Coupled Flight Dynamic and Unsteady Aeroservoelastic Modeling and Control of a Flexible Wing Aircraft

Recent developments in airframe design include the increasing application of modern lightweight materials. Airframe designs based on composite materials are able to provide sufficient structural strength at lower mass, but often have decreased structural rigidity. Flight vehicles with relatively flexible structures exhibit more prominent coupling of aeroelasticity and flight dynamics, and may suffer from degraded aerodynamic efficiency and decrease of control surface effectiveness. In order to address this issue, a multi-disciplinary approach to control effectiveness and aerodynamic efficiency of flexible aircraft is required. The purpose is not only to neutralize negative aeroelastic effects, but also to employ deliberate reshaping of the elastic wing to improve efficiency and handling of the aircraft. To this end, NASA is researching a novel type of control effector, the Variable Camber Continuous Trailing Edge Flap (VCCTEF). Using the multi-segment flaps of the VCCTEF, it is possible to adapt the camber of the wing in order to achieve an optimum lift distribution. In the context of aircraft with flexible airframes, a representation of flight characteristics based on a rigid-body 6DOF flight dynamic model is inadequate. The prominent coupling of flight dynamics, structural dynamics, and high-bandwidth control surfaces calls for coupled flight dynamic and aeroservoelastic modeling of flexible vehicles. The purpose of this thesis project was to develop such a coupled model for application during the conceptual design phase of adaptive aeroelastic wing technologies. A comprehensive flight dynamic and aeroservoelastic modeling approach for a flexible wing aircraft with VCCTEF in turbulent air was developed. Unsteady aerodynamics of the flexible wing and flap system were found using modified aerodynamic strip theory based on steady-flow vortex-lattice results and 2D unsteady aerodynamics models. Compressibility effects on the unsteady aerodynamics, based on the work by Beddoes and Leishman et al., were taken into account throughout the modeling effort and a comparison was made with unsteady aerodynamics for incompressible flow. In order to demonstrate the model and the effectiveness of the VCCTEF, a multi-objective flight controller for flight dynamic maneuvering, flutter suppression, and drag reduction was designed. Simulation results underline the potential of the VCCTEF as an enabling technology for adaptive aeroelastic wing shaping.Control and SimulationControl and OperationsAerospace Engineerin