How long before this same type tourist tragedy happens in space? Probably sooner, rather than later. It's one thing to explore new frontiers. That's justifiable risk. This wasn't that. This was a bunch of rich guys purchasing the ultimate selfie opportunity -
"look at me, I'm at the Titanic!" No different, really, than the tourists taking selfies while petting bison at Yellowstone. No self-awareness of the danger.

Thinking about this…

It would be pretty easy for me to simulate that event.

Buy some carbon fibre pipe. Make some metal end caps. One with an annular burst disk. Glue them on.

Put it in one of my 15k pressure test vessels and pressure it up until the burst disk ruptures or the bond breaks.

I could even put some bacon in there to see it the fat makes it explode… it won’t.

I was thinking, there was oxygen on board, but looking at the schematic, I think the oxygen was outside of the carbon tube in the tail section. During the implosion, the fittings into the cabin were separated and the escaping oxygen most likely shot that tank into the great unknown. (If the escaping pressure were greater than the sea pressure)
My point, I see an instance where there COULD have been an explosion, but just as likely, no explosion.

Also, I wonder how much air eventually rose to the surface - would it have been enough to make a bubble that could have been seen topside?

"Explosion" as in sudden release of energy not fire or anything chemically driven

Energy released is proportional to the change in volume and the pressure both of which would be vast in a sudden implosion.

However a more gradual delamination seems not unlikely at this point.

I can't help but think it is like a compression ignition event -- without any fuel other than the oxygen of course. I don't know what the compression ratio would be, so to speak.

I'm morbidly curious about the physics.

My morbid curiosity is what happens to a human body at that depth after the implosion. I assume one disintegrates instantly and there's not much left. But if not, does the pressure compress them into a small ball of flesh?

It is very much so. Check out adiabatic compression. Or as someone mentioned before the inside of a diesel cylinder during the compression stroke. In my simple mind the rapid decrease in volume causes a rapid and extreme increase in the temperature as well.

https://en.wikipedia.org/wiki/Adiabatic_process

The Combined Gas law may offer some math that could help.

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5000/14 roughly so very high but very low chance of combustible mixture under compression

Have you ever seen the video of the railroad tanker car imploding? It's out there on the web. It compresses like someone stepping on a beer can in a fraction of a second.

Here it is. . .

https://www.youtube.com/watch?v=Zz95_VvTxZM

:eek: crikey

The atmosphere inside would be super-heated though? Or is the pressure of the water too great?

Mythbusters tested an extremely mild version of this event. https://youtu.be/LEY3fN4N3D8

Built a "meat man" from plastic skeleton and pig meat, put into an old-style diving suit with a bell helmet, lowered to 300 feet, turned off pressure to the airline. As air left the suit interior, water pressure compressed the suit exterior. Inside the suit, the "body" was compressed up into the diving helmet.

35X greater depth + instant compression + we being 60% water anyway.

the navy knew since sunday they were dead IMO.

thats why the second there was a deep search vehicle on site, they found the sub. the navy was like "we cant tell you how we know, but look right here" and they found it right away.

SOSUS is a hell of a drug.

The thing that blows me away is that the actually visibility from the "sub" was reportedly atrocious and most of the "viewing" occurred via onboard screens in the sub. WTF?

What's interesting to me is how many times James Cameron has been to the Titanic, I believe 33 times. Plus he's taken his one-man sub to the bottom of the Mariana Trench. He pilots a single seater and it looked infinitely safer than that sewer pipe "tourist" sub. Still not without risk, but Cameron has mitigated as much risk as possible.

James Cameron to Mariana Trench. That's 7 miles down, not 2 1/2.
https://www.npr.org/sections/thetwo-way/2013/05/23/186302916/Mariana-Trench

What "blows me away" is these people going that deep in a cold, dark, deep ocean......inside what essentially seems to me to be a crap mobile.

Live and let live, I guess but seriously?

So much for bragging rights.

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Interesting fact about this tragedy is that a piece of debris in the new OceansGate debris field 1600 feet from the bow of the Titanic has a cover from the same submarine that fell off on a previous dive.

CF doesn't really bend and collapse like metal. When it fails it shatters spectacularly. If the tube collapsed it would pop the end caps like a Pillsbury tube.

I am very impressed with the knowledge base of you Pelicans! You are some brilliant and educated people and I am fortunate to be part of this community.

Rock on, David

https://youtu.be/4qe1Ueifekg

Simple compression experiment.

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

video has several photos of the construction, and dear lord, its worse even than we thought.

