OceanGate Submersible Goes Missing During Titanic Dive

[Alex_Krycek]

4 hours ago, StringJunky said:

 Remind you of anyone? 

Edited June 26, 2023 by Alex_Krycek

[StringJunky]

1 hour ago, Alex_Krycek said:

 

Putin.

[swansont]

Debris brought ashore. One pic appears to be a titanium hemisphere, but without the viewing port.

https://www.bbc.com/news/world-us-canada-66045554

[mistermack]

I wouldn't find it surprising that the viewing port was out. You would think that it's design would be to resist huge outside pressure, and that pressure from within would push it out quite readily, and that on collapse, the internal pressure would momentarily be huge. Of course, it's still possible that it was the port that initially failed. 

I notice that there's no word about recovering bodies. They were almost certainly pulverised out of recognition in a millisecond, but it wouldn't be palateable to discuss that on official channels.

[Genady]

8 minutes ago, mistermack said:

I notice that there's no word about recovering bodies. They were almost certainly pulverised out of recognition in a millisecond, but it wouldn't be palateable to discuss that on official channels.

There is some, e.g.,

Quote

US Coast Guard Rear Admiral John Mauger said on Thursday that he was unsure whether it would be possible to locate the bodies of the five men who died in the Titan submersible. 

"This is an incredibly unforgiving environment," he said, referring to the deep and dangerous underwater area where the submersible disappeared. 

Titan implosion: What happened to bodies and will they ever be recovered? (geo.tv)

Breaking news: 'Presumed human remains' found in debris field of doomed Titan submersible, US Coast Guard says | CNN

[swansont]

44 minutes ago, mistermack said:

I wouldn't find it surprising that the viewing port was out. You would think that it's design would be to resist huge outside pressure, and that pressure from within would push it out quite readily, and that on collapse, the internal pressure would momentarily be huge.

Why would it be momentarily huge? It’s not going to be bigger than the external pressure.

 

44 minutes ago, mistermack said:

Of course, it's still possible that it was the port that initially failed. 

I notice that there's no word about recovering bodies. They were almost certainly pulverised out of recognition in a millisecond, but it wouldn't be palateable to discuss that on official channels.

If any remains were recovered, I suspect they would be kept away from the public eye.

[Genady]

Just now, swansont said:

Why would it be momentarily huge? It’s not going to be bigger than the external pressure.

 

If any remains were recovered, I suspect they would be kept away from the public eye.

Just announced: 'Presumed human remains' found in debris field of doomed Titan submersible, US Coast Guard says | CNN

[mistermack]

3 minutes ago, swansont said:

Why would it be momentarily huge? It’s not going to be bigger than the external pressure.

Kinetic energy. Like when you stomp in a puddle.

[Genady]

23 hours ago, mistermack said:

Kinetic energy. Like when you stomp in a puddle.

Can you estimate how this impact on a human body compares to that of a crushing WTC tower?

[toucana]

I have seen a couple of estimates of the energies involved in the implosion of a submersible like Titan. The figures usually suggested are these:

https://www.youtube.com/watch?v=aOoRLkC2wKs

- The hydrostatic pressure at 3500 metres deep is around 350 atmospheres.

- The speed of the implosion is around 800 kilometers/hour which occurs in less than a millisecond.

-  The air pocket inside the submersible is compressed and heated to around  5777ºK

This compression heating of the air is momentarily equivalent to the temperature of the surface of the sun. The occupants are simultaneously incinerated as well as pulverised - which happens well within the 13ms needed to receive sensory nervous inputs.

- The implosion shockwave turns into a short explosive expansion as equilibrium is regained, completing the destruction of the submersible

[Genady]

44 minutes ago, toucana said:

I have seen a couple of estimates of the energies involved in the implosion of a submersible like Titan. The figures usually suggested are these:

https://www.youtube.com/watch?v=aOoRLkC2wKs

- The hydrostatic pressure at 3500 metres deep is around 350 atmospheres.

- The speed of the implosion is around 800 kilometers/hour which occurs in less than a millisecond.

-  The air pocket inside the submersible is compressed and heated to around  5777ºK

This compression heating of the air is momentarily equivalent to the temperature of the surface of the sun. The occupants are simultaneously incinerated as well as pulverised - which happens well within the 13ms needed to receive sensory nervous inputs.

- The implosion shockwave turns into a short explosive expansion as equilibrium is regained, completing the destruction of the submersible

In such a short time the system perhaps did not reach thermal equilibrium, so the incineration might be not total. Some DNA might be found.

[mistermack]

21 hours ago, Genady said:

Can you estimate how this impact on a human body compares to that of a crushing WTC tower?

I can't. There are too many variables. But chance of survival would be less at the bottom of the ocean, that's for sure.

19 hours ago, toucana said:

-  The air pocket inside the submersible is compressed and heated to around  5777ºK

But only for a millisecond, I would have thought. The heat wouldn't be the main threat, when cold seawater was slamming into the void.

