From: henry@spsystems.net   
      
   In article ,   
   aSkeptic  wrote:   
   >The silly idea I have is using something like NERVA to preheat one or   
   >both components of a chemical bipropellant...   
      
   There have been proposals to do something somewhat related:  injecting LOX   
   into the nozzle of a NERVA, as an "afterburner".  It hurts Isp, of course,   
   but increases thrust, and if the LOX is "free" -- e.g., if it comes from   
   the Moon while the LH2 has to come from Earth -- apparently you can see a   
   net benefit.   
      
   >Ok heres annother wild example. Yes this is probably one of the   
   >dumbest/impractical ideas you'll find here.. The combustion   
   >temperature of the SSME is around 4000 K (if memory serves). Could a   
   >greater combustion temperature be achieved by heating both components   
   >(O2/H2) to say 2000 K before they are burned? Or would the burn still   
   >be close to 4000 K as they are now?   
      
   The latter.  If memory serves, even at SSME pressures, flame temperature   
   is limited more by dissociation of the reaction products than by energy   
   available.  To put extra energy into the exhaust of a good rocket engine,   
   you need to use non-thermal means.  (Running an electromagnetic thruster   
   on the exhaust of a NERVA, with the reactor supplying the power, has been   
   suggested.)   
   --   
   MOST launched 30 June; science observations running     |   Henry Spencer   
   since Oct; first surprises seen; papers pending.        | henry@spsystems.net   
      
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    * Origin: you cannot sedate... all the things you hate (1:229/2)