Spaced armor
A thin plate mounted away from the hull, which strips explosive and shaped-charge shells before they reach the real armor.
Also known as screens, side skirts, schurzen, track absorption.
Spaced armor works by geometry rather than by thickness. A HEAT shell detonates on the screen and its jet loses penetration crossing the gap, and a high explosive shell spends its blast on the outer plate.
Against solid shells it does much less: an armor-piercing round passes through and its penetration is reduced only by what the screen was worth. Tracks count as spaced armor too, which is why aiming at a target's track from the front is usually a wasted shot.
Related terms
HEATA shaped-charge shell with high penetration that ignores distance entirely, but is defeated by tracks, screens and any spaced armor it detonates on.High explosiveA shell that explodes on contact, dealing reduced damage through armor it cannot penetrate and splashing everything nearby.TracksThe running gear, which immobilises the vehicle when broken and absorbs shells like spaced armor when intact.Effective armorThe thickness a shell actually has to defeat once the angle of the plate is accounted for, which is what penetration is compared against.