Stuff That’s Hard to Do (Falcon9 Starlink night launch)

Another success.
Nobody’ll think less of you if you
skip this ’cause you’ve seen it before,
but we retired ol’ rocket/satellite nerds love this stuff


  1. Posted August 28, 2022 at 7:38 am |

    Doug, question for us liberal arts majors turned aerospace IT geeks – what are the dynamic forces that make up ‘max-Q’??


  2. blake
    Posted August 28, 2022 at 10:24 am |

    Doug, are you going to link to the SLS launch? Personally, I think there’s a decent chance for an earth shattering kaboom.

    Okay, maybe I’m hoping there’s an earth shattering kaboom.

  3. DougM (just entertaining myself here)
    Posted August 28, 2022 at 1:35 pm |

    blake ^
    Sure, I’ll put up a condensed link afterwards.
    I don’t get up at a decent-enough hour to watch it real-time,
    but you can

    leelu ^^
    It’s been a few decades since I’ve even read the equations, much less understood ‘em; but maximum dynamic pressure (max-Q) is one of the main engineering design points* (like launch, stage separation, etc.) where aero loads and aero effects on vehicle dynamics or skin heating may be at an extreme (peak, knee, hilltop, inflection, etc in its curve on a graph).

    Think of dynamic pressure as a kind of kinetic energy.
    Q = 1/2 x air density x velocity squared
    It’s value goes from zero at launch to zero in space
    (velocity is zero at launch, and air density is zero in space),
    so it must have a maximum somewhere in between, right?

    * engineering design points
    On ascent, they’re situations where the probability of *kablooie* (or other failure) reaches a local maximum
    Note: each engineering specialty has its own, unique sphincter-tightening profile during a mission

  4. blake
    Posted August 28, 2022 at 2:28 pm |

    ^So, would that mean part of the engineering equation includes trying to design an acceleration curve which puts off Max Q as long as possible so as to reach thinner air?

  5. DougM (just entertaining myself here)
    Posted August 28, 2022 at 7:46 pm |

    blake ^
    A space elevator would do that,
    but nah, see: tyranny of the rocket equation.
    The max-Q design point requirements result from the mission profile, they don’t usually drive it. But, yeah, if you find it ain’t gonna work, modify/redesign the vehicle or mission profile. The whole system-engineering process is iterative.

  6. blake
    Posted August 28, 2022 at 9:50 pm |

    ^Doug, thank you for the article. Very informative.

  7. DougM (just entertaining myself here)
    Posted August 28, 2022 at 11:13 pm |

    ^ Next week: the proper way to apply duct tape and WD-40 after system testing to compensate for design oversights

  8. Dave
    Posted August 29, 2022 at 3:45 am |

    Send that case of duct tape over to NASA. I hear it works for stubborn fuel leaks.

  9. blake
    Posted August 29, 2022 at 6:54 am |

    ^heh, Dave, yeah, SLS launch was delayed, from what I can tell.

  10. Posted August 29, 2022 at 8:26 am |



  11. Posted August 29, 2022 at 8:34 am |

    ^Blake and all:

    Scrubbed b/c ‘engine bleed‘.