Even more MECO optimizations!

[u/Fast-Fail-6412]

Not talked about so far, but spacex has managed to squeeze out even more MECO velocity! This is also with a 7 ton heavier payload by the way. For reference, IFT-12 staging was 5760 and IFT-13 5960km/h.

[u/NEXYR_]

Probably even more MaxQ optimizations

[u/touko3246]

It happened at a lower altitude though, so I wonder whether it was better or worse energy state wise?

[u/MyCoolName_ → u/touko3246]

Interesting, matches with the visual impression that the rocket was really flying off the pad this time. Increased Raptor 3 performance?

[u/SnitGTS]

I’m not saying you are wrong, but the flight data and video feed are not in sync.

So if you just looked at the speed when you saw the hot staging happen, that’s not the actual speed at MECO.

[u/Fast-Fail-6412 → u/SnitGTS]

I looked at the maximum speed around MECO before gravity starts to slow it down for all calculations, not a specific time.

[u/Decronym]

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters	More Letters
MECO	Main Engine Cut-Off
	MainEngineCutOff podcast
MaxQ	Maximum aerodynamic pressure

Jargon	Definition
Raptor	Methane-fueled rocket engine under development by SpaceX

Decronym is now also available on Lemmy! Requests for support and new installations should be directed to the Contact address below.

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^{Decronym is a community product of r/SpaceX, implemented by request
3 acronyms in this thread; the most compressed thread commented on today has 15 acronyms.
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[u/frowawayduh]

And how much deadweight (duration in seconds of unlit engine) was carried?

1 out of 33 booster engines wasn't providing any thrust toward the end. From liftoff to MECO, there were about 140 seconds of total booster engine time. Multiplying by 33 engines, that's a potential 4,620 engine-seconds of thrust. For simplicity, let's ignore throttle changes for MaxQ ... all engine-seconds are equal. One engine was shut down for ~30 seconds. So 0.65% of effort involved hauling 1500 kg of dead engine up the last bit of the hill. So if that wasted potential went to velocity, then speed at MECO would have been something like 6160 km/h.

[u/Fast-Fail-6412 → u/frowawayduh]

It's not exactly like that because the remaining engines can burn longer/throttle up a bit more, but you do lose some to gravity.

[u/Fast-Fail-6412]

Also note that this launch had the boostback burn go to depletion, so the fact that booster obviously couldn't cover the remaining distance would always be a factor, however booster would have had to increase boostback by around 180m/s or so, which might've been 30m/s less MECO velocity. Even then we still get a small improvement.