Titanic submersible

[gerry maddenParticipant @gerrymadden53711]

Posted by Roger Williams 2 on 23/06/2023 09:39:05:

The sub would implode at something like 2200 ft per second and the poor souls would be incinerated and turned to dust in about a millisecond , which is a lot quicker than you can blink your eye !!. The human brain would react to this in something like 150 milliseconds. Jesus..

Roger, an interesting comment. I'm not disputing that the collapse would be very fast indeed, but where does the figure of 2200 ft/sec come from ? I guess there is some simple hydrodynamic theory related to the inward acceleration of the surrounding fluid under a hydrostatic pressure into a void, but can you give me a little more of a lead please ? Thinking about, it I suppose its cavitation theory… ?

Gerry

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, Robert Atkinson 2 taking about imploding TV screens, which I also did a few, stand back and throw a brick at the point where the cathode ray tube meets the back of the screen, and if you get it right you get a pop and the cathode ray tube and any splinters of glass get sucked in.

Regards Nick.

Edited By Nicholas Farr on 23/06/2023 12:08:59

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 23/06/2023 11:52:57:

[…] One the domes was fitted with an Acrylic Window, which maybe doubled as a hatch […]

.

With the greatest respect, Dave … Given the dimensions of the Window, I think that ^^^ is highly unlikely.

In the words of Stockton Rush : 

“It is seven inches thick and weighs about 80lbs. When we go to the titanic it will squeeze in about three-quarters of an inch and just deforms.

“Acrylic is great because before it cracks or fails it starts to crackle so you get a huge warning if it’s about to fail.”

[ my emboldening ]

MichaelG.

Edited By Michael Gilligan on 23/06/2023 12:57:21

[HopperParticipant @hopper]

I think Dave is right. My understanding, from multiple reports, is there is only one way in and out of the vessel. That is via the forward hatch, which includes the sole window. It is bolted on from the outside after the crew are aboard.

So there were concerns that even if they emergency surfaced, they could bob about in the Atlantic unfound and run out of air because they could not open the hatch from the inside. And if they did, the water would come in and flood the vessel anyway. That is the reason submarines have conning towers sticking up well above the waterline.

It is not a unique idea. IIRC the original space "capsule" in which the Apollo astronauts etc plopped into the ocean after their return to Earth had a similar exit hatch bolted from the outside. But it had exploding heads on the bolts that presumably could be triggered from the inside if need be to allow emergency escape if things went pear shaped.

When you read Tom Wolfe's book "The Right Stuff" (NOT the movie) about the US space program in its early days, it sounds like it was almost as basic as Titan in its own way. To 'win' the space race, the Yanks in effect stuck a Spam can on the nose of a very large ballistic missile, sealed a couple of blokes up in it and fired it into space, with a parachute to bring them back down.

But the pressure differentials on a space craft between the 14.7 psi or so inside and the zero or so outside are chicken feed compared with Titan's operating conditions.

Edited By Hopper on 23/06/2023 13:22:33

[JAParticipant @ja]

Posted by gerry madden on 23/06/2023 12:04:35:

Posted by Roger Williams 2 on 23/06/2023 09:39:05:

The sub would implode at something like 2200 ft per second and the poor souls would be incinerated and turned to dust in about a millisecond , which is a lot quicker than you can blink your eye !!. The human brain would react to this in something like 150 milliseconds. Jesus..

Roger, an interesting comment. I'm not disputing that the collapse would be very fast indeed, but where does the figure of 2200 ft/sec come from ? I guess there is some simple hydrodynamic theory related to the inward acceleration of the surrounding fluid under a hydrostatic pressure into a void, but can you give me a little more of a lead please ? Thinking about, it I suppose its cavitation theory… ?

Gerry

I wondered where this velocity came from, perhaps the detonation velocity of a low powered high explosive.

Theorising about the gas dynamics of such a compression: It would be adiabatic at the start at least but I doubt if the air would remain a perfect gas for long.

All this is irrelevant, if the pressure difference between the outside and inside of you body is suddenly 6000 psi you are DEAD.

JA

Just read Hopper’s comments about American engineering – Agreed, from my own experience.

