The BT tanks were mass produced (ca 7.000) from 1932 to 1941 in basically 4 models who all got thicker armour. They were able to go on railroad tracks as well as roads and terrain. With their thin armour they were fast (in Russian BT= Bystrochodnij Tank= fast tank) and meant to be active in large numbers on the battle field and going by railroad on their own. A small chassis imported from the USA in 1931 was the protoytpe. In BT-7 armour was increased up to to 22 mm, and the hull was largely electro-welded and several variants existed.
This vehicle is often wrongly told about as the World's first tank with sloping armour. An earlier tank with this design was the Swedish Landsverk 100 The chassis was from a BT tank and the turret had a new design later to be standard on various models. The front was pulled down and made in a steeper angle, as the sides, and a new design came to light. This led to the prototype A 20 and model T 32.
This tank was an development of the BT 7 and had sloping armour on its sides and was enlarged in width. (The turret in the picture comes from an earlier BT model). After getting a straight sloping front and a turret like the BT SV (see it from menu left) the vehicle was developmed to the A-20 and A-32 models later to be T-32.
This vehicle was a product of the efforts in the 1930s to get a new battle tank. It's hybrid and seemed to have wheels like a BT and three supporting rollers for the band like the prototype t-46 from 1936. The big tower and a smaller one at front makes it look very like the T-28. Chief of construction was M Koshkin who was in charge in Leningrad and the tank had to versions (4 and 5) both built on a chassis from a BT tank. The T-29 tank never came into production, and the project stopped when Koshkin was called to Kiev 1937 to develop a new tank, the famous T-34.
This machine closely resembled the original T-37 but with improvements in the hull arrangement and transmission. The T-38 had new final drives in place of the automobile differential, and a better steering system. A new improved suspension system with wider tracks increased the performance across marshy ground, and the Russians later stated that they have found this machine much more maneuverable than the earlier T-37 models. The prototype model had another lower, fixed turret for the driver situated to the right of the main one. The T-38M had a radio.
Koshkin (constructor) and Morozov (designer) made this T-46 #5 in around 1936. It was a fast medium tank prototype which was not taken into serial production. Note the flat slightly sloping front in this vehicle, a design feature that followed into their next models.
The engineers were both transferred to another plant to be heads of a project that finally ended up with the famous T-34.
The T-111, also called T-46-5, was an improved BT-IS. This vehicle appeared in March 1937, and Alexander Morozov was the designer of it. With 60 mm thick armour plates in the front, this was going to do the T-111 immobile against 37 mm AT-guns, and also against 76 mm AT-guns on ranges above 1.200 yards. This vehicle weighed 28 tons and used a dieselengine with 300 hp. This resulted in a maximum speed of 30 km/h. The armament consisted of a 45 mm antitank-gun, and two machineguns, of which the first one was co-axially mounted with the gun, and the second one fitted in the rear turret. The crew consisted of 4.
From A-20 prototype came the development of the A-32, which didn't use the wheel/track-option, but was now fitted with a short 76 mm gun. The A-32 prototype had proved very good in trials and a small production was delivered by the name T-32. However battle experience in the Spanish Civil War made it clear that it had insufficient (too thin) armor protection. After getting a thicker hull and other changes made it was called T-34 and should be the most famous tank of its time.
This was a prototype during the work with a new tank in the years 1938-1939. It was developed from the experimental vessel BT IS (1936-1938) and had got sloping armour on all sides. It was the forrunner to A 32 (see this tank) and the armament was the same as the contemporary BTs - a 45 mm gun. The all over design was similar to the T 34 to come with one exeption: The wheels were still four in number compared to five with a diameter 10 percent smaller. First and last wheel kept its place and the other three were distributed (slightly uneven) inbetween. Its armour was thinner than the model T-32.
