Experimental Analysis of Unsteady Aerodynamic Covert Feather Behavior

The interest in man-made flying vehicles has existed for over 100 years. Bird flight has been the major inspiration for the creation of such vehicles. More recently, UAVs (unmanned aerial vehicles) have become more popular and their use in more applications has developed the need for improved maneuverability. UAVs are also decreasing in size which has allowed them to operate within similar flight conditions as birds. Studying bird feather behavior may open doors and shed some light as to how the bird achieves such agility and control, which may then be adapted to UAV flight. In this research, the motion of the freely moving covert feathers on a live trained American kestrel and a preserved pre-existing Red-tailed hawk wing were studied. High-speed and GoPro video footage was taken of an American kestrel while landing on a perch inside of the WVU Emissions and Free Flight Wind Tunnel. The distance between the perches varied. The GoPro and high-speed cameras were setup in different locations capturing movement from a variety of perspectives. Video analysis was performed on this footage to obtain flight data, including velocity and covert feather frequency as the bird approached the landing perch. The pre-existing Red-tailed hawk wing was tested in the WVU Closed Loop Wind Tunnel. A high-speed camera was used to capture feather movements. The test regime included static and dynamic angles of attack. The dynamic motion was achieved using a motor and link system. Frequencies recorded during static angle testing were compared to frequencies found during dynamic motion. Both sets of frequencies were found to be within the same range. These recorded feather frequencies were then compared to the frequencies obtained in the free flight experiment. Frequencies observed during the free flight experiment were slightly higher than those found while testing the preserved wing