text: S= wing surface area, sq. ft. 
  
  The force of drag is shown as the product of 
  dynamic pressure, surface area, and drag co- 
  efficient, C,. The drag coefficient 
  this 
  equation is similar to any other aerodynamic 
  is the ratio of drag pres- 
  force coefficient-it 
  sure to dynamic pressure. If 
  the drag co- 
  efficient of a conventional airplane were plotted 
  versus angle of attack, the result would be 
  typical of the graph shown in figure 1.13. At 
  low angles of attack 
  the drag coefficient is 
  low and small changes in angle of attack create 
  only slight changes in drag coefficient. At 
  
  in 