Design, manufacturing and flight tests of a fixed-wing vertical take-off and landing unmanned air vehicle

For the last 40 years, high capacity unmanned air vehicles have been used mostly for the purpose of tracking, observation, active engagement with weapons or simply for data collection in the military field. Although unmanned air vehicles commercially receive demands due to their low production and operational costs compared to manned systems, flexibility to modify the aircraft for the customer needs and non-presence of the risk to lose the pilot in difficult missions, there are still missing points in terms of integration into the manned flight air space, reliability and flight safety. Even though civil unmanned air vehicles constitute 3 \% of the total vehicle market, it is predicted that this rate will reach up to 10\% within the coming 5 years. Together with the useful loads that are attached on the UAV systems (camera, hyper-spectral imager, air measurement sensors and with similar instruments), many implementations such as tracking and monitoring agriculture / forest / marine pollution / waste, tracking and monitoring in case of disasters, mapping for land registry and cadastre, wildlife and ecologic monitoring, geology and mine researches, traffic monitoring are performed more often day by day and the advantages brought by the air vehicle can be presented with the minimal risk factor and costs in many civil implementations, during which the usage of manned air vehicles was risky and costly. When the costs of unmanned air vehicles designed and produced for military service are taken into account, civil market demands lower cost and original products which are suitable for civil implementations. Most of the implementations which are mentioned above require vehicles that are able to take off and land on limited runway, and moreover, move quickly in the operation region for mobile implementations but hover for immobile measurement and tracking when necessary. Meanwhile, a cost-effective solution is needed in respect of the applicability / convertibility of such a system for many different civil and commercial implementations. It means an air vehicle which has easily detachable useful loads depending on the implementation concept and programmability of the operational area (their forward flight and hovering time) according to the implementation. Considering the abovementioned issues within the scope of this thesis, the design, production and flight tests of the unmanned air vehicle, which we call TURAÇ VTOL UAV through the inspiration for FRANCOLIN (TURAÇ) that vertically flies in the nature, were handled with the industrial theses support program (San-Tez) of the Ministry of Science, Industry and Technology. The suggested UAV system has the co-axial main rotor in the body and 2 tilt rotors at the front. Together with this configuration structure, it can complete its vertical take-off and landing and hovering missions like a helicopter and it has the same capacity of high forward velocity as that of a fixed-wing UAV system. Thanks to its usability with different sized wings presented by the detachable wing structure, different flight missions can be accomplished with a single body. The detachability characteristic also provides the air vehicle with the easy packaging and mobility feature. More volume is provided for the aerodynamic efficiency and useful load with the blended wing configuration. Within the scope of the thesis, the design process of the TURAC VTOL UAV, system engineering including structural and aerodynamic analyses, development and testing of propulsion systems, development of simulation and control algorithms, flight control system, flight management computer, useful load systems, software and hardware developments, low-cost rapid prototyping method and flight tests subjects were discussed. Firstly the motivation that drive us to design such an UAV was presented. For a competitive UAV design, similar designs were investigated. Possible problems that we can face were determined. The features and advantages of the concept of the TURAC VTOL UAV were explained. Especially the unique propulsion concept that differs from other UAVs was presented. An iterative method was followed in designing studies. Design modifications were conducted according to the analysis and test results. While designing and analyzing the detailed parts, structural and aerodynamic analyses were performed considering the efficiency of the whole system. Thanks to the original propulsion configuration of the TURAC VTOL UAV, both the energy was used in the most efficient way and no balance problems occurred in the triple rotor system. Engine-propeller-ESC combinations were tested and simulated with the developed and produced thrust test bench. Linear and non-linear dynamic models of TURAC VTOL UAV were created with the aerodynamic coefficients obtained by means of the computational fluid dynamic (CFD) and vortex lattice method (VLM). Scenarios for the TURAC VTOL UAV's transition from the hover to the forward flight (and reverse) were formed and analyzed. In line with these scenarios, flight control systems were developed and the flight simulations were successfully accomplished for the transition from the hover to the forward flight (and reverse). Control system designs and their embedded softwares were developed to enable hovering and autonomous transition from the hover to the forward flight. Avionic systems were developed as software and hardware. The developed ground station system includes the mission planning module, live control module, telemetrical data reception and recording module and playback module. Real-time video images can be transmitted to the ground station. Multispectral camera images were analyzed. A cost-effective and quick prototyping method was explained step by step. Different TURAC versions produced by means of this method were used in flight tests. Flight performance of each version became an input of the iterative design process and determined the next version. While autonomous flights such as autonomous landing and take-off and route tracking were performed with the wingless TURAC VTOL UAV in the tricopter mode, the forward flight, hovering tests and transition from the hover to the forward flight were successfully completed on manual and autonomous basis with 1/2 and 1/3 scaled TURAC VTOL UAVs.