Tourist submarine exploring Titanic wreckage disappears in Atlantic Ocean

[ExWrench]

A triangular sub would implode.

A triangular sub wouldn't benefit from isostatic forces like a sphere would, but that doesn't necessarily mean a triangular sub would implode Though it mightrequire ~100x the build materials and budget, a successful triangular sub, though prohibitively impractical, could be possible.

 

[sdmuleman]

M

Anyone have an actual transcript without youtune 'analysis' trying to tell me what I should think? I'd like to read the raw info.

 

[ExWrench]

Anyone have an actual transcript without youtune 'analysis' trying to tell me what I should think? I'd like to read the raw info.

That video uses an unconfirmed / alleged "transcript". Could be pure horse shit.

TL/DR = sub went down too fast, came up too slow, had to drop outer frame after ballast, had 1/2 of elec. system fail, & stopped communicating around the time of <poof>.

 

[sdmuleman]

A triangular sub wouldn't benefit from isostatic forces like a sphere would, but that doesn't necessarily mean a triangular sub would implode Though it mightrequire ~100x the build materials and budget, a successful triangular sub, though prohibitively impractical, could be possible.

Possible, but limited in depth. Subs are unique because buoyancy, i.e. displaced volume must be equal or greater than weight. Consequently, there's a physical limit to how much a boat of a given volume can weight, and if you try to add material to increase strength you will no longer have a sub, but rather an expensive anchor. So if you make a triangular boat, it's going to be far more limited in depth than a more effectively shaped boat.

As a general SWAG, I would guess a triangular hull of titanium similar in size to Titan would be limited to no more than 3-4000 ft of depth.

 

[ExWrench]

Possible, but limited in depth. Subs are unique because buoyancy, i.e. displaced volume must be equal or greater than weight. Consequently, there's a physical limit to how much a boat of a given volume can weight, and if you try to add material to increase strength you will no longer have a sub, but rather an expensive anchor. So if you make a triangular boat, it's going to be far more limited in depth than a more effectively shaped boat.

As a general SWAG, I would guess a triangular hull of titanium similar in size to Titan would be limited to no more than 3-4000 ft of depth.

Yeah, and I agree. However, Crusty made an absolute statement so I took 20 seconds to shred it.

 

[sdmuleman]

That video uses an unconfirmed / alleged "transcript". Could be pure horse shit.

TL/DR = sub went down too fast, came up too slow, had 1/2 of elec. system fail, then stopped communicating around the time of ~total pressure equalization.

Thats why I wanted to read the entire transcript. Some of it seemed like crap, but could also be valid - slow leak in an external pressure vessel is a realistic casualty, and could cause fast decent and slow ascent, although it is difficult to conceive a scenario that would then lead to implosion.

There's lots of failures that could cause them to be stuck on the bottom, or kill personnel without structural damage, but implosion of the pressure hull is a very odd failure for a sub unless it exceeds design depth. A boat operating in water much deeper than design depth can easily sink out and implode due to another failure (i.e. Thresher), but in this case it's designed to reach the bottom in the water she was in.... so loss of depth control means your stuck on the bottom but not going to overstress the pressure vessel.

 

[TrailTamer]

Possible, but limited in depth. Subs are unique because buoyancy, i.e. displaced volume must be equal or greater than weight. Consequently, there's a physical limit to how much a boat of a given volume can weight, and if you try to add material to increase strength you will no longer have a sub, but rather an expensive anchor. So if you make a triangular boat, it's going to be far more limited in depth than a more effectively shaped boat.

As a general SWAG, I would guess a triangular hull of titanium similar in size to Titan would be limited to no more than 3-4000 ft of depth.

Did you know that buoyancy doesn’t need to be entirely within the pressure vessel?

 

[Sandy Johnson]

A triangular sub wouldn't benefit from isostatic forces like a sphere would, but that doesn't necessarily mean a triangular sub would implode Though it mightrequire ~100x the build materials and budget, a successful triangular sub, though prohibitively impractical, could be possible.

what are you talking about? They already built one in 2018.

 

[ExWrench]

implosion of the pressure hull is a very odd failure for a sub unless it exceeds design depth

. . . unless its design depth was pencil-whipped bullshit, having not taken into account imperfections in the composite (CF) hull and the unknown number of stress cycles that CF hull could take before degrading.

