This study is addressed to the control system of a mini-launcher. A reaction control based on purge pressure from a solid propellant engine of a main stage, or using cold gas from a storage tank will be the control method. Pulse modulator system will be the actuation method studied, and simulations about its suitability will be done with Simulink. In this thesis, we try to check if this method is able to be implemented in a low cost way the Wiki-Launcher, a mini-launcher less than 100 kg. At the time we try to check if the control allowed by the reaction control can manage all the phases of the flight. Both possible control configurations are going to be analyzed.