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

Abstract

A new generation of unmanned-air-vehicles (UAVs) called extremelyflexible (X) high-altitude long-endurance (HALE) aircrafts are beingactively studied today. These special kind of UAVs are characterized by highlyflexible structural members undergoing complex motions in space. In this paper,the authors present a numerical framework to study the dynamical behavior of aX-HALE-UAV concept. The aircraft is modeled as a set of rigid bodies linkedeach other through elastic joints. The motion equations for the entire UAV arederived by using an energetic approach based on Lagrange?s equations for constrained systems, which are differential-algebraic of index-3 in nature. Allgoverning equations are numerically integrated by means of different time-marching schemes such as: (i) direct-based methods (Newmark, Hughes-Hilber-Taylor and a-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.