Time-Domain System Identification of Rigid-Body Multipoint Loads Model

Abstract

Loads monitoring is of central interest for both aircraft manufacturers and operators. The proper monitoring approach can represent the success or failure of a new aircraft design as well as the economic growth of air carriers. This paper introduces the development of a rigid-body multipoint loads model based on flight test data using System-Identification in time domain. Several strain sensors were calibrated to enable local loads measurements. Direct loads measurements at different positions of the aircraft structure were used to extend the typical set of observation variables, in order to enable the prediction of local aerodynamic loads by this model. For this purpose specific flight test maneuvers covering low frequency inputs at different airspeeds were performed. The test platform is a high-performance sailplane equipped with special flight test instrumentation, in order to allow the modeling of the multipoint loads model at several aircraft load stations. The main contribution of this work is the extension of the conventional System-Identification approach for enabling the simulation of local loads in real time. In this context, the multipoint model structure is outlined and a host of results from the identification of a rigid-body seven-point loads model is presented.