Rocket Design and Manufacture

Firework rockets vary in size (and price) from small number 4 rockets which will contain a thunderflash or a coloured star, to number 6 with more coloured stars, then to numbers 7 and 8 with larger star heads, to number 10 which provides the largest bouquet of stars. There are screechers, whistlers and maroon-type rockets with exploding heads, all in various calibres. 

For the more adventurous, parachute rockets are available in 22 and 25 mm calibre, or even festoons or bag rockets with sticks up to three metres in length. The latter are definitely fired individually  

When a thunderflash effect is required, a square of touch-paper is placed on the rear propellant surface inside the case at the opposite end to the choke, and a hairpin of quickmatch is placed inside the case in contact with the square of touch-paper. Some flash composition, based on potassium perchlorate, barium nitrate and aluminium, is then poured around the quickmatch and the head of the case is closed off with a pressing of clay or by simply being taped over. The all-important stick is then glued to the outside of the case using the wrappings of the paper label for support. 

Inside the plastic cone at the head of the rocket might be a payload of small green stars, each about the size of a pea, containing ingredients such as barium chlorate, potassium chlorate, gums and binders. 

A length of match or a pressing of delay fuse connects the rocket motor with the payload so that when the motor burns-out the fuse is lit and communicates with an ejection charge of gunpowder which ignites and ejects the stars. 

The latter show multi-effects including coloured floral bursting patterns, crackle, glitter, rain and stars, while maroon-type rockets are commonly used to signal the start or finish of a display. 

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