text: the centrifugal flow engine has relatively large 
  acceleration margins and good acceleration 
  the low rotational 
  characteristics result with 
  inertia. The axial flow compressor must oper- 
  ate relatively close to the stall-surge limit 
  to 
  obtain peak efficiency. Thus, the acceleration 
  fuel flow boundary for the axial flow engine is 
  set by these stall-surge limits which are more 
  immediate to steady state conditions than tur- 
  bine temperature limits. The fixed geometry 
  axial flow engine encounters relatively small 
  acceleration margins and, when compared to 
  the centrifugal flow engine with 
  larger accel- 
  inertia, 
  eration margins and lower rotational 
  has inferior acceleration characteristics. Cer- 
  tain variation of the axial flow engine such as 
  variable nozzles, variable stator blades, multi- 
  ple-spool compressors, etc., greatly improve 
  the acceleration characteristics. 
  
  A note of caution is appropriate at this 
  If the main fuel control and govern- 
  point. 
  ing apparatus should malfunction or become 
  inoperative and an unmodulated secondary or 
  emergency system be substitued, extreme care 
  must be taken to avoid abrupt changes in 
  throttle position. 
  In such a case, very gradual 
  movement of the throttle 
  is necessary to ac- 
  complish changes in power setting without 
  excessive turbine 
  stall or surge, or flameout. 