Smoke grenade dischargers (smoke dischargers, smoke mortars) are a softkill measure of the active protection system (APS) of combat vehicles, designed to fire smoke grenades. Tanks typically sport a battery of six to eight smoke mortar tubes on each turret side, while turret-less tank destroyers and amoured personnel carriers make do with one battery at the hull front or rear. The smoke mortar tubes of each battery are aligned at different angles to ensure that the smoke grenades impact at the proper distance and in a fan-shaped pattern around the vehicle. Once deployed, a rapidly developing smoke screen enables the vehicle to evade visual and electro-optical tracking by the enemy. Vehicle crews are trained to use the cover of a smoke screen to re-deploy to an alternate firing position, thereby neutralizing the threat posed by anti-tank guided missiles (ATGM) and high-performance kinetic energy projectiles.
The Airfix Centurion tank, the ROCO Chieftain, and many other scale model tanks are sold without smoke grenade dischargers, although these components are usually mounted in prominent positions and define the unique appearance of a main battle tank. Old and used tank models are often marred by damaged or lost smoke mortar tubes, because a previous owner may have relied on MiniTanks' plug-and-play parts staying on the vehicle interminably. Sometimes, smoke grenade dischargers are just so badly designed or oversized that a discerning collector may not want to mount them on his/her model tank. Whatever the case may be, experienced modellers often resort to scratchbuilding their own smoke grenade dischargers from brass or polystyrene tubing.