For the design of the MIDRES UAV, various possible configurations were identified and studied (e.g. fixed-wing, multicopter, helicopter, flapping wing). The design requirements were set by considering not only the mission of the UAV, but also the responses from end-users (civil protection operators, firefighters etc.) on carefully designed questionnaire, which addressed 20 pivotal design features / capabilities, critical to the functionality of the UAV. The initial conceptual design phase was aided by Machine Learning algorithms, in order to identify the dependency between crucial sizing parameters and performance metrics. During the preliminary design phase, the optimization of the platform took place, with a combination of high-fidelity aerodynamic (CFD) and structural (FEM) analyses, along with quick 3D printing prototyping and testing. These trade studies have resulted in a configuration that features reduced frame and electronics weight, increased structural integrity, improved flight performance, as well as better manufacturability.