text: Ta= thrust, lbs. 
  
  Q= mass flow, slugs per sec. 
  
  Vi= inlet (or flight) velocity, ft. per sec. 
  
  V,= jet velocity, ft. per sec. 
  
  The typical ramjct or turbojet powerplane de- 
  rives its thrust by working with a mass flow 
  relatively smaller than that of a propeller but 
  a relatively greater change of velocity. From 
  the previous equation it should be appreciated 
  that the jet thrust varies directly with the mass 
  flow Q, and velocity change, Va-Vi. 
  This 
  fact is useful in accounting for many of the 
  performance characteristics of the jet power- 
  plant. 