text: stability. Ati airplane with high static longi- 
  tudinal stability will exhibit great resistance 
  to displacement from equilibrium. Hence, 
  the most critical conditions of controllability 
  will occur when the airplane has high sta- 
  bility, 
  will set the upper limits of stability. 
  
  i.e., the lower limits of controllability 
  
  There are three principal conditions of 
  fli~ght which provide the critical requirements 
  of 
  Any one 
  or combination of these conditions can de- 
  termine the longitudinal control power and 
  set a limit  to forward c.g. position. 
  
  MANEUVERING 
  
  The spring Zoadcd tab of figure 4.18 cotisists 
  of a free tab preloaded with a spring which 
  furnishes a constant moment about the tab 
  hinge line. When the airplane is at zero air- 
  speed, the tab is rotated up to the limit of 
  deflection. As airspeed is increased, the aero- 
  dynamic hinge moment on the tab will 
  finally 
  equal the spring torque and the tab will begin 
  to streamline. The effect of this arrangement 
  is to provide a constant hinge moment to the 
  control system and contribute a constant push 
  force requirement at speeds above the preload 
  speed. Thus, the spring loaded tab can im- 
  prove the stick force gradient in a manner 
  similar 
  the 
  spring loaded tab may be more desirable 
  because of greater effectiveness and the lack of 
  undesirable control 
  forces during ground 
  operation. 