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</o:shapelayout></xml><![endif]--></head><body 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"'>>…</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <b>On Behalf Of </b>Dan<br><b>Subject:</b> [ExI] Engine anomaly on Dragon ascent<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif";color:black'><a href="http://en.wikipedia.org/wiki/SpaceX_CRS-1#Engine_anomaly">http://en.wikipedia.org/wiki/SpaceX_CRS-1#Engine_anomaly</a><o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>>…</span><span style='font-family:"Arial","sans-serif";color:black'>Interesting that the anomaly occurred at all and that it didn't impact the end result (yet).</span><span style='font-family:"Arial","sans-serif";color:#1F497D'> </span><span style='font-family:"Arial","sans-serif";color:black'>Regards,</span><span style='font-family:"Arial","sans-serif";color:#1F497D'> </span><span style='font-family:"Arial","sans-serif";color:black'>Dan</span><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p></o:p></span></p></div><div><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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>There is an overall advantage in launchers for a design that tolerates one-engine-out. The obvious question is that if the launcher can work with one less engine, then why not save the weight and eliminate it to start with? Answer: because if it can fly with one engine out, then you can push the envelope harder on reducing weight in all the engines, edging closer to the margin, trimming away more excess weight. <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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The second reason is that in a launcher, the critical time where you really need to burn fuel quickly is right at the start. This engine didn’t fail until after max-Q (maximum dynamic pressure), where you can tolerate a failure much more readily. Soon after max-Q, they often need to throttle back anyway: the rocket gets lighter as fuel is expended, so they can’t stay at launchpad thrust, otherwise the acceleration stress increases on the payload.<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I predict the overall mission will not be impacted at all. Way to go, SpaceX!<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>spike<o:p></o:p></span></p></div></div></div></body></html>