Hull-down - Armoured Warfare - Tank Design

Tank Design

Tanks and other fighting vehicles must be able to depress their gun to be able to take advantage of a hull-down position, since a vehicle's hull is usually tilted upwards when it is behind a crest. A vehicle with a relatively small range of gun depression may have to drive up onto an exposed crest or forward slope to be able to fire on lower ground to the front.

Notably, Soviet and Russian tanks after World War II have very low profiles, but pay for this advantage by having a poor range of gun depression. Their low turret roof stops the rising gun breech when the muzzle is depressed. Thus, Soviet tank crews would have a hard time finding a hull-down position from which they could cover much of the terrain by fire. The typical Soviet tank had a range of elevation of -5 to +15 degrees, about two thirds that of Western tanks with a range of about -10 to +20 degrees.

This disadvantage was deemed acceptable, since Soviet armoured doctrine emphasized the massed attack with local superiority in numbers. Soviet mechanized forces were supposed to spend more time advancing under fire than in defensive hull-down positions.

Soviet doctrine didn't neglect the defence, however. Newer Soviet tank models were equipped with an integral dozer blade, so given time, they could improve a hull-down position. Soviet tactics also emphasize the use of tanks on the defense in the mobile counter attack role, rather than engaging an enemy advance from prepared positions where they could be more vulnerable to air attack.

The polar opposite of the Soviet tanks was the defensively-designed Swedish Stridsvagn 103. Built much like a tank destroyer, but serving the role of a tank, this turretless vehicle was made to nearly disappear in a hull-down position. It has even lower profile than Soviet MBTs, with a fixed, auto-loaded gun that is nearly flat against the roof; the entire tank hull moved to elevate, depress, or traverse the gun. The Stridsvagn 103 also had an integral dozer blade, so it could dig itself. A second set of rear-facing driver controls for the radio operator allowed it to withdraw from a hull-down position at full speed. This radical design was specialized for defense on roads of a forested country.