Multi-physics design of a truncated aerospike nozzle for an ammonium perchlorate solid fuelled hobby rocket

The performance of a rocket is highly dependent on thepropulsive efficiency of its engine. Through the use of conventionalbell and conical nozzles it is only possible to achieve high efficiencyat a single external pressure design point whereas the aerospikeconcept is able to achieve high efficiency throughout the rocketsflight regime. The external pressure of the nozzle of a hobby rocketis variable and primarily dependant on the velocity of the rocketdue to aerodynamic bluff body effects. In this research a truncatedaerospike nozzle was designed using the Angelino approximationmethod at the point of minimum external pressure, measured at 75kPa. It was calculated that the increase in nozzle expansionperformance would provide an increase in thrust of 0.325% whencompared to the conventional Cesaroni conical nozzle operating inthe same aft flow conditions. These promising results indicate thatfurther work should be carried out on the design and integration ofthe nozzle into the body of the rocket, including nozzle cooling andablation rates as well as nozzle mass reduction.