Author Topic: COPV protection: armored box around pressure vessel?  (Read 1817 times)

Offline Bubbinski

The recent events at LZ-1 on the Cape with the Crew Dragon got me to thinking. Would it be possible for future vehicles to have COPV’s enclosed in armored boxes to contain them if they were to let go? Or covering COPV’s with Kevlar? I know there’d be a mass penalty involved....but have there been studies done about this?

Edit: This of course pre supposes that COPV’s were involved, which we don’t know about at all. But COPV’s were implicated in the Amos-6 explosion and there was some concern about COPV’s during the last part of the shuttle program
« Last Edit: 04/23/2019 07:45 pm by Bubbinski »
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline Spindog

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Re: COPV protection: armored box around pressure vessel?
« Reply #1 on: 04/23/2019 07:55 pm »
I'm no expert on the weight difference but it would seem you could just build more safety margin into the COPV's or worst case build them out of steel or titanium. I know commercial steel pressure vessels are darn near indestructible though heavy.

Online ugordan

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Re: COPV protection: armored box around pressure vessel?
« Reply #2 on: 04/23/2019 07:57 pm »
Once you're at the point of having to add shielding mass to protect against a COPV letting go, what's the point of the COPV in the first place? Their primary advantage is lower weight.

Just go with a thick metal container that is rated way, way above expected operating pressure and be done with it. A kevlar shield here and there sure won't contain a high pressure tank that decides to let go either way.

Offline Coastal Ron

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Re: COPV protection: armored box around pressure vessel?
« Reply #3 on: 04/23/2019 08:01 pm »
The recent events at LZ-1 on the Cape with the Crew Dragon got me to thinking. Would it be possible for future vehicles to have COPV’s enclosed in armored boxes to contain them if they were to let go? Or covering COPV’s with Kevlar? I know there’d be a mass penalty involved....but have there been studies done about this?

Edit: This of course pre supposes that COPV’s were involved, which we don’t know about at all. But COPV’s were implicated in the Amos-6 explosion and there was some concern about COPV’s during the last part of the shuttle program

A COPV is composite overwrapped pressure vessel, which means it's is already enclosed in armor made out of high strength material like Kevlar, and likely has a titanium inner core. If they need to be stronger, they just add more layers of overwrap.

And no, I don't think COPV's were involved with the Crew Dragon accident. Certainly not the same ones on a Falcon 9 rocket.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline meberbs

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Re: COPV protection: armored box around pressure vessel?
« Reply #4 on: 04/23/2019 08:14 pm »
The recent events at LZ-1 on the Cape with the Crew Dragon got me to thinking. Would it be possible for future vehicles to have COPV’s enclosed in armored boxes to contain them if they were to let go?
COPV "letting go" seems to refer to the failure on a CRS mission that boiled down to a strut failing not holding it in place. putting the COPV in a box does nothing to solve that problem.

Or covering COPV’s with Kevlar?
COPV stands for "Composite overwrap pressure vessel." It consists of a metal liner with a composite material wrapped over it to provide lightweight structural integrity. Carbon fiber is a typical fiber material used in composites for these applications (usually results in a black  outer layer). Another typical fiber for composites is Kevlar. Wrapping the composite carbon fiber with composite Kevlar does not gain you anything, and may actually cause problems due to the different properties of the 2 composites. If anything this may increase the likelihood of a problem like the Amos failure where liquid oxygen squeezed into a gap in the composite and then froze.

As others have stated, there are simpler and more direct options if COPVs are an issue, but we need to find out the real root cause first.

Added: It looks like Coastal Ron beat me to the comment about Kevlar, but I already typed this.

Offline Bubbinski

Thank you all for your responses. I’ve learned a few things. One reason I enjoy NSF.com, learning what’s practical in spaceflight and what isn’t.
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

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