text: In this form, the aerodynamic force coefficient 
  Js appreciared as the aerodynamic force per 
  surface area and dynamic pressure. In other 
  words, the force coefficient is a dimensionless 
  ratio between the average aerodynamic pres- 
  sure (aerodynamic force.per ‘area) and the air- 
  stream dynamic pressure. All the aerodynamic 
  forces of lift and drag are studied on this basis- 
  the common denominator in each case being 
  surface area and dynamic pressure. By such a 
  definition, a “lift 
  coefficient” would .be the 
  ratio between lift pressure and dynamic pres- 
  sure; a “drag coefficient” would be the ratio 
  between drag pressure and.:d.ynamic pressure. 
  The use of the coefficient form of an aero- 
  dynamic force is necessary since the force 
  coellicient is: 
  
  (1) An index 04 the aerodynamic force 
  independent of area, density, and velocity. 
  
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