text: design features which result in a large positive 
  dihedral effect are high sweepback, high wing 
  position, or large, high vertical tail, When 
  the inertia axis is inclined below the aero- 
  dynamic axis at low or negative angles of 
  attack, the roll induced inertia couple results 
  in proverse yaw. 
  
  The first four items can be effected,only during 
  design or by design changes. Some roll per- 
  formance restriction is inevitable since all of 
  the desirable characteristics are difficult 
  to 
  obtain without serious compromise elsewhere 
  in 
  the airplane design. The typical high 
  speed airplane will have some sort of roll pet- 
  formance limitation provided by flight restric- 
  tions or automatic control devices to prevent 
  reaching some critical condition from which 
  recovery is impossible. Any roll restriction 
  provided an airplane must be regarded as a 
  principal flight operating limitation since the 
  more severe motions can cause complete loss 
  of control and structural failure. 
  
  Depending on the flight condition where the 
  roll coupling problem exists, four basic types 
  of airplane behavior are possible: 
  
  (1) Coupled motion stable but unacceptabk. 
  
  In this case the motion is stable but proves 
  unacceptable because of poor damping of the 
  it 
  motion. Poor damping would make 
  dificult 
  to track a target or the initial am- 
  plitudes of the motion may be great enough 
  to cause structural failure of loss of control. 