Fireworks Families & Types

Fireworks Definitions

The design and construction of some of the commonest types of fireworks are given with emphasis on the safe use of fireworks. 1^st Galaxy Fireworks Ltd believe that by understanding the basic principals behind the design and construction it will be easier for you to understand and appreciate what they do and to assess their suitability for a given display.

Types

The main types of firework used for displays are listed and briefly described below. The names are taken from BS 7114, 1988 under Categories 3 and 4. It must be realised, however, that fireworks may appear under a variety of names, and that they may be described by different generic names within the industry. The only sure way to identify a firework type is by reading the accompanying instructions for use, and a description of the effects. Also, within the various types, individual fireworks can vary greatly in size, power, and performance.

Bangers

A tube containing an explosive composition which produces a single loud report when ignited.

Gerbs, Drivers and Motors

They can all be described as being from the same family although they are different in their application. How they operate depends on the burn rate and the choke size.

A tube containing a composition which produces a fountain-shower of sparks and flames, in varying forms and colours usually silver or gold. There may be some sound effect, but not a report. Within this group may be found:

a. Fountains, Bouquets of Fountains

Fountains are designed to project ornamental and brilliant sparks into the air much like a water fountain.

The composition is rammed or pressed into the case burns progressively down the tube. The height of the fountain is controlled by the choke. The smaller the diameter of the choke, the higher the fountain effect.

b. Wheels

The thrust produced by one or more choked gerbs when attached to a pivoted piece of wood or a wheel fixed centrally to give a rotating effect. Burning takes place from one end of the firework to the other and provides up to 30 seconds of constant force-called “the driver”. If connected in series could produce 60 seconds burning or more. Where a wheel is set up to rotate in a horizontal plane, this is known as a cascade.

c. Flying Saucers (Crown Wheels)

These are wheels fixed over a spindle in a similar manner to cascades. The wheel is rotated by drivers to spin it and then additional rocket motors lift it in to the air. They need a great deal of space as they can develop a wobble and could travel in unpredictable directions. Bigger ones have a double lift which allows it to lower down and then gain height before burning out.

d. Rockets

All rockets, irrespective of size have four main characteristics:i) They have their own propellant charge ii) that this charge is contained in a cartridge or case iii) that this case is fitted with a choke or venturi, iv) that the rocket is fitted with a flight stabilising device.

The rocket is propelled by compacted gunpowder burning over a formed surface (usually a cone with a hollow centre) and the rapid rate of burn (5secs) and thus the large volume of gas quickly created is forced out of a clay, or more usually aluminium, choke or venturi. This provides the force necessary to lift the rocket quickly into the air.(Flight rockets are of more traditional construction with cardboard case, clay choke and black powder charge).

The head of the rocket (the pot or star chamber) contains the stars or other effects and the bursting charge of gunpowder or flash powder. The burning fuel flashes to ignite the content of the pot the instant the rocket reaches the highest trajectory. The stick of the rocket stabilises its flight.

These fireworks are amongst the most potentially dangerous in a display!

The stick and the spent case are going to return to Earth and so the launching tube or frame should be angled away from spectators. In this respect allowance should be made for wind speed and direction and checked again before the display is fired.

It should also be understood that a rocket will have a tendency to turn into the wind. This is because the effect of the wind against the stick is greater than that of the motor and pot.

If a rocket is fired down wind from the spectators it will turn back towards them. Remember this ! Allowance MUST be made when considering “fall out zones”.