OceanGate Expeditions Titan DSV loss

[quellish]

I’m still trying to figure out where the batteries were. This is a weird design.

Under the cabin floor, I think. (Not 100% sure; this pic may be Cyclops 1 rather than Titan, but they seem to be similar in general config.)

View attachment 702397

That would be an odd place. First, fire hazard of having the batteries in there. Second, how do you get the power from the batteries to the thrusters, etc. without penetrating the pressure vessel?

 

[aim9xray]

Two separate power systems? (Inside/outside? Hi-amp batteries outside for thrusters?). There's room in the aft "bustle" for equipment.

Guess we'll have to wait to the end of the inquest to determine what the systems architecture was.

 

[1635yankee]

b) that water is compressible, so its density will increase with the depth

Whoa!! Who changed the Laws of Physics while I wasn't watching . . . ?

Water Compressibility | U.S. Geological Survey

Water is essentially incompressible, especially under normal conditions. Yet, in industrial applications water can be tremendously compressed and used to do things like cut through metal.

www.usgs.gov

cheers,
Robin.

They didn't change the laws of physics; the USGS is simplifying. The bulk modulus of water is 2.2 GPa, For comparison, the bulk modulus of air is 0.142 MPa, and that of steel is 160 GPa. If water -- or anything else -- was truly incompressible speed of sound would be infinite.

Bulk modulus is original volume times change in pressure divided by change in volume. A gigapascal (GPa) is 10,000 bar.

 

[quellish]

Two separate power systems? (Inside/outside? Hi-amp batteries outside for thrusters?). There's room in the aft "bustle" for equipment.

Guess we'll have to wait to the end of the inquest to determine what the systems architecture was.

From

How Cloud-Based Design Collaboration Drives Product Innovation

Cloud-based design collaboration allows engineers to work on a design simultaneously, driving product innovation.

web.archive.org

Note that it appears OnShape recently removed this article from their website.

There is some "stuff" in the tail where the fairing is, but I can't tell what it is. Only 1 of the items looks like it could be a battery, I think the vertical cylinders/spheres are probably compressed gas. Putting the batteries in the tail I think would mess with the balance but I don't know what type of batteries they were using. Typically a deep submergence vehicle would use a pressure compensated lead acid battery - and use a lot of them. Their power density isn't like a lithium ion battery, and submersible thrusters use a lot of power.


This is an example of a lead acid submersible battery:

SeaBattery® Power Module | DeepSea

www.deepsea.com

That COULD be the orange box in the tail.... but I would think there would need to be many more of them.

Here is a battery pack for a Pisces submersible:

Batteries in Deep Sea Submarine - Stock Image - C011/8868

These lead acetate batteries are packed in oil to resist the extreme pressures at the bottom of the sea. This is one of the two sets of batteries used in the Pisces IV, a three-person, battery-powered submersible with a maximum operating depth of 2000 meters (6,280 feet). TED KINSMAN/SCIENCE...

www.sciencephoto.com

Triton apparently has only recently developed a LiPo deep sea battery, and in Japan there is a submersible that uses a lithium ion battery. These do not appear to be widespread yet, and they're still big batteries.

 

[quellish]

As a point of comparison, this is a Triton full ocean depth submersible. You can see the large batteries in the sketch.

Sourced from https://tritonsubs.com/subs/t36000-2/ and https://www.scubadiving.com/augment...ced-sub-world-limiting-factor-challenger-deep

 

[TomS]

I’m still trying to figure out where the batteries were. This is a weird design.

Under the cabin floor, I think. (Not 100% sure; this pic may be Cyclops 1 rather than Titan, but they seem to be similar in general config.)

View attachment 702397

That would be an odd place. First, fire hazard of having the batteries in there. Second, how do you get the power from the batteries to the thrusters, etc. without penetrating the pressure vessel?

Looking closer, I think the systems under the floor may be air rather than battery.

Tracing the cable runs, it looks like they do actually run from the tailcone fairing up the aft Ti ring, along the top of the PV, with some wiring feeding the vertical thrusters, and then down the front Ti ring to the horizontal thrusters.

But there must be a hull penetration somewhere, because at very least you have to get control functionality from the inside of the PV to the outside, and communications back the other way. Unless they relied on wireless transmission/induction through multiple inches of composite or titanium, which seems like an even worse idea.

That COULD be the orange box in the tail.... but I would think there would need to be many more of them.

