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Morphing Aerospace Vehicles and Structures by John Valasek

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7

Flight Dynamics of Morphing Aircraft with Time-Varying Inertias

Daniel T. Grant, Stephen Sorley, Animesh Chakravarthy and Rick Lind

University of Florida, USA

7.1 Introduction

The moments of inertia of a body obviously have a profound influence on the dynamics and associated motion of that body. Certainly aerospace systems, with multiple degrees of freedom for translation and rotation, must properly account for inertia to a high level of accuracy in order to model the dynamics. The time-varying aspect of these inertias must be considered with similar accuracy to note the influence of variations in geometry and mass on the system.

Some extensive and rigorous evaluations of traditional causes of time-varying inertia, such as fuel expenditure and multi-body rotation, have been performed for space systems. The effects of translating mass within a space station are derived under an assumption of harmonic motion and used to compute librational stability (Spenny and Williams 1991). Moving mass was also included in the dynamics of a vehicle with a solar sail that could move for control purposes. The dynamics and associated time-varying inertia were modeled for a two-vehicle formation in which a Coulomb tether controlled the relative distance and mass distribution (Natarajan and Schaub 2006). Another study optimized a design for a two-vehicle formation with a flexible appendage whose motion altered the inertia properties (Oliver and Asokanthan 1997). The influence of thrusters, which ...

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