Not quite sapper - but I see what you're saying.
Picture, if you will, a 'tube' flying directly away from you leaking liquid fuel under pressure from a puncture in the side. That would produce exactly the patterns seen as the relatively stable ballistic flight provides the 'fixed point' you talk about, even if that point is only in a single plane and 'fixed' only relative to the observer.
Picture, if you will, a 'tube' flying directly away from you leaking liquid fuel under pressure from a puncture in the side. That would produce exactly the patterns seen as the relatively stable ballistic flight provides the 'fixed point' you talk about, even if that point is only in a single plane and 'fixed' only relative to the observer.