Development of an aeroelastic in-flight testing system for a flexible wing unmanned aerial vehicle using acceleration and strain sensors

Abstract

© 2019 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.This paper presents a methodology employed to characterize the aeroelastic behavior of an Unmanned Aerial Vehicle (UAV) with high aspect ratio and structural flexibility. Commonly, modal characteristics of aircraft are experimentally obtained by means of a Ground Vibration Test (GVT), which in turn could be used to correlate and update numerical models and further applied to aeroelastically characterize the aircraft. The input-Output experimental modal analysis is not easily applied to aeroelastic tests in actual flight conditions because of the difficulties measuring the actual inputs due to aerodynamic loads. Therefore, the Ouput-Only (O-O) approach also known as Operational Modal Analysis (OMA) was used to identify the modal characteristic of aircraft using accelerometers and strain sensors. In this study the OMA based on the Enhanced Frequency Domain Decomposition (EFDD) was applied to process the operational vibration data. This paper discusses and compares the results between Input-Output modal analysis and OMA approaches. A numerical flutter analysis was performed to observe the evolution of aeroelastic damping and frequencies as a function of airspeed, and to understand coupling mechanisms. The Aircraft aeroelastic behavior is studied for different flight conditions. The g-method for aeroelastic stability analysis was employed. Based on information from the GVT a flight test planning was conducted. The data acquisition system is described below.