Flexible Aircraft Modeling for Flight Control Law Design and Analysis

Abstract

This report consists of two parts. In the first part we will discuss a so-called bottom-up approach to integration of flight mechanics and aeroelastic aircraft models. In the second part we demonstrate a new method for flutter analysis, the µ-method, that that has been developed at NASA-Dryden. The flutter analysis is an example application of the model discussed in the first part. After a brief introduction we will derive the flexible aircraft equations of motion from first principles, emphasizing how rigid body and structural aircraft models fit together, and what key-assumptions we make. The aerodynamic model is the most important component. We will discuss what and how data from different modeling sources (flight mechanical / aeroelastic) is to be used in the equations of motion. Our modeling software is Dymola: due to its object-oriented nature it is very suitable for multidisciplinary modeling purposes. As an example, we will show the implementation of a generic flexible aircraft model, and present some nonlinear simulation results.