Edited By JA on 23/06/2023 13:28:22

Edited By JA on 23/06/2023 13:30:08

[HopperParticipant @hopper]

The Guardian (see, I don't just read the red tops) quoted Professor Stefano Brizzolara, the co-director of Virginia Tech Center for Marine Autonomy and Robotics  saying the water would enter the imploding vessel at 1,000kmh. No mention of where he got that figure from though. Still bloody fast. I think he said it would be all over in 20 milliseconds. Faster than the message "Darn" could get to the brain.

Edited By Hopper on 23/06/2023 13:34:39

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Hopper on 23/06/2023 13:17:52:

I think Dave is right. My understanding, from multiple reports, is there is only one way in and out of the vessel. That is via the forward hatch, which includes the sole window. It is bolted on from the outside after the crew are aboard.

[…]

.

In that case, we’re all on the same page, and I simply mis-interpreted Dave’s words:

an Acrylic Window, which maybe doubled as a hatch

Life is full of these little ambiguities

MichaelG.

[HopperParticipant @hopper]

Posted by JA on 23/06/2023 13:20:51:

…

Just read Hopper’s comments about American engineering – Agreed, from my own experience.

The Harley-Davidson school of philosophy.

[HopperParticipant @hopper]

Posted by Michael Gilligan on 23/06/2023 13:33:32:

Posted by Hopper on 23/06/2023 13:17:52:

I think Dave is right. My understanding, from multiple reports, is there is only one way in and out of the vessel. That is via the forward hatch, which includes the sole window. It is bolted on from the outside after the crew are aboard.

[…]

.

In that case, we’re all on the same page, and I simply mis-interpreted Dave’s words:

an Acrylic Window, which maybe doubled as a hatch

Life is full of these little ambiguities

MichaelG.

Indeed. And the bit my learned friend Michael quoted about said window " will squeeze in about three-quarters of an inch and just deforms" raises another big question mark about repeated fatigue cycles etc.

I don;t know that I would want to trust my life to "Acrylic is great because before it cracks or fails it starts to crackle so you get a huge warning if it’s about to fail.” Huge enough to get back to the surface from 3800 metres? I'd rather not find out.

Seems a rather cavalier attitude in a rather critical environment.

Edited By Hopper on 23/06/2023 14:14:51

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Hopper on 23/06/2023 13:45:48:

Posted by Michael Gilligan on 23/06/2023 13:33:32:

[…]

Life is full of these little ambiguities

MichaelG.

Indeed. And the bit Dave quoted about said window […]

.

Could we make that “the bit Michael quoted” please

MichaelG.

[mike TParticipant @miket56243]

Posted by Hopper on 23/06/2023 13:45:48:

Posted by Michael Gilligan on 23/06/2023 13:33:32:

Posted by Hopper on 23/06/2023 13:17:52:

I think Dave is right. My understanding, from multiple reports, is there is only one way in and out of the vessel. That is via the forward hatch, which includes the sole window. It is bolted on from the outside after the crew are aboard.

[…]

.

In that case, we’re all on the same page, and I simply mis-interpreted Dave’s words:

an Acrylic Window, which maybe doubled as a hatch

Life is full of these little ambiguities

MichaelG.

Indeed. And the bit Dave quoted about said window " will squeeze in about three-quarters of an inch and just deforms" raises another big question mark about repeated fatigue cycles etc.

I don;t know that I would want to trust my life to "Acrylic is great because before it cracks or fails it starts to crackle so you get a huge warning if it’s about to fail.” Huge enough to get back to the surface from 3800 metres? I'd rather not find out.

Seems a rather cavalier attitude in a rather critical environment.

Especially so, when the manufacture of the acrylic viewport would only certify the viewport to a depth of 1,300 metres. Despite the manufactures depth limitation, Oceangate saw fit to use it on Titan operating at a depth of 3,800 metres. The acrylic viewport manufacture offered to redesign the viewport for the full depth rating… at extra cost… but Oceangate declined the offer.

