Titanic tourist sub goes missing in Atlantic Ocean, June 2023 #4

[Interested_But_Confused]

I don't know if we have any structural engineers on here or experts in composite materials, but if we do I'd like to know a few things. I don't know much about composites, they are strong and light weight. But would repeated dives to depth weaken the structure? What is believed to have failed here, was it the carbon tube itself, or where it connected to the titanium end bowls? It was mentioned above that the sub had made this dive before so that would give him confidence that it worked. And that makes sense. But would it also be true that each successive dive might make the structure weaker?

I'm not a structural engineer but I've been interested in Titanic and the various submersibles for a long time.

Composites like carbon fiber are very strong in certain directions but much weaker (and sometimes REALLY weak) in other directions. IMO repeated dives would absolutely weaken the structure, and it's also my opinion that the carbon fiber tube is more likely to have failed than any of the joints.

Think of it like a toilet roll where the layers are wound together. If all the layers are glued together it's REALLY strong. But over time, as the layers start to split apart (delaminate), you're left with an increasingly weak and floppy tube that will eventually collapse.

IMO the problem is that Rush was trained in aerospace engineering. Composites are usually very strong in tension, which is what happens when the tube is pressurised from the inside like in a plane. But when the tube is compressed from the outside, like with a submersible, it will degrade with each compression cycle. It will start out really strong but get weaker and weaker each time.

You can take a small plane and increase the size without too much difficulty. That's the kind of engineering Rush was familiar with. But he thought he could translate that to water, taking a small submersible designed to go down just 500m and simply making it bigger with a thicker hull. He seemingly didn't realize the effects of deep water are a completely different animal to the effects of air pressure at high altitude.

I think Rush really believed he knew what he was doing, even when he was repeatedly told otherwise. And he was wrong.

 

[LinasK]

I don't know if we have any structural engineers on here or experts in composite materials, but if we do I'd like to know a few things. I don't know much about composites, they are strong and light weight. But would repeated dives to depth weaken the structure? What is believed to have failed here, was it the carbon tube itself, or where it connected to the titanium end bowls? It was mentioned above that the sub had made this dive before so that would give him confidence that it worked. And that makes sense. But would it also be true that each successive dive might make the structure weaker?

In previous articles, and speaking with my husband who is a Mechanical Engineer, the answer is YES. Successive dives DO weaken the structure of composite materials, and they are designed for expansion (air travel), not compression (diving). And my understand is that the caps popped off at the end. The window wasn't rated for the depth.

 

[Charlot123]

Problem is… those making the trip to go get such items and attempt to maintain their condition are paying an enormous price to do so. Kudos for those who are attempting to recover history before it Is completely destroyed by the ocean.

What we do know is the price is high enough that the British or American governments have not committed to pay it.

IMO who cares if the work is done by a private group and sold to a private owner? Many many traveling museum collections are funded by wealthy private owners.

JMO

But, the issue is transparency vs corruption.

Imagine this: a big museum that has been founded by donations from private owners or their children has Shagal. But, say, wants to buy Leonardo. Or even easier: the museum has Malevich's 4th variation of the black square.

If the museum decides to sell Malevich to fund purchase of Leonardo, should they at least notify the donors, or not? I know, big wealthy donors means, tax-deductions and all, but not every donor is that wealthy. And, the cost of old masterpieces is going up not down.

I think it can not be done behind the backs of the citizens.

 

[Odeto BJ]

I don't know if we have any structural engineers on here or experts in composite materials, but if we do I'd like to know a few things. I don't know much about composites, they are strong and light weight. But would repeated dives to depth weaken the structure? What is believed to have failed here, was it the carbon tube itself, or where it connected to the titanium end bowls? It was mentioned above that the sub had made this dive before so that would give him confidence that it worked. And that makes sense. But would it also be true that each successive dive might make the structure weaker?

Somebody asked an engineer....

A large scale cylinder pressurized from the inside, will first bulge and eventually split and burst outward. All these are tensile mechanisms and ductile materials will stretch quite a bit prior to the wholesale failure (as opposed to brittle materials which will tend to crack and then shatter, very shortly thereafter.)