 

[sdmuleman]

Did you know that buoyancy doesn’t need to be entirely within the pressure vessel?

Certainly. Buoyancy outside the pressure vessel at depth isn't exactly easy though..... Nor is overly efficient, especially when you include structure to attach it to the pressure vessel. Which comes back to the difficultly in sub design.

Moreover, I was assuming for the purposes of discussion something similar to the Titan vehicle - i.e. small relatively self contained essentially self buoyant vehicle.

 

[D_JEEPER]

Certainly. Buoyancy outside the pressure vessel at depth isn't exactly easy though..... Nor is overly efficient, especially when you include structure to attach it to the pressure vessel. Which comes back to the difficultly in sub design.

Moreover, I was assuming for the purposes of discussion something similar to the Titan vehicle - i.e. small relatively self contained essentially self buoyant vehicle.

Dont forget temperature cycles as well as pressure. Lots of shit they willingly overlooked on this one

 

[sdmuleman]

. . . unless its design depth was pencil-whipped bullshit, having not taken into account imperfections in the composite (CF) hull and the unknown number of stress cycles that CF hull could take before degrading.

Agree, and I would not have been surprised if it failed on first submergence. But it didn't so obviously wasn't totally wrong. You are likely right that cyclic damage is a cause, although the details of how are interesting as CF really doesn't fatigue in the usual sense. Nor would modes of degradation than occur in a normal application (tensile, i.e. fibers pulling apart) necessarily be applicable in compression. It also seems like progressive damage would be somewhat a function of time at depth as well as pressure, i.e. most likely time for failure is towards the end of the bottom time, not before it even sees max pressure.

This ties back to the transcript though - if accurate, there was something else going on and having whatever that was happen on the same dive that happened to exceed the progressive hull damage threshold is difficult to believe.

 

[fordguy]

Somebody that worked closely with this program informed me that it was a planned incident, to take out one of the guests. But you didnt hear it from me

 

[clodhopper]

New form of clintonciding?

 

[bgaidan]

Somebody that worked closely with this program informed me that it was a planned incident, to take out one of the guests. But you didnt hear it from me

New form of clintonciding?

Hey ev13wt you just won an all expenses paid ride on the IBB submarine. You leave tomorrow!

 

[fordguy]

New form of clintonciding?

oh hell I dont know man Im just talking out of my ass.

 

[TrailTamer]

Certainly. Buoyancy outside the pressure vessel at depth isn't exactly easy though..... Nor is overly efficient, especially when you include structure to attach it to the pressure vessel. Which comes back to the difficultly in sub design.

DCV1 is built to go down 36,000ft. The submersible weigh 26,000lbs. Sphere pressure vessel.

Deepsea Challenger - Wikipedia

en.wikipedia.org

34,000lbs DSV Alvin submersible, also have sphere pressure vessel and buoyancy on the outside. Test depth of 21,300ft.

DSV Alvin - Wikipedia

en.wikipedia.org

Trieste’s pressure sphere is 31,400 lbs.

Granted Trieste was built to go down 36,000ft, nearly 3x deeper than the Titanic.

Trieste (bathyscaphe) - Wikipedia

en.wikipedia.org

Moreover, I was assuming for the purposes of discussion something similar to the Titan vehicle - i.e. small relatively self contained essentially self buoyant vehicle.

It’s a flawed design, considering no other deep sea submersible vessels, that I can find at this time, resembles Titan’s non-sphere pressure vessel.

Crazy on how they thought they can get away with untested and unproven carbon fiber cylinder for the pressure vessel, let alone carrying fare-paying passengers in it.

 

[plym49.2]

DCV1 is built to go down 36,000ft. The submersible weigh 26,000lbs. Sphere pressure vessel.

Deepsea Challenger - Wikipedia

en.wikipedia.org

34,000lbs DSV Alvin submersible, also have sphere pressure vessel and buoyancy on the outside. Test depth of 21,300ft.

DSV Alvin - Wikipedia

en.wikipedia.org

Trieste’s pressure sphere is 31,400 lbs.

Granted Trieste was built to go down 36,000ft, nearly 3x deeper than the Titanic.

Trieste (bathyscaphe) - Wikipedia

en.wikipedia.org

It’s a flawed design, considering no other deep sea submersible vessels, that I can find at this time, resembles Titan’s non-sphere pressure vessel.

