Poll

Which Starship will first achieve orbit (not break the Karman line but actual orbit)?

SN4
4 (0.4%)
SN5
4 (0.4%)
SN6
72 (7%)
SN7
159 (15.4%)
SN8
258 (25%)
SN9
288 (27.9%)
SN(N+1) - you pick the N
224 (21.7%)
SNNever
25 (2.4%)

Total Members Voted: 1034

Voting closed: 07/06/2020 03:20 pm


Author Topic: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion  (Read 1281433 times)

Offline meberbs

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2140 on: 06/02/2020 04:43 pm »
SpaceX’s Starship explosion explained by Elon Musk - https://www.teslarati.com/spacex-starship-explosion-explained-elon-musk/
Nothing new to see here, just explanation and extrapolation around the single statement we already heard:
“What we thought was going to be a minor test of a quick disconnect ended up being a big problem.”

I read the article and I saw mentioned that they disconnected and reconnected the QD(quick disconnect). That didn't seem to me to be correct? Anybody?
That piece of the article was pure speculation by the author. It is a possible explanation, but not the only one, since we don't know all of the details of the GSE and what the test consisted of.

Offline Johnnyhinbos

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2141 on: 06/02/2020 04:45 pm »
SpaceX’s Starship explosion explained by Elon Musk - https://www.teslarati.com/spacex-starship-explosion-explained-elon-musk/
As usual Teslarati writes a long article based on a single short phrase tweeted by Musk. There is no additional information in the article - no official information from Spacex and certainly nothing more than has been discussed here at length.
Just a FYI, Eric is an active member of this forum and contributes often. Teslarati articles are targeted at a broader audience then just members of this forum and Elon often gives them his thumbs up.


Also - just a reminder to post commentary over here on the Discussion thread, not the Updates and Photos thread...
« Last Edit: 06/02/2020 04:48 pm by Johnnyhinbos »
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Offline SkyRate

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2142 on: 06/02/2020 04:53 pm »
SpaceX’s Starship explosion explained by Elon Musk - https://www.teslarati.com/spacex-starship-explosion-explained-elon-musk/
Nothing new to see here, just explanation and extrapolation around the single statement we already heard:
“What we thought was going to be a minor test of a quick disconnect ended up being a big problem.”

I read the article and I saw mentioned that they disconnected and reconnected the QD(quick disconnect). That didn't seem to me to be correct? Anybody?
It's a reasonable assumption. A QD only has those two fundamental actions. And it had to have been connected for the fueling that preceded the static fire. So the simplest test from that partially-fueled state is a disconnect, followed by a reconnect for detanking. The timing of the test also points to that. SX would likely want to do one or more maximum fidelity tests of the QD before the hop.

Offline fael097

A two ring high sleeve was put over the dome.
Hmm, curious as to the two ring instead of 3. Will this indicates that this is actually another bopper instead of full SN7 to test corrected quick disconnect? Kinda doesn't make sense since there's SN5 & SN6 full-size isn't it? (or will they actually jump the test campaign to SN7 bopper, and keeping the already-assembled SN5 & SN6 for nosecone, flaps (for the latter) and three-engine tests?)

What if they will use use lap weld to add stiffness to fairing? Like I illustrated in image below.
We saw fairing 5 stack collapse and also they welded in circular stiffeners. It isn't maybe most efficient way how to do, but if it will be sufficient, this is easier to mass produce than weld something inside.

they probably just welded stiffeners so it wouldn't collapse again from wind. nosecones #1 and #2 were welded onto single rings for testing, and they used lap welds, although that's probably not enough stiffness for the fairing as that thing should be able to keep its shape unpressurized, and also support the weight of the fwd fins, header tank+lox, and transfer the loads on the fins during reentry.

They might pressurize the fairing during fueling LOX header and flight and definitely on reentry. So it has to support static weight of fins and nose cone.

Crew variant should have the crew cabin pressurized to human acceptable levels, which means equal to ambient sea level pressure (or even lower than 1 bar if similar to the cabin of an airliner). That doesn't increase structural integrity. I should also mention that crew cabin volume isn't equal to the entire volume of the fairing, and some areas might remain unpressurized.

Therefore, fairing structural integrity will rely entirely on its own shape/thickness and likely additional support structures, and not on pressure like the tanks.

Also, there's no need for the cargo or tanker variants to have a pressurized fairing, nitrogen is heavy, could easily weigh more than a tonne when filling the entire fairing (even more when compressed), and helium is expensive.
« Last Edit: 06/02/2020 05:26 pm by fael097 »
Rafael Adamy

Offline rsdavis9

A two ring high sleeve was put over the dome.
Hmm, curious as to the two ring instead of 3. Will this indicates that this is actually another bopper instead of full SN7 to test corrected quick disconnect? Kinda doesn't make sense since there's SN5 & SN6 full-size isn't it? (or will they actually jump the test campaign to SN7 bopper, and keeping the already-assembled SN5 & SN6 for nosecone, flaps (for the latter) and three-engine tests?)

