Definition
The aerial shell is the archetypal firework: a cardboard sphere or cylinder filled with stars and a burst charge, lifted out of a mortar by a lift charge. A time fuse ignited at launch opens the shell at the top of its trajectory. Shells are named by calibre, typically 50 to 300 mm for regular displays, with the largest sizes reserved for major events. A 100 mm shell climbs to about one hundred metres and opens a bouquet of comparable diameter; a 150 mm shell breaks above 150 m. Spherical shells (symmetrical break, Japanese tradition) coexist with cylindrical shells (Italian tradition, successive effects). In Europe, display shells belong to category F4 and may only be used by professionals holding the appropriate qualification.
In practice, for the display company
Every shell commits a safety distance, a mortar of the right calibre and a firing cue. In PyroDesk a shell is a stock item with its calibre, net explosive content and product sheet; dropped into the firing plan it claims a mortar, computes its burst delay and is rendered in PyroSimulator at its true height before being listed in the CERFA declaration.