I neglected some numbers in the rocket design, and now it looks like I have to rebuild the whole idea from scratch.
Ehrm... I think you should devote the main chunck of effort to develope the story and then derive the technical data you need. Very little of that world building stuff will actually go onto the page (if you want some reader, that is).
I've settled reasonably firmly on the questions I want to focus on - how to make decisions when gathering useful information to help make those decisions carries a risk of an immense cost, especially when the stakes are meaningful enough to be significant - and I've just finished working out the technical details of what my protagonist will have been doing up to the point where he can't put off making those decisions any longer.
I have a rule-of-thumb for science-fiction, in that knowing what a character /can't/ do is more important than knowing what they /...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.