How Do Mortar Shells Work?

This is the mortar that mortars are named after.

A mortar is a muzzle-loading, indirect fire weapon used by armed forces. Named for its resemblance to a mortar and pestle, it launches several kinds of projectiles upward in a steep trajectory to fall and penetrate targets from above.

Mortar Shells

Mortar shells are the ammunition for mortars. Each shell consists of a fuse and a charge. The mortar round is launched by a separate explosive packed into the barrel of the mortar that puts the round in flight. The fuse then ignites the shell charge, whether by impact or time.

Fuse Variations

Impact fuses cause the charge to ignite when the round actually strikes a hard target. High explosive rounds that destroy targets and smoke rounds used to mask the battlefield use impact fuses. Suspended by small parachutes, timed fuses ignite illumination rounds to light the battlefield. Improved conventional munitions, a kind of mortar cluster bomb, also use timed fuses. Variable time fuses can be adjusted to delay high-explosive ignition, for example to penetrate a bunker before exploding inside, or to explode just prior to ground impact and shower flak on personnel below.

Fuse to Charge

The fuses attach to a squib, a small explosive packet that works as a blasting cap that ignites the shell charge. In the case of delayed fuses, when the round is to detonate after initial impact, there is a squib attached to an additional short fuse that ignites a second squib that ignites the main charge.

Endgames

Mortars have been fitted with numerous different kinds of rounds. Included among them are high explosive, parachute illumination -- including infrared illumination rounds, white phosphorus, weaponized chemicals, smoke and target practice rounds.

References

• Federation of American Scientists: Mortars
• Global Security: FM 6-30, Call for Fire
• Global Security: Mortars

Resources

• Scribd: US Armed Forces Mortar Manuals