text: Because of the variation of c, with altitude, 
  the majority of turbojet engines achieve maxi- 
  mum efficiency at or above 35,000 ft. For this 
  reason, the turbojet airplane will find optimum 
  range and endurance conditions at. or above 
  35,000 ft. provided the aircraft is not thrust 
  or compressibility limited at these altitudes. 
  The governing apparatus of the turbojet engine 
  consists primarily of the, items which control 
  In addition, 
  the flow of fuel to the engine. 
  there may be included certain functions which 
  operate variable nozzles, variable stator vanes, 
  variable inlets, etc. Generally, the fuel con- 
  trol and associated items should regulate fuel 
  Generally, the stall-surge and turbine 
  tem- 
  perature limits predominate to form an ac- 
  celeration fuel flow boundary typified by curve 
  
  121 