Aerodynamics of Slow Flight & Acceleration Dissertation advisor: Bret Tobalske. Image: Air velocities around a Diamond dove, taken using Particle Image Velocimetry. Collaborators: Doug Warrick, Ty Hedrick, Andy Biewener, Bret Tobalske, Charles Bishop Image: Sonic anemometer used to detect minute changes in wind speed and direction, as used in Warrick et al., 2016 ![]() Collaborators: Ondi Crino Image: Zebra Finches in nest ![]() While slow flight is the most energetically demanding form of flight, birds are capable of mediating take-off flight with propulsive leg forces. In general, it is easier to propel from a solid surface than air or water - and so birds rely heavily on their legs during the take-off phase, modulating their wings to produce additional forces following take-off. My research focuses on trade offs between force production by the legs and wings, as well as the interplay of natural materials on the ability to accelerate during take-off. Collaborators: Pauline Provini, Anick Abourachid Image: Transitional wingbeats, from Provini et al. 2012 The avian wing has specialized morphologically via fusion and reduction of skeletal and muscular elements in order to reduce distal limb mass. Surprisingly, then, despite a hypothesized four-bar linkage system (wherein action of only the proximal muscles allows the distal muscles to flex and extend), the bird remains capable of bending and twisting the distal hand-wing to provide additional aerodynamic forces during upstroke. From detailed morphological studies, it has been proposed that a majority of wing supination and extension is due to passive bone-bone interactions at the wrist (Vasquez, 1992). To address hypotheses of joint function, I am combining high-speed biplanar flouroscopy with micro-CT reconstructions of skeletal morphologies to recreate a digital model of motion, using XROMM techniques. Collaborators: Dave Baier, Ashley Heers, Brandon Jackson, Beth Brainerd, Andy Biewener Image: 3D reconstruction of a japanese quail skeleton from a mico-CT scan U Unsteady, time-dependent airflow around the wing is critical for take-off, maneuvering, and even landing. Thus, in order to fully understand wing shape we must immediately move beyond assumptions that it performs as a rigid surface and fully embrace its function as a dynamic, living wing as it performs in nature. However, a large gap in knowledge exists as to how time-varying aerodynamic mechanisms contribute to the morphology and behavior of birds. To improve our understanding of the evolution of flight, I have designed a portable high-speed camera setup to record take-off flights in the wild. By coupling field recordings and habitat analyses with detailed morphological analyses (with the spread wing collection at the Burke Museum, left), I will elucidate correlations between performance, habitat, and wing shape. Image: Simplified phylogeny of waterfowl wings (average mass inset) My research explores the potential mechanical and ecological tradeoffs in adhesive pads and claws by exploring organismal-level performance and morphology in relation to habitat use. Collaborators: Kellar Autumn, Anthony Herrel, and Jonathan Losos. Image: Anolis sagrei hanging by a single toe-pad to a glass microscope slide Micro-morphology and performance of biological adhesive structures ![]() The subdigital toe pad has evolved in three genera of squamates (geckos, anoles, and skinks), and consist of subdigital scales that contain millions of microscopic hair-like structures (setae) that facilitate adhesion via molecular-level van der Waals forces. Mechanical models of van der Waals interaction suggest that geometry can dictate the limits of setae function; We are exploring the association between variation in microstructure morphologies (from Anolis sagrei, right) and performance. Exploring morphologies across species allows us to infer the evolutionary dynamics as well as establish general design principles. Image: Microstructure of the anoline toe-pad: sub-digital adhesive scales (lamellae) contain microscopic hair-like structures (setae), with flattened tips (spatulae) |