| Insect flight serves as an excellent platform for exploring motion control. Although insect flight is an established model system for myriad sensory systems, and substantial progress has been made in understanding the complex aerodynamics of insect flight, integrative models aimed at bridging the nervous and mechanical systems have faced an important obstacle Insect wings are flexible structures that deform during flapping flight. Yet, the aerodynamic consequences of such emergent deformations have been largely unknown. In Chapter 1, I review our current understanding of the functional morphology and aerodynamics associated with insect wing deformations, and discuss limitations of the primary insect flight models in incorporating flexible wings.;In Chapter 2 (Mountcastle & Daniel, 2009), we use Particle Image Velocimetry to explore the affects of emergent deformations on induced flows in the moth, Manduca sexta. We robotically actuate real moth wings, of varying flexural stiffnesses, at natural wing beat frequency. We find that flexible wings, with greater deformations, yield mean advective flows with substantially greater magnitudes, and orientations more favorable for lift, than those of stiff wings.;In Chapter 3, I quantify wing deformation during free flight hovering in Manduca sexta, and explore the extent to which deformation relates to aerodynamic forces on the body. I digitize wing and body kinematics during flight, and use simple Newtonian mechanics to separate the aerodynamic forces on the body from predicted inertial reaction forces due to wing motions. I find that wing deformation varies from stroke to stroke, and these deformations are correlated with the predicted aerodynamic lift during ventral stroke reversals.;In Chapter 4 (Mountcastle & Daniel, in review), we address questions of aerodynamic performance tuning as a function of spatial distribution of wing stiffness and boundary conditions governing wing actuation. We use a combination of computational structural mechanics methods and a 2-D computational fluid dynamics model to ask how aerodynamic force production, mechanical advantage and their control potential are affected by pitch/elevation phase and variations in wing flexural stiffness. Our results show that lift and thrust forces, as well as the mechanical advantage of wing motions are highly sensitive to flexural stiffness distributions, with performance optima that lie in different phase regions. |
