text: RPM. Since the variation of thrust with 
  RPM is quite powerful, the tachometer in- 
  dication is a powerful reference. 
  
  (2) The exhaust gas temperature gauge 
  provides an important reference for engine 
  operating limitations. While the tempera- 
  ture probe may be located downstream from 
  the turbine (tailpipe or turbine discharge 
  temperature) the instrument should provide 
  an accurate reflection of temperatures up- 
  stream in the turbine section. The exhaust 
  gas temperature relates the energy change 
  accomplished by fuel addition. 
  
  (3) The fuel flowmeter can provide a fair 
  reflection of thrust output. and operating 
  efficiency. Operation at high density alti- 
  tude or high inlet air temperatures-reduces 
  the output thrust and this effect is related by 
  a reduction of fuel flow. 
  
  in 
  the jet 
  the tailpipe) can be correlated with 
  thrust for a given engine geometry and set of 
  operating conditions. The output 
  thrust 
  can be related accurately with various com- 
  binations of compressor inlet total pressure, 
  tailpipe total pressure, ambient pressure and 
  temperature. Hence; pressure differential 
  (Ap), pressure ratio, and ,tailpipe total pres- 
  sure instruments can provide more accurate 
  immediate indications of output thrust than 
  combined indications of RPM and EGT. 
  This is especially true with variable geom- 
  etry or multiple spool engines. 
  Many other specialized instruments furnish 
  additional information for more detailed items 
  of engine performance. Various additional 
  engine information 
  is realized from fuel pres- 
  sure, nozzle positions, compressor inlet air 
  temperature, etc. 
  
  (4) The’ tailpipe  total pressure (p+q 