text: frequency is 
  lower than the pitching frequency, a divergent 
  condition would lirst reach critical proportions 
  in yaw, closely followed by pitch. Of course, 
  whether the airplane motion becomes divergent 
  is of academic 
  directionally or longitudinally 
  interest only. 
  
  Since the uncoupled yawing 
  
  type of coupling 
  problem that 
  is referred to as “autorotative 
  A rolling airplane which has a high 
  rolling.” 
  positive dihedral effect may reach a large pro- 
  verse sideslip as a result of the inertia couple and 
  the rolling moment due to sideslip may exceed 
  that available from lateral control. 
  In such 
  a case it would not be possible to stop the air- 
  lateral control 
  plane from rolling although 
  was held full against the roll direction. The 
  
  There is one additional 
  
  Since the roll coupling induces pitching and 
  yawing motion, 
  the longitudinal and direc- 
  tional stability is important in determining the 
  overall characteristics of the coupled motion. 
  A stable airplane, when disturbed in pitch and 
  yaw, will 
  return to equilibrium after a series 
  of oscillations. For each flight condition, the 
  fte- 
  airplane will have a coupled pitch-yaw 
  quency between the uncoupled and separate 