text: vortex filaments which consist of the tip or 
  trailing vortices coupled with 
  the bound or 
  line vortex. The tip vortices are coupled with 
  the bound vortex when circulation is induced 
  with 
  lift. The effect of this vortex system is 
  to create certain vertical velocity components 
  in the vicinity of the wing. The illustration 
  of these vertical velocities shows that ahead 
  of the wing the bound vortex induces an up- 
  wash. Behind the wing, 
  the coupled action 
  of the bound vortex and the tip vortices in- 
  duces a downwash. With 
  the action of tip 
  and bound vortices coupled, a final vertical 
  velocity (220) is imparted to the airstream by 
  the wing producing lift. 
  This result is an 
  inevitable consequence of a finite wing pro- 
  ducing lift. 
  The wing Producing lift applies 
  the equal and opposite force to the airstream 
  and deflects it downward. One of the impor- 
  tant factors in this system is that a downward 
  velocity is created at the aerodynamic center 
  (w) which 
  the final downward 
  velocity imparted to the airstream (2~). 
  
  age relative wind which is different from the 
  remote free stream wind. Since the aerody- 
  namic forces created by the airfoil sections of a 
  wing depend upon the immediate airstream in 
  which 
  they operate, consideration must be 
  given to the effect of the inclined average rela- 
  tive wind. 
  
  To create a certain lift coefficient with 