I think perhaps there would be several side by side in the final version. But also, Titan didn't use much energy, it seems. I think they mostly dropped it up-current of the wreck and let it drift down, with only minor steering adjustments. Some of the failed missions happened when they ran out of power before they reached the target, perhaps because the currents were not as predicted.

 

[Halcyon66]

Based on everything other shortcut, they probably used WiFi for communication from inside to outside.

Regards,

 

[quellish]

I think perhaps there would be several side by side in the final version. But also, Titan didn't use much energy, it seems. I think they mostly dropped it up-current of the wreck and let it drift down, with only minor steering adjustments. Some of the failed missions happened when they ran out of power before they reached the target, perhaps because the currents were not as predicted.

That's a whole other thing - there does not seem to be much ballast.
There is trim ballast attached to the landing skegs, and then a couple of weights hanging from the structure near the center of mass / center of bouamcy. I assume those tiny weights are the descent ballast, I do not see any other place that could be. That would mean a slow descent and ascent - unless it was also powered to ascend and descend.

 

[Scott Kenny]

I think perhaps there would be several side by side in the final version. But also, Titan didn't use much energy, it seems. I think they mostly dropped it up-current of the wreck and let it drift down, with only minor steering adjustments. Some of the failed missions happened when they ran out of power before they reached the target, perhaps because the currents were not as predicted.

That's a whole other thing - there does not seem to be much ballast.
There is trim ballast attached to the landing skegs, and then a couple of weights hanging from the structure near the center of mass / center of bouamcy. I assume those tiny weights are the descent ballast, I do not see any other place that could be. That would mean a slow descent and ascent - unless it was also powered to ascend and descend.

(images deleted for space)

I mean, it doesn't take a whole lot of weight to change depth.

We were doing hovering on the trim pump on the Georgia and Kentucky and it only took 500lbs of water to move a 19000ton sub up or down.

 

[Halcyon66]

The little weights on the legs are for emergency, supposedly they can be made to fall off if the crew moves side to side.

The other smaller weights on the rope under the hull are also emergency one's that drop off after 16 hours of so as they are made from some material that dissolves in salt water. So if everyone is unconscious the vessel should float back to the surface.

Supposedly there were another set of ballast that were steel pipes that were dropped when time to return.

Regards,

 

[quellish]

From 2020:

https://www.geekwire.com/2020/oceangate-raises-18m-build-bigger-submersible-fleet-get-set-titanic-trips/

OceanGate will take advantage of lessons learned during the construction of its carbon-hulled Titan submersible, which was originally built for Titanic journeys. Rush said tests that were conducted at the Deep Ocean Test Facility in Annapolis, Md., revealed that the Titan’s hull “showed signs of cyclic fatigue.” As a result, the hull’s depth rating was reduced to 3,000 meters.

“Not enough to get to the Titanic,” Rush said.

That meant the Titanic trips — which had been planned at first for 2018, then 2019, then 2020 — had to be put off until mid-2021. By that time, Rush expects the new submersibles to be ready to enter service. He said mission specialists who have paid more than $100,000 each to participate in the Titanic expeditions were “generally supportive but disappointed” by the delay.

 

[martinbayer]

What happens next with the wreckage of OceanGate's submersible Titan?

An international investigation into the cause of the undersea implosion of a tourist submersible that killed all five people on board is underway. So, what happens next?

www.abc.net.au

Severe forensics (hopefully) and further complete socalled business case implosion?

 

[Scott Kenny]

What happens next with the wreckage of OceanGate's submersible Titan?

An international investigation into the cause of the undersea implosion of a tourist submersible that killed all five people on board is underway. So, what happens next?

www.abc.net.au

Severe forensics (hopefully) and further complete socalled business case implosion?

Definitely massive forensics and recovery of wreckage.

Their business, however, is likely to get sued out of existence on the grounds that they lied about how safe it was (particularly that acrylic window!).

 

[patryk]

Source: https://www.smithsonianmag.com/inno...bmarine-plans-tourists-see-titanic-180972179/
Original caption: "A rear camera allows the pilot to dock Titan on the submerged platform after completing a dive. The platform and sub are then raised to the surface. Becky Kagan Schott"

 

[Rhinocrates]

Some docos on how to do it properly.

