From: cphoenixNOSPAM@crnano.org   
      
   I posted on this last night, but it hasn't showed up back at my   
   newsreader yet.  Basically, it looks to me like a rotating hybrid engine   
   will carve spiral grooves on its fuel grain as the oxidizer flows past   
   it.  And those will impart a swirl to the gas.  The faster the ship   
   rolls, the stronger the carving effect.  The grooves form in the   
   direction that tends to increase the rotation, which increases the   
   spiral cutting: vicious circle.   
      
   And of course this can only be seen outside the atmosphere, not on a   
   test stand or preliminary flights.   
      
   This implies that the roll starts more or less randomly, and gets worse   
   rapidly.  Will they get lucky this time?  If not, have they figured out   
   that it's important to cancel the roll ASAP and maybe even to reverse   
   the roll to cut counteracting grooves?   
      
   Chris   
      
   Anvil wrote:   
      
   > Watching the second launch of Spaceship 1 and thinking on the   
   > roll couple that begins as the rocket is fully started and   
   > seems to get a step increase crossing the sound barrier. Ideas   
   > range from mass swirling through the nozzle to various   
   > interactions between aerodynamic elements. The continued rolling   
   > would seem more an artifact due to rolling while exiting the   
   > effective atmosphere.   
   >   
   > Ideas?   
   >   
   > I am hoping that after the 3rd flight further studies will be   
   > made to better understand exactly what's going on rather than   
   > simply adding a correcting force and ignoring the effect.   
   > Virgin Airlines has announced plans to license the design to   
   > evolve into a slightly larger version.   
      
      
   --   
   Chris Phoenix                                  cphoenix@CRNano.org   
   Director of Research   
   Center for Responsible Nanotechnology          http://CRNano.org   
      
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