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I've seen lots of flight profiles that give Max Q during ascent. Around 33 to 35 kilopascals, if memory serves. But I have been having a hard time finding Max Q during descent.

With the recent reuse of a SpaceX booster there has been some talk of also reusing an upper stage. The re-entry dynamic pressure and temperature seem to me to be the major obstacles barring re-use. But I don't really know the Max Q of an upper stage re-entering the atmosphere. Given that an upper stage will have a delta V budget of around 6 or 7 km/s, the dry mass fraction is less than that of a re-entering capsule. If the dry mass fraction is 5%, it would be difficult to give the re-entering stage robust structure and thermal protection.

HopDavid
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  • I'm voting to reopen, as this question asks for the Max Q during descent, while the linked question talks more about the dynamic pressure profile during descent. – William R. Ebenezer Feb 22 '20 at 11:16
  • I asked my question first. So why is it the one labeled a dupicate? If the questions are the same (and they aren't, in my opinion) then the more recent question should be closed. – HopDavid Feb 27 '20 at 05:11

1 Answers1

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According to https://www.flightclub.io/results/?code=SS10 , reentry Q for flights like SES-10 peak at almost 92kPa at T+434 sec, about 3x the ascent max Q.

The reentry prep burn brings velocity down to about 1500m/s, about 1/5 of orbital speed, so it doesn't need the kind of thermal protection an orbital capsule would. An orbital capsule also comes in much more shallowly, so spends more time at substantially lower Q.

Russell Borogove
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