text: to maximize 
  
  The procedure of employing different cruise 
  velocities to account for the effects of wind is 
  necessary only at extreme values of wind 
  is necessary to consider the 
  velocity. 
  change in optimum cruise airspeed when the 
  wind velocities exceed 25 percent of the zero 
  wind cruise velocity. 
  
  It 
  
  ENDURANCE PERFORMANCE 
  
  The ability of the airplane to convert fuel 
  energy into flying time is an important factor 
  in flying operations. The “specific endurance” 
  of the airplane is defined as follows: 
  
  specific endurance==1 
  
  1 
  fuel flow, Ibs. per hr. 
  specific endurance= 
  
  im 