From: jsb@at.hal-pc-dot.org.retro.com   
      
   "Scott Moore"  wrote in message news:OJQBc.157831   
      
   > 3. How much bigger (more thrust) would SS1 have to have to achieve orbit ?   
      
   More (longer/bigger) = more fuel = larger structure = more weight = more   
   fuel = etc.   
      
   -)   
      
   You can look at it several ways, but one interesting comparison is this:   
      
   SS1 max speed = about 2500 fps (IIRC)   
   Orbital speed = about 25000 fps   
      
   You need ten times more speed, but that's not the whole story either. You   
   have to impart a bunch of energy to a mass to get it into orbit. You can   
   sort of approximate this with the sum of the kinetic and potential energy   
   per pound of mass for a low orbit. I can't recall what the potential energy   
   is for orbits (I would have thought it's simply mgh, but something tells me   
   that's _almost_ right) but kinetic energy is much greater at 0.5mv^2. The   
   kinetic energy scales with the square of velocity. IOW, you need to impart   
   100 times more energy to the vehicle _per_pound_ to get it into orbit   
   (actually more, because you have to make up losses due to drag). Remember,   
   too, that they have to carry fuel onboard to perform a deorbit manuever   
   later on.   
      
   Maybe the answer is to fit a rocket engine or two to WhiteKnight. If White   
   Knight could carry SS1 to 60 miles and Mach 22 then maybe there's a chance   
   ..   
      
   -)   
      
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