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SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

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Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#61

Post by SECProto »

_Microft wrote: post #5

It looks as if not only the bulkhead got separated but also the top-most ring where it was attached. I don't remember right now how that section looked, but maybe it was not the bulkhead at a fault but the seam between the first and second ring from the top.

I agree that's what it looks like. Interestingly, during fabrication, the bulkhead was attached to the ring, and then the whole ring was lifted up and welded on. Maybe there was interaction of the heat affected area from the two welds? The bulkhead was welded only ~100mm up from the bottom of the ring.

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#62

Post by ethbro »

outworlder wrote: post #58
JshWright wrote: post #45

Earlier quoted context omitted.

Fuel is very cheap. SpaceX has built their whole business around the idea that it's worth trading payload for re-usability.

Fuel is cheap on a monetary basis. _Lifting_ that fuel is NOT CHEAP. See also, the rocket equation.

But the primary cost of lifting fuel (if you have a reusable rocket) is fuel. Leaving us back at cheap.

But we're essentially arguing whether max payload per launch or payload efficiency to orbit is more important.

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#63

Post by newnewpdro »

kev009 wrote: post #34

I had an unpopular opinion amongst friends that this thing looked like a total piece of shit, like a movie prop. They were using rented lifts and cranes to assemble it in the field. Clock right twice a day or maybe there's a reason everything about Apollo spacecraft was meticulously assembled.

It looking like a piece of shit is an unpopular opinion?

I assumed that was a consensus. The thing isn't trying to win any beauty contests, it's covered in ugly seam welds.

And none of that matters, not one bit.

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#64

Post by saagarjha »

ethbro wrote: post #62
outworlder wrote: post #58

Earlier quoted context omitted.

Fuel is cheap on a monetary basis. _Lifting_ that fuel is NOT CHEAP. See also, the rocket equation.

But the primary cost of lifting fuel (if you have a reusable rocket) is fuel. Leaving us back at cheap. But we're essentially arguing whether max payload per launch or payload efficiency to orbit is more important.

With exponential compounding, I wouldn’t be so sure that it’s still cheap…

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#65

Post by brmgb »

JshWright wrote: post #45
brmgb wrote: post #43

Earlier quoted context omitted.

Fuel is not cheap. Fuel is heavy and payload reduction is money lost.

Fuel is very cheap. SpaceX has built their whole business around the idea that it's worth trading payload for re-usability.

SpaceX has built part of their business around the idea that it's worth trading a moderate amount of payload for re-usability as long as they can still reach the orbit their customers care about and it was considered an extremely risky bet before they made it routine.

It doesn't make fuel cheap, let alone very cheap.

Actually another significant part of SpaceX business is modern engineering and modern mean of production. They used to launch without recoverability for some high orbit payloads and they were competitively priced for that too.

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#66

Post by CydeWeys »

db48x wrote: post #60
CydeWeys wrote: post #21

Earlier quoted context omitted.

Soda cans are actually incredibly strong for their weight.

At least when filled and pressurized.

An empty soda can is much stronger relative to its weight than a full one.

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#67

Post by blackguardx »

senectus1 wrote: post #56
vkou wrote: post #52

Earlier quoted context omitted.

When their entire business depends on very carefully managing their PR, you're not going to get a public post-mortem without spin. If a government regulator runs the investigation, you might. I don't know if a regulator's going to get involved in this, though.

> When their entire business depends on very carefully managing their PR You really think this? My perception is that their PR is fairly blunt and upfront. while they may not tell you everything they dont seem to be trying to "spin" anything

There was a public accusation that a competitor shot one of their rockets with a rifle, causing it to fail. If they had reasonable suspicion of that, they should have kept it to themselves and the FBI/law enforcement. What really happened is that a strut failed due to faulty batch of material that wasn't tested before fabrication.

I'm not sure if this was deliberate spin, but it seemed pretty shady to me at the time.

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#68

Post by adventured »

vkou wrote: post #52
perspective1 wrote: post #42

During prototype tests you don't have to target 6-sigma, obviously, but I hope we get a post-mortem without spin.

When their entire business depends on very carefully managing their PR, you're not going to get a public post-mortem without spin. If a government regulator runs the investigation, you might. I don't know if a regulator's going to get involved in this, though.

These are the guys that give us amusing compilations of some of their more explosive mistakes:

https://www.youtube.com/watch?v=bvim4rsNHkQ

So much for very carefully managing PR.

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#69

Post by errantspark »

cracker_jacks wrote: post #9

Is the Starship Mk1 more structurally sound than it looks? From a first glance and having no knowledge of its design, it looks like an empty soda can that would deform at the slightest disturbance. And the way it crumpled in the video doesn't seem far off from what I would expect.

You're actually spot on. For example the Space Shuttle main tank had a 96:4 contents:structure ratio[0]. A soda can is 94:6.

[0] https://www.nasa.gov/mission_pages/station/expeditions/exped...

Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident

#70

Post by walrus01 »

DennisP wrote: post #28
lmilcin wrote: post #26

Earlier quoted context omitted.

Depends on what kind of test that was supposed to be. If they pumped it until it explodes it would be a kind of test (also called experiment) where it makes sense. If you design something with a margin of safety, then pump it to working pressure and it blows, then it means you made a mistake. If you made a mistake it shows you don't know what is necessary to design a rocket (yet). Seriously, they don't build skyscrap…

I think SpaceX has proven they know how to design rockets. But they are newcomers to building rockets from welded steel.

It is my understanding that the pressure vessels are carbon fiber composites. The skin is steel.
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