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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>>…From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> extropy-chat-bounces@lists.extropy.org [mailto:extropy-chat-bounces@lists.extropy.org] <b>On Behalf Of </b>Anders Sandberg<br><b>Subject:</b> [ExI] Electromagnetic launcher efficiency<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='color:#1F497D'>>…</span>Just a quick question I hope Spike, Keith or some of you others already know the answer to:<br><br><span style='color:#1F497D'>>…</span>What is the theoretical limit to electromagnetic launcher efficiency?<br><br><span style='color:#1F497D'>>…</span>Real electromagnetic launchers have far bigger energy losses of course, but I am interested in the theoretical limit. Assume you can get as much superconductors, perfect timing and energy as you like. --<span style='color:#1F497D'> </span>Anders Sandberg,<o:p></o:p></p><pre> <o:p></o:p></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Anders, I don’t know where I last saw the equations on that, but it is an interesting question. <o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>A few years ago I went with the fam to Disneyland California Experience, where they have a maglev launched roller coaster. I stood and watched it for half an hour. After each launch, they have sprayers that cool the track. I tried to estimate the amount of energy being dissipated by the amount of steam that comes off, but it was hopeless. What I needed was some kind of IR thermometer, which would allow me to find the temperature of the track after the launch, then estimate the mass of the steel, then use the specific heat of iron. I could estimate the mass of the roller coaster and the speed it was going at the end of the launch event, estimate half the waste energy goes into the track and half goes into the rollercoaster and the air, and get it that way.<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Or we could just look up actual data, that might work too.<o:p></o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></pre><pre><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>spike<o:p></o:p></span></pre></div></body></html>