[StringJunky]

1 hour ago, mistermack said:

I can't. There are too many variables. But chance of survival would be less at the bottom of the ocean, that's for sure.

But only for a millisecond, I would have thought. The heat wouldn't be the main threat, when cold seawater was slamming into the void.

The pressure is the first effect, and that causes ignition, then it gets swamped.

18 minutes ago, StringJunky said:

The pressure is the first effect, and that causes ignition, then it gets swamped.

Would the combined pressure of the ignited air/components, and incoming seawater be additive on the occupants ie their bodies experienced a pressure greater than just from the depth pressure itself, albeit briefly?

Edited June 30, 2023 by StringJunky

[Genady]

1 hour ago, mistermack said:

But chance of survival would be less at the bottom of the ocean, that's for sure.

Can't be less than zero; nobody survived WTC collapse.

 

23 minutes ago, StringJunky said:

Would the combined pressure of the ignited air/components, and incoming seawater be additive on the occupants ie their bodies experienced a pressure greater than just from the depth pressure itself, albeit briefly?

I think, in such a short time it was a chaotic system, without defined pressure or temperature.

[StringJunky]

2 minutes ago, Genady said:

Can't be less than zero; nobody survived WTC collapse.

 

I think, in such a short time it was a chaotic system, without defined pressure or temperature.

Cheers

[mistermack]

46 minutes ago, StringJunky said:

The pressure is the first effect, and that causes ignition, then it gets swamped.

I think the effect of heat is being overestimated. Maybe the air temp might go up very high for a millisecond, but the volume of air at that point would probably be tiny, I'm guessing one thousandth of it's volume at one atmosphere. And it would probably be dispersed, not all in one bubble, so the water would cool it in an instant. 

 

33 minutes ago, Genady said:

Can't be less than zero; nobody survived WTC collapse.

Not true. I can't quote the details, but I believe about twenty survived. There's no concievable way of surviving that kind of sub collapse.

[studiot]

21 hours ago, Genady said:

In such a short time the system perhaps did not reach thermal equilibrium, so the incineration might be not total. Some DNA might be found.

Good point. +1

I just don't buy the fireball hypothesis.

 

The water pressure at titanic depth is around 400 atm and the volume of the titan is around 4 cubic metres at 1 atm

To compress  this to 400atm would reduce its volume to 0.01 cubic metres.

The only way this could happen would be if the remaining 4- 0.01 cubic metres was replaced by inflooding water.

This would surely crush and or drown the occupants ?

 

I said in my first post that connections between dissimilar materials should be carefully examined and the reports today seem to indicate that failure occurred at these places.

 

A further consideration is that no one has mentioned shear failure.

Carbon fibre composites rely on shear stress to tranfer the load from fibre to fibre.

Further swansont has already pointed out that although the outside loading is triaxial compression, the shape of the titan induces shear and bending stress due to unbalanced normal loads.

Squat objects subject to polyaxial compression fail in shear.

Edited June 30, 2023 by studiot

[Genady]

18 minutes ago, mistermack said:

I believe about twenty survived. There's no concievable way of surviving that kind of sub collapse.

Agreed.

[sethoflagos]

1 hour ago, StringJunky said:

Would the combined pressure of the ignited air/components, and incoming seawater be additive on the occupants ie their bodies experienced a pressure greater than just from the depth pressure itself, albeit briefly?

Given the scenario presented, the occupants are hit by a surge wave (essentially water-hammer) generated by the almost instantaneous deceleration of the incoming flow reaching something it can't shift (the water coming in the opposite direction).

We generally estimate this initial spike with the Joukowski formula which is summarised here.

Quote

The Joukowsky Equation lets us perform surge calculations by hand. It is named after Nikolay Zhukovsky, a founding father of aerodynamics and also hydrodynamics. (In this blog entry, I will stick with the more common spelling of the equation, "Joukowsky"). In addition to coming up with this equation, Zhukovsky was the first person to physically explain the lift on an airplane wing and produced many other important results in engineering and mathematics. I won't try to derive the Joukowksy equation here. Still, it follows from Newton's Second Law, force = mass times acceleration, combined with the physical fact that no disturbance can travel through a fluid any faster than the wave speed (the wave speed being roughly 300 m/s in gas pipelines and around 1-1.5 km/s in liquid pipelines). 

The Joukowsky Equation is ∆P = - ρ c ∆V. Where ∆P is the magnitude of the pressure surge caused by the velocity change and is what we are trying to calculate: ΔV is the velocity change causing the surge: p is the density of the fluid and c is the wave speed. (For there not to be any unit conversion factors, these quantities must be in a consistent set of units, like SI: pressure in Pascals, density in kg/m3, wave speed and velocity change in m/s). 

From the figures given, the Joukowsky 'spike' looks to be around 0.6 GPa (~6,000 bar), so 'Yes', very much so.

In passing, I would be very surprised if there were any significant heat transfer during such an extremely rapid deformation process. Simply not enough time.   