What if they will use use lap weld to add stiffness to fairing? Like I illustrated in image below.
We saw fairing 5 stack collapse and also they welded in circular stiffeners. It isn't maybe most efficient way how to do, but if it will be sufficient, this is easier to mass produce than weld something inside.

they probably just welded stiffeners so it wouldn't collapse again from wind. nosecones #1 and #2 were welded onto single rings for testing, and they used lap welds, although that's probably not enough stiffness for the fairing as that thing should be able to keep its shape unpressurized, and also support the weight of the fwd fins, header tank+lox, and transfer the loads on the fins during reentry.

They might pressurize the fairing during fueling LOX header and flight and definitely on reentry. So it has to support static weight of fins and nose cone.

Crew variant should have the crew cabin pressurized to human acceptable levels, which means equal to ambient sea level pressure (or even lower than 1 bar if similar to the cabin of an airliner). That doesn't increase structural integrity. I should also mention that crew cabin volume isn't equal to the entire volume of the fairing, and some areas might remain unpressurized.

Therefore, fairing structural integrity will rely entirely on its own shape/thickness and likely additional support structures, and not on pressure like the tanks.

Also, there's no need for the cargo or tanker variants to have a pressurized fairing, nitrogen is heavy, could easily weigh more than a tonne when filling the entire fairing, and helium is expensive.

Pressure does increase structural integrity. Makes it less likely to buckle.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline fael097

Pressure does increase structural integrity. Makes it less likely to buckle.
::)
Rafael Adamy

Offline Thunderscreech

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2146 on: 06/02/2020 05:29 pm »
Pressure does increase structural integrity. Makes it less likely to buckle.
::)
A structure pressurized to one atmosphere should have higher structural strength in a vacuum than one that's not pressurized, what am I missing? 
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Offline fael097

Pressure does increase structural integrity. Makes it less likely to buckle.
::)
A structure pressurized to one atmosphere should have higher structural strength in a vacuum than one that's not pressurized, what am I missing?

I think you're missing the fact that they have to manufacture, load, board and fuel it on earth.
Rafael Adamy

Offline Lars-J

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2148 on: 06/02/2020 05:50 pm »
Pressure does increase structural integrity. Makes it less likely to buckle.
::)
A structure pressurized to one atmosphere should have higher structural strength in a vacuum than one that's not pressurized, what am I missing?

I think you're missing the fact that they have to manufacture, load, board and fuel it on earth.

And how does this contradict the fact that it becomes even stronger when pressurized?
« Last Edit: 06/02/2020 05:50 pm by Lars-J »

Interview with Hans Königsmann (mostly about crew dragon) about plans for Starship Schedule

https://www.spiegel.de/wissenschaft/weltall/spacex-chefingenieur-zum-stat-des-crew-dragon-wilde-party-kommt-noch-a-998ff592-1071-44d5-9972-ff2b73ec8fb6
...

I hope it's not too off-topic -- but I found Google Translate way less readable than https://www.deepl.com/translator, pasting just the Starship bit at the end in there gave:

Quote
SPIEGEL: In Texas, SpaceX is already building the next largest spaceship, the "Starship". This is also supposed to be suitable for trips to the moon and Mars. But another prototype has just been destroyed during a test. Is the program still on course?

Königsmann: The program is clearly separated from our work with the "Crew Dragon". It's all about research. We want to see how far you can go with certain things. The goal is to learn as much as possible in a short time. If there are setbacks in the process, that naturally slows us down. But that is part of it.

SPIEGEL: So when does the Starship fly for the first time?

Königsmann: I expect the first test flights at an altitude of, let's say, 150 metres in the coming weeks. We'll do that a few times. If everything works out, we want to enter Earth orbit at the end of the year. But maybe it will take a little longer.

SPIEGEL: SpaceX is to deliver technology to Nasa for the moon landing. Will it really be possible to have an American on the lunar surface by 2024?

Königsmann: That is ambitious and won't be easy. But if we get the appropriate resources, it is quite possible.

SPIEGEL: You once said in an interview that you would feel too old for a Mars flight. Would you at least have ambitions for the moon?

Königsmann: I'd like to take back what I said about Mars. If it goes quickly, maybe I'm not too old after all. And I could also imagine the moon.

Translated with www.DeepL.com/Translator (free version)
« Last Edit: 06/02/2020 06:20 pm by Chris Bergin »

Offline oldAtlas_Eguy

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2150 on: 06/02/2020 06:36 pm »
The impression is that Koingsman sees the progress on Starship progressing faster than he expected. With him now contemplating that he may not be too old for that Mars trip.

Probably the difference between manned flights to Mars in 10 years vs 15 or 20.

Offline especedespace

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2151 on: 06/02/2020 06:46 pm »
Handrails have appeared on the mystery fabrications from a couple of weeks ago; work platforms/walkways, then?
[zubenelgenubi: deleted embedded image]

IF you look at how there are 2 platforms attached one on top of the next but with the top one extended forward, it's clear they're nose cone work platforms.
« Last Edit: 06/02/2020 06:52 pm by zubenelgenubi »

Offline Nomadd

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2152 on: 06/02/2020 07:11 pm »
Pressure does increase structural integrity. Makes it less likely to buckle.
::)
A structure pressurized to one atmosphere should have higher structural strength in a vacuum than one that's not pressurized, what am I missing?

