User talk:TomCraver

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Dear Tom,

I moved your discussion of momentum transfer slingshot type space elevator to Part 2 of the book on the structural methods page. Part 2 is where general discussion of space transport methods belongs. Part 4 is a specific chain of combined systems which build in series, and have the numbers worked out. The distinction is Part 2 lists every known method: good, bad, current or theoretical. Part 4 is a selected subset which serves two purposes. One is educational, by showing the design procedure with worked out examples it is intended to teach how the engineering is done. The second is advocacy. The particular series of systems represents the "best design so far" of what I think should actually be built. Like any design, it will evolve and change as more work gets done on it, and the intent is to update that section of the book as that happens. By presenting it as is, other people can work on details, critique it, or otherwise make improvements.

I also wanted to thank you for sparking a discussion under Space Elevators in Part 2 about structural dynamics. A slingshot with moving parts (extending cable and swinging it) points up the fact that *all* space elevators will have complex dynamics. They are typically slender in the structural sense (more than 20 times longer than wide, so bending dominates over compression), and because the loads on the structure vary from a lot of causes. So a good theoretical understanding of the dynamics is necessary, and a lot of computer simulations, before you build anything like this. I don't think a complete theoretical understanding even exists yet. I have seen pieces discussed in technical papers, but not the design as a whole.