Author Topic: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION  (Read 438290 times)

Offline Keldor

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #960 on: 12/07/2023 10:42 pm »
Thank you for your responses.

If I understand you correctly, you are suggesting that the velocity fluctuations are caused by pogo oscillation, is that understanding correct?

If so, I have to ask, we know that pogo can cause hardware failures (N1), if you claim that the later failures occurred due to pogo, that is interesting and possible (just like many other possibilities, possible until proven otherwise), but I have a hard time understanding how they can cause the velocity fluctuations (if they are real) and on a scale which does not match to the supposed pogo frequencies (and the total thrust is the combined effort of many engines with different pogo frequencies).
Are you talking about the first flight?

Longitudinal oscillations with a period of 12 seconds were caused by attempts by Starship control system to suppress Pogo by reducing engine thrust and the fact that in the initial process of self-oscillations they occurred with a maltiplicity of 3. And with a decrease in pressure in combustion chamber, and, accordingly, after  pump, the frequency of hydroacoustic oscillations increased, and self-oscillations, when the thrust decreased, they switched to a heavier mode with a maltiplicity of 2. This caused superspikes.

That is, oscillations with a period of 12 seconds are not Pogo, but a superstructure over Pogo, which arose for the first time in history due to flexible control system and unusually wide range of Raptor-2 operating modes. Previously, the control system would have had simply turned off the engines the first time Pogo appeared. Or there would have been an explosion if it didn’t have time.

This is written in more detail in end of the first article.

Just one glance at the graph tells me that it's a telemety issue rather than anything physical.  If it was real, then the engines would be spiking from 250 to 500 tons of thrust every 12 seconds, which just isn't physically plausible.

Rather, it looks like every 12 seconds, a telemetry update has been dropped, so on the graph we see a stale value, followed by a value that skips over the missed value, making it look like it stops and then suddenly has double the usual progress all at once.  As for the graph not *exactly* showing 0 followed by double, there's clearly some smoothing going on.

As for why they're missing data in this pattern, there are a number of explainations, from a synchronization issue to interference from the likes of a weather radar.  It could easily be deliberate too, if for instance they had other important but lower priority data they wanted to send back, they might substitude a burst of that in place of the normal telemetry update once every 12 seconds.  This sort of multiplexing is not at all unusual in telecommunications.

Online FutureSpaceTourist

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #961 on: 12/07/2023 10:59 pm »
https://twitter.com/_mgde_/status/1732892278971052210

Quote
So…for the first time in about 8 years, I’ve written an article!

Give it a read and check it out - there was so much invested into this last trip to Starbase for IFT-2. A massive shoutout to @Lensrentals for the aid in documenting history 🤙🏻

https://www.lensrentals.com/blog/2023/12/photographing-the-largest-rocket-ever-flown/

Quote
Photographing the Largest Rocket Ever Flown
By Max Evans Published December 7, 2023

SpaceX, the trailblazing aerospace company founded by Elon Musk, continues to redefine the possibilities of space travel with its ambitious Starship program. The recently completed second integrated flight test of Starship Super Heavy marked a crucial milestone in the journey towards the company’s goal of interplanetary exploration and Mars colonization. Amidst the excitement and anticipation, photography served as a vital tool for documenting this historic event, offering enthusiasts and professionals alike a glimpse into the future of space travel.

Offline Guillerz

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #962 on: 12/07/2023 11:15 pm »
Since SpaceX's license is for 5 flights per year, isn't it possible that SpaceX wants to launch the IF3 this month to avoid using up one of those attempts in 2024?

Offline JaimeZX

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #963 on: 12/08/2023 01:50 am »

One funny thing you can see during the Booster RUD are the grid fins getting yeeted out of the forward section lol

My education continues, even at 75.

I'm now introduced to the verb "yeet."
Behold: the origin of "yeet."
https://www.youtube.com/shorts/JqdDrYuefEQ


Source of many glorious sayings, such as "the Lord Yeeteh, and the Lord Yoinketh away."

Offline daveglo

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #964 on: 12/08/2023 03:39 am »
Quick review of some of the screens captured by Tony.

Offline catdlr

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #965 on: 12/08/2023 04:05 am »
Quick review of some of the screens captured by Tony.

Thanks, daveglo
This is what I was hoping for.  If any others want a hand in interpreting what systems they may be monitoring, so at it.  Either add to this picture or modify it from the original.

Toy
Tony De La Rosa, ...I'm no Feline Dealer!! I move mountains.  but I'm better known for "I think it's highly sexual." Japanese to English Translation.

Offline Brigantine

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #966 on: 12/08/2023 04:40 am »
Since SpaceX's license is for 5 flights per year, isn't it possible that SpaceX wants to launch the IF3 this month to avoid using up one of those attempts in 2024?

