IN-FLIGHT AEROELASTIC SYSTEM IDENTIFICATION OF A HIGH-ASPECT-RATIO MOTOR GLIDER

摘要

The development of high-bandwidth automatic flight control systems (AFCS) requires the simultaneous consideration of both the aircraft flight dynamics and the aircraft structural dynamics. The knowledge of the aircraft elastic modal shapes and their properties (damping factors and frequencies) is acquired by generating structural models that are validated in ground vibration tests and then supplemented with unsteady aerodynamic models. The aeroelastic model is validated in flight test, especially to confirm the calculated aerodynamic damping factors. Subsequently, the aeroelastic model and the flight mechanical rigid-body model may be combined to the flight mechanical model for the flexible aircraft that is used for control law design. For small general aviation aircraft for which theoretical aeroelastic models are lacking, an alternative approach is to derive a model from in-flight aeroelastic model identification. With this objective, a flight test campaign was performed for the motor glider STEMME S15. Sine-sweep commands of the control surfaces provided the excitation of the aircraft structure. The most important results of the in-flight modal analysis are presented and discussed in this paper.