text: In isentropic flow the ratio of total pressure to static pressure  is given by:
  where:
   is total pressure
   is static pressure
   is the ratio of specific heats<br />
   is the freestream Mach number
  Taking  to be 1.4, and since 
  Expressing the incompressible dynamic pressure as  and expanding by the binomial series gives:
  where:
   is dynamic pressure