I also had that thought, but it turns out it's not an issue.
At Starbase, given they're only licensed for 5 launches a year
The Launch License imposes no flight rate limit (nor even mentions one). The 2022 PEA evaluated impacts using a model that assumed 5 orbital launches per year. The most recent WR to that PEA for IFT-2 used the assumption of 10 launches per year for modelling impacts of the deluge system. For perspective, the original SLC-4E EIS assumed 5 Falcon 9 and 5 Falcon Heavy launches per year: in 2023, SLC-4E hosted 25 Falcon 9 launches, 5 times the 'limit'. Same situations at SLC-40 and LC-39A. As with every other SpaceX launch pad, the 'limit' will move as actual launch rate approaches it.
To the best of my knowledge, not a single Launch License application (from SpaceX or anyone else) has ever been rejected due to a vehicle flying too often.

Also, perhaps this thread is more appropriate for IFT-3 discussion.
« Last Edit: 12/08/2023 04:41 am by Brigantine »

Online edzieba

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #967 on: 12/08/2023 02:07 pm »
The pictures shown previously were taken as screenshots on my 1080p laptop while watching YouTube. I downloaded the original 4K video and captured the same shots in a higher resolution (3820X2160) using the VLC snapshot app with full-resolution settings.

There is a lot of detail captured from the individual PC monitors. However, the clarity would have been better if the video had been originally recorded with stationary cameras mounted on tripods instead of using steady cam equipment or software.

Enjoy exploring the images.

Let me know if you want any additional snaps.  I did spot a chuck of debris leaving the OLM from the launch. I included a few more selected shots of the flight portion.
Recovered as much of the telemetry view as I could.

Offline Streamflow

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #968 on: 12/08/2023 04:54 pm »
Just one glance at the graph tells me that it's a telemety issue rather than anything physical.  If it was real, then the engines would be spiking from 250 to 500 tons of thrust every 12 seconds, which just isn't physically plausible...
Where did you see the thrust graphs? This is only an incomplete (due to the rarity of data reading) envelope of the oscillatory acceleration graph. You have clearly never seen a single frame with Pogo oscillations in your life; there, on full-fledged recordings of oscillatory acceleration, it was easy to get not only +/- 5 – 7 m/s^2, but also +/- 200 - 300 m/s^2. So, in some cases, the thrust of the J-2 engines increased from 90 tons to +/- 1800 - 2700 tons for each? How do you evaluate this “practical opportunity”?

In this regard, let me remind you of an old joke.
Somebode asks armenian radio: “Why does a Prussian lieutenant always laugh 3 times when listening to jokes?”
Armenian radio answers: “Because the first time he laughs when he listens, the second time he laughs with everyone, and the third time he laughs when the meaning of the joke reaches him.”

True, they say that there are lieutenants who laugh only twice, and never more. And now I’m explaining everything for the third time, so it’s time to at least pretend to laugh in understanding.

Offline daveglo

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #969 on: 12/08/2023 06:28 pm »
Quick review of some of the screens captured by Tony.

Thanks, daveglo
This is what I was hoping for.  If any others want a hand in interpreting what systems they may be monitoring, so at it.  Either add to this picture or modify it from the original.

Toy

You're welcome, Tony!

Attached below is a zoom in on the AFTS console from my first markup.  A couple of things to note:  You can see a blob in the center of the red area that likely indicates the location(s) of the booster and ship within the AFTS corridor, as this was taken just after staging.  I'm guessing this system is displaying an Instantaneous Impact Point calculation in realtime as a part of the AFTS.

The second crop is from another screengrab from later in the mission, where both vehicles have destructed.  Note that now on the display there are two red lines below the graphic, probably showing two activation events.  Also note that the blob that was visible just off the Texas coast is gone, and there is a new blob (maybe two?) near the eastern extreme of the enclosed zone.  Can't be sure that wasn't there before, though, as it's not visible in staging image.

Enjoy!

Offline zodiacchris

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #970 on: 12/08/2023 06:32 pm »
Streamflow, you’re still not selling it 🤷

Often it’s less the content of what is presented but more the way it is presented. If the data that it’s based on is even partially in doubt, the resulting calculations would be indicative at best. You present your findings as facts when that is just not justified given the data.

And it might be a special type of Russian humour and bravado and you might be a fun guy to have a beer with, but in this context you come across as pretty full of yourself and more than borderline annoying.

My 2c worth…

Offline InterestedEngineer

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #971 on: 12/08/2023 06:36 pm »
Given the pictures of the monitoring datastreams we see, is it likely unlikely that SpaceX would have detected any pogo oscillations?

I think the answer is yes they would have.

Offline alugobi

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #972 on: 12/08/2023 06:47 pm »
Given the pictures of the monitoring datastreams we see...
...I'm wondering if they'll see that that doesn't happen again.

Online ugordan

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #973 on: 12/08/2023 07:07 pm »
Given the pictures of the monitoring datastreams we see...
...I'm wondering if they'll see that that doesn't happen again.

