text: A hovering helicopter exhibits some degree 
  
  of apparent stability by virtue of its velocity 
  it has neutral angle of 
  stability although 
  This type of hovering sta- 
  attack stability. 
  bility 
  is analogous to the apparent lateral- 
  directional stability an airplane exhibits due 
  to dihedral effect. Additional hovering sta- 
  bility can be obtained by the use of mechanical 
  stabilizers such as th,e Bell stabilizer bar, by 
  the use of offset flapping hinges, or by syn- 
  thetic or artificial stabilization devices. 
  
  The total static stability of a helicopter is 
  determined by combining 
  the stability con- 
  tributions of all the components. The usual 
  result for a typical helicopter 
  is instability 
  with angle of attack and a variable velocity 
  stability which becomes neutral or unstable 
  at high speeds. Of course, the helicopter 
  could be made stable with angle of attack by 
  providing a large enough horizontal stabilizer. 
  Unfortunately, adverse effects at low speed or 