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Every time I watch Falcon-9 moments like that at

, I wonder:

Is it really intentional that the main engine of stage 2 after startup blows directly into stage 1´s top, maybe: in order to decelerate it?

Why would one risk damaging the booster which is planned to be reused? Is the energy saving so significant and the possible damage so irrelevant that it is a good idea? They could wait five seconds or so until the booster distanced itself a bit.

Because, if it is intentional, could it be that they put the booster at an angle first (how?) so that the main engine´s blow does not only decelerate but also support the turning of stage 2 so it heads further in the right direction for landing?

I mean, well, that´s quite a daring maneuver that needs great precision, especially the turn-moment achievement, no?

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    $\begingroup$ Does this answer your question? Why isn't the Falcon 9 first stage severely damaged by the blast of the second stage following separation? $\endgroup$
    – Suma
    Dec 6 '20 at 20:47
  • $\begingroup$ First one does seem to be a duplicate; this answer does in fact seem to answer this question as well. $\endgroup$
    – uhoh
    Dec 7 '20 at 6:46
  • $\begingroup$ The russians famously did hot staging -- it avoids ullage. This isn't even hot staging, the others tage is already separated. $\endgroup$
    – Polygnome
    Dec 7 '20 at 10:38
  • $\begingroup$ @Suma saw that -- no $\endgroup$ Dec 9 '20 at 22:03
  • $\begingroup$ I don´t see the offered questions as dupes, their answers don´t answer mine. It´s not just if the plume has any effect on the first stage -- it´s whether SpaceX uses the first stage to actively move the first stage away, and to turn it. Because I suspect they do. Which would be amazing $\endgroup$ Dec 9 '20 at 22:06