This paper presents a one-dimensional mathematical modelling of the upwards flight phase of the experimental minirocket Stan, under development by the UFJF’s model rocket team Supernova Rocketry, to reach the apogee of 1 km. An airbrake system was designed to allow Stan to reach the desired apogee with greater accuracy. It has three drag-generating surfaces driven by a single servomotor. They increase the aerodynamic drag force acting on the minirocket during the upwards flight ballistic phase and dissipate the excess energy converted by the rocket engine. Crosswind interference is neglected; it is assumed that Stan is launched at the best moment to lessen the influence of horizontal disturbing forces. A simulator, implemented based on the softwares MATLAB®/Simulink®, was built from the mathematical model developed. Simulated results are presented and discussed.