I think you're missing the fact that they have to manufacture, load, board and fuel it on earth.

And how does this contradict the fact that it becomes even stronger when pressurized?
He's claiming the fairing won't be pressurized on the pad. I'm not convinced myself, since that skin is pretty floppy. I have to think they'll pressurize it some on the pad for launch. It's not like 1 1/2 bar absolute inside will do anything but pop a few ears.
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Offline tssp_art

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2153 on: 06/02/2020 07:24 pm »
SpaceX’s Starship explosion explained by Elon Musk - https://www.teslarati.com/spacex-starship-explosion-explained-elon-musk/
Nothing new to see here, just explanation and extrapolation around the single statement we already heard:
“What we thought was going to be a minor test of a quick disconnect ended up being a big problem.”

I read the article and I saw mentioned that they disconnected and reconnected the QD(quick disconnect). That didn't seem to me to be correct? Anybody?
It's a reasonable assumption. A QD only has those two fundamental actions. And it had to have been connected for the fueling that preceded the static fire. So the simplest test from that partially-fueled state is a disconnect, followed by a reconnect for detanking. The timing of the test also points to that. SX would likely want to do one or more maximum fidelity tests of the QD before the hop.
In the comments to the article and found this interesting speculation/observation on the quick disconnect/reconnect scenario from reader John Hind:
Quote
...
Normally a quick release umbilical would not need to be designed to reattach under pressure. It only detaches as the rocket leaves the pad and is attached only to an empty rocket when it can presumably be done manually in safety. A mechanism intended for automatic attachment under pressure implies they are getting ahead and developing a combination mechanism that can also operate for on-orbit refuelling.

The idea that the QD is indeed a Quick Disconnect (under pressure) but is only intended to reconnect without the pressure of a partially filled tank might point to a process error or human error as the cause of this failure.

Offline enbandi

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2154 on: 06/02/2020 07:27 pm »
That fairing (or parts of it) have to be depressurized for cargo load and unload for some periods on the pad (or Moon, Mars).
If not, than all loading ops have to be done through airlocks.

Online Slothman

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2155 on: 06/02/2020 07:30 pm »
Pressure does increase structural integrity. Makes it less likely to buckle.
::)
A structure pressurized to one atmosphere should have higher structural strength in a vacuum than one that's not pressurized, what am I missing?

I think you're missing the fact that they have to manufacture, load, board and fuel it on earth.

And how does this contradict the fact that it becomes even stronger when pressurized?
He's claiming the fairing won't be pressurized on the pad. I'm not convinced myself, since that skin is pretty floppy. I have to think they'll pressurize it some on the pad for launch. It's not like 1 1/2 bar absolute inside will do anything but pop a few ears.

For crew models there will be a lot of interior construction, walls, bulkheads, floors and ducting which will act like cross stiffeners.

For cargo models, they could add internal aluminium stiffeners (weld steel tabs to hull, rivet Al rods to them) in a way that doesn't interfere with cargo capacity and won't remove too much payload margin

Offline SkyRate

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2156 on: 06/02/2020 08:04 pm »
For cargo models, they could add internal aluminium stiffeners (weld steel tabs to hull, rivet Al rods to them) in a way that doesn't interfere with cargo capacity and won't remove too much payload margin
Using Al would require the tabs to be pretty long or the rivet joints to have insulation. One of the points of stainless is that it can take much more reentry heat than Al.

Offline rsdavis9

For cargo models, they could add internal aluminium stiffeners (weld steel tabs to hull, rivet Al rods to them) in a way that doesn't interfere with cargo capacity and won't remove too much payload margin
Using Al would require the tabs to be pretty long or the rivet joints to have insulation. One of the points of stainless is that it can take much more reentry heat than Al.

Just weld stringers on. Simple an effective.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline OTV Booster

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2158 on: 06/02/2020 08:14 pm »
That fairing (or parts of it) have to be depressurized for cargo load and unload for some periods on the pad (or Moon, Mars).
If not, than all loading ops have to be done through airlocks.
There should not be any flight loads during cargo access.


A thought occurred to me. Every bar above the top dome negates a like amount of force from its ullage pressure. This could allow flattening or raw mass reduction. This looks too good to be true. Am I missing something?
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Offline SkyRate

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Re: SpaceX Starship : Texas Prototype(s) Thread 9 : Discussion
« Reply #2159 on: 06/02/2020 08:15 pm »
The idea that the QD is indeed a Quick Disconnect (under pressure) but is only intended to reconnect without the pressure of a partially filled tank might point to a process error or human error as the cause of this failure.
Sure, but I can see three scenarios that may have led SX to design it to be reconnected while fuel is present:
1. When doing a hop, maybe they intend to disconnect before ignition. If hop is aborted before liftoff you need to detank after.
2. Even in a successful hop, you don't burn all the fuel. High-rate detank is highly desirable.
3. Eventually, orbital refueling is crucial. It will be on the main risk-reduction path.

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