Titanic tourist sub goes missing

[Northwoods]

Unless there's an autoignition of the air (and there's no fuel to cause that) there's no way for the interior pressure of the CF vessel to exceed the exterior vessel. 

The human fat would be a good fuel to ignite.  Plus anything else flammable, like their clothes, plastics, etc.

[dogmush]

Remember reports of what the Thresher and Scorpion looked like, like they had gone through a shredder.
I could see the viewport giving way the energy released by the implosion, again calculation by Manley to be equal to 50kg of TNT, shattering the CF hull and the caps popping off like corks in a corkgun. But again the viewport very well could have popped out then.

Sure, except that both Thresher and Scorpion also have pretty large, mostly intact pieces.  Scorpion in particular is intact enough that they could figure out which frames failed first and in which order the bulkheads failed. Both have a solid debris field and there was violent tearing apart of stuff but niether pressure hull just "shredded".  Of course Steel isn't Carbon Fiber, and a Multi compartment submarine full of loose stuff isn't a single compartment submersible.  So failures could very well look different.

I respect Scott Manley's videos but I think that calculation was a little "YouTube"y.  I'm sure he got the joules correct, but an explosion and an implosion are very different things, and buy tying it to TNT, I think he's inviting visualization of very different forces.

[WLJ]

I respect Scott Manley's videos but I think that calculation was a little "YouTube"y.  I'm sure he got the joules correct, but an explosion and an implosion are very different things, and buy tying it to TNT, I think he's inviting visualization of very different forces.

I keep a salt shaker handy at all times.

IIRC he was calculating based on the volume of air in the sub and didn't included the occupants in that. I would have to go back and watch the video again.
and I think his calc was amount of energy created by the implosion not necessarily outward. But it's still going to be one heck of a shock to the structure

[WLJ]

If they're removing stuff just to make it easier to lift that bugs me considering the fact the viewport is/was considered a potential failure point and that would be messing with evidence. What would have been so hard about putting the front cap into a lifting net without removing the viewport?

[WLJ]

Pissing in the dark and my feet are wet.

[230RN]

The human fat would be a good fuel to ignite.  Plus anything else flammable, like their clothes, plastics, etc.

Thanks.  The air doe not ignite.  It ignites other things by the heat of its compression, as in  diesel engines. At only 25 atmospheres (14.7psi  x 25) compression it is hot enough to ignite the diesel fuel injected into that hot air.

I'd like to look over the energy calculations to equate to TNT but I don't have time. You'd have to consider the average velocity of all the imploding particles as well as the inrushing water, and the inrushing vesssel parts,  plus  the mass of all these things.  Once all that is done by guessing and averageing and hoping, the calculation is easy.  Energy equals the guessed-at-mass time the square of the guessed-at velocities.  We are all familiar with that when calculating bullet energy.

I've also posted a vid of a big TV tube implosion here and you will note the particles end up everywhere, despite their initial direction being inward.  And this is with a pressure differential of only 14.7 PSI, one atmosphere.

I also wonder about the possible reverberation effects we have seen in slo mos of guns being fired under water.  It can be seen that the gaeous bubbles expand and contract, expand and contract.  This effect can also be seen in slo mos of things like firecrackers set off in fishtanks.

There's certainly a lot to consider... as another example, might the hot compressed air turn some of the seawater into high pressure steam and cause outward forces after the initial collapse thereby causing some of the scattering and "blendering" effects?

Fun to play with "extremism" in the physical world... like shouldn't the gravity at the center of a black hole really be zero, as it is at the center of the earth??
 
Or if maybe I should say, as Perd touched on... "the ifysical world."

Nap time.

Terry, 230RN

[dogmush]

I tried calculating the temperature of the air in the sub if it compressed all at once to 380 atm, but I came up with wildly varying numbers so I gave up. One of my assumptions is off. I remain skeptical that without any sort of hydrocarbon in there you would get a detonation like we were discussing.  Fabrics, fats, electronics, even batteries don't detonate as much as they burn, and the window for that to happen before any combustion is extinguished by seawater is very small.

I would point out that a lot of diesel engines don't actually manage to ignite diesel with pure compression.  they need glow plugs until the heads get hot enough to sustain the compression ignition.

The auto ignition theory would also pretty much require a single failure at one end of the pressure hull, with the rest of the hull holding atmosphere as the water rushed in.  If the hull collapsed along the length of the cylinder the air would escape bubbles through the fractures before autoignition could occur.

interesting side note:  Glancing at the vaporization temperature of water at pressure tables I don't see any that hit 380 atm, but at 220 atm it's 375*C.  Eyeballing the math, it's in the realm of possible that the air bubbles got hot enough that they boiled the water compressing them and there were some *very* short lived steam pockets before they cooled and re-condensed.

