text: speed will not cause any significant reduction 
  of glide ratio. This is fortunate and allows the 
  specifying of convenient glide speeds which 
  will be appropriate for a range of gross weights 
  at which power-off gliding may be encoun- 
  tered, e.g., small quantities of fuel remaining. 
  An attempt to stretch a glide by flying at 
  speeds above or below the best glide speed will 
  prove futile. As shown by the illustration of 
  figure 6.6, any C, above or below the optimum 
  will produce a lift-drag 
  less than the 
  ratio 
  If the airplane angle of attack is 
  maximum. 
  increased above the value for (L/D),,, 
  a tran- 
  sient reduction in rate of descent will take place 
  but this process must be reserved for the land- 
  ing phase. Eventually, the steady-state condi- 
  tions would be achieved and the increased 
  angle of attack would incur a lower airspeed 
  and a reduction in (L/D) and glide ratio. 
  
  The effect of gross weight on glide performance 
  
  may be difficult to appreciate. Since (L/D)- 
  of a given airplane configuration will occur at a 
  specific value of C,, the gross weight of the air- 
  plane will not affect the glide ratio if the air- 
  plane is operated at the optimum C,. Thus, 
  two airplanes of identical aerodynamic con- 
  figuration but different gross weight could 
  glide the same distance from the same altitude. 
  Of course, this fact would be true only if both 
  airplanes are flown at the specific C, to produce 
  (L/D),,. 
  The principal difference would be 
  that the heavier airplane must fly at a higher 
  airspeed to support the greater weight at the 
  optimum C,. In addition, the heavier airplane 
  flying at the greater speed along the same flight 
  path would develop a greater rate of descent. 
  The relationship which exists between gross 
  weight and velocity for a particular C, is as 
  follows: 