text: reducing 
  
  Since the exhaust gases have considerable 
  energy, exhaust turbines provide a source of 
  supercharger power. The turbosupercharger 
  (TB.S) allows control of 
  the supercharger 
  speed and output to very high altitudes with 
  a variable discharge exhaust turbine (PDT). 
  The turbosupercharger is capable of providing 
  the engine airflow with 
  increasing altitude by 
  increasing turbine and supercharger speed. 
  Critical altitude for the turbosupercharger is 
  usually defined by the altitude which produces 
  the limiting exhaust turbine speed. 
  
  The minimum specific fuel consumption of 
  the supercharged engine is not greatly affected 
  by altitudes less than the critical altitude. At 
  the maximum cruise power condition, specific 
  fuel consumption will decrease slightly with 
  an increase in altitude up to 
  the critical 
  altitude. Above critical altitude, maximum 
  ,cruise power cannot be maintained but the 
  
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