The Pod Bay

« first day (3570 days earlier) ← previous day next day → last day (667 days later) »

TheMatrix Equation-balance

01:39

2 hours later…

TheMatrix Equation-balance

03:46

I think the only way you could get an acceleration chart for Super Heavy that way, is only when Raptors output diminished proportionally to the percentage of propellant left. Otherwise, spacecraft would accelerate faster while getting lighter.

fyrepenguin

04:08

@TheMatrixEquation-balance not the best comparison; they’re two totally different craft. I’d suggest looking at the expected trajectory and flight profile and compare it to what went down in the actual test flight

@TheMatrixEquation-balance I mean, yeah, they lost entire engines so the acceleration is a lot lower. But you do see a constant trend upwards

In general though I don’t think you can make many inferences about the final vehicle performance based on a test launch with numerous failed and damaged engines

8 hours later…

TheMatrix Equation-balance

11:51

@fyrepenguin - in the video (above) they mentioned that SpaceX decided to do away with Nitrogen tank (a classic way to maintain fuel tank pressure). And used exhaust guesses instead to compensate for used fuel. If that new approach did not quite work, it could possibly explain progressive loss of performance (tank pressure).

5 hours later…

Rory Alsop

16:58

@TheMatrixEquation-balance We don't need any theories about tank pressure to explain loss of performance, and in fact in this case it isn't useful, as there was so much damage, nothing was working nominally

PearsonArtPhoto

Exactly.

Rory Alsop

While some speculation can be interesting where iterations are trying new things, I'd point you towards Everyday Astronaut, who is much closer to reality, and his commentary rather than trying to work your theories into what happened

PearsonArtPhoto

No need to invent problems when we already know for a fact there were a LOT of problems.

I can promise that SpaceX will have the data to assess such and they will look for potential problems like that in the data.

Rory Alsop

@PearsonArtPhoto And going by previous incidents, they will probably publish a good chunk of the data openly

PearsonArtPhoto

Have they ever really posted data publicly?

Or just a summary of the findings?

Rory Alsop

17:02

So eventually we can see for ourselves if we need to, but by then SpaceX engineers will have done a better job than any armchair expert

@PearsonArtPhoto Summary plus broad findings

not minute detail, no

Which is a pity

PearsonArtPhoto

Yeah.

I mean, they can't, for a variety of reasons...

Rory Alsop

I'd like the detail - because I like maths and analysis

PearsonArtPhoto

They posted a large amount of data in real time, but I doubt we get any more than that.

Being a guy who works with similar data sets, I can agree and also say they won't release enough data to be useful, so...

Rory Alsop

@PearsonArtPhoto :-(

PearsonArtPhoto

Well, useful for everything.

The fact they gave rough orientation, video, engines working, velocity, and altitude, well, that's huge.

TheMatrix Equation-balance

17:08

@RoryAlsop - not sure why you are upset. I did have a very reasonable question: "What could be the reason(s) for a seemingly functional liquid rocket booster's slowing acceleration after burning most of its propellant?"

Rory Alsop

@TheMatrixEquation-balance What are you talking about? Upset?

@PearsonArtPhoto that's true

@TheMatrixEquation-balance be aware that part of having conversations is making sure you are communicating appropriately with the other person. Non sequiturs like that, and starting from random assumptions that aren't agreed/shared with others make it very difficult to have a conversation. Sometimes too much effort.

PearsonArtPhoto

Oh, and the estimated fuel levels...

TheMatrix Equation-balance

"We don't need any theories about tank pressure to explain loss of performance" - you are trying to shut me off.

Rory Alsop

@TheMatrixEquation-balance not really, just a bit frustrated with your insistence on start points that aren't based on the reality of the situation. If there had been no damage, and the performance was weird, then there may be a good case for it. Remember, tank pressure was your initial estimate even before anyone had seen the damage

PearsonArtPhoto

So one of two things is possible. 1. The engines failing is enough to explain the issues. 2. There is a further issue that we can't possibly know from the data publicly released.

Rory Alsop

17:14

^ yep. This

PearsonArtPhoto

We know that engines were failing left and right. 3 engines were declared failed from near launch, at least 6 weren't working a minute in to flight, and it seems like only a few engines were working at the end, although I think something else was going on there.

Rory Alsop

We are all on this site to learn, to watch etc. But we all need to communicate in the same space with reasonable assumptions that come from how things have been shown to work in the past

And sure, with SpaceX, they iterate rapidly, so we see a lot of things that look new, but y'know, it's only rocket science

PearsonArtPhoto

Elon has stated that 31 engines is sufficient to make it to orbit. He hasn't said anything about 30, and I really doubt 27 is enough a minute in to flight...

One reason it might have lowered the thrust later on is that it knew it couldn't make it to orbit and simply was trying to stay in the flight envelope.

1 hour later…

fyrepenguin

18:38

@TheMatrixEquation-balance “we don’t need” as in “it is not necessary to add an additional parameter to explain the phenomenon”

TheMatrix Equation-balance

18:55

@fyrepenguin - people who studied 20th century History, would be careful not to use this idiom.

1 hour later…

Erin Anne

20:23

I haven't been able to find the primary source yet, but the Fish and Wildlife Service issued a statement on the Starship test launch. Excerpt here aerospaceamerica.aiaa.org/…

No big surprises except for maybe the 3.5 acre fire? But that's really also not that surprising, I just hadn't heard about it

checked here for the primary source fws.gov/press-release?type=%5B%22press_release%22%5D

Erin Anne

20:36

it's been a little surreal seeing stuff like the "STARSHIP GROUNDED" stories get kicked around (which I think just means there's no license yet for the next launch? I also haven't seen a primary source on that, everybody seems to point back to the Politico story) which is in the first paragraph in the AIAA link above too

TheMatrix Equation-balance

Reading between lines, Elon apparently expects the next Starship launch closer to the end of 2023. They will have time to sort it out with FAA (my guess).

PearsonArtPhoto

The launch license was issued for the first 3 launches. That license is suspended pending an FAA investigation, as is standard practice.

PearsonArtPhoto

20:55

Looks like the launch site is finally being examined carefully.

3 hours later…

uhoh

23:42

Q: What are the exact transgression(s) that Norway is complaining about regarding Sweden's off-course rocket's recovery?

The BBC's April 26, 2023 Norway criticises Sweden's response after research rocket goes awry begins: Sweden has got into hot water with Norway after one of its research rockets malfunctioned and landed in its neighbour's territory. The rocket was launched at 07:20 local time (05:20 GMT) on Monda...