Static and Dynamic Aeroelastic Tailoring with Variable-Camber Control

This paper examines the use of a variable-camber continuous trailing-edge flap system for aeroservoelastic optimization of a transport wing box, the Common Research Model. Along with patch-level structural wing-box design variables, the quasi-steady and unsteady motions of the flap system are used as design variables, for maneuver load alleviation, cruise fuel burn reduction, and active flutter suppression. The resulting system is able to minimize structural weight and/or fuel burn while satisfying constraints upon elastic stresses, panel buckling, actuator hinge moments, flutter margins, actuator work, and control cost metrics. Limitations to this success are imposed by including load cases where the actuation system is not active (open-loop) in the optimization process. Large open-loop safety factors, for either maneuver loads or flutter, dilute the importance of the closed-loop actuation mechanism, whereas small open-loop safety factors may produce an overly flexible wing, prone to failure. Similar tradeoffs between system performance and actuator work constraints are provided. A final theme of the paper explores aeroelastic performance penalties that may arise if the shapes available to the variable-camber actuation system are limited (i.e., if certain control segments are linked together).