A large scale composite cylinder with pressure applied to the outside fails due to buckling as it collapses. Skinny columns in a building withstand compressive forces to a certain point but immediately when the load gets too great or is off-center to any extent, they buckle and loose a large portion of their rigidity....Once buckling starts, it will tend to progress very readily. Think of a fishing rod: If you try to pull it apart, it takes a huge force but if you stand it on the handle end and bear down on the skinny end it will buckle readily and at a pretty low applied force. Most of the flexing will occur at the skinny end and if it happens to be a 2-section rod and you apply a similar effort to the handle section, it will take a whole lot more force to create buckling on the bigger diameter, shorter member than it did the full length rod.

Fishing rods are made with carbon fiber today, but that composite is adhered and spun under pretty tightly controlled manufacturing techniques; the best of them are made inside vacuum chambers to eliminate pockets of air as the fiber is wound around a mandrel and to minimize the entrapment of any vapor released as the bonding agents cure. Very similar for the shafts of golf clubs.

The shell of the Titan was not made with these types of manufacturing control and that left small voids and irregularities in the composite matrix. The cylinder was constrained on both ends by the very rigid titanium end bells. If the material of the cylinder were a higher quality homogeneous material (like titanium plate) the mathematics is fairly well established. Carbon fiber formed to this scale and in the fashion shown in some of the videos above is not going to be homogeneous and has an entirely different ultimate stress in tension than it does in compression. That was compounded by the discontinuities: they represent pockets where stresses were concentrated as well as sites where the history of pressurization cycles and the effects of towing over a rough ocean or running the vehicle into an obstruction would cause residual stresses and in worst cases localized cracking. If you have ever gotten under the hull of an old fiberglass boat, you will see the effects of localized stress concentrations: the surface, once near-glass smooth is covered in little pock marks, overall rough and may even have fibers projecting through the surface. That hull is simply not as strong or as tolerant of passing through water at high speed, compared to when it was new.

Note the thickness of the flanges and the count of bolts around the flange ring on these vacuum pots: and the external pressure here is atmospheric, less than 15 PSI. Also see Page 114 the PDF and the lower left diagram: that is the "flexed" shape of a cylinder with external pressure applied and end caps that are greatly more rigid than the cylinder body. (restrained end faces). The mathematics is somewhat involved: But the ratio of diameter to length is highly determinant, a long skinny vessel is much more prone to collapse from external pressure. For internal pressure, length is not a player in the stress equations: only the diameter and thickness.

 

[somequestions]

When describing the acrylic window of the submersible, Titan, Oceangate CEO Stockton Rush said that if it started to fail there would be many spider cracks that would form giving you notice that it was going to fail. But if it fails when you are an hour and a half into the dive, wouldn't people be nervously on edge waiting for an hour and a half to get back to the surface while hoping the acrylic window does not fail completely? This is hard to understand why someone who is an engineer would think this way. I suppose this is what submersible operator, Karl Stanley, meant when he described Stockton Rush as having a death wish.

In the clip below, I completely agree with Rob McCallum about CEO Stockton Rush and Oceangate's safety culture. Once you know the whole story about safety, it is surprising how many people tried to warn CEO Stockton Rush and Oceangate. When the investigation is over, it will be interesting to find out what caused the implosion. The implosion really was an accident waiting to happen.

 

[ilovewings]

When describing the acrylic window of the submersible, Titan, Oceangate CEO Stockton Rush said that if it started to fail there would be many spider cracks that would form giving you notice that it was going to fail. But if it fails when you are an hour and a half into the dive, wouldn't people be nervously on edge waiting for an hour and a half to get back to the surface while hoping the acrylic window does not fail completely? This is hard to understand why someone who is an engineer would think this way. I suppose this is what submersible operator, Karl Stanley, meant when he described Stockton Rush as having a death wish.

In the clip below, I completely agree with Rob McCallum about CEO Stockton Rush and Oceangate's safety culture. Once you know the whole story about safety, it is surprising how many people tried to warn CEO Stockton Rush and Oceangate. When the investigation is over, it will be interesting to find out what caused the implosion. The implosion really was an accident waiting to happen.

It was a ticking time bomb

 

[Interested_But_Confused]

I think it's important to note that a lack of certification doesn't automatically mean something isn't safe. In many cases something that hasn't been certified is perfectly safe: it simply hasn't been tested to make sure. A good engineer can often design a safe product on the first try. They don't need to test and certify it to be sure it works. But they have it certified because that's what a good engineer is supposed to do.

