text: is changed to 
  separa- 
  
  flow along the surface-provided 
  tion does not occur. 
  
  (3) The static pressure of 
  behind the wave is decreased. 
  
  the airstream 
  
  (4) The density of -the airstream behind 
  flow 
  the wave is decreased. 
  
  (5) Since the flow changes in a rather 
  and 
  gradual manner there is no “shock” 
  no loss of energy in 
  the airstream. The 
  expansion wave does not dissipate air- 
  stream energy. 
  The expansion wave in three dimensions is 
  a slightly different case and the principal 
  difference is the tendency for the static pres- 
  sure to continue to increase past the wave. 
  
  (1) The airstream is slowed to subsonic; 
  the local Mach number behind the wave is 
  approximately equal to the reciprocal of the 
  if 
  Mach number ahead of the wave-e.g.,  table is provided to summa- 
  rize the characteristics of the three principal 
  wave forms encountered with supersonic flow. 
  
  The following 