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Posted (edited)

I'm about certain this is a handheld camera shot and not extremely far from the landing zone.  It doesn't seem shaky enough to be a highly zoomed handheld shot.  But after all the successful landings of F9, I'd risk standing as close as it appears, no hesitation, to get a front row experience like this.  But I'd volunteer to propulsively land in a Crew Dragon, so...  YOLO

 

Edited by darthgently
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2 minutes ago, darthgently said:

I'm about certain this is a handheld camera shot and not extremely far from the landing zone. 

I don't think this is handheld, way too steady.

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Posted (edited)
6 hours ago, tater said:

I don't think this is handheld, way too steady.

Not sure.  All the auto trackers on launches seem to lag, then catch up, repeatedly.  Good handhelds seem to track more smoothly but can have some higher freq jitter or transients.  Could also be remote control by hand

Edited by darthgently
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4 hours ago, Flavio hc16 said:

 

There has been a Test stand rich combustion today.

 

Better on the stand than on the stack.

 

We might say they did a full duration test stand disassembly fire?

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58 minutes ago, Cuky said:

We might say they did a full duration test stand disassembly fire?

If I could start over again, I would totally start a demolition business, only instead of jackhammers and prybars, I'd use rocket engines

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this is proof that raptors are unreliable and ipso facto full duration burns are neccesary and like such as period comma

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https://x.com/SpaceX/status/1793998848584794574 

https://www.spacex.com/updates/#flight-3-report

Still jettisoning the hotstage ring. This has to be a temporary thing, right? Can't be fully reusable if you're intentionally discarding hardware.

https://www.spacex.com/launches/mission/?missionId=starship-flight-4

S29 will be attempting a flip and burn (mentioned in the flight timeline), not just a splashdown. Higher confidence in reentry?

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Posted (edited)

So the issue with flight 3 boostback and entry burns wasn't anything to do with Raptors, Quelle Surprise.

Oxygen line filtration issue and roll control thruster clogging.

1 hour ago, cubinator said:

Looks to me like the total duration of 'going well' was about 2 frames.

The video started at the anomaly, later on it goes back and shows the engine firing apparently normally.

Edited by RCgothic
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Given that this filter issue has caused the flight 2 failure and 2 separate failures on flight 3, I think it is safe to say that the theory about them pumping nearly a ton of water ice into the tank over the course of the flight is probably correct, as that's the only thing that comes to mind that could be responsible for such widespread filter clogging.

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3 hours ago, NFUN said:

this is proof that raptors are unreliable and ipso facto full duration burns are neccesary and like such as period comma

I see @Exoscientist is currently busy. No doubt running the numbers on other engines that had test stand mishaps and the later service lives of said engines.

 

41 minutes ago, Ultimate Steve said:

Given that this filter issue has caused the flight 2 failure and 2 separate failures on flight 3, I think it is safe to say that the theory about them pumping nearly a ton of water ice into the tank over the course of the flight is probably correct, as that's the only thing that comes to mind that could be responsible for such widespread filter clogging.

I've been out of the loop for a bit. So this failure mode is similar to the FOHE on the British 777 at Heathrow a decade or so back?

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30 minutes ago, Meecrob said:

I've been out of the loop for a bit. So this failure mode is similar to the FOHE on the British 777 at Heathrow a decade or so back?

I can't say I'm familiar with that particular incident, but word on the street is that, instead of using autogenous pressurization, where you use heat from the exhaust to boil the propellant and use that gas as a pressurant gas, SpaceX is attempting to pressurize their fuel tanks directly with preburner exhaust. I haven't looked at the methane tank, but in the oxygen tank, this would lead to a significant amount of carbon dioxide and water being injected into the tanks along with the oxygen. Some of this will freeze into ice upon contact with the propellant, and can lead to all sorts of problems if it gets anywhere important.

If this is true (I cannot think of another explanation for such widespread filter clogging), SpaceX likely calculated that the mass of the filters required was less than the mass of the heat exchangers, but given how poorly this appears to be going for them, I wouldn't be surprised if they return to autogenous pressurization.

Another, more long term concern, is that you need a way to melt this ice and drain the resulting liquid or gas between flights, which is not exactly a great thing to have to do for airliner like operations.

I haven't verified this myself, but some people have said that the CO2 ice isn't much of a problem as it is fluffy and sinks in liquid oxygen, and is fairly uniformly ingested into the Raptors. The water ice may produce giant clumps or sheets, and reportedly they have strung a giant mesh across the bottom of the tank to keep these chunks and sheets away from the propellant intakes.

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3 hours ago, Ultimate Steve said:

I can't say I'm familiar with that particular incident, but word on the street is that, instead of using autogenous pressurization, where you use heat from the exhaust to boil the propellant and use that gas as a pressurant gas, SpaceX is attempting to pressurize their fuel tanks directly with preburner exhaust. I haven't looked at the methane tank, but in the oxygen tank, this would lead to a significant amount of carbon dioxide and water being injected into the tanks along with the oxygen. Some of this will freeze into ice upon contact with the propellant, and can lead to all sorts of problems if it gets anywhere important.

If this is true (I cannot think of another explanation for such widespread filter clogging), SpaceX likely calculated that the mass of the filters required was less than the mass of the heat exchangers, but given how poorly this appears to be going for them, I wouldn't be surprised if they return to autogenous pressurization.

Another, more long term concern, is that you need a way to melt this ice and drain the resulting liquid or gas between flights, which is not exactly a great thing to have to do for airliner like operations.

I haven't verified this myself, but some people have said that the CO2 ice isn't much of a problem as it is fluffy and sinks in liquid oxygen, and is fairly uniformly ingested into the Raptors. The water ice may produce giant clumps or sheets, and reportedly they have strung a giant mesh across the bottom of the tank to keep these chunks and sheets away from the propellant intakes.

They could also still use the exhaust heat, but via a heat exchanger to isolate.  But they'd still need something to heat and expand, but maybe less of it since the heat could allow it to do more work pressurizing.  But ice clogged heat exchangers are a thing too I suppose

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