text: obtained only if there is an increase in mass 
  flow, Q, or jet velocity, Vs, When at low 
  reduce 
  velocity, an increase in velocity will 
  the velocity change through the engine with- 
  out a corresponding increase in mass flow and 
  the available thrust will decrease. At higher 
  velocity, the beneficial ram helps to overcome 
  this effect and the available thrust no longer 
  decreases, but increases with speed. 
  
  Generally, the overall fuel-air ratio of the 
  turbojet is quite low because of the limiting 
  temperature. The overall air- 
  turbine 
  fuel ratio is usually some value between 80 to 
  40 during ordinary operating conditions be- 
  cause of the large amount of secondary air or 
  cooling flow. 
  
  inlet 
  
  High temperature, high energy combustion 
  gas is delivered to the turbine section where 
  power is extracted to operate the compressor 
  section. Partial or near-complete expansion 
  can take place through the turbine section with 
  the accompanying pressure and tempcratute 
  drop. The exhaust nozzle completes the ex- 
  pansion by producing the final jet velocity and 
  momentum change necessary in the develop- 
  ment of thrust. 
  
  The propulsive power available from 
  
  the 
  roduct of available 
  t T e propulsive horsc- 
  
  turbojet engine is the 
  thrust and velocity. 
  power available from the turbojet engine’is 
  related by the following expression: 
  
  pyav -- 
  325 