Özge Süelözgen, Gertjan Looye, Thiemo Kier, Matthias Wuestenhagen, Ramesh Konatala, Keith Soal, Nicolas Guérin, Bálint Vanek
DOI Number: N/A
Conference number: IFASD-2024-128
A validated aeroservoelastic (ASE) model allows, among other things, the extensive study of system performance and characteristics, the verification of analytical predictions, the support of flight envelope expansion during prototype testing, and the design of flight control laws. The ASE stability analysis is another crucial component of the configuration optimization and certification process over the intended operational envelope. In this context, the flutter phenomenon is a well-known example of a self-excited aeroelastic instability resulting from the interaction between unsteady aerodynamic forces and structural vibrations. The investigation of flutter through flight flutter testing is an essential part of aircraft certification. Significant amplitudes of vibration can be induced, eventually resulting in the structure’s catastrophic failure. Instabilities have been derived that exceed well beyond the basic bending-torsion flutter into complex mechanisms involving ASE dynamics. With the guidance of accurate ASE models, a reliable prediction of an aircraft’s susceptibility to flutter across its intended flight envelope is possible. Using data from flight tests of the fixed-wing P-FLEX UAV with a 6m wing span, this paper will demonstrate post-flight system identification results and, by extension, ASE model updating using modal parameters identified from Ground Vibration Test. Predictions provided by the updated model regarding flutter boundary will be thoroughly assessed. An additional significant topic is the post-flight verification of the open-loop flutter speed obtained through system identification using flight test data. This is achieved through the monitoring of aeroelastic damping and qualitative comparison of the stability diagrams of the system’s poles at different flight
speeds. Finally, flutter boundary expansion enabled by the Active Flutter Suppression (AFS) controller of the closed-loop system will be verified via post-flight analysis of the critical flight flutter test data.