[K Frame]

"I remain skeptical that without any sort of hydrocarbon in there you would get a detonation like we were discussing."

As gross as it sounds... could the people in the sub have provided the source of hydrocarbons?

Ah, I see that someone else has already posited that.

[dogmush]

I was accounting for the people. I don't think that's  rich enough fuel for a boom.  But I confess that's more gut feeling from dealing with engines and biofuel than actual knowledge.

Side note: is animal fat a hydrocarbon?   My chemistry isn't that good.

[Northwoods]

I was accounting for the people. I don't think that's  rich enough fuel for a boom.  But I confess that's more gut feeling from dealing with engines and biofuel than actual knowledge.

Side note: is animal fat a hydrocarbon?   My chemistry isn't that good.

The three most common fatty acids stored in human adipose tissues are oleate (C18H34O2), palmitate (C16H32O2), and linoleate (C18H32O2),

They’re hydrocarbons.  So, yeah.  Flammable.

[Northwoods]

At an average 20% body fat (possibly low) and 170lbs average weight (likely low), that 170lbs of human fat onboard that submersible.  At well above diesel ignition pressures that could be a substantial kaboom.

[HankB]

From the standpoint of igniting the people - there have been a number of people shot at contact distance with rifles over many years and many wars. Muzzle pressure is on the order of 10,000 PSI, and I don't recall any people being ignited by the pressure - even locally around the muzzle.  For that matter, bullet impacts will create a lot of localized pressure, too - but they don't set the meat targets on fire. I'm not convinced a sub implosion will ignite the passengers before the water saturates them. In fact, living tissue does contain a good percentage of water to begin with. (Wet kindling?)

Surely someone, somewhere, has run an experiment with the application of sudden high pressure on tissue.

[Northwoods]

The energy from a single gunshot is insignificant compared to the power of the force an implosion at 3500m.

[230RN]

^
"I would point out that a lot of diesel engines don't actually manage to ignite diesel with pure compression.  they need glow plugs until the heads get hot enough to sustain the compression ignition."

True, but that's for cold-starting conditions. where there's iinitial heat loss to the cold surrounding steel. It would not be necessary if the designed compression ratio were higher, but this involves more stress on the engine parts.  Put it this way, if sudden compression to, say, 25 or 30 atmosphere will ignite diesel, sudden compression to 380 atmospheres will get it hot enough to ignite anything.  I might jokingly add that it could be hot enough to sustain fusion reactions... <big grin, har-de-har-har.>
 
^
"...interesting side note:  Glancing at the vaporization temperature of water at pressure tables I don't see any that hit 380 atm, but at 220 atm it's 375*C.  Eyeballing the math, it's in the realm of possible that the air bubbles got hot enough that they boiled the water compressing them and there were some *very* short lived steam pockets before they cooled and re-condensed."

That's why I offered the possibility of ummm... let's say an oscillating bubble throwing crap all over.  (That 375°C at 220 Atm steam pressure seems low.  No tables, no math, just my left eyebrow raised itself.)

There are enough rapid dynamically-changing extreme circumstances in this playbook that any change in any assumption changes most the other assumptions and there are too many un-assessed variables so that attaining "truth" requires a couple of Crays  or extensive empirical testing with a tightly limited number of "variable variables." (Egad,Terry, did you actually say that?  For shame, Shane!)

But fun to play with them based on what evidence is available.  Too bad such tragic circumstances are involved.

Terry, 230RN
 

[MechAg94]

My understanding is that you can tell the difference between someone shot at contact distance and someone shot further away.  Burns on the skin/clothing is part of it. 

In the order of a things for a sub decompression, I think the people inside would be smashed to pulp before the heat of compression takes effect.  Then the water will absorb the heat immediately anyway. 

[230RN]

...
Surely someone, somewhere, has run an experiment with the application of sudden high pressure on tissue.

Yes, probably the Nazis in the camps or the Japs in their Unit 731 in China.  I am told that our data on death by hypothermia was obtained from German human experiments.

