mockingbirdnest
Burn definition for vessels without attitude control
A common use case would be planning a correction burn on a unguided and spin stabilized probe that just performed a TLI burn, since the only parameter that you can tune is the timing of your burn, but that makes the manouver move around the navball.
It is a sensible idea to provide something to help with planning burns for vessels without attitude control (for which the burn definition lives in a two-dimensional space, with, e.g., timing and duration as a chart, rather the usual four-dimensional space).
This has nothing to do with a vessel-centred frame (we have one already, the target frame), and the idea that using such a frame as the manœuvre frame would help betrays a profound misunderstanding of what the manœuvre frame is. In a reference frame centred on your vessel, your vessel does not move, so the Frenet frame of its free-falling trajectory is singular: it would simply be ill-defined to use such a frame as the manœuvre frame.
