Performance optimization and gust load alleviation of a UAV wing using variable camber

It is vital for an Uninhabited Aerial Vehicle (UAV) to meet contradictory mission requirements originating from the different tasks this type of aircraft has to fulfil. Among the most prominent requirements are manoeuvrability, endurance and range. The ability to switch between configurations that meet these requirements greatly enlarges the range of possible missions. A UAV wing has been developed to demonstrate the capacity to optimize the aerodynamic and structural performance. The wing is equipped with 4 Macro Fibre Composite (MFC) benders that can be controlled individually and each of these MFC benders actuates a section of the wing. It was chosen to use MFC benders as they possess several advantageous properties over conventional piezoceramic benders: they combine a wide frequency bandwidth with large deformations, yielding a high control authority, and they are less sensitive to cracks and failure, making them more robust for aerospace applications. A numerical study was conducted with XFLR5 to determine the optimal configurations of the flap positions for both range and endurance. A wind tunnel study was performed to verify these results. The wide frequency band of the actuators allows using the developed system also for other purposes such as load alleviation. UAVs are often light and fly at low airspeeds, which make them very sensitive to gust excitation. For this purpose the experimental model was equipped with two accelerometers to measure the amplitude of the first two deformation modes. The wing was designed such that the frequency of the first bending dominated mode and the first torsion dominated mode were close to each other. Consequently, a multiple-input multiple-output controller was used to reduce the amplitude of both modes due to a gust loading simultaneously. This was done with both range and endurance optimized flap configurations as steady state conditions. Finally, it was demonstrated during the wind tunnel tests that the variable camber concept provides enough forces and moments to replace the ailerons.