text: INDUCED DRAG 
  
  Another important influence of the induced 
  flow is the orientation of the actual lift on a 
  wing. Figure 1.30 illustrates the fact that the 
  lift produced by the wing sections is perpen- 
  dicular to the average relative wind. Since 
  is inclined down- 
  the average relative wind 
  is inclined aft, by the 
  ward, the section lift 
  same amount-the 
  induced angle of attack, 
  ai. The lift and drag of a wing must continue 
  to be referred perpendicular and parallel to the 
  In this 
  remote free stream ahead of the wing. 
  respect, the lift on the wing has a component 
  of force parallel to the remote free stream. 
  in the drag direction 
  This component of lift 
  unavoidable-conse- 
  is the undesirable-but 