I'm familiar with that shuttle status check, "go at throttle up." Did the Saturn V have the same, or similar status check vocalized during the ascent? Did the Saturn V have to throttle down during Max-Q then throttle up afterwards?


1 Answer 1


The Saturn V's first-stage engines don't throttle, so there's no "throttle bucket" and no "go at throttle-up" call. One of the first-stage engines is shut down late in the burn, but that's to limit maximum g-force for crew comfort, not for Q limiting.

Maximum Q for the Saturn is about 33.8 kPa and for the shuttle it's 28.7 kPa. Compared to the shuttle, the Saturn V is aerodynamically pretty simple, and generally a little more robustly constructed; it just bulls through max Q instead of throttling back.

According to the Apollo 11 Flight Journal, the progress calls during this early part of ascent were centered on the varying abort modes that were available. The closest thing to a "go at throttle-up" call might be CAPCOM telling them they're good at the 1-minute mark:

000:01:02 McCandless: Apollo 11, Houston. You're good at 1 minute.

000:01:06 Armstrong: Roger. [Long pause.]

Max Q for the Saturn-Apollo stack is at about 84 seconds into the flight; the crew and mission control don't acknowledge it, but the public affairs officer does on the public channel (no timestamp):

PAO: We're through the region of maximum dynamic pressure now.

The next "go" call is at the 2 minute mark:

000:02:03 McCandless: Apollo 11, this is Houston. You are Go for staging. [Pause.]

Shortly after that we have:

000:02:17 Armstrong: Inboard cut-off.

The center engine of the 5 on the first stage is shut off here to hold acceleration down to 4g, for crew comfort. Dynamic pressure at this point is about 3.2kPa, only about 1/10th of max Q.

  • 1
    $\begingroup$ Thank you also for explaining the need for the shuttle to throttle up. $\endgroup$
    – Bob516
    Commented Nov 7, 2019 at 15:13
  • $\begingroup$ Also, Saturn V missions from Apollo 14 onwards shut down the center engine considerably earlier than earlier Saturn V missions, in order to avoid the severe pogo oscillations experienced on Apollo 13. $\endgroup$
    – Vikki
    Commented Jan 15, 2020 at 22:24
  • 1
    $\begingroup$ Citation? I don't remember pogo being an issue for the first stage. $\endgroup$ Commented Jan 16, 2020 at 3:59

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