Delayed stall
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Delayed Stall
The existence of the delayed stall can be related to the a prolongement attachmenet of the leading edge vortex on an insect's wing. Insects fly at high angles of attack, and through their motion, a leading edge vortex (LEV) and a trailing edge vortex (TEV) develop on the wing. However, contrary to a translating 2D airfoil or plate, the LEV of the wing remains constant in shape and size. Thus, no additional vorticity is created at the trailing edge (see Kutta condition). The fact that the LEV remains attached assures that 1) a non negligible upward suction is imparted to the wing, thus an increase in lift and, 2) energy is not dissipated in the wake by the von Karman street.
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