Soviet Fast Tank BT-2 (Bystrochodnyj Tank)

The idea of wheel-tracked vehicle was born during the 20s, when constructors analyzed the task of operational movement tank on roads. The wheels were enlarged to the car wheels and the track was made removable.
For Soviet Union with its large plains it a very perspective idea. Soviet constructors made wheel-tracked tank called BT-2 ("bystrochodnyj tank" means "fast-moving tank" - SJ), The mass production began in the September, 1931. The experienced crew needed only 30 minutes to remove or put on the track. Its mass was 11 ton, crew - 3 people. Its armament was: 37mm cannon and 7.62mm DT machinegun, installed in the turret separate from the cannon. Its armour was 13mm in the front and side parts of the hull and on the turret. The "Liberty" aviaengine of 400hp was installed. Maximum speed was 52km/h on tracks and 72km/h on wheels. Operational range was 200km on tracks and 300km on wheels. The tank was not equipped with a radiostation.
New vehicle had a lot of "child sicknesses". American engines did not work properly and often overheated. There was a high danger of flaming in the inner section.

Soviet Fast Tank BT-5 (Bystrochodnyj Tank)

After further development in 1933 appears a new model called BT-5. The defects of its ancestor were removed: tank received Soviet motor M-5, reinforced transmission and the turret of a new form. But the main feature was the installation of a 45mm cannon (the same as T-26 had). The tank's mass was increased up to 11.5 ton, but speed and armour protection remained the same. Some BT-5 had installed 76.5mm/16.5calibre gun. They were called artillery tanks BT-5A.
In a new cylinder turret of a new construction a 45mm cannon and the machinegun DT were installed. Some tanks had another machinegun installed in the back of the turret. Tank had 72 cannon shells if it had a radiostation or 115 if not. It also 2709 bullets for the machinegun.
Tanks BT-5 were used during the Civil War in Spain, where their great minus was found out - the weak armour protection.

"During the dark August night, 1941, tank platoon, commanded by Lieutenant A.Sergeev, slowly moved through the sparse forest. Three machines, it were light tanks BT-7, returned from the reconnaissance raid from the rear of the enemy. Tankists gained a lot of valuable information and even took the "jazyk" ("tongue" in English, the prisoner which is supposed to speak an important information - SJ), who was in one of the machines now. Night was on the wane. The east began to become lighter and lighter. There was a river forward. Not wide, but with high slopes. Segreev received radio transmission, that ford, that was crossed by the tanks, when they move to the rear of the enemy, was occupied by the powerful forces of Nazis.
The forest ended and the river was close about 100 metres. Sergeev stopped his tank, to the back closed two other machines, he jumped out and called the commanders of both vehicles to him. Together with them he came to feel the terrain. There was a battle not far from here. The sounds of artillery bombardment were close. There were seen explosions. Tankists came to the river. The nearest bank was high and the water was deep about 2 metres. The far one is low and, is as far it is seen in the darkness, not muddy. Then there was a mead, then forest, behind which, as tankists knew, were positioned our forces. They were not far at all. But how to cross the river? To find the other better place of river is impossible - the enemy is too close: the motor roars and tracks are too noisy. Crossing the river from a such hill is impossible for tanks. The small squad could not break through the enemy positions - it was too badly outnumbered. To left machines and return by foot - never! And then Lieutenant Sergeev remembered that when he studied in the tank school, teachers told the students about the jumps on the fast tanks BT. He read this in newspapers also. What is possible in time of peace - is a must in war. So, the resolution was chosen - to jump! And the first one would be ridden by the platoon commander. But for the safety of lives of people, he ordered all, but drivers, to cross the river by swimming. Sergeev took the place of mechanic-driver and started the tank motor. After a few seconds of 100m path the tank's velocity was about 50km/h. Then it flew through the air, drew the curve and fell into the water near the opposite coast. Column of water nearly covered the tank. But the water was not deep there and the tank jumped to the coast due to inertia. Sergeev drove it to the shrub. Inspired by their commander's jump, the others follow his example. Everything was going fine. Crews took their places in machines, which not spotted by the enemy entered the forest. The were no Germans in the forest. And after a half of an hour the scouts were happily met by our warriors."
In the middle of 1930's the tank in USSR the possibilities of so-called dynamical obstacle crossing by tanks. That meant also jumps over trenches and narrow rivers. Only fast light tanks BT could complete this tasks successfully.
On proving grounds BT-2 and BT-5 tanks jumped with the 50km/h speed more than 20m through the air.
These experiences also tested dynamical elements of tanks transmission. Thanks to them T-34 was later equipped with the most reliable transmission. These datas also helped to count other transmissions for tracked vehicles. No other army in the world did make such tests.
Tanks BT were the most famous and favourite tanks between the Soviet tankists during 30s.
As its brother T-26, BT was used as a base for many other vehicles. On BT-5 and BT-7 flamethrower tanks were producted that had also a flamethrower, but the main armament. Also bridge tanks were made on their bases.
Tanks of BT series, mainly BT-7, were the main tanks of the Red Army tank forces up to the 1941.