From: schillin@spock.usc.edu   
      
   marsbeyond@yahoo.com (Tony Rusi) writes:   
      
   >I have heard aerospace engineers say that SS1 would need 95% more   
   >energy to get to LEO. That would be roughly 20 times. Any vehicle that   
   >makes the use of a mothership a waste of time, as a staged rocket   
   >traverses the first 60k in less than a minute and a half.   
      
   The purpose of the "mother ship" is not to save the spacecraft the   
   trouble of crossing the first 60k feet.  The purpose of the "mother   
   ship" is to save the spacecraft the trouble of carrying to space   
   the very specialized hardware necessary to support itself on and   
   lift itself off the ground (which may or may not be substantial,   
   depending on detailed design decisions for which there is no obvious   
   best answer), and to allow it to use rocket engines optimized for   
   high-altitude operation (which are substantially more efficient than   
   rocket engines designed for sea-level operation, but which would   
   tear themselves apart if lit off at or near sea level).   
      
      
   >Flying around for an hour will not lead to a practical commercial space   
   >vehicle.   
      
   Flying around for an hour is essentially irrelevant to whether or not   
   a space vehicle is commercially practical.   
      
      
   >Wings on such a vehicle are really more of a liability than any type of   
   >advantage, as we have witnessed with the shuttle.   
      
   As we have witnessed *on the shuttle*, wings are *essential* to such a   
   vehicle.  Space shuttles with wings have conducted many space flights   
   with >98% reliability.  A space shuttle stripped of its wings would   
   fall out of the sky and make a smoking hole in the landscape at the   
   end of its first flight.   
      
   Perhaps you meant to say, "as we have witnessed by comparing the shuttle   
   with the wingless vehicle I imagine should have been built in the shuttle's   
   place".  But first off, that's something only you have witnessed.  Second,   
   the wingless vehicle you imagine should have been built in the shuttle's   
   place, will still need *something* to keep it from falling out of the   
   sky and making a smoking hole in the landscape.  And people have put a   
   lot of effort into looking at all the systems for handling that part of   
   the mission, including but not limited to wings, without finding a clear   
   and unambiguous answer as to which is best.   
      
   (hint: they *all* involve carrying a lot of dead weight to orbit, on the   
   order of 10% of the vehicle's landing mass)   
      
      
   >The only reason the space shuttle had wings is because some aging USAF type   
   >demanded it, and no one wanted to argue.   
      
   I think you're selectively remembering history here.  The USAF, in the   
   form of officers who were not aging any faster than the rest of us, demanded   
   that the wings be deltas of relatively high planform area.  The shuttle's   
   civilian designers had *already* decided on wings, albeit rather stubbier   
   ones, because they felt that they were as good a way as any of keeping the   
   thing from falling out of the sky and making a smoking hole in the ground   
   at the end of its flight.   
      
      
   >Thank God Elon Musk found Tom Mueller and is leading America's commercial   
   >space future into LEO with a no nonsense 3 stage rocket design.   
      
   Neither Elon Musk nor Tom Mueller invented the three-stage rocket.   
      
      
   >Don't get me wrong. I think Rutan is a genius. I wish Paul Allen would   
   >give him a billion to build a moon-mars transportation infrastructure.   
   >It will probably look a lot like the Seadragon concept. The SS1 is   
   >just a first step back towards rationality. Truax outlined a rational   
   >approach to low cost access to space in Aerospace America a few years   
   >back. It should be required reading for every aerospace engineer.   
      
   Nor did Truax.   
      
   And we get more than enough True Believers here, sure that they and their   
   designated rocket-building heroes have the One True Way to Space, ready   
   to spark a Holy War with all the unbelievers who still cling to their   
   winged/VTVL/hydrogen/airbreathing/kerosine/hydrogen/airbreathing/rocket/   
   SSTO/TSTO/BDB concepts.   
      
   And they're all wrong.  There *is* no One True Way, but a diverse assortment   
   of concepts whose relative merit is very sensitive to details impossible   
   to pin down in any absolute sense at this time.   
      
      
   Required reading for every aerospace engineer?  That's a long list, but   
   in your case we'll start with Mitchell Burnside-Clapp's "The Palpable   
   Superiority of Horizontal Landing", from right here in this newsgroup   
   a few years back.   
      
      
   --   
   *John Schilling                    * "Anything worth doing,         *   
   *Member:AIAA,NRA,ACLU,SAS,LP       *  is worth doing for money"     *   
   *Chief Scientist & General Partner *    -13th Rule of Acquisition   *   
   *White Elephant Research, LLC      * "There is no substitute        *   
   *schillin@spock.usc.edu            *  for success"                  *   
   *661-718-0955 or 661-275-6795      *    -58th Rule of Acquisition   *   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)