Sacred feces! I can envision a lot of regs coming down due to this epic failure.

Well, that was quite something. Thanks for posting that.

yeah that wrap is so much worse than i was imagining. it is so easy to have inclusions there, and its a weakest wrap.

as is the fitting on the end caps. the narrator is correct, one of the key problems with deep submergence is differential shrinks. its so bad that if you put like gold plated electrical connectors under there, the gold will flake off, because the differential shrinking. everything shrinks under load differently, and that carbon tube is going to shrink likely faster than the end caps, and that means you now have a shear line cracking at that seam. 6000psi might as well be a drill bit at that point.

i can't believe they didnt use like 1 inch thick titanium core, and then wrap that. or use a titanium outer sleeve over the whole thing and let that shrink and push on the carbon fiber.

like, yeah, this is not how you build submarines.

He admitted to breaking the rules of building a submersible from cf.

Rick, the way I'm visualizing it is, imagine if a steel rod is placed on one square inch of your body, and a 4,700 lb SUV dropped onto the other end of the rod. With thousands of other steel rods placed on all the other square inches of your body, and thousands of SUVs dropped on those rods. All at once. Those steel rods would instantly pulverize your body, flesh and bone alike, until they meet in what used to be your center.

Your body is 60% water anyway. I think the other 40% of you would instantly become disassociated particles, perhaps gooshing in all directions. That's just my morbid guess and the logic behind it.

This seems way more extreme than an astronaut suffering sudden decompression in space, because he's going from 14 psi to 0 psi, these persons instantly went from 14 psi to 4700 psi.

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Juan Brown is a 777 pilot and not an engineer but he has some good information. He is wrong about a couple things here like NDT of composites but the video is worth watching.

I sorta agree with you but not completely. The rail tanker implosion is not representative because it is steel. Don’t forget that the CF had already suffered some delamination. This (even more than usual) non homogeneous structure would have meant it likely wouldn’t just shatter. Sure the delaminated pieces would have fallen off but some would still remain attached to the main tube.

Carbon fibre delaminates and the thin layers rip. The damage is normally confined to the break, not everywhere…


http://forums.pelicanparts.com/uploa...1687547846.png

You know what could have happened though…

They heard a crack, and released ballast.

As they ascend, a small leak develops that floods the vessel and compressed the air inside the vessel. With a pressure differential of 5530 psi, a small leak can be pretty fast…

As they ascend further, the pressure inside the vessel becomes higher than the pressure outside the vessel.

At some point the pressure of the now compressed air inside the vessel is enough to blow the end off including all of the contents. Perhaps exploding the carbon fibre tube.

Mic drop.

Unless a now water laden vessel won’t float when atleast partially full of water.

An explosion like that from a 377 times volume change of that volume (20’ long x 7’ in diameter = 245 cubic feet compressed into .650 cubic feet) should have been easily detected by a listening device within a couple hundred miles…

I suspect they went with CF because it can be constructed with DIY methods (not well obviously but only an expert would know). Whereas titanium would require specialized tools and skills to construct anything with it.


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Here is a great You Tube Video showing the Titanic wreck close up.

Some remarkable video.

https://www.youtube.com/watch?v=tiVctx-121g

From Reddit:

<blockquote class="reddit-embed-bq" style="height:500px" data-embed-height="500"> <a href="https://www.reddit.com/r/ThatsInsane/comments/14glhqe/the_video_shows_how_titanic_sub_imploded/">The video shows how Titanic sub imploded.</a><br> by <a href="https://www.reddit.com/user/Genesis_001">u/Genesis_001</a> in <a href="https://www.reddit.com/r/ThatsInsane/">ThatsInsane</a> </blockquote><script async="" src="https://embed.reddit.com/widgets.js" charset="UTF-8"></script>

Sure except that's not how CF fails...

Fatigue modeling (remember it has successfully made it to titanic prior) of a thick wall composite (non homogeneous) tube under external pressure is an extraordinarily difficult problem for the most skilled of specialists, so forgive me if I don't trust that reddit video even the tiniest bit.

I was suspicious of carbon fiber as a reasonable material when I first heard of this, and after watching a bunch of interviews with experts it is 100% confirmed. Should have been made out of good ol' fashion linear elastic metal or very thick cast acrylic.

If you gotta be fancy find some way to print it by direct deposition.

Imagine how much it cost to buy and machine that giant piece of titanium. I wonder why they went with all these exotic materials, could a conventional sub, even way overbuilt, not survive?