To see that *what* doesn't happen again? The resolution is so low that you can't tell what these plots are actually showing. Make no mistake, SpaceX are not rookies to accidentally release something that actually is useful for us observers without actually blurring the important bits out.

I challenge anyone to figure out what the plots shown in post #967 here are *actually* showing.
« Last Edit: 12/08/2023 07:09 pm by ugordan »

Offline alugobi

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #974 on: 12/08/2023 07:13 pm »
Well, you just need to "enhance".








Like in the movies.

Offline Streamflow

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #975 on: 12/08/2023 07:46 pm »
Streamflow, you’re still not selling it 🤷
I don't sell in the temple. Christ drove merchants out of the temple.

Often it’s less the content of what is presented but more the way it is presented. If the data that it’s based on is even partially in doubt, the resulting calculations would be indicative at best. You present your findings as facts when that is just not justified given the data.
All your data, except for that which you receive from mass-media, always raises and will raise doubts, because you don't have your own opinion, but live only by the opinion of the crowd. And the facts show that all the key events in 5 episodes associated with Starship fit perfectly into the picture predicted from the solution of the equations. This used to be, but apparently no longer is, the main proof of the correctness of this or that theory. But you only believe what you read yesterday in newspapers, which only promote what you likes - the result is a kind of intellectual homosexuality.

And it might be a special type of Russian humour and bravado and you might be a fun guy to have a beer with, but in this context you come across as pretty full of yourself and more than borderline annoying.

My 2c worth…
And I don’t care how I look in the eyes of people unknown to me, which I don’t know about what they’re worth. It is important to me how I look in my own eyes – whether I will break under the pressure of the crowd or not. And so far no one has succeeded to make this. With us, you either live like this, or you will be everyone’s litter.

My 2c worth…

Offline Streamflow

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #976 on: 12/08/2023 07:53 pm »
Given the pictures of the monitoring datastreams we see, is it likely unlikely that SpaceX would have detected any pogo oscillations?

I think the answer is yes they would have.
Do you really take SpaceX for idiots? They are quite smart guys, and, of course, they discovered these fluctuations immediately, before me, because I watched that video stream a couple of hours after the event. And they solved this problem, the second flight fully proves this. But instead of it they got 3 others, just like in the fairy tale about dragons. And this is all written in my last article, which you obviously didn’t even open, but you are starting to evaluate it.

Offline Streamflow

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #977 on: 12/08/2023 07:58 pm »
...I'm wondering if they'll see that that doesn't happen again.
They took care of what was there ago, and received new worries with what wasn't there on the first flight.

Online eriblo

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #978 on: 12/08/2023 08:07 pm »
Quick review of some of the screens captured by Tony.

Thanks, daveglo
This is what I was hoping for.  If any others want a hand in interpreting what systems they may be monitoring, so at it.  Either add to this picture or modify it from the original.

Toy

You're welcome, Tony!

Attached below is a zoom in on the AFTS console from my first markup.  A couple of things to note:  You can see a blob in the center of the red area that likely indicates the location(s) of the booster and ship within the AFTS corridor, as this was taken just after staging.  I'm guessing this system is displaying an Instantaneous Impact Point calculation in realtime as a part of the AFTS.

The second crop is from another screengrab from later in the mission, where both vehicles have destructed.  Note that now on the display there are two red lines below the graphic, probably showing two activation events.  Also note that the blob that was visible just off the Texas coast is gone, and there is a new blob (maybe two?) near the eastern extreme of the enclosed zone.  Can't be sure that wasn't there before, though, as it's not visible in staging image.

Enjoy!
You can see in other frames that neither the white blob nor the possible amber one at the end are present at the earlier time. You can also see that the red (presumed AFTS) outline is the same and ends there.

Some speculation regarding the vertical amber line and the final position of (presumed) IIP:

My guess is that the line is either a border/gate that can be crossed dependent on fulfilling some condition or a mark of the beginning of a different AFTS mode.

The fact that the final IIP is right at the end of the AFTS outline suggest that it would nominally have safed no later than the time it activated. The wording "safe command destruct" is quite specific and would certainly be consistent with a termination due to not receiving a safe command before reaching the AFTS border.


I personally would not read much into the fact that that there are two red lines. They look like they overlay/replace the bottom set of three status lines while the top set is still there. They could represent two different activations but could just as well be two redundant command strings for the same AFTS or two separate criteria violations.

Offline catdlr

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Re: SpaceX Starship IFT-2 : Starbase TX : 18 Nov 2023 DISCUSSION
« Reply #979 on: 12/08/2023 09:21 pm »
I've extracted some more frames from the video hopefully these may be clearer than the others.

Tony De La Rosa, ...I'm no Feline Dealer!! I move mountains.  but I'm better known for "I think it's highly sexual." Japanese to English Translation.

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