text: glide distance, ft. 
  glide altitude, ft. 
  glide ratio= 
  
  glide ratio = (L/D) 
  
  Figure 6.6 illustrates the forces acting on the 
  airplane in a power-off glide. The equilibrium 
  of the steady glide is obtained when the sum- 
  mation of forces in the vertical and horizontal 
  directions is equal to zeta. 