One on the Alvin:

View: https://www.youtube.com/watch?v=2H3a1oMDkRE&t=4s


One on how the Limiting Factor was built (I'm surely not the only one who thinks it looks like a watermelon in a tote bag):

View: https://www.youtube.com/watch?v=pb5j9oeZCm0&t=1s


Trailer for a film on James Cameron's Deep Sea Challenger:

View: https://www.youtube.com/watch?v=-8r_-79SjpA

 

[Halcyon66]

Maybe best to read the thread, these were previously posted.

Regards,

 

[Arjen]

True for Deep Sea Challenger and Limiting Factor. The clip about the Alvin reminded me that some of the rejected-by-Oceangate 'uninspirational' 50+ sub-experts weren't even born when Alvin was commisioned - in 1964. It's still operational. But hey, if you're working on innovative, paradigm-shifting concepts, why bother looking at old folks' work?

 

[1635yankee]

Based on everything other shortcut, they probably used WiFi for communication from inside to outside.

Regards,

Through a conductive pressure hull surrounded by a very effective connection to ground? While it does match the use of a game controller, he probably used holes molded into the CRP cylinder.

Of course molded holes in composites are not a good idea, as tempting as they may seem.

 

[patryk]

That's what I meant. The thrusters are mounted to that outer wrap, which I think just attaches to the titanium rings at the end of the pressure hull. I just thought it was fiberglass.

Oops, sorry, I misunderstood you. I thought the "fiberglass" was a reference to the composite PV.

I’m still trying to figure out where the batteries were. This is a weird design.

Source: https://www.cbc.ca/player/play/2232048195658 (around 1:04)
Searching for 'Ict SUB' brings:

Source: http://www.ictineu.net/productes/battery/

Of course this is only a guess, but that orange casing looks similar to what is visible in the aft portion of the sub (the picture I shared earlier).

There seem to be 2 or 4 of these:

Source:

View: https://youtu.be/jZ6AJTYzBmw?t=104

 

[edwest4]

https://www.cbc.ca/news/canada/newfoundland-labrador/titan-horizon-arctic-missing-submersible-wreckage-titanic-1.6891003

 

[Halcyon66]

Well looks like the first issue is that there seems to be nothing in the viewing port?

Some more images,

https://edition.cnn.com/2023/06/28/americas/titan-submersible-debris-st-johns/index.html

Regards,

 

[aim9xray]

Would imagine that the viewing port was blown outwards by the initial pressure pulse from the hull implosion. Note that the viewport mounting is designed to resist massive inward pressure, outward - not so much. Death by compression and defenestration?

 

[Scott Kenny]

Would imagine that the viewing port was blown outwards by the initial pressure pulse from the hull implosion. Note that the viewport mounting is designed to resist massive inward pressure, outward - not so much. Death by compression and defenestration?

Still could have collapsed inward, it's not like the window wasn't under 3x the pressure it was rated at...

 

[aonestudio]

https://twitter.com/x/status/1674185468580118529

View: https://twitter.com/rawsalerts/status/1674185468580118529

 

[Orionblamblam]

Death by compression and defenestration?

The remains were reportedly found *within* the wreckage, so at least a meaningful portion of them didn't get shot out. Still, I imagine that what they got looks a lot like the results of the Byford Dolphin... just worse.

 

[Scott Kenny]

Death by compression and defenestration?

The remains were reportedly found *within* the wreckage, so at least a meaningful portion of them didn't get shot out. Still, I imagine that what they got looks a lot like the results of the Byford Dolphin... just worse.

I'm not expecting much "remains" to be found so much as "cremains"...

 

[Yellow Palace]

Europa's possible ocean is estimated to be 100-200km deep. Despite the great depth of the Europa's ocean, hydrostatic pressure at the seafloor would be 130-260 MPa, corresponding to 13-26 km depth of a theoretical Earth's ocean. The hydrostatic pressure is not beyond the edge of existing deep-sea technology.

FWIW, the TRIESTE's pressure sphere was designed for a collapse depth of 60,000 feet, which would be insufficient for Europa's oceans given a factor of safety. Under some design codes, it would actually be insufficient for the Challenger Deep!

The contemporary French bathyscape ARCHIMEDE had a pressure sphere with a design collapse depth of 100,000 feet. Depending on the design codes used, that would be sufficient for the shallower range of possible depths. As far as I can tell, ARCHIMEDE never went deeper than 31,350 feet (in the Kuril-Kamchatka Trench - an odd place for the French Navy to go diving!) but was theoretically capable of reaching Challenger Deep.

