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Wingtip Vortices

 Wingtip Vortices


 Formation of Vortices
  • The action of the airfoil that gives an aircraft lift also causes induced drag.
  • When an airfoil is flown at a positive AOA, a pressure differential exists between the upper and lower surfaces of the airfoil.
  •  The pressure above the wing is less than atmospheric pressure and the pressure below the wing is equal to or greater than atmospheric pressure.
  • Since air always moves from high pressure toward low pressure, and the path of least resistance is toward the airfoil’s tips, there is a spanwise movement of air from the bottom of the airfoil outward from the fuselage around the tips.
  •  This fl ow
  • of air results in “spillage” over the tips, thereby setting up a whirlpool of air called a “ vortex.”
  • At the same time, the air on the upper surface has a tendency to fl ow in toward the fuselage and off the trailing edge.
  •  This air current forms a similar vortex at the inboard portion of the trailing edge of the airfoil, but because the fuselage limits the inward fl ow, the vortex is insignifi cant.
  •  Consequently, the deviation in fl ow direction is greatest at the outer tips where the unrestricted lateral fl ow is the strongest.

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