[HopperParticipant @hopper]

Posted by Michael Gilligan on 23/06/2023 14:06:58:

Posted by Hopper on 23/06/2023 13:45:48:

Posted by Michael Gilligan on 23/06/2023 13:33:32:

[…]

Life is full of these little ambiguities

MichaelG.

Indeed. And the bit Dave quoted about said window […]

.

Could we make that “the bit Michael quoted” please

MichaelG.

Yeah we can do that. Sorry, I am/was totally confused. Situation normal.

Edited By Hopper on 23/06/2023 14:21:34

[HopperParticipant @hopper]

Posted by mike T on 23/06/2023 14:08:21:…

…

Especially so, when the manufacture of the acrylic viewport would only certify the viewport to a depth of 1,300 metres. Despite the manufactures depth limitation, Oceangate saw fit to use it on Titan operating at a depth of 3,800 metres. The acrylic viewport manufacture offered to redesign the viewport for the full depth rating… at extra cost… but Oceangate declined the offer.

Oww. That is nasty. Well beyond cavalier. I think the enquiry into this accident is going to be some interesting reading.

Re the question raised earlier of who will run the enquiry, latest speculation seems to be the US Coast Guard have been the lead agency so far and will probably continue to do so through the enquiry stage. All a bit uncertain though due to international waters, multiple countries involved, convention that the port the vessel sailed from does the enquiry which in this case would be Canada and so forth.

[JAParticipant @ja]

Reading the news reports there are a lot of persons saying they had serious doubts about the design of the vessel before it was first used. Some of these may just be being wise after the event but there is a very telling quote from James Cameron who has a working submersible:

"I thought it was a horrible idea. I wish I’d spoken up, but I assumed somebody was smarter than me, you know, because I never experimented with that technology, but it just sounded bad on its face".

I worked in an industry that had been dominated by the blame game, litigation and all the rest. Since the late 1960s under the industrial safety law in the UK one had to report anything you thought unsafe to your manager etc. who did very little. This fertilsed a "turn the blind eye" culture. So much so that the industry introduced a "no blame culture" and lesson learnt logs. Everyone, at all employment levels, was encouraged to report anything he/she thought unsafe from the use of a ladder to the design of a critical engine part. This included failures in service. Such reports were taken very seriously all the way up the company management structure with person making the report being kept in the loop. It worked very well, even James Cameron's comments would have been dealt in such a manner. I guess that all this does not apply to cowboys businesses. Why have cowboys got such a bad name…….

JA

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Hopper on 23/06/2023 14:13:41:

Posted by Michael Gilligan on 23/06/2023 14:06:58:

Could we make that “the bit Michael quoted” please

MichaelG.

Yeah we can do that. Sorry, I am/was totally confused. Situation normal.

.

Thanks, Hopper

… I see you actually managed to edit the post before the window of opportunity closed

… nicely done.

MichaelG.

[Roger Williams 2Participant @rogerwilliams2]

JA , got the information from a post from another forum , an article by David Corley , a former nuclear powerered submarine officer .

[Michael GilliganParticipant @michaelgilligan61133]

 

Rewind to 2018

This is more detail than I have seen before: **LINK**

https://www.compositesworld.com/news/oceangate-ceo-pilots-carbon-fiber-submersible-in-4000-m-solo-dive

… and that’s a lot of filament-wound carbon !!

MichaelG.

.

Edit: __ and this might be the most unfortunate piece of wishful thinking:

The RTM system is used to assess the health of the hull throughout every dive. The system uses acoustic sensors to detect sounds emitted by the carbon fiber material as it responds to the external pressure and also employs strain gauges to measure the physical deflection. The system makes it possible for Titan pilots to predict a potential failure, stop the descent and safely return to the surface.

 

Edited By Michael Gilligan on 23/06/2023 16:08:01

[JAParticipant @ja]

Posted by Roger Williams 2 on 23/06/2023 16:01:39:

JA , got the information from a post from another forum , an article by David Corley , a former nuclear powerered submarine officer .

Thanks. I wonder if my chief engineer would have accepted that.

There is experience, I think, on what happens to a nuclear reactor during or after the catastrophic implosion of a submarine hull. How many nuclear submarines did the Soviets lose.