When looking at the weights of bathyscaphes, detail is important - the figure usually listed is the 'dry' weight before the buoyancy tanks are filled. In the case of the TRIESTE, the dry weight is apparently 50 (long) tons, but that doesn't include 29,000 US gallons of aviation fuel - bringing the surfaced displacement up to about 134 tons. The equivalent figures for ARCHIMEDE are 61 tons and 192 tons. TRIESTE II had a lot more buoyancy despite not being as deep diving - it had a remarkable amount of payload capacity.

 

[martinbayer]

Death by compression and defenestration?

The British have the perfect and almost poetic terminus technicus to accurately describe what happened there - death by misadventure.

 

[Foo Fighter]

Death by Darwinianism.

 

[martinbayer]

Death by Darwinianism.

Now where's that annual prize award, I say!

 

[Archibald]

Death by Darwinianism.

Now where's that annual prize award, I say!

Stockton truly deserves both - Darwin award and IG-Nobel. Posthumously. It will be sooo inspirational, his legacy will live forever, through these two prices... rest in peace, aptly named Mr Rush. Although you should have been named Stockton Botched...

 

[publiusr]

He probably thought that— in the same way New Space upset steely eyed missile men—that he could do the same with submariners.

 

[robunos]

He probably thought that— in the same way New Space upset steely eyed missile men—that he could do the same with submariners.

Thing is, for the most part, space vehicles are unmanned, so when they fail, the only thing lost is money . . .

cheers,
Robin.

 

[publiusr]

Now with EAA, I understand a free hand.
With subs—you don’t play around—at all.

Space somewhere in the middle?

 

[Scott Kenny]

Now with EAA, I understand a free hand.
With subs—you don’t play around—at all.

Space somewhere in the middle?

Manned space flight is less tolerant of idiots and errors than subs are, mostly due to a lack of people to second check your work.

 

[publiusr]

True—but the pressure differential is closer to aviation…and most launches unmanned.

Musk shook up steely eyed missile men.
…but submariners are something else again.

A walk around isn’t enough for a launch…but you usually don’t have nukes atop rockets either.

 

[martinbayer]

I've heard that the Titanic's wreck has decayed a surprising amount since its discovery. I've got to wonder how much ROVs prodding at it or now poorly designed submersibles imploding nearby have contributed to that.

Titanic was dissolving away when first discovered; it's time as a recognizable "wreck" is limited no matter what anyone does. And if the wreckage of the sub is 1600 feet away, it seems like it wasn't that close when it imploded.

Right on - following the perverse logic of "don't touch the Titanic", the WTC site should just have been left a colossal pile of rubble post 9/11.

 

[martinbayer]

The Open Water SCUBA certification was meant as a joke

If that's true, the fact that they thought joking about their operations was acceptable alone is revealing.

 

[Hobbes]

Musk shook up steely eyed missile men.
…but submariners are something else again.

The Falcon 1 and 9 are very conventional designs, using an engine type common in the industry, construction techniques common in the industry etc.
Musk shook up the industry in several ways:
- he changed the approach to logistics: he is manufacturing parts in-house instead of relying on external suppliers. This drove the manufacturing cost down.
- he found a way to land and reuse the first stage that nobody had considered. The hopper tests proved the fundamentals, and then they were able to switch to testing during regular missions. They realized that at that point, it didn't matter if a test failed: the main mission (getting a satellite to orbit) was already a success, and anything that happened during the landing was useful data, whether the rocket landed or crashed. So they crashed a dozen rockets without it costing them a lot.

Similarly, for Starship, Musk makes changes that are well-supported by a solid understanding of the fundamentals, and backed up by extensive testing. As an example: the initial plan was to use carbon fibre. They built a massive tank and tested it, and based on those test results they scrapped the whole project and started again in a different material, again testing extensively as they built knowledge from the ground up.

OceanGate, by contrast, were just handwaving well-known risks. They didn't test their pressure hull design (there are facilities where you can test at full ocean depth). They deliberately ignored warnings from people with experience in deep-sea operations.

 

[martinbayer]

I agree with most of Hobbes' statements above, with the exception of Musk's approach way to land and reuse the first stage - that was by no means something that "nobody had considered" before, but had been in fact been repeatedly and successfully demonstrated by the DC-X(A).