text: AERODYNAMIC FORCE COEFFICIENT. 
  The aerodynamic forces of lift and drag depend 
  on the combined effect of many different vari- 
  ables. The important single variables could 
  IX: 
  
  (1) Airstream velocity 
  (2) Air density 
  (3) Shape or profile of the surface 
  (4) Angle of attack 
  (5) Surface area 
  (6) Compressibility effects 
  (7) Viscosity effects 
  
  If the effects of viscosity and compressibility 
  are not of immediate importance, the remain- 
  ing items can be combined for consideration. 
  Since the major aerodynamic forces are the 
  result of various pressures distributed on a 
  surface, the surface area will be a major factor. 
  Dynamic prcssurc of the airstream is another 
  common denominator of aerodynamic forces 
  and is a major factor since the magnitude of a 
  pressure distribution depends on the source 
  energy of 
  the free stream. The remaining 
  major factor is the relative peJJ#re dittribution 
  
  22 