The acrylic view port was only rated to 4,000ft because that's the depth of testing Rush was willing to pay for. Greater depth testing would have been hugely expensive. It's entirely possible the view port was safe at 12,500ft and had absolutely nothing to do with the implosion. But because it was never properly tested, taking it down to Titanic was basically a coin toss.

Rush's hubris (or self-delusion about his abilities) seems to be at the heart of this.

 

[ilovewings]

I think it's important to note that a lack of certification doesn't automatically mean something isn't safe. In many cases something that hasn't been certified is perfectly safe: it simply hasn't been tested to make sure. A good engineer can often design a safe product on the first try. They don't need to test and certify it to be sure it works. But they have it certified because that's what a good engineer is supposed to do.

The acrylic view port was only rated to 4,000ft because that's the depth of testing Rush was willing to pay for. Greater depth testing would have been hugely expensive. It's entirely possible the view port was safe at 12,500ft and had absolutely nothing to do with the implosion. But because it was never properly tested, taking it down to Titanic was basically a coin toss.

Rush's hubris (or self-delusion about his abilities) seems to be at the heart of this.

The sad part is that he took gullible wealthy people with him to their deaths.

 

[PrairieWind]

The sad part is that he took gullible wealthy people with him to their deaths.

It would be interesting to know how that played out. I would assume these extremely wealthy clients would have checked into the safety. These were pretty smart people. Did they really just take Rush's word? And what about Paul Henri Nargeolet? He should have known. Had he been down on Titan previously? I can't remember.

 

[Interested_But_Confused]

Some "crew members" such as the young son may not have known exactly what they were getting into. But I think many people are willing to take a risk to achieve a dream. Even knowing the risks they may have been willing to take them. Given his comments in previous interviews, I think that's how P.H. Nargeolet felt about being at the bottom of the ocean--it's where he wanted to be, and he was completely comfortable with never coming back to the surface.

And TBH, I think Titan would have been fairly safe when the carbon fiber tube was brand new. If they had completely replaced the tube after every dive an accident like this probably wouldn't have happened.

 

[ilovewings]

Some "crew members" such as the young son may not have known exactly what they were getting into. But I think many people are willing to take a risk to achieve a dream. Even knowing the risks they may have been willing to take them. Given his comments in previous interviews, I think that's how P.H. Nargeolet felt about being at the bottom of the ocean--it's where he wanted to be, and he was completely comfortable with never coming back to the surface.

And TBH, I think Titan would have been fairly safe when the carbon fiber tube was brand new. If they had completely replaced the tube after every dive an accident like this probably wouldn't have happened.

I'm not sure Mr. Nargeolet was ready to croak just yet!
I believe if people thought they could really die they would not have gone --
sure they read a form which gave some info about the risk of the Titan, but I believe they really thought they would be just fine- I believe Mr. Nargeolet had been on the Titan previously, though I am not sure about that. I think they trusted Stockton Rush---a fatal mistake.

 

[PrairieWind]

Some "crew members" such as the young son may not have known exactly what they were getting into. But I think many people are willing to take a risk to achieve a dream. Even knowing the risks they may have been willing to take them. Given his comments in previous interviews, I think that's how P.H. Nargeolet felt about being at the bottom of the ocean--it's where he wanted to be, and he was completely comfortable with never coming back to the surface.

And TBH, I think Titan would have been fairly safe when the carbon fiber tube was brand new. If they had completely replaced the tube after every dive an accident like this probably wouldn't have happened.

I don't know that anyone would be willing to pay for it, but it would be very interesting to see a lot of testing done on additional titan subs to see how they responded to multiple dives, etc.

 

[Interested_But_Confused]

I'm not sure Mr. Nargeolet was ready to croak just yet!
I believe if people thought they could really die they would not have gone --
sure they read a form which gave some info about the risk of the Titan, but I believe they really thought they would be just fine- I believe Mr. Nargeolet had been on the Titan previously, though I am not sure about that. I think they trusted Stockton Rush---a fatal mistake.

