text: there is a 
  balance of torque from the forces along the 
  blade so that the RPM is maintained in equi- 
  librium at some particular value. The region 
  of the rotor disc where there is a net drag force 
  on the blade is called the “propeller region” 
  and the region of the rotor disc where there 
  force is called the 
  is a net in-plane thrust 
  These regions are 
  “autorotation 
  shown for vertical autorotation and forward 
  in figure 6.17. 
  speed (or normal) autorotation 
  Forces acting on the rotor blades in forward 
  flight autorotation are similar 
  those in 
  vertical autorotation but the difference will 
  consist mainly of shifts of the autorotation 
  region to the left and the addition of reverse 
  
  During a steady autorotation, 
  
  AUTOROTATION CHARACTERISTICS. 
  One of the unique characteristics of helicopters 
  to take part of the energy of 
  is their ability 
  turning and 
  the airstream to keep the rotor 
  glide down 
  to a landing with no power. 
  Consideration of the rotor during a vertical 
  autorotation will provide an understanding of 
  the rotor continues to rotate without 
  why 
  the flow of air 
  power. During autorotation, 