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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

#231

Post by Roark66 »

tinco wrote: post #213
Roark66 wrote: post #167

Earlier quoted context omitted.

Why would they be using hardened steel for a pressure vessel that has to deal with vibrations? Also, someone on twitter said a horizontal weld failed. If this is true I'm surprised they didn't do two things: - tune their welding procedure by destructive testing with the same type of steel - and X-ray (or use another non-destructive method) the welds after assembly. Welding (including more interesting metals) is my ho…

Maybe they did both things, and the weld still failed. The rocket's being engineered, which means they make it as weak as possible without it blowing up. Those welds might be perfect in the x-rays, they might've done all sorts of destructive analysis, and still the thing might fail in staging. Of course, they might also be on a deadline, and just went ahead and built it to spec and test it. But I don't think you can…

>Maybe they did both things, and the weld still failed. The rocket's being engineered, which means they make it as weak as possible without it blowing up. Those welds might be perfect in the x-rays, they might've done all sorts of destructive analysis, and still the thing might fail in staging.

Yes, that is also a possibility. I'm not sure how likely is it that a pressure vessel would fail along a weld if that weld was without faults and as strong as other surfaces. Perhaps it matters that there is also a sharp corner there?

>Of course, they might also be on a deadline, and just went ahead and built it to spec and test it. But I don't think you can just say there's routine testing procedures that ensure rockets never blow up.

I agree if they are trying to make it as light as possible and pushing the boundaries a bit while experimenting. One can't innovate without risk.

It would be good if they released more info about this incident.

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

#232

Post by ablation »

LeoPanthera wrote: post #115
roywiggins wrote: post #13

Earlier quoted context omitted.

Rockets are actually pretty easy to poke holes in. They're meant to keep stuff in, not out. A dropped torque wrench blew up a Titan. https://en.m.wikipedia.org/wiki/1980_Damascus_Titan_missile_...

Non-mobile URL: https://en.wikipedia.org/wiki/1980_Damascus_Titan_missile_ex...

I find the mobile view a lot easier to read on my laptop, funnily enough. I've started preferring mobile links to wikipedia lately.

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

#233

Post by new_realist »

This integration test is way too late to be finding faults like these. This is top down design, which is expensive an error prone. The ship should be designed and tested in a bottom up fashion, such that the failure modes of every individual component is already known, as per Feynman. SpaceX is repeating the mistakes of the Space Shuttle program.

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

#234

Post by ncmncm »

Retric wrote: post #223
Retric wrote: post #112

Earlier quoted context omitted.

Fuel becomes more expensive on reusable spacecraft. Granted, the first pound of fuel is cheap, but the costs keep rising. With one and done you have a larger mass fraction to work with. Reusable spacecraft operate on much tighter constraints. Every single wasted pound in Space X’s design likely costs them 100’s of thousands of dollars in lost profit over time.

Not sure what’s to disagree with about that: “The reusable Falcon 9’s performance to GTO is listed at 5,500 kilograms. The same rocket in fully expendable version can lift 50 percent more payload — 8,300 kilograms. For the Falcon Heavy, the performance to GEO is about 2.8x that of the reusable version” https://spacenews.com/spacexs-new-price-chart-illustrates-pe... Reusable means cost savings, but it has a dramatic r…

Which trips each cost much less because you don't have to build another rocket to do each with.

Or, equivalently, in one trip with a bigger rocket you have left over from another launch, because you didn't ditch it.

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

#235

Post by MR4D »

Just another test.

However...

To me there is an issue with large diameter pressured tubes - the point where the tube connects to the top is affected by the surface area divided by the diameter. Obviously one of those scales linearly, and the other squared.

That suggests to me (I'm definitely not a rocket scientist!) that the upper bound might be smaller than this diameter, or the weight will have to increase in order to beef up the strength of this point.

Pretty interesting problem to deal with now that they are this far into the design. I'm sure there are many possible solutions, and it will be fun to see what they come up with.

