But that pressure had somewhere to go in the void of the helmet. So it shoved everything into it like a tube of toothpaste. Without that helmet you'd get a different result.

That video was sickening. YT has removed vids showing injury involving blood, even Stumpy Nubs when he messed up with one of those angle grinder rotating carvers.

Why that horrible video and all the delight of the cast?

I lose so much respect for today every day.

Alan, when I'm designing race car parts my approach is to try and work out all the way it can 'f*@k up and find a design/manufacturing spec. that avoids this

From the brief video I can see quite a few ways it could go all wrong

Titanium end ring bond surfaces don't appear to have been either shot blasted or have an etching primer, the metallic side of a metallic/carbon bond joint usually fails 1st and more often that not due to poor bond preparation

Titanium end ring side bond surfaces don't appear to have any draft, this would minimise/avoid smearing/wiping off the glue when fitting into position the titanium part onto the carbon tube

Titanium end ring doesn't appear to have any design features to maintain a consistent glue gap, a bond joint requires a specific bond joint thickness for maximum strength

Titanium end ring is being wiped down with an old rag and not clinically clean lint free clothe, cleanliness is everything to avoid bond joint surface contamination

Titanium end ring is being lowered using a garage chain hoist, a concentrically accurate sliding bong jig assembly should have been used to minimise smearing/wiping off glue

Stiffness transition from titanium only thickness to carbon only thickness appears very abrupt, a gentle stiffness transition would minimise local stress hot spots that could start a bond joint failure propagating

Titanium ring doesn't appear to have any provision of air holes, this prevents prevent aircpockets hydraulicing the glue out ,

Titanium ring doesn't appear to have any glue injection holes, these feature makes sure the whole bond gap has been filled in all areas by injecting extra glue until it can bee seen squeezing out around the bond joint edges

Glue appears to be mixed in a tub by hand and not de-gassed in a vacuum chamber, this removes any included air bubbles which will weaken the glue strength

The carbon bond joint surface appears to be uni-directional fibers ie all in one direction, instead of a more stress friendly woven fiber +/-45 diagonal direction

Resin weight % to fibre weight appears very high as it's possible to scrape off excess resin, the excess resin wouldn't lend the carbon to being cured under pressure in an autoclave, at best cured under vacuum which makes it far less structurally sound than it could be if autoclaved cured

I'm not a composite submersible structural specialist but have design many titanium/carbon bonded structures 100x smaller in scale and I've been down to 150ft on a tourist submarine ;)

^^^

Great post!

I had many of the same WTF?! observations that you articulated so well (shiny, unscuffed bond surface on titanium ring, old rag wipe down, glue application without any regard for air bubbles and minimal regard for uniformity, chain and straps lowering of ring right out in the open air, and so forth) - nuts.

Captain, we need more clues. Do you think it could possibly be the Titanium end ring.

Nah - reading between the lines I think he’s saying the water soluble glue was the issue…

as long as it wasn't salt water soluble....all is ok.

Had this been posted yet?
It's interesting as he takes you right up to and into the sub, and this guy seems thankful he did not make it down...

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^^^
Very well thought out observations and assessment.

There are, of course, ACTUAL experts in all endeavors, but …
the most dangerous person is the one who BELIEVES they know better, and confidently goes down a path regardless of input they’re receiving. When someone has fooled themself into thinking they’re smarter, more clever, etc, no one can tell them any different. They will likely continue down that path all the way to failure.

A reasonable person who knows that there are limitations to their expertise will be open to input and continual improvement.

This can apply to managing finances, running an organization, sports, medicine, etc.

<iframe width="676" height="380" src="https://www.youtube.com/embed/S4lvLBe6fsE" title="Man's Got To Know His Limitations" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

Absolutely no idea how, why or what failed to cause the sub to implode

Only picked up a few concerning things from the short video, enough to make me question, if the same level of engineering thought/deligegence was applied to the rest of the subs design/construction

Just don't know enough about what was done, why it was done and how it was done. Also I know nothing about designing anything for a deep sea marine environment

So many theories being thrown around, hard to know what is credible but I'm sure some real experts will work it all out

He bragged about buying a big grab handle inside the tube from a local Camper World store.

I wonder if he bought all the stainless nuts and bolts from the same place.

My dad and his brother attached a hose to a bucket and used a bicycle pump to provide air. They put the bucket on their head and put a rock on the bucket. Pretty high-tech stuff, like Titan.

It appears that the composite outfit that helped design and eventually constructed the Titan's pressure capsule also help with design and constructed the DeepFlight Challenger.

https://www.compositesworld.com/articles/deepsea-submersible-incorporates-composite-pressure-capsule

"HOT subcontractor Spencer Composites Corp. (Sacramento, Calif.) was given the task of designing and fabricating the DeepFlight Challenger’s inner carbon/epoxy composite pressure capsule. A filament-wound cylinder, the capsule has a thick glass viewing dome on one end and a titanium foot dome on the other. The domes would be attached to the composite laminate via bonded titanium rings. The tube wall thickness had to be sufficient to resist a biaxial stress field exerted by the deep ocean pressure of approximately 16,000 psi/1,100 bar, with a 1.5 factor of safety. According to Spencer Composites’ principal Brian Spencer, all other design factors, which included water ingress, temperature performance and ability to withstand handling loads in and out of the water, were insignificant compared to the external pressure load."



