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CHAPTER 4 III The Wing: Particulars of Flight 53

side surface area aft of the plane’s center of gravity. birds are about to set down, they rotate and cup their
However, birds may achieve a similar effect by curling wings and drop their tails, presenting maximum
their wingtips (Figure 4-13) and arching their tails surface area to the wind, and increasing drag. This
horizontally (Figure 4-14). results in a controlled stall and soft landing (Figures
4-15 and 4-16).
III WING ROTATION, CUPPING,
AND TAIL-DROP III HOVERING

With the exception of the V-22 Osprey, which is able to Wing rotation combined with tail fanning enables terns
land and take off vertically, airplanes are incapable of to hover high above the water, locate their prey, and
independently rotating their wings, something birds plummet beneath the surface of the water for the
do routinely when landing. For example, as water capture (Figure 4-17).

Figure 4-13 • A goose flares, curling its wingtips and
extending its neck and feet, just as it is about to
touch down.

Figure 4-14 • A goose begins a slow shallow turn before
landing. Note that both the wings and tail are arched.

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