6
Flight Dynamics Modeling of Avian-Inspired Aircraft
6.1 Introduction
A morphing vehicle can be defined as an aircraft that undergoes a radical shape change. The ability to morph the vehicle configuration enables one aircraft to take on the roles of several different aircraft, allowing, for instance, optimized flight over a large flight envelope instead of merely one flight condition. Morphing constitutes a considerable challenge due to several problems. The actuators required to perform large-scale shape changing often add weight to the vehicle to the point where performance increases due to the morphing are counter-balanced by the performance decreases due to additional payload. Morphing provides additional degrees of freedom to the system and has a huge influence on the stability and handling of a vehicle. There are certain configurations in which an otherwise stable vehicle could become unstable when morphed, or when morphed to quickly. Additionally morphing complicates the modeling and control process, changing discrete configuration variables such as wing span or dihedral angle, and adding other variables with spatial content including lift and chord distributions.
One interesting class of morphing vehicles is medium to large-scale flapping-wing aircraft, or ornithopters. These vehicles use large beating wings to excite unsteady aerodynamics and generate lift and thrust forces ...
