text: is a very efficient 
  conventional section which has been used on 
  many airplanes. One of the features of the 
  ~section is a relatively high c& with only a 
  small c,,,,,,; The pitching moment coefficients 1 
  for this section are shown on figure 1.22 along 
  with 
  the effect of various type flaps added to 
  the basic section. Large amounts of camber 
  applied well aft on the chord cause large nega- 
  tive moment coefficients. This fact is illus- 
  trated by the large negative moment coefli- 
  cients produced by the 30” deflection of a 25 
  percent chord flap. 
  
  The NACA 23012 airfoil 
  
  is a quantity determined by the 
  shape of the mean-camber line. Symmetrical 
  airfoils have zero c,,,,. and the c.p. remains at 
  the a.~. in unstalled flight. The airfoil with 
  positive camber will have a negative c,,,~,~, 
  which means the c.p. is behind the a.~. Since 
  the c5.c. is constant in unstalled flight a certain 
  relationship between lift coefficient and center 
  of pressure can be evolved. An example of 
  this relationship is shown in figure 1.22 for the 
  NACA 63i-412 airfoil by a plot of c.p. versus 
  c,. Note that at low lift coefficients the center 
  of pressure is well aft-even past the trailing 
  edge-and an increase in C~ moves the c.p, for- 
  ward toward the a.~. The c.9. approaches the 
  
  me kc. 