text: The NACA 63,412 is a cambered 12 percent 
  type. 
  the ‘“laminar 
  thick airfoil of 
  This airfoil 
  is shaped to produce a design lift 
  coe5cient of 0.4. Notice that the drag curve 
  of this airfoil has distinct aberrations with 
  very low drag coefficients near the lift coeffi- 
  cient of 0.4. This airfoil profile has its camber 
  and thickness distributed to produce very low 
  uniform velocity on the forward surface (mini- 
  mum pressure point well aft) at this lift coeffi- 
  cient. The resulting pressure and velocity 
  flow 
  distribution enhance extensive laminar 
  in the boundary layer and greatly reduce the 
  skin friction drag. The benefit of the laminar 
  flow is appreciated by comparing the minimum 
  drag of this airfoil with an airfoil which has 
  one-half the maximum thickness-the NACA 
  ooo6. 
  
  flow” 
  
  The drag characteristics of three illustrative 
  airfoil sections are shown in figure 1.14. The 
  section drag coe&cient, c,, is plotted versus 
  the section lift coefficient, cr. The drag on 
  the airfoil section is composed of pressure drag 
  and skin friction. When the airfoil 
  is at low 
  lift coe&cients, the drag due to skin friction 
  predominates. The drag curve for a conven- 
  tional airfoil tends to be quite shallow in this 
  region since there is very little variation of 
  skin friction with angle of attack. When the 
  airfoil 
  lift coefficients, form or 
  pressure drag predominates and the drag co- 
  efficient varies rapidly with 
  lift coefficient. 
  The NACA 0006 is a thin symmetrical profile 
  which has a maximum thickness of 6 percent 
  located at 30 percent of 
  the chord. This 
  section shows a typical variation of cd and cr. 
  The NACA 4412 section is a 12 percent thick 
  airfoil with 4 percent maximum camber at 