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space X test failure.
3

space X test failure.

space X test failure.

(OP)
https://youtu.be/wFXQ5SRCy74

Doesn't look like buckling to me. More of a someone opened the wrong tap without opening another one first to equalise the pressure.

RE: space X test failure.

It looks like the failure has already started at the beginning of the video. The buckling seems to have started in the intertank area, but I can't find anything online that describes the tanks configuration of the vehicle so that's just speculation.
Also, Elon Musk commented later that it may have been caused bye a 'test configuration mistake'.
https://www.nasaspaceflight.com/2020/04/spacex-sta...
The forum section has a long thread discussing the lead-up and aftermath of the test. I'll have to peruse it thoroughly and maybe a likely cause will emerge. You have to register to access it.

Brad Waybright

It's all okay as long as it's okay.

RE: space X test failure.

Thin shell buckling is notoriously difficult to predict. Very sensitive to initial imperfections. Hopefully they didn’t design it using eigenvalue buckling analysis. Lots of good info on shell buckling here: shellbuckling.com.

RE: space X test failure.

(OP)
there is a huge fuel tank under those shells.. And it is the loadbearing structure. There is pics in the forum links.

I have seen a silo with a tank in it do this before because someone started pumping the contents out without injecting N2 in at the top to maintain positive deferential tank pressure to outside.

RE: space X test failure.

Looks more like a variety of vacuum collapse; if there were a cryofuel leak, it could supercool the atmosphere inside the cylinder, causing a pressure differential. Even a small pressure differential would be enough to buckle from the external air pressure.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: space X test failure.

(OP)
Does anyone actually know what the test involved doing?

From the video it was clean outside then loads of condensation and ice formed then it rapidly melted again after a period.

Do they just use liquid nitrogen or fill both tanks with fuel and oxidiser?.

RE: space X test failure.

A great example of thin-shell compressive buckling. The shell really tried to do an Euler buckling as shown by the initial diamond-like buckling mode shapes.

Andries

RE: space X test failure.

2
I think they miscalculated the viscosity of the snake oil in the cylinder.

RE: space X test failure.

I have been following the construction of starship as a hobby
they did an initial test with water in both tanks and were testing in cold conditions using liquid Nitrogen

Starship does not have an inter-tank since lox and liquid methane are chilled there is a common bulkhead.
it failed is the lower tank which had lost pressure due to ground equipment (is the assumption)

Scott Manly has a good video with the common speculation
also goes into detail on the welding methods
https://www.youtube.com/watch?v=XJslqGkb9So

Hydrae

RE: space X test failure.

(OP)
which tank is highest I am presuming LOX is on the bottom.

RE: space X test failure.

Since I haven't looked at the Starship in detail before, it would not make sense for me to pretend to know much about their design, but I'm really puzzled by something I see ("don't see) in the photos. Here's an example:



So while I can see strong evidence of numerous reinforcing members in the lower tank and possibly even a double-wall, the upper tank looks completely unreinforced. Those perforated straps would have some purpose, and I can see that there a a number of them in there, but with no evidence of inherent stiffness in the straps themselves, and few points of connection to the walls, I can't picture what they're there for. Also, the surfaces inside the upper tank wall are clean of any attached members. Not even a ring stiffener!



Say what you want about this structure withstanding 1G standing vertically in gravity, my question is how this was expected to tolerate >5g under rocket thrust.

A lot was learned from the Atlas rocket program (1960's) which was the first design like this one that used (a) stainless steel balloon tanks and (b) relied on propellant pressure to stand its own weight vertically on the pad.

www.sparweb.ca

RE: space X test failure.

This is why we need real engineers and not just "designers"....

MJCronin
Sr. Process Engineer

RE: space X test failure.

I know there is a small envelope of performance for rockets to keep the weight at an absolute minimum. Years back a rocket on display at the U.S. Air Force museum (I believe it was an Atlas) collapsed during a power failure. A blower was used to keep the fuel tanks under a small amount of pressure and absent that it was unable to support itself. It was structurally sound when loaded with the many tons of fuel necessary for flight, up until the moment it was jettisoned. I'd be surprised if any testing of SN3 involved filling it with water. I guess the LN2 used for this test is close enough to that of methane and LOX, and was probably included in the design criteria to allow such a test.

Edited- Sorry, SparWeb, I just saw your comment about Atlas, you beat me to it.

Brad Waybright

It's all okay as long as it's okay.

RE: space X test failure.

Quote (Elon Musk)

Rockets are hard.
Well it is rocket science.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: space X test failure.

I had a physics prof who took part in the 50's and could verify that it was, with lots of failures.

RE: space X test failure.

Hokie66

With regards to the snake oil comment - Still rofl
Could not find LMAF emoji

RE: space X test failure.

