News SpaceX Starship Mk. 1 Bulkhead Failure

[Thunder Chicken]

Looks like the top bulkhead on the LOX tank failed during pressurization. Were they attempting a launch today?

EDIT: I wonder if they did their tank scaling right. For same flight pressure P, the applied load per unit length of weld or fastener line increases proportionally with the rocket body diameter. Starship is ~ 2.5 times the diameter of Falcon 9, indicating 2.5 the load per unit circumference.


IIRC the Falcon tank domes are friction stir welded, and the Starship ones...aren't?

 

[GLS]

It also failed at the bottom.

 

[Urwumpe]

Yay, that looks ugly.

Maybe an issue with the weld design, its possible that the welds looked good when just pressure testing the tank and failed when cooled by doing tanking tests.

A part of the upper tank structure also buckled inside, which suggests some tension there.

Still no big issue, they could fix this in the next development cycle.

 

[Thunder Chicken]

It also failed at the bottom.

Not sure, but I think that is the gas escaping down between the interior tank and the outer rocket skin.

 

[Urwumpe]

It also failed at the bottom.

Yes, with a long delay. Possibly caused by the rapid loss of pressure, not by the initial fault.

---------- Post added at 23:41 ---------- Previous post was at 23:39 ----------

Not sure, but I think that is the gas escaping down between the interior tank and the outer rocket skin.

That is also possible, it travelled only slightly faster than the cloud outside the rocket.

 

[MaverickSawyer]

Hmmm... They did reposition the upper dome yesterday, and apparently a sledgehammer was involved at one point. Wonder if they didn't make the new welds to spec?

EDIT: http://twitter.com/John_Winkopp/status/1196880896806313985?s=20

 

[Linguofreak]

Yes, with a long delay. Possibly caused by the rapid loss of pressure, not by the initial fault.

---------- Post added at 23:41 ---------- Previous post was at 23:39 ----------




That is also possible, it travelled only slightly faster than the cloud outside the rocket.

Around the 23 second mark you see a cloud that plummets rapidly down the side, indicating a significant volume of liquid was ejected and remained in big enough drops to fall quickly.

I presume that what you see at the bottom is similar: liquid falling through the gap between the stage and the skin and falling downward under gravity.

 

[GLS]

Not sure, but I think that is the gas escaping down between the interior tank and the outer rocket skin.

I have no idea about the structure of that thing...
BTW, wasn't it established long ago that "integral tanks" are lighter? :shrug:

 

[Thunder Chicken]

Hmmm... They did reposition the upper dome yesterday

They seriously repositioned it today :huh:

EDIT: Quick math with about 10 s hang time from explosion to when dome returned to elevation at top of rocket suggests it went up about 120 m or 400 ft above the top of the rocket.

 

[Urwumpe]

BTW, wasn't it established long ago that "integral tanks" are lighter? :shrug:

Yes, but it is a poor heat shield and heat insulation at the same time. And internal insulation, as the Saturn V used is also not too popular today.

 

[4throck]

Nothing to worry about

“The purpose of today’s test was to pressurize systems to the max, so the outcome was not completely unexpected,” said SpaceX in a statement.

Really don't know how to interpret this.

 

[Urwumpe]

Nothing to worry about

“The purpose of today’s test was to pressurize systems to the max, so the outcome was not completely unexpected,” said SpaceX in a statement.

Really don't know how to interpret this.

Well, if you are testing if the tank can withstand the pressure, there is of course the possibility that it does not do that. If you would be sure, that it will withstand the pressure - why are you testing it?

 

[HAL-9000]

Meh.

I told y'all this thing was a flying trash can and a publicity stunt. Musk is never taking anyone to Mars in a "Starship."

 

[Urwumpe]

Meh.

I told y'all this thing was a flying trash can and a publicity stunt. Musk is never taking anyone to Mars in a "Starship."

Quite a lot of testing effort for just a publicity stunt. :rofl:

 

[francisdrake]

The bulkhead fail makes me think these Starship prototypes are makeshift cobbled-together. Elon tweeted it failed when being pressurized to the max and this was not unexpected ...

In a cylindrical vessel the longitudinal welds are stressed double as high as the circumferential welds by internal pressure. As the failed weld is a circumferential one, this indicates a manufacturing problem rather than a design error.

Reasons could be bad welding quality. I would never do site welds on stainless steel without a proper shielding against wind and humidity. This ''we don't need no workshop, we build it outside in the open' strategy may backfire now. As far as I understand, the rings and bulkheads are pre-manufactured in the workshop, then stacked and welded on top of each other on site. Maybe they will reconsider their manufacturing procedure to improve the reliability of these site welds.

 

[Urwumpe]

In a cylindrical vessel the longitudinal welds are stressed double as high as the circumferential welds by internal pressure. As the failed weld is a circumferential one, this indicates a manufacturing problem rather than a design error.

Of course it was - that is why you test. In the computer, the weld likely worked fine.



That has nothing to do in first place with "cobbled-together", but rather how the model fits to reality. Its a difference to simulate a complete perfect tank in the computer and to produce a long weld without a flaw.

 

[Sbb1413]

I believe that the explosion is the result of constructing the Starship Mk1 in rush. There is nothing to be sad, there are other prototypes to be constructed.

Meh.

I told y'all this thing was a flying trash can and a publicity stunt. Musk is never taking anyone to Mars in a "Starship."

Flying trash? The failures are not always a curse, they teach us many lessons.

 

[RisingFury]

“The purpose of today’s test was to pressurize systems to the max, so the outcome was not completely unexpected,”

"Don't worry! We totally expected our rocket to blow up and send its lid 150 m into the air!"

 

[Kyle]

Meh.

I told y'all this thing was a flying trash can and a publicity stunt. Musk is never taking anyone to Mars in a "Starship."

This post is just absolutely inane and contributes nothing to the discussion. Why would SpaceX build multiple, full-flow staged combustion, methane-fueled rocket engines for a publicity stunt? The Raptor has to be one of the most complicated engines ever produced.