text: Di=CDigS 
  
  where 
  
  Di=induced drag, lbs. 
  
  4= :Vymic pressures; psf 
  
  =295 
  
  Cni= induced drag coefficient 
  
  S=wing area, sq. ft. 
  
  (2) The induced drag coefficient can be 
  
  derived as : 
  
  CD,-C, sin ai 
  
  or 
  
  CD& 
  
  c,P 
  -Jjj 
  ) 
  ( 
  =0.318 
  
  where 
  
  C,= lift coefficient 
  
  sin ai=natural sine of the induced angle 
  of attack, Eli, degrees 
  
  r=3.1416, constant 
  AR= wing aspect ratio 
  
  68 
  
  hWd  Jonua~ 1965 