A genetic algorithm optimization technique has been successfully applied to
the design of a large hybrid rocket booster. Optimizations to minimize gro
ss liftoff weight or total inert weight have been carried out using a hybri
d rocket sizing code developed at Purdue University. The genetic algorithm
was able to find optimal or near-optimal designs that contained both contin
uous and discrete variables. Discrete variables included the propellant com
bination and the number of fuel ports, whereas the continuous variables, ta
nk pressure, chamber pressure, and oxidizer massflux level, were simultaneo
usly optimized using the genetic algorithm. Design solutions have been obta
ined from a discontinuous design space that contains a very broad, shallow
minimum in weight. The resulting designs are discussed with some detail, il
lustrating their feasibility and some significant differences with previous
ly published designs. The use of a genetic algorithm with ii rocket sizing
code appears to offer great potential to designers of rocket systems.