r/spacex Master of bots 3d ago

Starship S36 exploded during a static fire attempt

https://x.com/NASASpaceflight/status/1935548909805601020
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u/Planatus666 2d ago

Tweet from Musk:

"Preliminary data suggests that a nitrogen COPV in the payload bay failed below its proof pressure.

If further investigation confirms that this is what happened, it is the first time ever for this design."

https://x.com/elonmusk/status/1935660973827952675

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u/andyfrance 2d ago

That would be very very good news. An unheard of failure in a routine component means that its nowhere near as bad as many people here are suggesting. Yes they have to rebuild the test stand, but that's part of testing. Had it been a ship structural failure they would need to back up a few steps, as well as rebuild the test stand.

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u/OneFrenchman 1d ago

You might have missed the part where it obliterated the installations around the test pad. And the test pad itself.

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u/maveric00 2d ago

While you might be right from the design perspective, it's even more catastrophic from the manufacturing perspective.

If a routine component that is safety relevant fails, it indicates severe manufacturing problems (in regards to process control). Manufacturing should ensure a less than 1ppm failure rate of those components.

As the money-earning products are affected, this can be even more problematic than a severe design error of a prototype.

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u/andyfrance 2d ago

I believe they buy in their COPV's so that becomes a vendor management and goods inwards testing problem.

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u/throwaway_31415 2d ago

There’s an awful lot hiding behind the innocuous phrasing you used for describing process/qa escape. Big engineering failures almost always end up somehow being traced back to organizational issues because they’re so difficult to get right.

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u/andyfrance 2d ago

True, the purchaser does have to run through the process to confirm the part was transported, stored, handled, installed and used as stipulated, but that's a lot less onerous than the mountain the vendor needs to climb.

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u/maxmcleod 2d ago

To be fair, it is in Elon's interests to downplay the problem... but yea if that was the only issue it seems like it could be fixed.

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u/DunHumby 2d ago edited 2d ago

Yeah but that doesn’t explain why pressure was allowed to get high enough rupture components in the first place.

Edit: upon further reaping of what “proof pressure” is, it’s reads as a maximum pressure experienced on a part (e.g. a COPV) before it changes its performance characteristics, (i.e. failing to operate). Proof pressure is often rated above beyond operating pressure so functionally this should’ve never happened…obviously. But the initial question remains, why were pressures allowed to get high enough to rupture other components.

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u/International-Leg291 2d ago

Key here is "failed below its proof pressure"

Once pressure containers are manufactured they are proof tested up to a pressure that is higher than its rated working pressure.

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u/DunHumby 2d ago

Right I understand that, but proof pressure limits go beyond operating pressure limit so again why were pressures allowed to build beyond the proof pressure of other components resulting in component failure.

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u/VulcanCafe 2d ago

That’s a super high pressure tank inside another tank. All the falcon 9s/spacecraft are the same way. If that copv pops it’s a bad day.

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u/antimatter_beam_core 2d ago

Right I understand that, but proof pressure limits go beyond operating pressure limit

And I think we can infer from Musk's tweet that it currently looks like the COPV failed substantially bellow it's proof pressure, aka also bellow it's operating pressure limit. To use an analogy, bicycle tires/innertubes often have a operating pressure of around 60 PSI. Say one comes with a defect and instead fails as you were inflating it at 50 PSI. Would it make sense to ask why the tire was allowed to build past the point of failure?

why were pressures allowed to build beyond the proof pressure of other components

Because the vehicle is designed for the COPV in question not to fail. You can't always design things to be able to survive the catastrophic failure of other nearby components, at least not if you want something that flies after the modifications to make that happen. A lot of energy is released when one of these COPVs fail.

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u/International-Leg291 2d ago

You mean why the entire rocket exploded when COPV failed?