Aircraft design and testing of flexop unmanned flying demonstrator to test load alleviation and flutter suppression of high aspect ratio flexible wings

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.