Some took part in the Soviet invasion of Poland, but by the summer of 1941, perhaps half of their original numbers were still available, so their apparition on the battlefield was almost a rarity. The crew unanimously preferred the better armed and more reliable BT-5s, although the BT-2 remained until the end of the war the fastest tank in service. Such performances were unmatched until the arrival of the third generation of MBTs in the 90s.
|Dimensions (L-w-h)||5.58 x 2.23 x 2.2 m (18.3×7.32×7.21 ft)|
|Total weight, battle ready||10.2 tons|
|Crew||3 (commander/loader, gunner, driver)|
|Propulsion||8-cyl petrol KhPZ M5, 400 bhp (298 kW)|
|Speed||55 km/h (39.2 mph)|
|Range||200 km (120 mi)|
|Armament||37 mm (1.46 in) model 33 gun
1/2 DT 7.65 mm (0.3 in) machine-guns
|Armor||6 to 12 mm (0.24-0.47 in)|
Links and references
BT-2 model 1932, 37 mm (1.46 in) gun only.
A BT-2 1932 model, twin machine-gun variant.
BT-2 at the battle of Khalkin Gol, August 1939.
BT-2 command tank, invasion of Poland, September 1939.
BT-2 of the reserve force, 1940.
Fictional BT-2 in Spain, Republican Forces, battle of Madrid, 1937. The only tanks of the BT series sent to Spain were BT-5s.
Winter war, Karelian front in eastern Finland, December 1939.
A BT-2 during the battle of Moscow, winter 1941/42.