Previously on rec.arts.sf.tv.babylon5.moderated, James A. Robbins said:   
      
   > The biggest problem the article glosses over is the need to bring the   
   > launch vehicle up to supersonic velocity by the end of the track.   
   > Ram and scram-jet engines do not work below supersonic velocities.   
   > Moving an object at supersonic velocities along a fixed track produces   
   > lots of problems (as the land speed record vehicles have to contend   
   > with), like shock-waves reflected between the bottom of the vehicle   
   > and the ground or track. Nothing that cannot be overcome, but a real   
   > engineering headache.   
   >    
   > I think they really need to take advantage of existing terrain to get   
   > the vehicle above as much atmosphere as possible, but where to do this?   
   > The high peaks of the Rockies have protected invironments around them   
   > and you don't want the overpressure wave to blow out all the windows in,   
   > say, Denver every time you launch.  That's why there are restrictions on   
   > flying supersonic over the continental US.  Stuff to think about.   
      
   Maybe we should just say "screw the launch vehicle concept" altogether   
   and build an elevator.  Any materials scientists around to speculate on   
   what to build it with?   
      
   --    
   Jeffrey Kaplan                                         www.gordol.org   
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