Tourist submersible visting the Titanic is missing 101

[dik]

[quote="I'd like to be remembered as an innovator," Rush told vlogger Alan Estrada in 2021.][/quote]

More likely he'll be remembered as a Darwin award winner...

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

-Dik

 

[TugboatEng]

He was just seeing what would happen

 

[dik]

Yes... and I wonder what his last thoughts, observations and comments were? "O...", if he got that far... When I was a kid, I came up with an observation (not having heard it before), "How long is the instant between live and death, and how short is eternity?"

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

-Dik

 

[dik]

With the substantial difference between the Young's Modulus between carbon fibre and titanium even the junction connection could be quite a problem to maintain a watertight connection.

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

-Dik

 

[waross]

It looks as if there is a lifting sling passes through the port hole.
My thought is that if the view port was the initial point of failure, I am surprised at the damage to the rest of the craft.
If the view port breached, the differential pressure on the hull would be immediately reduced with little further damage.
If the hull collapsed, the differential pressure on the view port would be relieved.
Perhaps the view port failed initially and the craft then fell to the bottom.
A fairly high speed impact with the bottom may have caused the hull damage.

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

 

[SWComposites]

The modulus difference is not that much depending on direction. Ti modulus is 16 msi. Carbon composite (assuming intermediate modulus fiber) in the tube 0/90 layup is around 10-12msi in the laminate plane, but ~ 1.3 msi thru the thickness.

Yes, the extreme pressure could force water into the laminate, but it was supposedly ~ 5 inch thick so would take a very long time to diffuse thru that thickness. Unless the laminate was very poorly made.

However, we don’t know the details of the composite tube in the sub that was lost. Apparently the Spencer fabricated tube was in a previous sub version. And we don’t know if they attempted some sort of “repairs” after a previous dive.

 

[dik]

Thanks, SWC...

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

-Dik

 

[TugboatEng]

With the substantial difference between the Young's Modulus between carbon fibre and titanium even the junction connection could be quite a problem to maintain a watertight connection.

I disagree with this statement. I am a proponent of adhesives mount fasteners in the maritime industry. When using adhesives to attach fasteners to metallic structures, fatigue is a concern. However the plastic/epoxy adhesives have a Young's modulus that can fully accommodate the elongations of the steel structure over all conditions that would not also contribute to a fatigue failure or the steel structure.

Adhesive fastening systems are superior but the salespeople don't know how to push their products. All cases require the use of leveling just like concrete installs.

However, the sales people don't see this and look bad when fasteners pull off during tightening. There is little trust for their products outside of the aviation industry that has specific procedures.

 

[dik]

Sorry Tug... with the pressures involved, I suspect differential movement could be an issue. I, however, have no idea of how the carbon fibre cylinder and the titanium hemispheres will interact. I wouldn't rely on the high pressure to provide the 'clamping' action to keep them in contact and waterproof. I spec Hilti chemical anchors several times a day, usually. I'm also on Masterbond's mailing list and often get information on the various types of epoxies they have... structural, medical, and electronic, conductive and non-conductive. I'm somewhat aware of some of the epoxies out there.

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

-Dik

 

[Tomfh]

My thought is that if the view port was the initial point of failure, I am surprised at the damage to the rest of the craft.

If the window gave way then the shock when the internal bubble collapsed to nothing would have been catastrophic. All that energy coming to a crashing halt, with nowhere to go.

 

[LittleInch]

It might have been the other way as well, i.e. everything in its design is to resist external pressure. On implosion the internal pressure could peak at higher than external for a very short period and blow the view port out?

don't think anyone is really going to know, but we can all speculate given we have no access to the parts they have recovered and the spread of debris.

The CF cylinder remains the main weak point IMHO but the view port probably isn't far behind alright.

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

 

[Alistair_Heaton]

I suspect the port window will be a plug fit with no real strength for opposite direction loads.

Aircraft windows are the same but opposite.

There is a safety 0.5 psi pressure valve to stop the hull imploding if the cabin ends up lower pressure than ambient.

 

[Tomfh]

It might have been the other way as well, i.e. everything in its design is to resist external pressure.

Yep, makes sense.

 

[Cool_Controls]

The dome looks have been seperated from the the end ring and it also appears the view port outer flange is missing. This may indicate it was a hull failure and the resulting water hammer blew the view port out and snapped the bolts connecting the dome to the end ring.

 

[1503-44]

On one voyage it seems they had one thruster installed backwards.
Guess they reversed the wires on the game controller.

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

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[ldeem]

TugboatEng regarding the epoxy joint. My first thought is the differential movement of the Ti and CF hull due to different thermal coefficients and E would have to be taken in the joint. Either creating large stresses across the joint surface or (if the epoxy is strong enough) large forces in either the Ti or CF due to forced displacements.

I have experience working in large kilns where temperature differences can create very large stresses if movement is constrained. In this case the temperature of materials would be similar but different thermal coefficients would cause the same issue.

Would the epoxy joint have enough flexibility to allow the Ti and CF sections to move independently?

 

[debodine]

SWComposites brought up another good point in this quote:

"However, we don’t know the details of the composite tube in the sub that was lost. Apparently the Spencer fabricated tube was in a previous sub version. And we don’t know if they attempted some sort of “repairs” after a previous dive."

Regarding previous dives, I do wonder if OceanGate had any detailed inspection plan to assure after-dive integrity, and any validated maintenance plan to address any issues found by inspection.

 

[LittleInch]

debodine,

I'm not sure you've really grasped just how much this looks like a "fly by the seats of an X box controller" this whole operation appears to have been...

As soon as anyone who needed a corporate or other third person sign off to do the dive started looking, the holes in the swiss cheese kept on lining up before they had even entered the water. Individuals just got overawed with the potential and essentially put all doubts behind them. Some even admit now to be a "bit naïve".

Think you'll be looking for a long time for a "detailed inspection plan". IMHO.

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

 

[waross]

Inspection plan:
Step 1. Kick the tire and you're good to go.
But there are no tires.
Okay. Skip that step.
Step 2.
There is no step two.

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

 

[1503-44]

Reversed thruster says they're not interested in pre-testing anything. They'd rather listen for unusual noises. Good luck with that theory as the problem is its only one big noise. I couldn't have any faith in listening for noise as a warning of immenent catastrophic failure. Compressive failures are never user friendly.

This looks safer.

I think it's a classic example of tunnel vision. Only the objective was important.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."