I found summat and would like to share it, so others may avoid the waste of time I spent sorting it out.
See broken link here and broken link here (see comment below).
Is that on-topic? I have a feeling it is too much like a discussion or poll question, even though I try to avoid that.
Could I instead make it a question specifically about the topic (e.g. how do I calculate arc length along an orbital path?) that I answer myself?
Thanks.