Definition
A mortar is the tube into which a shell or mine is loaded and which guides its exit under the push of the lift charge. Closed at the base by a plug, it is nowadays made of high-density polyethylene (HDPE), fibreglass or heavy cardboard for small calibres; steel, once common, has been abandoned because of fragmentation risk. Its length is generally five to eight times its calibre: a 100 mm mortar is 60 to 80 cm long. The mortar must match the shell's calibre exactly, be buried, sandbagged or wedged in a rack, and oriented to the planned firing angle. After the show it is inspected and cleaned; a cracked mortar is scrapped. The word “tube” refers indifferently to the mortar and to the tubes of candles and cakes.
In practice, for the display company
The mortar fleet is a company asset: how many 75s, 100s, 150s, in what condition, in which racks. PyroDesk keeps the inventory of mortars and racks alongside the pyrotechnic stock, assigns each shell in the firing plan to a mortar of the right calibre and flags a shortfall before the truck is loaded.