text: If the airplane is unrestrained and sideslip is 
  allowed, the affect of the directional stability 
  and dihedral effect can be appreciated. The 
  conventional airplane will develop adverse 
  yawing moments due to aileron deflection and 
  rolling motio6. Adverse yaw tends to produce 
  yawing displacements and sideslip but this is 
  resisted by the directional stability of the air- 
  plane. 
  If adverse yaw produces sideslip, di- 
  hedral effect creates a rolling moment opposing 
  the roll and tends to reduce the roll rate. The 
  typical transient motions (A) and (B) of the 
  time history diagram of figure 4.29 show that 
  high directional stability with 
  low dihedral 
  effect is the preferable combination. Such a 
  combination provides an airplane which has 
  no extreme requirement of coordinating aileron 
  and rudder in order to achieve satisfactory 
  rolling performance. While the coupled mo- 
  tion of 
  is important, 
  further discussion of lateral control will be 
  directed to pure uncoupled rolling performance. 
  ROLLING PERFORMANCE. The required 
  rolling performance of an airplane is generally 
  
  The helix angle of roll, $i,  is, actually a com- 
  
  in roll.” 
  
  to the right, 