From: lwcamp@gmail.com   
      
   The equation as derived deals with waste heat delivered to the engine, not   
   total power.  Most of that power goes into accelerating the propellant exhaust   
   gasses.  Much of what is left over remains as thermal energy of the exhaust   
   gasses.  The figure you    
   need is the power absorbed by the engine bell.   
      
   In addition, chemical rocket engines can use their cryogenic fuel to help cool   
   the engine bell, running it through pipes around the bell to transfer heat to   
   the propellant before combustion.  This active cooling helps deal with the   
   heat load.   
      
   I can't remember the conversation where we were discussing this, but it may   
   have been while figuring out the limits of torch ship performance, in which   
   case the waste heat would be the x-rays absorbed by the surrounding structure,   
   and the energy imparted    
   by neutrons scattering off nuclei in the structure.    
      
   Luke   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)