text: CONTRIBUTION OF THE COMPONENT 
  SURFACES. The net pitching moment about 
  the lateral axis is due to the contribution of 
  each of the component surfaces acting in their 
  appropriate flow fields. By study of the con- 
  tribution of each component the effect of each 
  component on the static stability may be ap- 
  preciated. 
  It is necessary to recall that the 
  pitching moment coefficient is defined as: 
  
  not vary with C, since all changes in lift would 
  In this case, the wing 
  take place at the c.g. 
  to stability would be neutral. 
  contribution 
  When the c.g. is located behind the a.c. the 
  wing contribution 
  i,s unstable and the curve 
  of C, versus CL for the wing alone would have 
  a positive slope. 
  
  Since the wing is the predominating aero- 
  dynamic surface of an airplane, any change in 
  the wing contribution may produce a sig- 
  This 
  nificant change in the airplane stability. 
  fact would be most apparent in the case of the 
  flying wing or tailless airplane where the wing 
  contribution determines the airplane stability. 
  In order for the wing to achieve stability, 
  the 
  c.g. must be ahead of the a.c. Also, the wing 
  must have a positive pitching moment about 
  the aerodynamic center to achieve trim at 
  lift coefficients. The first chart of 
  positive 
  figure 4.7 illustrates that the wing which 
  is 
  trim at a negative lift coefficient if 
  stable will 
  If the stable wing has a 
  the C,,, is negative. 
  positive C,,, it will 
  then trim at a useful posi- 
  tive CL. The only means available to achieve 
  trim at a positive CL with a wing which has a 
  negative C,,, is an unstable c.g. position aft of 
  tailless aircraft 
  the ax. As a result, 
  incur 
  cannot utilize high lift devices which 
  any significant changes in C,,,. 
  
  the 