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--></style></head><body lang=EN-US link="#0563C1" vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Hey cool. I was cleaning out a bunch of old junk and ran across a tech paper I wrote in 1989. I was pitching it at a aerospace conference that year, and explaining how I had found a standard atmosphere model, which back in those benighted times was a page in a reference book. It gave atmospheric characteristics as a function of altitude, such as temperature, density, pressure and all the usual stuff you would need if you wanted to model a rocket launch.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Over on the second to the last column is dynamic viscosity, which you need to model if you want it to be accurate, for that number influences drag. I wanted my model to be accurate. So I scanned the data into digital format and put it in my spreadsheet, along with rocket motor performance data (fuel rates and thrust, etc.)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><img width=367 height=218 style='width:3.8229in;height:2.2708in' id="_x0000_i1025" src="cid:image001.jpg@01DC309D.ECA8DAC0"><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>But for some damn reason, my model kept screwing up at around 15k ft, and I couldn’t figure out why.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>I eventually traced it back to a mistake in the table in the book. The numbers 3 and 2 were switched. Shoulda been .23544 there.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Hey rocket science is unforgiving of fools and electric car moguls:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><img width=349 height=243 style='width:3.6354in;height:2.5312in' id="Picture_x0020_1" src="cid:image002.jpg@01DC309D.ECA8DAC0"><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>I fixed that, then the spreadsheet returned answers that agree with actual real-world rocket performance.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>I don’t know that I kept a copy of that spreadsheet, probably not, but Keith fooled with it for a while back in about the mid 1990s. I used it a jillion different ways in my launcher studies, trying to see if there is any configuration that makes single stage to orbit practical. After calculating it a hundred different ways, my conclusion is that single stage to orbit can be done. You just can’t carry enough actual payload to make it worth doing.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Second conclusion: anything you can do with one stage can be done better with two.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>History and Mr. Musk pretty much confirmed everything I learned back then and if Keith has any commentary on it, it should be interesting.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>We were primitive savages back then. We had fun.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>spike <o:p></o:p></span></p></div></body></html>