First-Ever Airfoil Profile of In-Flight Bird May Inspire Future MAV Concepts

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  • By Shelly Rich
  • Munitions
EGLIN AIR FORCE BASE, Florida --  In an attempt to unlock some of the secrets enabling birds to achieve agile flight, Air Force Research Laboratory is funding the efforts of researchers at the United Kingdom's Oxford University to quantify the flight performance of large birds. In close partnership with its European Office of Aerospace Research and Development, AFRL is looking to natural flyers for inspiration and insight towards increased flight agility for future micro air vehicle concepts. What began as an interesting foray into mounting cameras on large birds in order to observe various aspects of avian flight has become an active area of research for AFRL.

The advent of micro cameras and remote connection/communications technology has allowed researchers to place wireless camera packs on birds to observe various in-flight features. Initial observations of an eagle's wing showed deployment of the bird's "covert feathers" during certain maneuvers, a natural mechanism similar to that of an aircraft's deployment of leading-edge slats. Most remarkable about this observed, seemingly innate response is that it happened so quickly and only under certain flight conditions. Also witnessed during the eagle's flight were wing morphing (or bending) for flight control, head movement in coordination with turns, and various other occurrences.

As part of this effort, researchers with Oxford's Animal Behaviour Research Group used high-speed cameras in conjunction with stereo-vision cameras to capture the airfoil shape of a bird in free flight. The research activity involved training a falcon to fly from its handler and down an instrumented corridor. At some point during this flight, six cameras captured simultaneous images of the upper and lower surfaces of the bird's wing. The researchers then used stereo-vision analysis techniques to derive a three-dimensional mapping of the wing from the images. This resulted in the first-ever measurement of a live bird's wing airfoil profile while in unrestrained flight. This data will enable engineers to study not only the shape of the bird's wing but also the morphing that occurs during maneuvers. The primary objective of this work is to gain knowledge of natural flight in order to engineer the MAV concepts of tomorrow. With flight agility being a key enabler for any future MAV system, the need to adequately characterize aerodynamics and flight mechanics is crucial for AFRL strategic goals concerning "ubiquitous swarming sensors and shooters."