Pyrotechnics in the Open

Mealed gunpowder (or black powder) confined In tough cardboard cases or plastic containers is commonly used for pyrotechnic explosions in the open. There are also several commercial products known as bomb simulators which produce explosions of differing hues. Some have light grey smoke, and others a browny/black.

The mortar

This is a heavy steel tube with one end sealed. Primed with a charge of black powder and loaded with a paper wad and stout wooden dowel, this device is employed to hurl items into the air. It can be used to demolish wooden sheds, tip over piles of drums, fling dummy soldiers over parapets and blast out ‘lightweight’ tree stumps. The effect is enhanced if secondary, more visual, pyrotechnics are placed around the base of the mortar.

Ground explosions

For the best and safest effects, ground maroons or bomb simulators should be fired in steel pans sunk into the ground. These prevent stones from being flung around like shrapnel. On their own, simulators provide a satisfactory explosion, but their effects can be enhanced by piling peat, cork chips and pieces of builders’ softboard on top of them. Placed in between bags of flour they will produce an improved fire-ball effect. For the large fire-balls associated with napalm bombs or exploding automobiles, one or more simulators are placed below plastic bags containing gasoline.

The trip-wire

In order to ensure that ground explosions fire at exactly the right moment and at a safe distance from performing actors, trip-wires are set out in the field through which the actors run. The action must be carefully rehearsed and each actor must traverse only the pre-deter-mlned path.

The trip-wire consists of a cord stretched between two tent pegs which when snatched pulls a small piece of insulating plastic from between the jaws of a clothes peg. The jaws, having been fitted with metal contacts, then fire the bomb.

PYROTECHNICS ON LOCATION

1. Steel mortar and wooden plunger used for throwing items into the air or demolishing buildings.

1.a Loosely wrapped gunpowder to eject the plunger. It is essential to place a wad of paper or cloth between the charge and the projectile.

2.Mortar pan used to fire ground bursts and bomb simulators.