Titanic wreck diver Paul Henri Nargeolet: 'In deep water, you’re dead before you realise it's happening'

In this 2019 interview, Paul Henri Nargeolet — who is on board a submarine that has gone missing during a tour of the Titanic's wreckage — tells Ellie O’Byrne about the joys and controversies of his work, ahead of a talk about his work in Cork, where his family lives.

www.irishexaminer.com

Paul Henri Nargeolet is matter-of-fact - nay even jolly - when discussing the risks associated with his work.

“If you are 11m or 11km down, if something bad happens, the result is the same,” the 73-year-old former French Naval Captain says, chuckling merrily. “When you’re in very deep water, you’re dead before you realise that something is happening, so it’s just not a problem.”

Paul Henri’s mirth comes from a question that may seem silly to him, but which is completely normal for those of us unused to exploring the deepest parts of the planet’s oceans: Isn’t he ever scared down there?

 

[BeachSky]

Some "crew members" such as the young son may not have known exactly what they were getting into. But I think many people are willing to take a risk to achieve a dream. Even knowing the risks they may have been willing to take them. Given his comments in previous interviews, I think that's how P.H. Nargeolet felt about being at the bottom of the ocean--it's where he wanted to be, and he was completely comfortable with never coming back to the surface.

And TBH, I think Titan would have been fairly safe when the carbon fiber tube was brand new. If they had completely replaced the tube after every dive an accident like this probably wouldn't have happened.

BBM
The young son was terrified. Evidently his intuition was strong enough to share that fact with the Aunt. Hauntingly tragic IMO.

Teen On Titan Sub Was 'Terrified' But Agreed To Dive For Father's Day, Aunt Says

Suleman Dawood, 19, "wasn't very up for" the expedition, according to aunt Azmeh Dawood.

news.yahoo.com

 

[ifindedout]

BBM
The young son was terrified. Evidently his intuition was strong enough to share that fact with the Aunt. Hauntingly tragic IMO.

Teen On Titan Sub Was 'Terrified' But Agreed To Dive For Father's Day, Aunt Says

Suleman Dawood, 19, "wasn't very up for" the expedition, according to aunt Azmeh Dawood.

news.yahoo.com

This was contradicted by his mom a few days later. He wanted to go--so much so that she, who was originally supposed to accompany her husband, gave up her seat so that the son could solve Rubik's Cube at depth.

Teenager on sub took Rubik's Cube to break record, mother tells BBC

Christine Dawood told the BBC she lost hope of her son being found alive when the 96-hour mark passed.

www.bbc.com

In her first interview, Mrs Dawood said she had planned to go with her husband to view the wreck of the Titanic, but the trip was cancelled because of the Covid pandemic.

"Then I stepped back and gave them space to set [Suleman] up, because he really wanted to go," she said.

[...]

Speaking of her son, Mrs Dawood said Suleman loved the Rubik's Cube so much that he carried it with him everywhere, dazzling onlookers by solving the complex puzzle in 12 seconds.

"He said, 'I'm going to solve the Rubik's Cube 3,700 metres below sea at the Titanic'."

 

[somequestions]

Some "crew members" such as the young son may not have known exactly what they were getting into. But I think many people are willing to take a risk to achieve a dream. Even knowing the risks they may have been willing to take them. Given his comments in previous interviews, I think that's how P.H. Nargeolet felt about being at the bottom of the ocean--it's where he wanted to be, and he was completely comfortable with never coming back to the surface.

And TBH, I think Titan would have been fairly safe when the carbon fiber tube was brand new. If they had completely replaced the tube after every dive an accident like this probably wouldn't have happened.

I would not have gone even once if the carbon fiber hull was brand new. If I knew about the many emails, phone calls, the firing of the test engineer pilot Lockridge, and the numerous warnings Rush had received, I would have passed. If I somehow knew about submersible engineering design as knowledge or as my profession, I would also have passed. Many of the dates on this safety communication to Stockton Rush was 4 or 5 years before the accident.

I understand someone needs to be inside the sub to pilot and test it, but as Rob McCallum said, the game changes when you take passengers because you cannot really consent to something you know very little or nothing about.

Maybe though, after 4 or 5 years, when nothing bad happened, even the people that warned him might even have thought they were overreacting to the safety warnings? I do not know what those people were thinking though.

When the investigation team is finished, it will be interesting to find out if they figured out what caused the implosion. Hopefully 60 Minutes or another news program does a follow up report when the investigation is complete.

 

[Charlot123]

Someone has to say it.