[HeroHog]

I may need to reduce my meds. When I read "Sub Transcription", my mind immediately went to:

Jimi Hendrix - "3rd Stone From The Sun" Scout Ship to Mothership Transcription:

{intro slowed down talking begins}
Star fleet to scout ship, please give your position. Over.
I'm in orbit around the third planet from the star called the sun. Over.
You mean it's the Earth? Over.
Positive. It is known to have some form of intelligent species. Over.
I think we should take a look.
{intro slowwed down talking ends}

Strange beautiful grass of green,
With your majestic silver seas
Your mysterious mountains I wish to see closer
May I land my kinky machine?

{start slowed down}
Strange beautiful, grass of green
With your majestic silver seas
Your mysterious mountains I wish to see closer
May I land my kinky machine?
{end slowed down}

{Distorted}
Although your world wonders me,
With your majestic and superior cackling hen
Your people I do not understand,
So to you I shall put an end
And you'll never hear surf music again

{start slowed down...rough guess at lyrics}
Secret
Oh, secret
Oh
Shhhh...
{end slowed WAY down}

https://youtu.be/Zts332Y-nyg

[K Frame]

"Side note: is animal fat a hydrocarbon?   My chemistry isn't that good."

I'd have thought yes, but I'm finding conflicting statements on da Googles...

Apparently the additional oxygen atoms in animal fat take away its hydrocarbon status. According to a snipped from a Nat Geo article, we'd have to be hydrogenated before we got to hydrocarbon status.

Interesting.

[230RN]

^ Agreed.I knew there was a difference between hydrocarbons and "fats" (stearins?) but I didn't want to dig up the techinicals.  In either case, they are both carbon-rich burnables, as you may remember from having fat fires in the kitchen and the flareups in BBQs.

I'm not sure we should be talking combustion per se in the present discussiop, per the water infusion pointed out above, but maybe just instant pyrolysis or boiling or both, or what.  As I said, add a variable, and two more rise up immediately.

Also as noted above, I doubt that a full, complete, unredacted coroner's report will ever be forthcoming, so the --not "guesswork," but let's call it "estimatework --will go on for a significant portion of forever. The very complexities provide a rich source of discussion.

[HankB]

Yes, probably the Nazis in the camps or the Japs in their Unit 731 in China.  I am told that our data on death by hypothermia was obtained from German human experiments.

Wouldn't have to be human experiments - someone must have done ultra high pressure tests on mice or rats or even just tissue samples.

The energy from a single gunshot is insignificant compared to the power of the force an implosion at 3500m.

In total, yes. But not locally, that is, within a couple of centimeters of the muzzle. And the temperature of the hot, burning powder gas would itself provide an additional ignition source (besides the compression of the sudden ultrahigh pressures) and cause powder burns. But I still don't recall ever seeing anything about actual tissue ignition. Some things can be, well, vaporized/pulverized without igniting themselves.

[230RN]

I'm going ro go with "they were crushed to death instantly and painlesly by a huge high-speed column of exremely high pressure sea water."

Terry, 230RN

[WLJ]

And now we have this

No it wouldn't have dove like an arrow if it lost propulsion. A sub isn't an airplane

Spanish submarine expert José Luis Martín suggested the submersible lost stability due to an electrical failure that left it without propulsion, causing it to fall toward the seabed 'like an arrow vertically' with its porthole facing down.

He estimated that the sub began freefalling at a depth of around 5,600 feet and fell 'as if it were a stone and without any control' for about 3,000 feet until at around 8,600 feet it 'popped like a balloon' due to the rapidly changing pressure.

The Titan changed position and fell like an arrow vertically, because the 400 kilos of passengers that were in the porthole compromised the submarine. They all rushed and crowded on top of each other,' Martín added.

Titanic sub victims knew their fate for a MINUTE before vessel popped like 'balloon': Expert reveals 'horror, fear and agony' as the five men were piled on top of each other in total darkness during 3,000ft nosedive
https://www.dailymail.co.uk/news/article-12286881/Titanic-sub-victims-knew-fate-minute-3-000ft-nosedive-expert-says.html

He's an

[RoadKingLarry]

A sub isn't an airplane

 
That's what they want you to believe.
   

[Brad Johnson]

The Titan changed position and fell like an arrow vertically, because the 400 kilos of passengers that were in the porthole compromised the submarine.
...

He estimated that the sub began freefalling at a depth of around 5,600 feet and fell 'as if it were a stone and without any control' for about 3,000 feet until at around 8,600 feet it 'popped like a balloon' due to the rapidly changing pressure.

So buoyancy of a totally submerged vessel is now dependent on orientation? Riiiiiight....

Brad

[dogmush]

I'm not sure why he thinks the CG or CB would change appreciably if the thrusters cut out.