From: LFLekx@NOSPAM.rogers.com.retro.com   
      
   On 29 Dec 2004 22:57:15 -0800, ilpolagerste@jippii.fi (Ilpo   
   Lagerstedt) wrote:   
      
   >Why not any first stage with LH2/LOX before Delta IV?   
   >Maybe this is a dump question too but I have always wondered that: How   
   >much powerful Saturn 5 would have been LH2/LOX in the first stage?   
      
      The problem with using hydrogen in a first-stage is the low density   
   of hydrogen.  You need extremely large tanks to hold it, and   
   insulation to keep it cold.  The Isp increase by using hydrogen is   
   (IMO) negated by the additional increase in tank size, feed-line size,   
   insulation, purge system, etc.   
      
      Look at the Space Shuttle - it needs the lower-Isp solid boosters   
   to get it moving.  :-(   
      
      But every major launch-systems designer seems to be fixated on   
   using hydrogen for everything.   
      
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