Developed in 1937–1938 under the "20-ton vehicle" project and was intended to replace the D2 tank. The project included two turret variants: with a 37-mm or a 47-mm gun. By 1938, two vehicles were built for trials. Never saw mass production.
Time for the successive autoreloading of each shell into the magazine.
Characteristics are specified for Siege mode.
Characteristics are specified for Rapid mode.
Reload time of the first and second guns on double-barreled vehicles.
Characteristics are specified for vehicles with crews trained to 100%.