text: NAVWEPS 00-8OT-80 
  BASIC AERODYNAMICS 
  
  ure is not too accurate because of the sharper 
  variation of parasite drag at high angles of 
  attack. 
  In a sense, the airplane efficiency fac- 
  tor would change from the constant value and 
  decrease. The deviation of the actual airplane 
  drag from the approximating curve is quite 
  noticeable for airplanes with low aspect ratio 
  and sweepback. Another factor to consider is 
  the effect of compressibility. Since compressi- 
  bility effects would destroy this relationship, 
  the greatest application is for subsonic perform- 
  ance analysis. 
  
  in with the induced drag coefficient by a con- 
  stant factor which is defined as the “airplane 
  e5ciency factor”, c. By this method of ac- 
  counting the airplane drag coe5cient is ex- 
  pressed as : 
  
  minimum parasite drag 
  coefficient 
  C DPmB= 
  The total airplane drag is the sum of the 
  
  parasite and induced drags.  CD;= induced drag coe5cient 
  
  e = airplane e5ciency factor 
  D= D,+D< 
  where 
  
  In this form, the airplane drag coefficient is 
  expressed as the sum of drag not due to lift 
  Di= induced drag 