XPost: rec.arts.sf.movies   
   From: chakatfirepaw@gmail.com   
      
   On Sat, 01 Aug 2015 08:51:03 -0400, J. Clarke wrote:   
      
   > In article , chakatfirepaw@gmail.com says...   
   >>   
   >> At _best_, what they have here is a highly power-inefficient photon   
   >> drive.  Note, photon drives are reaction drives and don't get the whole   
   >> "infinite propellant with a mass ratio of 1," thing.   
   >   
   > You only get "infinite propellant" if you have free energy.  Otherwise   
   > you are still expending mass to make energy.   
      
   You don't need free energy, you just need to avoid carrying your fuel.   
   For instance, you could use a beamed power setup.   
      
   > Discussing the efficiency   
   > of space engines for which the means of energy production is separate   
   > from the means of thrust generation is not something that lends itself   
   > to a simple figure of merit.   
      
   The power required for a given thrust is a very simple and useful   
   measure.  Note that I was specifically referring to the power efficiency,   
   (an ideal photon drive requires 300MW/N, the claimed figure for the EM   
   Drive is about 1GW/N).   
      
   --   
   Chakat Firepaw - Inventor and Scientist (mad)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)