The idea of the EU funded FLEXOP project is to raise efficiency of a currently existing wing by derivative solution with higher aspect ratio at no excess structural weight. In order to enable such a resulting highly flexible wing the project goal is to develop methods for active suppression of flutter and passive load alleviation. The developed methods will be tested and validated with a UAV flutter demonstrator. The demonstrator is a 7m wingspan, 65kg MTOW UAV equipped with a jet engine. It features three different wing pairs. The first wing is a stiff design reference case, which is flown to get the baseline measurements for comparison. The second one is a wing designed very flexible specifically for active flutter control. The third wing is aeroelastically tailored for gust load alleviation. The paper describes the results of the aeroelastically tailored wing compared to the baseline reference wing. @en

Ground testing campaign conducted on the FLEXOP demonstrator aircraft is presented in this paper. The conducted tests are grouped in structural, flight system and integration tests. Along with the description of the test setup and test execution, the main findings and conclusions are also given. The structural tests comprise the static, ground vibration and the airworthiness test. The static and the ground vibration tests were used for structural characterisation of the manufactured wings and airframe as a whole. Assessment and calibration of the Fibre Brag strain sensing system for wing shape and load reconstruction is also presented within this context. The airworthiness test is used to demonstrate the structural integrity of the manufactured wings under specified limit loads. Within the context of the flight system tests, the main components of the on-board autopilot hardware-software system are briefly introduced including the signal data flow from the RC transmitter to the aircraft controls, the functionality of the baseline autopilot software and the communication with the ground station. All of these components are integrated into the hardware-in-the-loop environment, which is also briefly introduced along with the servo motor identification and the hardware delay measurements. The measured hardware delay was considered in the design of the baseline and flutter controllers. The flutter controllers were tested together with the baseline controller in the software-in-the-loop environment. System integration tests are presented last. In this context the airbrake, the engine, the compatibility of electronic components, the range and the taxi tests are presented. @en

The idea of the EU funded FLEXOP project is to raise efficiency of a currently existing wing by derivative solution with higher aspect ratio at no excess structural weight. In order to enable such a resulting highly flexible wing the project goal is to develop methods for active suppression of flutter and passive load alleviation. The developed methods will be tested and validated with a UAV flutter demonstrator. The demonstrator is a 7m wingspan, 65kg MTOW UAV equipped with a jet engine. After ground testing, including static load and ground vibration tests the demonstrator will be flown within VLOS with three different sets of wings: One baseline rigid wing, one wing tailored for passive load alleviation and one very flexible wing to test active flutter control. The paper describes the design methods of the demonstrator and gives an overview about the planned tests on ground and in flight to validate the flutter prediction models. A special emphasis is on in flight wing shape measurement with an installed fiber brag system. @en