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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

#111

Post by Klathmon »

kev009 wrote: post #103
Klathmon wrote: post #98

Earlier quoted context omitted.

They aren't using any tax dollars for Starship. It's entirely funded by their profits (at least as far as I know). And this Starship MK1 is/was a prototype designed to test some aspects of their design in the real world. It was never going to be anywhere close to taking people onboard. Even this incident had all people far away before they started doing anything like pressurising. This is active development, every si…

Citations needed for the funding. Sounds like people being loose with the truth. The accounting alone would be close to impossible to keep separate.

I meant it as in no government contracts are going toward starship development, but looking it up it seems I'm actually wrong, maybe...

The air force has given them some money for development on their Raptor engine, and they've talked about wanting more government funding for starship itself, but they've also talked about how starship has been privately funded so far.

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

#112

Post by Retric »

CydeWeys wrote: post #74
saagarjha wrote: post #64

Earlier quoted context omitted.

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

Yeah, and with much higher required dv and more required stages this would be a huge problem. But we only need two stages to orbit when launching from Earth, so it's really not that big of a deal, and it turns out that optimizing for reusability ends up being a lot cheaper than optimizing for minimum fuel use. For example, it only costs $200k for a fuel load of Falcon 9 fuel. If you got rid of reusability you'd need…

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.

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

#113

Post by LeoPanthera »

cdumler wrote: post #105
taneq wrote: post #80

Earlier quoted context omitted.

That's why you take your maximum design stress and double it, right? /s

How else do you think I keep my reputation as a miracle worker? -- Scotty

"The tank can't handle that much pressure."

"Where'd you get that idea?"

"What do you mean, where did I get that idea? It's in the impulse engine specifications."

"Regulations 42/15: 'Pressure Variances in IRC Tank Storage'?"

"Yeah."

"Forget it. I wrote it… A good engineer is always a wee bit conservative, at least on paper."

- La Forge and Scott, Star Trek TNG "Relics"

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

#114

Post by pardavis »

WalterBright wrote: post #75
zionic wrote: post #14

Earlier quoted context omitted.

Looks like the welds holding the bulkhead on failed. For those who aren't keeping up with this the failure was on the Mk1 prototype. Mk2 has been build nearly in parallel with Mk1 and will take over early flight testing (20km hop). Elon has tweeted that this team will jump to Mk3 instead of trying to repair Mk1.

Airliners rarely use welds because they're very hard to make with consistent high quality and are also very hard to inspect. Instead, they're riveted together.

Friction stir welding is popular in rocketry because it is very controllable.

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

#115

Post by LeoPanthera »

roywiggins wrote: post #13
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.

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...

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

#116

Post by lopmotr »

kev009 wrote: post #102
ceejayoz wrote: post #100

Earlier quoted context omitted.

> There is no space mission in the near decades worth the loss of human life. This is a weird assertion. Tens of thousands of people die in car accidents each year, but no one proclaims that going to the grocery store isn't worth the risk to human life.

Yours is far weirder. How does mortality in daily life have anything to do with a billionaire’s fantasy.

That response doesn't make sense (normal people can risk lives but billionaires can't?). What does make sense is the fact that daily driving produces lots of economic value in the short term which manned space travel doesn't. So it's worth killing some drivers but not worth killing some astronauts. But that's still not obviously the right conclusion. Space travel has the potential for much greater value further in the future - most long term being survival of the species!

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

#117

Post by Agathos »

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.

Fuel on the ground is cheap. Halfway to orbit, nothing is cheap.

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

#118

Post by nwallin »

walrus01 wrote: post #70
DennisP wrote: post #28

Earlier quoted context omitted.

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.

Do you have a source?

My understanding is that the skin is the pressure vessel. The reason for going with stainless steel at all is because it maintains integrity at high temperature. Carbon fiber does not. So a stainless steel combined heatsink and structure can maintain integrity at 1000C or whatever, while carbon fiber+ceramic heatshield will need to hold temperatures below 400C or whatever.

And even though the fiber structure is much, much lighter, the amount of heat protection required is massive. And the stainless steel "cheats" by performing double duty. And you get a second free lunch because the heat protection requirements are slimmer.

It wouldn't be the first time I've been wrong today though. Nor the second.

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

#119

Post by JshWright »

Agathos wrote: post #117
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 on the ground is cheap. Halfway to orbit, nothing is cheap.

It's still a lot cheaper than the rocket.

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

#120

Post by dzhiurgis »

taneq wrote: post #89
londons_explore wrote: post #72

Aren't pressure tests done with water? That way, since water is non-compressible, if it fails, you just get a small hole or buldge somewhere rather than the catastrophic damage seen here. Perhaps they already tested with water and now needed to test with the real fuel/oxygen to get the temperature correct?

Is it strong enough to take a full tank of water? Liquid methane weighs less than half what water weighs.

Maybe they can use liquid nitrogen?
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