A Family of Motors

The Reed Warbler family of motors at the nominally 75mm scale are (to the best of our knowledge) the first student designed-and-built solid rocket motors in the UK. Based on an aluminised ammonium perchlorate composite propellant, they are a first step towards larger solid rocket motors.

R1.0

The first motor static-fired was in a configuration of four BATES grains cast into cardboard and insulated with phenolic. It had a phenolic nozzle with a graphite insert for the throat and an aluminium casing pressure-tested to 120 Bar.

R2.0

Subsequent motors had the propellant cast directly into the phenolic tubing, allowing for an increased propellant mass fraction. The nozzle assembly was successfully redesigned to avoid cracking of the phenolic. Furthermore, the closures were secured by threading them into the case instead of the previous radial bolts, simplifying assembly.

Motors were tested using varying nozzle configurations to better characterise the propellant. A moonburner configuration was tested, allowing for a long burn time at a lower thrust, burning for more than 10 seconds.

Mixing and casting of rocket propellant in the UK is classified as manufacture of explosives and requires a factory facility licensed by the Health and Safety Executive, and so this project is only possible thanks to the generosity of Event Horizon Ltd.