This paper presents a systemic model for the simulation of the design of a nozzle for R-Candy. This research is focused on a complex system using the methodology of 5 phases based on the tools of systemic modeling and general systems theory. The rocket motor was designed using Solidworks, which consists of the igniter system, the combustion chamber, and the nozzle. Usually, a Laval-type nozzle (convergent-divergent) is used for rocket motors, taking advantage of the exothermic properties of the potassium nitrate and sorbitol fuel mixture in a solid state. The simulation was carried out using the computational fluid dynamics software FEATool, evaluating temperature, velocity, and pressure. The results obtained by the R-Candy software give guidelines for a broad preliminary panorama for the manufacture of rocket motors in experimental rocketry.