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Starship Flight 7

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649 points chinathrow | 1 comments | 16 Jan 25 21:25 UTC | HN request time: 0.198s | 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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ChuckMcM ◴[17 Jan 25 03:22 UTC] No.42733753[source]▶
I would be surprised if that was the case, my reasoning to that is that computing where a thing is going, when it's under going with changing acceleration AND changing mass, is pretty complicated. Especially if you already have the capability to throttle the engines and keep 'a' constant.

They might, I'm not saying your wrong, I'm just saying that I cannot imagine how you would justify the added complexity of doing it that way.

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1. modeless ◴[17 Jan 25 04:01 UTC] No.42733936[source]▶
The computations are complicated but not that complicated relative to everything else SpaceX is doing. It's much more important to optimize the propellant mass by using it most efficiently than to simplify some computations. And it's probably most efficient to burn the propellant as fast as possible.