text: 40 percent chord. When this section is com- 
  the NACA 0006 section the effect 
  pared with 
  lift 
  of camber can be appreciated. At 
  coefficients the thtn, symmetrical section has 
  much lower drag. However, at lift coeffi- 
  cients above 03 the thicker, cambered section 
  has the lower drag. Thus, proper camber and 
  thickness can improve the lift-drag 
  ratio of 
  the section. 
  
  low 
  
  DRAG CHARACTERISTICS. 
  The total drag of an airplane is composed of 
  the drags of the individual components and 
  the forces caused by interference between these 
  components. The drag of an airplane con- 
  figuration must include the various drags due 
  to lift, 
  interference, leakage, 
  etc. To appreciate the factors which affect 
  is 
  the drag of an airplane configuration, 
  to consider the factors which 
  most logical 
  affect the drag of airfoil sections. 
  In order to 
  allow an objective consideration of the effects 
  of thickness, camber, etc., the properties of 
  two-dimensional sections must be studied. 
  Airfoil section properties are derived from the 
  basic profile in two-dimensional. flow and are 
  provided the lower case shorthand notation 
  to distinguish 
  them from wing or airplane 
  properties, e.g., wing or airplane drag coe5- 
  cient is C, while airfoil section drag coefficient 
  is c,. 
  
  it 