1/31 Avian Aerodynamics and Flight Morphology - Need to overcome drag and gravity - Alula helps redirect air - Induced drag o From pulling wing through air o Caused by redirection of air o Induced drag is proportional to amount of lift x angle of attack - Body drag (aka profile drag) o Based on surface area o Combination of skin friction and pressure drag - Pressure drag o From high pressure at beak vs low pressure after body (downstream wake) - Skin Friction o Molecular interactions between air molecules as they skim over surface of body - Cost of flight o Power to glide low, because induced drag can be easily o overcome Hovering is very expensive because requires power from air o Induced power- power needed to overcome induced drag o Profile power- power related to overcoming body drag
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o o Most efficient = profile power + induced power. Total power is going to look parabolic o Graphs are different for every kind of bird Wingtip vortices- at edge (end and railing edge) of wings, air packets go from bottom to top of wing and creates a vortex that is a downward force o In steep flight, creates vortex rings o Trailing vortex is where birds move at a speed where they pass vortices before they are affected