title: Diving-flight aerodynamics of a peregrine falcon (Falco peregrinus).
abstract: This study investigates the aerodynamics of the falcon Falco peregrinus while diving. During a dive peregrines can reach velocities of more than 320 km h⁻¹. Unfortunately, in freely roaming falcons, these high velocities prohibit a precise determination of flight parameters such as velocity and acceleration as well as body shape and wing contour. Therefore, individual F. peregrinus were trained to dive in front of a vertical dam with a height of 60 m. The presence of a well-defined background allowed us to reconstruct the flight path and the body shape of the falcon during certain flight phases. Flight trajectories were obtained with a stereo high-speed camera system. In addition, body images of the falcon were taken from two perspectives with a high-resolution digital camera. The dam allowed us to match the high-resolution images obtained from the digital camera with the corresponding images taken with the high-speed cameras. Using these data we built a life-size model of F. peregrinus and used it to measure the drag and lift forces in a wind-tunnel. We compared these forces acting on the model with the data obtained from the 3-D flight path trajectory of the diving F. peregrinus. Visualizations of the flow in the wind-tunnel uncovered details of the flow structure around the falcon's body, which suggests local regions with separation of flow. High-resolution pictures of the diving peregrine indicate that feathers pop-up in the equivalent regions, where flow separation in the model falcon occurred.
authors: Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg, Germany.
authors: Benjamin
authors: B
authors: Ponitz
authors: Institute of Zoology, Rheinische Friedrich-Wilhelms Universität Bonn, Bonn, Germany.
authors: Anke
authors: A
authors: Schmitz
authors: Clinic for Birds, Reptiles, Amphibians, and Fish, Justus-Liebig-Universität Giessen, Giessen, Germany.
authors: Dominik
authors: D
authors: Fischer
authors: Institute of Zoology, Rheinische Friedrich-Wilhelms Universität Bonn, Bonn, Germany.
authors: Horst
authors: H
authors: Bleckmann
authors: Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg, Germany.
authors: Christoph
authors: C
authors: Brücker
mesh_terms: D000818:Animals; D046093:Falconiformes; D005426:Flight, Animal; D008962:Models, Theoretical; D014741:Video Recording