CAREER: Gliding Flight in Snakes: How Wingless Gliders Produce Force, Maintain Stability, and Maneuver

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Flying snakes of the genus Chrysopelea glide like no other animal. Without appendages or membranes to use as lift-generating surfaces, flying snakes flatten from head to tail and glide using the body as a single "wing". In the air, the snakes simultaneously send traveling waves down the body while oscillating in the vertical plane, a flight behavior unlike any other found in the natural or engineering world. This project aims to understand the mechanisms that explain the unique flight abilities of flying snakes. Gliding in live snakes will be recorded to determine their detailed body movements and sectional shapes, including experiments to understand how snakes remain stable and maneuver in the air. Physical and computational models will be used to understand how the snake's shape and continuously changing body posture contribute to the production of aerodynamic forces for weight support and stability. Additional theoretical and physical models will be developed to investigate the requirements for producing snake-like locomotion in the air. The subject of this study is an exciting topic for students and the broader public, and the proposed research will additionally serve as a springboard for new initiatives that integrate physics, biology, and engineering into novel educational programming. Animal groups that fly have been tremendously successful in the biological world, and yet no clear picture has emerged to explain how powered flight has evolved from terrestrial species. In particular, we lack an understanding of how species have transitioned from static gliding to active flapping flight. The undulating movements of the gliding snake, which can be considered as a continuously morphing wing, present characteristics that bridge from passive gliding to powered flight. The flying snake is an active glider, representing the only functional intermediate across the spectrum of gliding to flapping flight. Understanding the mechanics of gliding flight in snakes will therefore lend insight into how one group of species has successfully overcome the biomechanical challenges resulting from shifting forces and rotational torques on the body, a similar problem associated with active flapping flight. Additionally, the aerodynamics of flight at low Reynolds number has received far less attention than the flight dynamics of larger engineered flyers, and this project will elucidate how a craft with symmetrical airfoil shape, but asymmetrical and dynamic body posture, can be physically advantageous. Specifically, the unexpected aerodynamic performance of the snake may originate in its ability to "surf" on its own wake. The determination of muscle activity patterns during perturbation and turning trials will provide the first evidence of the neuromuscular control system required for this type of undulating flyer. In combination, the proposed research to understand how snakes glide will provide contributions across disciplines and will potentially lead to the development of novel micro-air vehicles. Gliding flight in snakes is perhaps one of the most spectacular behaviors in the natural world, and has the potential to inspire new generations of students to take interest in STEM fields. This project taps into the natural appeal of this animal to develop new educational content for teachers and the public. Two major synergistic initiatives will be launched based on flying snake research. The first creates exciting, web-based multi-media material that can be easily adapted and used by teachers across educational levels. The new material will include informative video developed in collaboration with a professional television producer with years of experience creating programs for the National Geographic Channel. The second effort will use research in this project to create a new museum exhibit on flying snakes at the Science Museum of Western Virginia, with assistance from a public school teacher to help translate research into pedagogy. This exhibit will be offered for adaptation at museums worldwide, including the integration into a new exhibit on biomechanics at the Field Museum in Chicago. In addition to the global reach of these efforts, the appeal of flying snakes will be used as a mechanism to recruit underrepresented students into research at the undergraduate and graduate levels through targeted recruiting and visits to local universities with traditionally underserved student populations.