Tourist submersible visting the Titanic is missing 101

[Reverse_Bias]

Not actually the vacuum itself, it's the outside vs inside pressure difference. The Carbon fibers in the shell don't have high elasticity, so they aren't going to recoil like a spring.

 

[dik]

Great thread, John...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Tomfh]

Not actually the vacuum itself, it's the outside vs inside pressure difference.

Well yes, that's what a vacuum is. The pressure on one side is nearly zero relative to the pressure on the other side. As far as the water at 4000m deep is concerned, a pressure of 1 atmosphere is a vacuum.

 

[TugboatEng]

The carbon fibers don't but the polymer resins are elastic. The name composite implies multiple materials with various properties. That seems to be the problem, composites in compression don't have predicable properties.

I know we hate analogies but look at a rope. It's like carbon fiber without any resins. You pull on it and it grips down on itself to make it stronger as the strands grip themselves through friction. If you push on the same rope it's hard to predict what it is going to do.

 

[waross]

I agree Tomfh.
The pressure difference times the volume.
Any energy stored in the hull will be released outwards, not inwards.
The inrush of water will compress the internal volume of air to about 1/399 of its original volume.
That is where the bulk of the energy will be absorbed.
The air in the passengers lungs will also be compressed.
The rush of water will accelerate the broken pieces of the hull so as to traverse the cabin and continue until momentum is lost.
I suspect that there may be pictures of human remains that will never be released to the public.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Denial]

CoolControls.
A totally random website I just consulted claims that exploding TNT releases 4000[ ]J/kg, so 50[ ]kg would release 200[ ]megaJoules.[ ]My tatty envelope gives a figure of one-third of that:[ ] not in the same ballpark, but in the same general neighbourhood.

JustSomeNerd / Dik.
I completely ignored all strain energy other than that in the water at 400bar.[ ] I assumed, without really thinking about it, that the water's energy would predominate.
[Any volunteers to offer a figure for this?]

JustSomeNerd / Tomfh / Dik. Energy released or energy absorbed?
The strain energy in the water surrounding the capsule pre-exists simply by being at that depth and hence at a pressure of ~350[ ]bar.[ ] The capsule sneaks in down there and creates a capsule-sized void in which the pressure is zero (or 1[ ]bar to put a smile on Waross's dial).[ ] Capsule cracks open instantaneously.[ ] A capsule-sized volume of water at 350[ ]bar outside the capsule rushes inside at warp speed, depressurising to zero as it does so.[ ] It is this depressurising that releases the strain energy that the water previously held.[ ] That energy does a lot of things (shatters the capsule, sends an acoustic "hello" to the US Navy's submarine monitoring station, pressurises the small amount of air that was in the capsule, etc, etc, and also to some extent repressurises the water very soon after the implosion).

[sub][ ]—————————————————————————————————[/sub]
[sup]Engineering mathematician/analyst.[ ] See my profile for more details.[/sup]

 

[Factoter]

Reading through this thread has given me this idea; what if the forming cylinder for the carbon were a pressure tank, which is then hydro bulge-formed and the carbon fiber is cured in tension. With the metal pressure cylinder supplying sustained outward pressure, the carbon submarine is no longer under compression at depth, but in tension. Problem solved, or is this magical thinking?

 

[Tomfh]

The tension will vanish once the pressure is turned off.

 

[TugboatEng]

Keep in mind that plastics gain strength through polymerization and adding tension during thet process breaks bonds and reduces strength. Once polymerized there is the issue of creep. We see this a lot with polycarbonate and polyamide plastics. Some epoxies are polyamide, others are acrylic. It's hard to make generalizations here.

 

[Tomfh]

My tatty envelope gives a figure of one-third of that

Your numbers are wrong. You have a sub volume of 100m3. It's less than a tenth of that. The strain energy is very small compared to the energy associated with the relative vacuum inside the hull.

 

[IRstuff]

Alternately we could use the displacement of the water volume at depth, although we can't be sure of the actual depth where the Titan imploded, since they were ostensibly trying to surface, and of course, the Titan was not broadcasting any useful telemetry that we're aware of. Using this approach, I wind up with something like 500 lb of TNT equivalent at 350 atm pressure and a 2 ft average radial displacement.

TTFN (ta ta for now)
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[Tomfh]

Alternately we could use the displacement of the water volume at depth

That's the neatest way. 500lbs seems too high though?. What volume of displaced water are you using?

 

[Denial]

Many thanks, Tomfh.[ ] My results from about nine hours ago were, as you pointed out, too high by a factor of about 10.[ ] More precisely they were out by a factor of 9.81, a most embarrassing, rookie, error.[ ] The revised spreadsheet is attached.[ ] Its calculation now shows that the equivalent gravitational drop height has reduced to 64[ ]m.

[Edit. A corrected version of the spreadsheet can be found below in my post of 26 Jun 23 21:30.]

 

[LittleInch]

I don't think that criticism of the search efforts is justified.
Search and rescue craft and resources were mobilized almost immediately.

I wasn't trying to criticise the SAR efforts, just making the point that the communication from the mothership was less than informative and set up unrealistic expectations of a happy ending. Also I think it took them several hours before they raised the alarm?

So yes, until you've got proof of collapse and failure assume the vehicle could be in one piece and making its way to the surface, but be a bit more open about the fact that they knew where it was when it stopped responding ( a long way from the wreck), the location transponder has stopped working as well as comms and (maybe) the sub was making its way to the surface.

So one possibility is implosion , but other possibilities exist and until we know for certain we go looking. Then at least everyone has the same information.

I think this has ended up a bit like the modern version of Apollo 13. Four men lost in space with a damaged craft trying to get home.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Brian Malone]

Denial I like you have tried to have the energy of the implosion expressed in a tangible form for those of us who have little feel for kg of TNT! One small item with your updated spreadsheet: your comment in cell E15 still shows 'g' as a factor: '=V=m*g/r. Your actual formula in F15 has it removed.

 

[waross]

With friendly respect, LittleInch.
I was not thinking about you or your posts, or any posts here.
I was reacting to ignorance and politics by some news media.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[dik]

Some added information:

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

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

Thanks Denial and Tomfh...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[LittleInch]

Waross, No problem - it just came after mine so thought It was in response to that.

I did read something today from the mother of the 19yr old who dies who said essentially they waited several hours to see if the sub just popped up after loosing comms, so maybe that explains a bit of the thinking behind any delay in calling on the USCG etc.

I do feel though that the mother ship was not very open about what they knew and what it probably leant itself towards.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IRstuff]

For all we know OG had a backroom of graybeards or outside safety auditors involved.

Actually, we do know that the company fired at least one person who was insisting on doing ANY testing at all. We also know that the Titan was severely lacking in safety equipment, including not having any means for the passengers to get out on their own if needed. They also didn't have fail safe position locator nor even an independent pinger.

Moreover, we know that the hull was a known problem, having been completely rebuilt already, and that many potential passengers passed up the "opportunity" because of concerns about the hull and the popping and creaking noises therein. Had the company been truly safety conscious, they would have quickly trotted out their secret testing results to alleviate the concerns.

Again, hubris; we had, at a previous company, hired a famed designer/architect for a project that was touted to be "correct by design." We, the silly and stupid, conventional engineers thought that design rule checks should have been run. They were behind schedule, so they skipped those tests; eventually, they got around to running tests and they had to immediately rush-order a metallization mask because they found out their "correct by design" chip had a short from power to ground.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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