A Collective Assessment
12.1 Looking Around: State-of-the-Art
Researchers have obtained impressive empirical results to date that have yielded much insight into the mechanisms of morphing. It has become clear that morphing in flying animals is far more complex than is generally appreciated, ranging from the rather subtle twist and camber changes used by insects for control, to the massive changes in span, aspect ratio, and wing area used by birds to adapt their flight morphology for different flight missions. The way forward will no doubt contain elements of the competing approaches of either bio-inspiration or bio-mimicry, or perhaps a combination of both. Neither approach has been taken advantage of to date, and while it is too early to tell which approach will ultimately prevail, it is certain that physics-based modeling that is validated with newer and more detailed empirical data holds much promise for advancing the state-of-the-art.
This is an area in which more work clearly needs to be done. The majority, if not all, of the morphing aerodynamics to date are modeled on the assumptions of steady, inviscid flow. This largely results from the tradeoff between physics-based analytical models (difficult to generate and validate accurately), Computational Fluid Dynamics (CFD) models (straightforward but computationally cumbersome), and empirical models generated from wind tunnel testing (expensive ...