Crazy on how they thought they can get away with untested and unproven carbon fiber cylinder for the pressure vessel, let alone carrying fare-paying passengers in it.

Note they all have variable trim capability.

Anyone who can provide insight on the through-hull connectors used? Would love to see what kind of rubber grommet (/s) can withstand that kind of pressure.

 

[PAE]

Its a different design when it has several thousand PSI against it.

Polymer and design the more pressure the better it seals.


The sphere design works better than the dead rich guys sub as with a sphere pressure is equal all the way around.

 

[Spreader]

Our subs have been using one split seal for prop shafts for a while. I know there is quite a bit diff in operational depth here, but I find that amazing. One seal for a multiple billion dollar vessel.
Probably multiple seals orientated for tighter seal at more pressure. WAG.
PAE beat me to the punch.

 

[sdmuleman]

Our subs have been using one split seal for prop shafts for a while. I know there is quite a bit diff in operational depth here, but I find that amazing. One seal for a multiple billion dollar vessel.
Probably multiple seals orientated for tighter seal at more pressure. WAG.
PAE beat me to the punch.

One seal in action at a time, but there 2 identical seals in the assembly backup up with a emergency seal. Also designed where a failure of the sealing surface would cause a controllable leak, but a catastrophic failure. Multiple seals wouldn't work because you can't really control pressure differential without something very complicated to actively control pressure across each stage.

 

[sdmuleman]

Anyone who can provide insight on the through-hull connectors used? Would love to see what kind of rubber grommet (/s) can withstand that kind of pressure.

Haven't seen what the deep submergence ones look like, but standard sub practice I'm familiar with looks something like this. No rubber used, but rather epoxy/other non conductive material. Basically just a big connector. Not really that difficult to engineer.

 

[arse_sidewards]

Haven't seen what the deep submergence ones look like, but standard sub practice I'm familiar with looks something like this. No rubber used, but rather epoxy/other non conductive material. Basically just a big connector. Not really that difficult to engineer.

This. Like a potted bulkhead connector but with fancy engineered shapes so more pressure means more sealing.

 

[sdmuleman]

Granted Trieste was built to go down 36,000ft, nearly 3x deeper than the Titanic.

Trieste (bathyscaphe) - Wikipedia

en.wikipedia.org

It’s a flawed design, considering no other deep sea submersible vessels, that I can find at this time, resembles Titan’s non-sphere pressure vessel.

Crazy on how they thought they can get away with untested and unproven carbon fiber cylinder for the pressure vessel, let alone carrying fare-paying passengers in it.

Illustrates the point nicely - certainly you can use external flotation, but you pay for it with a big awkward vehicle for a still fairly small pressure hull. Also need more complex systems for trim, because likely have more change in buoyancy due to compression to compensate for. Also added risk, especially with the bathyscaphe - the float is a very thin wall tank filled with gasoline. Any leakage means a loss of buoyancy with no way to recover - i.e. you're stuck on the bottom waiting for the air to run out. Relatively easy to damage as well, so considerable risk. Not to mention handling someodd thousand gallons of gasoline. Modern snytatic foam is much harder to damage, but you still have potential for external damage to leave you stranded.

Disagree it's a flawed design. Properly done, I think it's an excellent idea, and there's a lot of value in something other than a small spherical hull. Cylindrical hulls are widely used for shallower submarines, so no fundamental flaw there. You don't see them on deep submergence vehicles because you need a very high strength to weight ratio for it to be practical to use anything but a small sphere at great depth. Composites is a key enabler here. That being said, there needed to be a far more rigorous engineering and testing program, and it may be there's fundamental reason composites. cannot be used, although I think the problems could likely be worked through.

 

[Elwenil]

I've always wondered if a gas could be stored in a pressurized cylinder as a liquid, and then used to inflate external bladders to allow a submersible to ascend to the surface in an emergency. I know that works for emergency rafts for ships and airplanes, but I have often wondered if it would be effective at the pressures at the depth the Titanic is. Seems like a simple idea, but I haven't heard of it being used, so there must be something wrong with it that I am ignorant about.

 

[Firstram]

I've always wondered if a gas could be stored in a pressurized cylinder as a liquid, and then used to inflate external bladders to allow a submersible to ascend to the surface in an emergency. I know that works for emergency rafts for ships and airplanes, but I have often wondered if it would be effective at the pressures at the depth the Titanic is. Seems like a simple idea, but I haven't heard of it being used, so there must be something wrong with it that I am ignorant about.