Edited June 30, 2023 by sethoflagos
grammar

[StringJunky]

3 minutes ago, sethoflagos said:

Given the scenario presented, the occupants are hit by a surge wave (essentially water-hammer) generated by the almost instantaneous deceleration of the incoming flow reaches something it can't shift (the water on the other side).

We generally estimate this initial spike with the Joukowski formula which is summarised here.

From the figures given, the Joukowsky 'spike' looks to be around 0.6 GPa (~6,000 bar), so 'Yes', very much so.

In passing, I would be very surprised that there was any significant heat transfer during such an extremely rapid deformation process. Simply not enough time.   

Thanks Seth.

Edited June 30, 2023 by StringJunky
Put wrong name

[studiot]

45 minutes ago, sethoflagos said:

Given the scenario presented, the occupants are hit by a surge wave (essentially water-hammer) generated by the almost instantaneous deceleration of the incoming flow reaching something it can't shift (the water coming in the opposite direction).

We generally estimate this initial spike with the Joukowski formula which is summarised here.

From the figures given, the Joukowsky 'spike' looks to be around 0.6 GPa (~6,000 bar), so 'Yes', very much so.

In passing, I would be very surprised if there were any significant heat transfer during such an extremely rapid deformation process. Simply not enough time.   

Yes I think the surge equation is a good way to approximate it.

+1

[John Cuthber]

On 6/24/2023 at 12:08 PM, Alex_Krycek said:

What about "hull integrity"?

Good question.
How do you intend to maintain an air supply and a route back to the surface without it?
Or did you not understand that it was implicit in the requirements I specified?

On 6/26/2023 at 9:38 AM, Alex_Krycek said:

No to mention Elon Musk is on record saying quite nonchalantly "a whole bunch of people will die", in the process of going to Mars.

They already started.
https://en.wikipedia.org/wiki/List_of_spaceflight-related_accidents_and_incidents

So he's just stating the obvious.

On 6/26/2023 at 10:25 AM, StringJunky said:

He's looking to have a cage fight with Zuckerberg.

Just a thought; If A kills B and is subsequently jailed for life for murder, is that a bad outcome?

On 6/26/2023 at 10:02 AM, toucana said:

But if you are going to adopt such a technique, then you don’t do it like this - out in an open warehouse space with a bunch of guys in carpenters aprons, standing on wooden step-ladders, and slopping the gunk on from a tin with paint brushes.

Actually, you sometimes can- as long as you make it 10 times thicker than it needs to be.
For a one-off design, overdoing the glue makes more economic sense than building a clean-room etc.

... just as long as you get the sums correct.

People seem to overlook teh fact that this sub dived successfully before.
The problem wasn't raw strength, but fatigue resistance.

To a very good approximation, nothing ever fails in straight compression.
Failure of stability.... not very rare.

[mistermack]

My feeling about carbon fibre is that metal has one advantage, in that it can be bent, and yet remain strong. Take the example of wrought iron. If you have a slight imperfection of fit on a metal body, it's possible that under extreme forces, the metal will give just enough to correct it, without failing catastrophically. Once it's moved that tiny amount, it will fit better the next time. 

With carbon fibre not having that ability, it will have to resist the extra forces that an imperfect fit throws up, or fail. And on the next dive, the fit will still be imperfect, so the risk is still there.

That's just my speculation, but I would far rather trust SS or Titanium than five inches of carbon. 

In a perfect world, carbon in the main body might be plenty strong enough, but what's it like, around bolts and joints? Everything has to be perfect. 

[swansont]

I had wondered why they kept referring to the passengers as “mission specialists”

https://www.newyorker.com/news/a-reporter-at-large/the-titan-submersible-was-an-accident-waiting-to-happen

“Although it is illegal to transport passengers in an unclassed, experimental submersible, “under U.S. regulations, you can kill crew,” McCallum told me. “You do get in a little bit of trouble, in the eyes of the law. But, if you kill a passenger, you’re in big trouble. And so everyone was classified as a ‘mission specialist.’ There were no passengers—the word ‘passenger’ was never used.” No one bought tickets; they contributed an amount of money set by Rush to one of OceanGate’s entities, to fund their own missions.”

[toucana]

A leaked copy of a transcript of the final text messages between the Titan submersible and its surface support vessel has been circulating for some days on the internet. There is a considerable amount of discussion in progress as to whether this log is veridical or not.

https://www.youtube.com/watch?v=4Dj8IJbP41c

The transcript indicates that an emergency of 19m duration preceded the loss of contact. The crew apparently reported that they had jettisoned their ballast weights and the craft’s metal landing frame after an abnormally fast descent, and red light alerts had appeared on their RTM (Real Time Monitoring) system which uses ultrasonic sensors to monitor hull stress. This indicates the crew had already aborted their descent and were attempting an emergency ascent.

Further messages indicate the craft was struggling to ascend, and that the crew who had reported hearing crackling sounds from the aft area, had also lost the use of their A Power Bus, and had switched to the backup B power Bus just moments before contact was lost. All of which suggests that one of their main electrical battery units had been compromised.