text: If the planform has curvature and the aver- 
  is not easily determined, an 
  age chord 
  alternate expression is: 
  
  of a planform are the principal factors which 
  determine the aerodynamic characteristics of a 
  .wing. These same quantities also have a defi- 
  nite influence on the structural weight and stiff- 
  ness of a wing. 
  
  The aspect ratio is a fineness ratio of the 
  wing and this quantity is very powerful in 
  determing the aerodynamic characteristics 
  and structural weight. Typical aspect ratios 
  vary from 33 for a high performance sail- 
  plane to 3.5 for a jet fighter 
  to 1.28 for a 
  flying saucer. 
  
  DEVELOPMENT OF LIFT BY A WING. 
  In order to appreciate the effect of the planform 
  on the aerodynamic characteristics, it is neces- 
  sary to study the manner in which a wing 
  Figure 1.29 illustrates the three- 
  produces lift.’ 
  dimensional flow pattern which results when 
  the rectangular wing creates lift. 
  (5) The raat chord, c,, is the chord at the 
  wing centerline and the rip chord, c,, is 
  measured at the tip. 