Inspired by the efficiency of soaring birds in crossing very large distances with barely flap their wings, this work presents a simple model of UAV that, adopting the capabilites of these animals, could improve the existent multi-rotor devices, not only in efficiency but also in safety and accessibility. Thus, simple analytical approximations to reproduce the behavior of flapping wings UAVs are explored, expecting their integration in on-board CPUs to be solved in real-time flight episodes. A comparison between gliding and wing flapping with these models indicates that the thrust generated by wingstrokes should be controlled in further studies in order to mitigate the oscillations along the path of the vehicle. The geometric parameters of the ornithopter are found to be decisive in this sense, so special attention should be paid during the design stage.