Multibody dynamic analysis of a high-altitude long-endurance aircraft concept

Abstract

A new generation of unmanned-air-vehicles (UAVs) called extremely flexible (X) high-altitude long-endurance (HALE) aircrafts are being actively studied today. These special kind of UAVs are characterized by highly flexible structural members undergoing complex motions in space. In this paper, the authors present a numerical framework to study the dynamical behavior of a X-HALE-UAV concept. The aircraft is modeled as a set of rigid bodies linked each other through elastic joints. The motion equations for the entire UAV are derived by using an energetic approach based on Lagrange’s equations for constrained systems, which are differential-algebraic of index-3 in nature. All governing equations are numerically integrated by means of different time-marching schemes such as: (i) direct-based methods (Newmark, Hughes-Hilber-Taylor and α-generalized); and (ii) index reduction-based techniques along with standard packages for ordinary differential equations (ODEs). The simulation tool developed is validated comparing results against well-documented problems. Finally, numerical simulations of a simplified concept of X-HALE-UAV is presented.