text: turboprop airplane but additional factors are 
  available to influence the specific endurance at 
  In other words, low altitude 
  low altitude. 
  endurance can be improved by shutting down 
  some powerplants and operating the remaining 
  powerplants at higher, more efbcient power 
  setting. Many operational factors could decide 
  whether such procedure would be a suitable 
  technique. 
  
  number, cruise-climb, or whatever the appro- 
  priate technique) will result in a loss of range 
  capability. 
  
  thrust means that 
  
  In- 
  creasing altitude has a powerful effect on both 
  the range and endurance of the turbojet air- 
  plane. As a result of this powerful effect, the 
  typical 
  turbojet airplane will achieve maxi- 
  mum specific endurance at or near the tropo- 
  pause. Also, the maximum specific range will 
  be obtained at even higher altitudes since the 
  peak specific range generally occurs at the 
  highest altitude at which the normal rating of 
  the engine can sustain the optimum aero- 
  low altitude cruise 
  dynamic conditions. At 
  conditions, the engine speed necessary to sus- 
  tain optimum aerodynamic conditions is very 
  low and the specific fuel consumption is rela- 
  tively poor. Thus, at low altitude, 
  the air- 
  plane prefers 
  speeds to obtain 
  the 
  the powerplant prefers the 
  (&/CD)- 
  higher speeds common to higher engine effi- 
  ciency. The compromise results in maximum 
  specific range at flight speeds well above the 
  optimum aerodynamic conditions. 
  In a sense, 
  low altitude cruise conditions are engine 
  dictated. 
  
  TURBOJET POWERED AIRPLANE. 