Engineering perspective on bird flight: Scaling, geometry, kinematics and aerodynamics

From the perspective of aeronautical engineers, this paper gives a systematical summary of the technical aspects of bird flight that should be considered in the analysis and design of flapping unmanned and micro air vehicles (UAVs and MAVs). The relevant aspects include the scaling laws, avian wing geometry, avian wing kinematics, aerodynamics models, computations, and special topics. Instead of extensively and uniformly reviewing a wide range of materials studied by avian biologists, we focus on the analytical and semi-analytical models and quantitative data as the useful guidelines for the design of flapping UAVs and MAVs.