text: Above the tropopause the temperature is con- 
  stant and altitudes slightly above the tropo- 
  pause cause no further decrease in specific fuel 
  consumption. Actually, altitudes much above 
  the tropopause bring about a general deteriora- 
  tion of overall engine efficiency and the~spkific 
  fuel consumption begins an 
  increase with 
  The extreme altitudes above the 
  altitude. 
  tropopause produce low combustion chamber 
  pressures, low compressor Reynolds Numbers, 
  low fuel flow, etc. which are notconduci,ve to 
  high engine efficiency. 
  
  to the maintenance of steady 
  state operation, the fuel control and associ- 
  ated engine control itemsmust provide for the 
  transient conditions of engine acceleration and 
  deceleration. 
  In order to accelerate the en- 
  gine, the fuel control must supply a fuel flow 
  greater than that required for steady state 
  operation to ,produce a’ turbine power greater 
  than the compressor power requirement. How- 
  ever, the additional fuel flow to accelerate the 
  engine must be controlled and regulated to 
  prevent any one or combination of the follow- 
  ing items: 
  
  (1) compressor stall or surge 
  (2) excessive turbine inlet temperature 
  (3) excessively rich fuel-air ratio which 
  may not sustain combustion 