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Starship Flight 7

(www.spacex.com)
649 points chinathrow | 3 comments | 16 Jan 25 21:25 UTC | HN request time: 0.001s | source
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ChuckMcM ◴[17 Jan 25 01:24 UTC] No.42733038[source]▶
Will be interesting to hear the postmortem on the second stage. The booster part seemed to work pretty flawlessly with the exception of a non-firing engine on boost back which then did fire during the landing burn.

If the person doing their on-screen graphics is reading this, I wonder if you have considered showing tank LOX/CH4 remaining as a log graph. I believe it decreases logrithmically when being used (well it would if you keep 'thrust' constant) so that would create a linear sweep to the 'fuel level' status.

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modeless ◴[17 Jan 25 03:06 UTC] No.42733674[source]▶
I don't believe they throttle the engines up or down much during the second stage burn. Fuel decreases ~linearly and thrust is relatively constant. Acceleration increases as fuel mass decreases.
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hinkley ◴[17 Jan 25 04:01 UTC] No.42733940[source]▶
Don’t they throttle back at MaxQ?
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1. modeless ◴[17 Jan 25 04:20 UTC] No.42734039[source]▶
Yes, on the first stage.
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2. hinkley ◴[17 Jan 25 07:20 UTC] No.42734932[source]▶
Oh! Second stage. Misread.

No, second stage has 3 vacuum engines and 3 atmospheric engines, so they'll have to be able to throttle for the cutover.

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3. modeless ◴[17 Jan 25 14:54 UTC] No.42738104[source]▶
The engines are able to throttle but they run all of them at 100% throttle for most of the second stage's first burn, I expect. For efficiency. The telemetry showed all of them firing at the same time. The vacuum engines will be used by themselves for on orbit maneuvers and the sea level engines will be used by themselves for landing, but for the first burn to reach orbit they need all the thrust they can get.