Flying Qualities of Multi-rotor UAVs: market analysis and parameter definition

Unmanned Aerial Vehicles (UAVs) are currently one of the most promising frontiers of technological development for our society. Some applications of this technology have been in use for a long time in military scenarios and in specific civil applications but only in recent years drones achieved a significant market diffusion. Unfortunately, their employment is still restricted by some constraints, limiting their applicability in many industrial environments. These limitations are mainly related to the safety and reliability of UAVs and to the management and acquisition of sensitive data in terms of privacy. In order to enhance the market diffusion of UAVs, scientific research can optimise their technical characteristics, making them both a safer, more reliable technology and an optimally performing solution for completing specific missions and industrial tasks. The development of this thesis is built around two main points: the definition of the industrial environments which could benefit the most from the implementation of UAV-based services, and the presentation of a method to improve the performance of a specific multirotor drone with respect to its operative environment. Therefore, in the first chapter, the concept of flying qualities is introduced as a reference for improving both aircraft and UAV performance. Accordingly, a method to evaluate and enhance the flying qualities of UAVs is presented. In the second part of the introduction the UAV market is investigated to define which main industries demand drone-based services. Additionally, the main characteristics UAVs are required to possess in order to effectively complete the assigned missions are outlined. In the second chapter, the operative scenarios are analysed to decide which category of UAV is the most promising for future market applications and, consequently, the most interesting to discuss as application in the thesis. In the third chapter the flight dynamics of a chosen drone is studied by means of its natural modes, eigenvalues and aerodynamic derivatives. At this point, a parametric analysis is conducted to highlight which influence each design parameter has on the UAV flight dynamics and, accordingly, on its flying qualities. Therefore, an adequate tool to enhance the flying qualities of the selected UAV is provided. Consequently, in the fourth chapter the parametric analysis is exploited to suitably modify the design of the UAV in order to mitigate the most critical aspects of its flight dynamics. Each mission implies different problems to deal with, and it may require a different design set-up with a degradation of the drone dynamics. In the fourth chapter it is showed how, by acting on specific design parameters, it is possible to improve the UAV flying qualities with respect to the assigned mission. It is important to underline that the target of this thesis is not to optimize the design of the considered drone, but rather to propose a simple and general strategy that allows the enhancement of UAVs flying qualities with respect to the operational requirements of the assigned mission.