text: Lift generation, by a “rotating wing” enables 
  the helicopter to accomplish its unique mission 
  of hovering motionless in the air, taking off 
  and landing in a confined or restricted area, 
  and autorotating 
  to a safe landing following 
  a power failure. Lift generation by “rotating 
  wing’ ’ 
  is also responsible for some of the 
  unusual problems the helicopter can encounter. 
  Since the helicopter problems are due to par- 
  ticular nature of .the rotor aerodynamics, the 
  the rotor must be 
  basic flow conditions within 
  considered in detail. 
  the 
  initial discussion will consider only the hover- 
  ing 
  term hovering 
  
  For simplicity, 
  
  rotor.  Although  the 