Date of Award

12-2014

Access Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Richard Prazenica, Ph.D. and Snorri Gudmundsson, Asst. Professor

First Committee Member

Ebenezer Gnanamanickam, Ph.D.

Abstract

Morphing wings have the potential to optimize UAV performance for a variety of flight conditions and maneuvers. The ability to vary both the wing sweep and span can enable maximum performance for a diverse range of flight regimes. For example, low-speed missions can be optimized using a wing with high aspect ratio and no wing sweep whereas high-speed missions are optimized with low aspect ratio wings and large wing sweep. Different static morphing wing configurations clearly result in varying aerodynamics and, as a result, varying dynamic modes. Another important consideration, however, is the transient dynamics that occur when transitioning between morphing configurations, which is clearly a function of the rate of transition. For smaller-scale morphing UAVs, morphing transitions can take place on a time scale comparable to the dynamics of the vehicle, which implies that the transient dynamics must be taken into account when modeling the dynamics of such a vehicle.

This thesis considers the dynamic effects of morphing for a variable-sweep, variable-span UAV. A scale model of such a morphing wing has been fabricated and tested in the low-speed wind tunnel at Embry-Riddle Aeronautical University. The focus of this thesis is the development of a dynamic model for this morphing wing UAV that accounts for not only the varying dynamics resulting from different static morphing configurations, but also the transient dynamics associated with morphing. A Vortex Lattice Method (VLM) solver is used to model the aerodynamics of the morphing wing UAV over a two-dimensional array of static configurations corresponding to varying span and sweep. In this analysis, only symmetric morphing configurations are considered (i.e., in every configuration, both wings have the same span and sweep); therefore, the analysis focuses on the longitudinal dynamic modes (i.e., the long period and short period modes). The dynamic model of the morphing wing UAV is used to develop a simulation in which it is possible to specify different morphing configurations as well as varying rates of morphing transition. As such, the simulation provides an invaluable tool for analyzing the effects of wing morphing on the longitudinal flight dynamics of a morphing UAV.

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