Quote (Thomas Burghardt)

...Elon Musk has since clarified the issue was the result of incorrect commanding resulting in the loss of pressure, as opposed to any material issue with the Starship build. As a result, SN4 will not require alternations to its structure, with construction work on the next Starship already taking place...

Ah, he blames software, not hardware. Elon has no sense of irony.

www.sparweb.ca

RE: space X test failure.

The Huntsville S&RC has a Mercury Atlas on display with an air compressor squirreled away behind a shrub that cycles on/off to keep the thing pumped up. Adds an audible element to the otherwise static displays. After viewing such an artifact I have enhanced respect for John Glenn & Co. climbing onto those beer cans with a pocketful of matches! Hopefully the center will reopen soon.

RE: space X test failure.

@Alistair, that payload deployment looks straight out of Wernher Von Braun or James Bond.

RE: space X test failure.

(OP)
The whole thing looks quiet 1960's space opera film like.

I wouldn't be surprised if Musk at one of the early design meetings said he wanted some thing that would work and look cool and chucked a 1960's space comic on the desk and smiled...…

And the design team leaders just smiled straight back and said we won't have a problem selling that idea to the troops.

RE: space X test failure.

Yes, I know some of the people who started with Space X as they hired a lot of engineers who used to work for McDonnell Douglas, particularly the team from Huntington Beach. As Space X was a client of ours (they used our CAD/CAE/CAM software) I've actually visited their Hawthorne facility where they assemble the Falcon rockets. I also saw the first mock-up of their Dragon capsule and watched them put the finishing touches on one of the Falcon engines. It was a very cool place to visit, and people I knew, who had been at McDonnell Douglas, confirmed that it was a really cool place to work. Now this was maybe six or seven years ago, when I was last there, but from what I've seen and read, it's probably still a pretty exciting place to be.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: space X test failure.

I have strongly suspected that since the beginning.
In the Boeing culture, most of the best minds would be looking for a better job.
Somewhere that they would be valued and respected.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: space X test failure.

(OP)
Maybe Musk will start making aircraft....

RE: space X test failure.

Wernher Von Braun had a similar payload concept about 10 years before the Bond feature. Youtube video.

How are you guys doing inline images? I can't get either the Image or the Link or the Upload Your File function to do it.




RE: space X test failure.

The issue with posting images is a known problem and is being looked at by the powers-to-be.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: space X test failure.

CAB, You can copy the image link and insert it into this [img link]

Sometimes, you need to add a ".png" to the end of the link to get it to appear correctly. At least, that is what has worked for me in the past.

For example:


is [ img https://res-1.cloudinary.com/crunchbase-production...] without the space after the first bracket.

To do the video in your above post, "[ youtube link ending]" should work (again without that initial space and only the text after the ".be/") though I don't think the start time adjustment works in that format though.


Andrew H.
www.MotoTribology.com

RE: space X test failure.

A little off topic but I just went own a Youtube rabbit hole and found this amazing doc on the V2/A4 rocket. Old school docs are still the best docs.

Thanks for the tip. I will try using the .png extension.


RE: space X test failure.

When I was in school, we had a lecture program that brought famous people to campus to give lectures and conduct programs. I can remember in my Freshman year, 1966, when Dr Wernher Von Braun gave a lecture about using satellites to gather date to help manage farmland and forests (our university had one of the country's largest and well known schools of forestry). Anyway, at the time I was struck by the fact that he didn't look at tall as he did in the movies winky smile

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: space X test failure.

charliealphabravo,
That video was interesting. I particularly liked the scene at 35 minutes, where about 20 people are standing around the base of the fully-fueled V2 rocket. They can't touch it any more, can't do anything else to get it ready to launch, but it hasn't occurred to them it's TIME TO LEAVE THE AREA.

If I'd been there at that moment, I can imagine myself backing away outside the crowd and then shouting "Five, four, three..."

www.sparweb.ca

RE: space X test failure.

Quote (SparWeb)

...it hasn't occurred to them it's TIME TO LEAVE THE AREA.

Maybe that says something about life in the Reich in those days :)

The problem with sloppy work is that the supply FAR EXCEEDS the demand

RE: space X test failure.

Ever see those photos of Kim Jung Un sitting at a table watching a launch of one of those North Korean missiles?



I don't know about you, but I wouldn't be caught sitting out in the open with nothing between me a ballistic missile sitting on the launch pad. All it had to do was fall-over in the wrong direction right after the engine had ignited or veer off course once it was in the air.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: space X test failure.

Apprently there are satellite photos of Kim Jung Un smoking beside a fully fueled ballistic Missle,

RE: space X test failure.

(OP)
no test fire today... they are defueling it. Hopefully tomorrow...

RE: space X test failure.

That could be just a pre-burner test
There are 3 combustion chambers in the raptor engine
fuel rich ,oxidizer rich, and main chamber
My guess they did not light the main chamber until they know the pre-burners are running fine

Hydrae

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