Word: attacke
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Dates: during 1940-1949
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...more besides. A bird's "propellers," explains Storer, are the big feathers at the ends of its wings. They are perfect airfoils with thick leading edges and thin trailing edges. When the bird flaps its wings downward, the "prop feathers" separate, twist to assume the proper "angle of attack," and act like propeller blades. They generate a forward force that pulls the wing forward, and the bird with...
...airplane is supported by the reaction between its stationary wings and the air that strikes them as the plane moves horizontally. A bird is supported in the same way. The broad inner portions of its wings, which move less than the tips, are kept at any angle of attack that gives them maximum lift...
Slots & Flaps. The lift in an airplane's wings can be increased by increasing the angle of attack (i.e., the angle at which it meets the air stream). If the angle becomes too great, the air stream does not flow smoothly over the wing; it breaks into turbulent eddies. The wing loses most of its lift, and the stall that results can throw the airplane, into a disastrous spin. The danger of stalling can be lessened by slots behind the leading edge of the wing. The slots feed thin layers of air to the wing's upper side...
...wings of many birds are also slotted so that the angle of attack (and the lift) may be increased without risking a stall. They have a movable feather called an "alula," which usually rests against the leading edge. When the bird needs extra lift from its wings (i.e., for a quick, high-angle climb), it increases its wings' angle of attack. Then it opens a slot by moving the alula. A thin stream of air rushes over the wing, preventing a stall...
...airplane will also stall when it flies too slowly. Birds, like planes, are equipped with "flaps": movable sections which can be protruded from the trailing edges of the wings. When slowing down for a landing, birds often spread their tails at a proper angle of attack. The tail acts exactly like airplane flaps, providing extra lift and keeping the bird from stalling...