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

#236

Post by AnIdiotOnTheNet »

danielbln wrote: post #175
CPLX wrote: post #172

Earlier quoted context omitted.

I must admit that Elon has done some fairly impressive things, and I respect his hustle and innovation. With that said, the cult that surrounds his projects where people say things like "this is what success looks like" when a big metal thing blows up unexpectedly or robot car goes flying off an exit ramp is a never ending source of amusement.

The cult is funny indeed, but do mind that the giant SpaceX booster rockets exploded in giant balls of fire a LOT before they eventually (and reliably) landed like in a sci-fi movie, on land and on a moving boat. SpaceX has earned some benefit of the doubt.

I don't think the issue is that a prototype didn't function as desired, it's the re-framing of that event as a "success" that reeks of cult-like worship mentality.

When something doesn't behave as desired, it is a failure. You can learn from failure, that's how you get to success, but the failure itself is not a success.

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

#237

Post by dwild »

aedron wrote: post #206
ehnto wrote: post #200

Earlier quoted context omitted.

I guess the parent comment was pointing out that this actually wasn't unexpected, it was one of the expected failure modes for the test and it happened. I don't see any constructive reason to look at it negatively, failure is part of testing. We don't test to find success, we test to find failures so that we can get them out of our systems.

Fine, so don't call it "success!". It's a step on the way to (possible) success, but the hypersensitivity isn't helping anyone.

You sound like the one hypersensitive here...

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

#238

Post by prestonh »

AnIdiotOnTheNet wrote: post #236
danielbln wrote: post #175

Earlier quoted context omitted.

The cult is funny indeed, but do mind that the giant SpaceX booster rockets exploded in giant balls of fire a LOT before they eventually (and reliably) landed like in a sci-fi movie, on land and on a moving boat. SpaceX has earned some benefit of the doubt.

I don't think the issue is that a prototype didn't function as desired, it's the re-framing of that event as a "success" that reeks of cult-like worship mentality. When something doesn't behave as desired, it is a failure. You can learn from failure, that's how you get to success, but the failure itself is not a success.

I agree calling it a success is too rosy, but I think people are really thinking od this as progress, not a regression like the event itself would naively suggest, because the company relies on hardware failure to inform design improvements.

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

#239

Post by Retric »

ncmncm wrote: post #234
Retric wrote: post #223

Earlier quoted context omitted.

Not sure what’s to disagree with about that: “The reusable Falcon 9’s performance to GTO is listed at 5,500 kilograms. The same rocket in fully expendable version can lift 50 percent more payload — 8,300 kilograms. For the Falcon Heavy, the performance to GEO is about 2.8x that of the reusable version” https://spacenews.com/spacexs-new-price-chart-illustrates-pe... Reusable means cost savings, but it has a dramatic r…

Which trips each cost much less because you don't have to build another rocket to do each with. Or, equivalently, in one trip with a bigger rocket you have left over from another launch, because you didn't ditch it.

That’s great if you’re transporting large numbers of the same thing like star link satellites. However, many payloads are worth sacrificing the first stage. Just look through the “No attempt“ missions in 2018 for some of the reasons why: https://en.m.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_...

Which again demonstrates reusability is really expensive, though clearly not always as expensive as a new rocket.

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

#240

Post by ravar »

conjectures wrote: post #185
SmellyGeekBoy wrote: post #180

Earlier quoted context omitted.

Way to misquote GP to confirm your preexisting bias. I think the quote you're looking for is: "So as manufacturing pathfinder, this is what success often looks like. " If blowing up a prototype enables changes to the manufacturing process that prevent the same thing happening later with a live crew on board, then it's considered a success. It doesn't matter who the CEO of the company happens to be.

On the other hand, perfection looks like nothing ever blowing up while job always getting done.

Rockets always blow up, the question is just how quickly.
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