text: In many parts of airplane performance it is 
  necessary to completely distinguish between 
  drag due to lift and drag not due to lift. The 
  total drag of an airplane is the sum of the para- 
  site and induced drags. 
  
  G=c++cD; 
  
  where 
  
  C, = airplane drag coefficient 
  
  C+=parasite drag coefficient 
  
  C,,= induced drag coeaicient 