Tank
With World War II the multi-turreted tanks proved impracticable, and as the single turret on a low hull design became standard, crews became standardized around a crew of four or five. In those tanks with a fifth crew member, usually three were located in the turret (as described above) while the fifth was most often seated in the hull next to the driver, and operated the hull machine gun in addition to acting as a co-driver or radio operator. Well-designed crew stations, giving proper considerations to comfort and ergonomics, are an important factor in the combat effectiveness of a tank, as it limits fatigue and speeds up individual actions.
Armoured fighting vehicle
The term "super-heavy tank" has been used to describe armoured fighting vehicles of extreme size, generally over 75 tonnes. Programs have been initiated on several occasions with the aim of creating an invincible siegeworks/breakthrough vehicle for penetrating enemy formations and fortifications without fear of being destroyed in combat. Examples were designed in World War I and World War II (such as the Panzer VIII Maus), along with a few in the Cold War. However, few working prototypes were built and there are no clear evidence any of these vehicles saw combat, as their immense size would have made most designs impractical.
A flame tank is an otherwise-standard tank equipped with a flamethrower, most commonly used to supplement combined arms attacks against fortifications, confined spaces, or other obstacles. The type only reached significant use in the Second World War, during which the United States, Soviet Union, Germany, Italy, Japan and the United Kingdom (including members of the British Commonwealth) all produced flamethrower-equipped tanks. Usually, the flame projector replaced one of the tank's machineguns, however, some flame projectors replaced the tank's main gun. Fuel for the flame weapon was generally carried inside the tank, although a few designs mounted the fuel externally, such as the armoured trailer used on the Churchill Crocodile.