- Rush was educated, but not too bright, sorry. JMO. Great education, but if your brain is not made to grasp physics, you don't get it. He might have known it all along from Princeton and then, all his behaviour was aimed at hypercompensation. His vindictiveness probably has the same roots as well.

- or else, he simply suffered from delusions of grandeur. Of course students working for him might have not noticed it, but the fact that there was no peer, and when he hired one, he ended up firing the man and later tried his hardest to ruin the man's life - is telling.

In science or industry, inadequate brains should be weeded out. But Stockton ended up, essentially, working alone, being own boss and making own decisions.

 

[PrairieWind]

Someone has to say it.

- Rush was educated, but not too bright, sorry. JMO. Great education, but if your brain is not made to grasp physics, you don't get it. He might have known it all along from Princeton and then, all his behaviour was aimed at hypercompensation. His vindictiveness probably has the same roots as well.

- or else, he simply suffered from delusions of grandeur. Of course students working for him might have not noticed it, but the fact that there was no peer, and when he hired one, he ended up firing the man and later tried his hardest to ruin the man's life - is telling.

In science or industry, inadequate brains should be weeded out. But Stockton ended up, essentially, working alone, being own boss and making own decisions.

I guess I wouldn't agree with this, at least from what I know so far. I understood he was extremely bright, just reckless. What kind of grades did he get in college? I don't think we should "weed out inadequate brains" in science and industry. We live in a free world (hopefully). He shouldn't get a pass on grades and licensing requirements of course, but he is free to choose his own course in life. Should he have been putting people in this sub? No, that seems clear. It needed testing, revisions, improvements, etc. But I don't blame him for thinking outside the box with his concept.

 

[Odeto BJ]

I don't know that anyone would be willing to pay for it, but it would be very interesting to see a lot of testing done on additional titan subs to see how they responded to multiple dives, etc.

I don't think we should "weed out inadequate brains" in science and industry. We live in a free world (hopefully). He shouldn't get a pass on grades and licensing requirements of course, but he is free to choose his own course in life. Should he have been putting people in this sub? No, that seems clear. It needed testing, revisions, improvements, etc. But I don't blame him for thinking outside the box with his concept.

Agreed. Especially the portion about passengers. I would add: The manufacturing control would have to get a lot better than what was employed here, or one vessel would perform entirely differently than the next, even if nominally the same. And when you start with "expired" materials....
From limited exposure, I characterize SR as a self-serving promoter, prone to aggrandizement, charging down a singular path without complete comprehension. That may work where things can be tested under the exact conditions of service all the way to disablement or destruction. Considering the materials, the final assembly techniques, the environment, the basic intention to fill the cabin space, and the criticality....that sort of proofing would take a long time and a lot of reps.
Engineers don't expect other engineers to make decisions for them, but they do need lots of contacts to source information, establish QC and repeatability and operability/performance requirements and review specific techniques of fabrication, assembly and manufacture. As an entrepreneur pursuing a business model, SR ignored the advice of his peers and those with similar goals and experiences. He then frameworked his own schedule and marketing effort; and fired his QC. Listen to the interviews with his prior partner: both his anecdotal content and his worshipful endorsement. Blind faith.

SR unfortunately was victim of his own hubris. His fate would never have made more than a couple lines of media if not for the passengers and their own pursuit of singular experience.

All that was missing was a wagon full of bottles labelled: Snake Oil.

MOO throughout.

 

[Charlot123]

I guess I wouldn't agree with this, at least from what I know so far. I understood he was extremely bright, just reckless. What kind of grades did he get in college? I don't think we should "weed out inadequate brains" in science and industry. We live in a free world (hopefully). He shouldn't get a pass on grades and licensing requirements of course, but he is free to choose his own course in life. Should he have been putting people in this sub? No, that seems clear. It needed testing, revisions, improvements, etc. But I don't blame him for thinking outside the box with his concept.

I am no physicist, but there is a reason why physics of the ocean and aerophysics are two different areas. The forces acting on the objects inside two media with different densities would be very different. And the truth is, Rush could probably deceive everyone, people working for him, investors, Nargeolet, the passengers and us, gullible public. He could not deceive the laws of nature. And if he didn't understand it, then he either was not that bright, or some other trait, extreme stubbornness, was clouding his judgment.