text: tail is subject to an increase in angle of attack 
  and the elevators tend to float up, the change 
  in lift on the tail is less than if the elevators 
  to 
  remain fixed and the 
  stability 
  stability of an airplane is usually less than the 
  A typical reduction of 
  stick-fixed stability. 
  stability by free elevators is shown in figure 
  4.14(A) where the airplane. stick-free demon- 
  strates a reduction of the slope of CM versus Cs. 
  While aerodynamic balance may be provided 
  tu reduce control forces, proper balance of the 
  surfaces will reduce floating and prevent great 
  differences between stick-fixed and stick-free 
  stability. The greatest floating tendency oc- 
  curs when the surface is at a high angle of 
  attack hence the greatest difference between 
  stick-fixed and stick-free stability occurs when 
  the airplane is at high angle of attack.  at which equilibrium will occur. As the ele- 
  vator is fixed in various positions, equilibrium 
  (or trim) will occur at various lift coefficients 
  and the trim CL can be correlated with elevator 
  deflection as in the second graph of figure 4.13. 
  When the c,g. position of the airplane is 
  fixed, each elevator position corresponds to a 
  particular trim lift coefficient. AS the c.g. is 
  moved aft the slope of this line decreases and 
  the decrease in stability 
  is evident by a given 
  control displacement causing a greater change 
  in trim lift coefficient. This is evidence that 
  decreasing stability causes increased controlla- 
  bility and, of course, increasing stability de- 
  creases controllability. 
  If the c.g. is moved 
  aft until the line of trim CL versus elevator de- 
  flection has zero slope, neutral static stability 
  neutral point 
  is obtained and the “stick-fixed” 
  is determined. 
  
  tail contribution 
  
  is reduced. Thus, the “stick-free” 