text: The principal advantage of afterburner is the 
  to add large amounts of thrust with 
  ability 
  relatively small weight penalty. The applica- 
  tion of the afterburner is most common to the 
  interceptor, 
  fighter, and high speed type 
  aircraft. 
  
  THE GAS TURBINE-PROPELLER COM- 
  BINATION. 
  The turbojet engine utilizes the 
  turbine to extract suflicient power to operate 
  the compressor. The remaining exhaust gas 
  energy is utilized to provide the high exhaust 
  gas velocity and jet thrust. The propulsive 
  efficiency of the turbojet engine is relatively 
  low because thrust is produced by creating a 
  large velocity change with a relatively small 
  mass flow. The gas turbine-propeller combin- 
  ation is capable of producing higher propulsive 
  efficiency in subsonic flight by having the pro- 
  peller operate on a much greater mass flow. 
  The turboprop or propjet powerplant 
  
  The use of wafer injection in the turbojet en- 
  gine is another means of thrust augmentation 
  which allows the combustion of additional fuel 
  within engine speed and temperature limits. 
  The most usual addition of water injection de- 
  vices is to supplement takeoff and climbout 
  performance, especially at high ambient tem- 
  peratures and high altitudes. The 
  typical 
  water injection device can produce a 25 to 35 
  percent increase in thrust. 