You could shoot a hole in a full scuba tank at that depth and the water would rush into the tank. With a liquefied gas, the temperature that deep is still too low to give any useful vapor pressure.

 

[ExWrench]

Cylindrical hulls are widely used for shallower submarines, so no fundamental flaw there. You don't see them on deep submergence vehicles because you need a very high strength to weight ratio for it to be practical to use anything but a small sphere at great depth. Composites is a key enabler here. That being said, there needed to be a far more rigorous engineering and testing program, and it may be there's fundamental reason composites. cannot be used, although I think the problems could likely be worked through.

I'm not claiming to be an expert, but . . .

I think every single step they did involving resin should have had high vacuum pulled on it before curing. Including ~JB Weld-ing the non-crushy parts to the composite . . . limit finder. Any porosity in that resin is an Achilles' heel when there's 6000 psi of hydraulic pressure to exploit any flaws. Chain porosity enabling penetration would be a death sentence for sure - repeated pressurization fatigues the resin bond, a bit more hidden real estate delaminates, and it's more vulnerable to the next assault from every angle - eventually, <poof>

 

[gt1guy]

I've always wondered if a gas could be stored in a pressurized cylinder as a liquid, and then used to inflate external bladders to allow a submersible to ascend to the surface in an emergency. I know that works for emergency rafts for ships and airplanes, but I have often wondered if it would be effective at the pressures at the depth the Titanic is. Seems like a simple idea, but I haven't heard of it being used, so there must be something wrong with it that I am ignorant about.

At bottom at the Titanic wreck you're at a pressure of 5340psi. If you had 6000psi HP bottles to fill emergency lift bags, you only have 660 usable psi before the bottle was empty. It would take a lot HP bottles to work, but it would be technically possible.
The weight of all those bottles creates it's own set of issues to be delt with.

A good friend of mine's dad was part of the Trieste dives. Very cool guy and some interesting stories about it.

*When the plexiglass view port started to fail on the shallower dives, they went to lexan. Which was one of the earliest uses of the material.

*The sphere was measured after the last dive to the bottom. It was actually smaller by a small amount.

*They determined where to launch the sub by tossing explosives over the side of the mother ship and timed the return of the sound.

Mr. Rechnitzer ( friend dad) was supposed to go on the dive to the bottom. But Paccard wanted his son to have the glory so my buddies dad got bumped. He said Paccard was an asshole, hated him for years. Buddies dad did make the dive down past 20k feet.

11/16/59

Left to Right: Lieutenant Larry Shumaker, Assistant Officer in Charge; Lieutenant Donald Walsh, Officer in Charge; Dr. Andreas B. Rechnitzer, Scientist in Charge; Jacques Piccard, Co-Designer and Technical Advisor of Bathyscaphe Trieste.

Bathyscaph Trieste, 1960. Lieutenant Don Walsh, right, and Dr. A.B. Rechnitzer, possibly during testing by the Naval Electronics Laboratory in San Diego, California.


I can actually remember seeing the Trieste in Point Loma. My dad also worked at the Naval electronics Labatory.

 

[gt1guy]

I'm not claiming to be an expert, but . . .

I think every single step they did involving resin should have had high vacuum pulled on it before curing. Including ~JB Weld-ing the non-crushy parts to the composite . . . limit finder. Any porosity in that resin is an Achilles' heel when there's 6000 psi of hydraulic pressure to exploit any flaws. Chain porosity enabling penetration would be a death sentence for sure - repeated pressurization fatigues the resin bond, a bit more hidden real estate delaminates, and it's more vulnerable to the next assault from every angle - eventually, <poof>

Exactly.
Just think what would happen to a single entrapped air bubble in the middle of that layup that was only 1cc in size after the resin ( most likely epoxy) had fully cured.

I think it should have been vacuum bagged and then put in a autoclave with high temp and pressure. On top of all that CF and titanium react differently to pressure and temperature.

 

[Ranchtruck]

Why not skip the whole buoyancy problem and put a tether on it? Unlimited power to run thrusters and a winch on the tender ship to haul it up. Could put small floats on the line to keep it vertical above the sub for maneuvering around the wreck to avoid a snag.