JA

or, perhaps, does not happen, …..

Edited By JA on 23/06/2023 17:47:32

[BufferParticipant @buffer]

There was a bit of a difference in the response between lunatic billionaires going down in a homemade sub and 750 migrants in a Greek fishing boat with a reported 100 kids in the hold. This is the thing that I find most maddening.

[larry phelan 1Participant @larryphelan1]

As long as you can walk to them.

[duncan webster 1Participant @duncanwebster1]

Posted by Michael Gilligan on 23/06/2023 12:49:45:

Posted by SillyOldDuffer on 23/06/2023 11:52:57:

[…] One the domes was fitted with an Acrylic Window, which maybe doubled as a hatch […]

.

With the greatest respect, Dave … Given the dimensions of the Window, I think that ^^^ is highly unlikely.

In the words of Stockton Rush :

“It is seven inches thick and weighs about 80lbs. When we go to the titanic it will squeeze in about three-quarters of an inch and just deforms.

“Acrylic is great because before it cracks or fails it starts to crackle so you get a huge warning if it’s about to fail.”

[ my emboldening ]

MichaelG.

Edited By Michael Gilligan on 23/06/2023 12:57:21

According to the interweb the density of acrylic is 0.43 lb/in^3, so if it's 7" thick and weighs 80 lbs, a plain disc would be 18.4" diameter. The hole in the titanium end dome would have to be smaller to provide an abutment, so unless they have very slim passengers there must be another way in.

[SteviegtrParticipant @steviegtr]

Well anything on this earth that is going to take any type of strain requires to be Loyds tested. Whatever it is there is a requirement for it to take 1.5 times & sometimes twice it's expected load. Weight, pressure electric etc. This thing as far as I can see was never tested at all.

Apart from in a swimming pool. There whole assets need stripping & given to the poor souls families.

Steve.

[mike TParticipant @miket56243]

Well, The Lloyds Register requirement for a pressure hull for manned occupation (i.e. a manned submersible hull) MUST be designed with a Safety factor of FIVE. By contrast, an un-manned hull only requires to be designed with a SF of THREE. Fully certified and tested submersible hulls are therefore immensely strong. Different design SF are applied to other classes of marine equipment

Edited By mike T on 23/06/2023 23:39:26

[SamsarandaParticipant @samsaranda]

Duncan

The entrance into the submersible was via the titanium end cover which had the acrylic window embedded in it, the titanium end cover, as far as I can see, was about the same diameter as the carbon fibre body of the submersible and was bolted to it, that is the way in by the whole titanium end cover which was then bolted into position. Dave W

[Nigel Graham 2Participant @nigelgraham2]

Well, Rush paid for his cavalier approach that seems emerging, with his life – but he took four others with him.

I am surprised he even came out with statements about using sounds from the stressed components as warning signals. Whowever conducts the enquiry and how, given the complexity, it will no doubt elicit a lot of failures.

Designing manually-operated deep-water submersibles is not in in its infancy, and nor is materials science. This was not some pioneering project, but two aspects that made Titan differ from tried and tested vehicles were its cylindrical rather than spherical accommodation (to take more passengers) and of inhomogenous construction.

.

The reference to early, manned space flights someone made further back misses the point that that was all still new engineering, but NASA did approach it properly. Also the pressure-hull comparison is wrong. A spacecraft has to hold a pressure of only 1 Bar, yes; but internally. A submersible or a submarine has to withstand 1 bar for every 10 metres depth, and externally. That difference in direction of load alone is crucial, even before you think of the pressure itself.

.

Buffer reminds us of the desperately overloaded fishing-boat sinking with all those migrants in the Mediterranean.

They have not been forgotten despite all the reporting surrounding the Titan's loss; and what we are beginning to learn about how abominably the traffickers treated their passengers, is adding even more to the horror.

I heard, but not properly, an interviewee on the radio this evening apparently asking of the possibility of recovering the vessel and the bodies. Sadly this may not be possible. I don't know in which region of it the boat sank, but much of the Mediterranean is generally over 2500m deep. My atlas gives a spot depth of 3065m in the Ionian, South of the "heel" of Italy.

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