... ; Prange and Schmidt-Nielsen, 1970 ; Sorensen, 1973 ). This increase in wave drag further limits the speed of the animal swimming at the air–water interface. Eider duck Surface swimming Ground effect Hull speed Steaming Summary: Eider ducks are able to exceed their hull speed through...

... such as the hawk, petrel and wood duck. However, the induced drag by strong wing-tip vortices is one of the dominant drag components. Finally, we examine ground effect on the aerodynamic forces of the gliding flying fish and find that the flying fish achieves the reduction of drag and increase of lift-to-drag...

...F. Reed Hainsworth ABSTRACT Ciné films of brown pelicans flying in formation were used to measure altitudes and wing tip spacing (WTS, distance perpendicular to the flight path between wing tips of adjacent birds at maximum span) for birds flying in ground effect, and vertical displacements and WTS...