The purpose of this study is to design a system control in order to obtain the best longitudinal stability of the UAV Ultra Stick 25e. The state-space model has been taken from a previous study of the University of Minnesota which its tittle is System Identification for Small, Low-Cost, Fixed-Wing Unmanned Aircraft. This study will be explained briefly as background but it is not the aim of the project to go in depth in this matter. This project focuses on the comparison of Classical Control, Optimal Control and Robust Control methods in order to find the best solution for the longitudinal stability of the Ultra Stick 25e. To design the controllers and to study the responses of the control systems I have used Matlab's Control System and Robust Control Toolboxes. Only continuous time systems have been treated.