"Spencer built a number of half-scale tubes to test several designs, including different hoop-to-axial fiber ratios, variations of fiber type and fibers of different moduli in the laminate. Tests were conducted at Pennsylvania State University’s (State College, Pa.) test laboratory, one of a handful in the U.S. able to generate the necessary compressive stress loads. Results were compared to the finite element model and anticipated failure modes. Spencer reports that the subscale samples withstood a maximum fiber compressive stress of more than 125 ksi/1,250 MPa and exhibited compressive strain capability that exceeded 0.48 percent."

The DeepFlight Challenger was designed by HOT:

https://en.wikipedia.org/wiki/DeepFlight_Challenger

https://en.wikipedia.org/wiki/Hawkes_Ocean_Technologies

It was designed to go to the Challenger Deep... about 2.5x deeper than the Titanic wreck's depth.

The idea was scrapped, and it appears at least in part because test results suggested that it could only dive to Challenger Deep depth once, and the sponsor wanted a vessel that could go multiple times with tourists. That was way back about a decade ago.

HOT apparently spent quite a few years (decade) working on engineering and material science challenges through a number of prototypes and perhaps even products they sold. I suspect that their subcontractor and others were involved as well.

We may or may not learn that the design, and/or construction, and/or testing of the Titan's pressure capsule was "informed" by learnings from a decade or more ago.

And of course the design challenges for the Marianas trench are different from those for a vessel designed for 4k meters.

I suspect that there is a relatively small community of expert folks in the super deep submersible space.

Some of them were likely at this 2019 conference:

https://oceanplanetconference.com/

I know for sure that Stockton Rush was there. And of course it is likely that the keynote speaker, Dr. Sylvia A. Earle, attended.

Interestingly it appears she was once married to the founder of HOT.

Again, condolences to those that lost family members/friends.

More on testing (2018):

https://www.compositesworld.com/news/titan-reaches-4000-m-depth

"As part of Titan’s extensive testing program, the OceanGate team conducted a series of unmanned dives by lowering the submersible on a monofilament line incrementally to 4,000 m. Onboard the sub, strain gauges, viewport displacement sensors and a custom designed acoustic sensor system measured the health of the hull to provide data that the team analyzed during and between dives. Many of these sensors will remain permanently mounted in the sub and will give the pilot real-time feedback on hull behavior on all future manned dives."

Not sure if that was the same hull that was recently lost. I doubt it.

You know your products. Particularly carbon fibre. What are you thoughts in regard to it being used on the sub?

In my limited knowledge of it; I'm not a huge fan of the stuff. Great for F1 and racing cars I guess. Light strong and stiff. I remember fishing rods breaking like a gun going off :eek:

Perhaps of interest regarding the DeepFlight Challenger from way back in 2009:

https://www.ingentaconnect.com/content/mts/mtsj/2009/00000043/00000005/art00029?crawler=true

"There were two problem areas: First, and as Jerry Stachiw predicted, modern development of carbon fiber resins had not solved the “unexplained” loss in compressive strength of massive carbon fiber at extreme compressive load. This surprised both the knowledgeable carbon manufacturer as well as myself. In order to test to failure, we had several 1/3-scale pressure hulls built, each with variations from the intended design in order to cause failure within the available test range. Typically, the model hulls predicted to fail at 13,000 psi would fail at 11,000 psi—a significant loss."

Apparently Mr. Hawkes is an expert on submersible design, among other things.

Apparently the (unmanned) Nereus used a ceramic material:

https://en.wikipedia.org/wiki/Nereus_(underwater_vehicle)

And interestingly a tubular design with ti flanges that were glued on.

http://forums.pelicanparts.com/uploa...1687738435.jpg

It appears to me that some thougfhtful engineers and scientists worked on Nereus.

Is there any latest on what parts were found and if any of it will be retrieved?

IDK if this has already been covered, but:
- The submersible had no sonar, correct? I read that the mother ship had to guide it to the the wreck via short “text” messages.
- So I assume the mother ship had its own sonar to do so, right?
- And if the US Navy heard the implosion
Then how in the hell did the mother ship not hear and understand immediately that the Titan imploded?

Exactly. The helmet and suit were not pressurized instantly at the full pressure of the environment. The suit acted like a roll of toothpaste, so as the suit was squeezed from the bottom up, and the helmet wouldn't (initially) succumb to the pressure, the suit squeezed the meat man into the helmet like the reservoir tip on a condom.

The Mythbusters example is not an apples to apples comparison. It's more like apples and oranges or maybe apples and strawberries.

I don't believe that the Navy's underwater listening devices are the same as SONAR. So even if the mothership had SONAR, that does not necessarily mean that they would have heard an implosion.

I suspect the current version is far removed from the version on wikipedia
https://en.wikipedia.org/wiki/SOSUS

what most folks think of is active SONAR. I suspect most active SONAR is automated, so the avg SONAR system echo-locates, but the system as purchased probably doesn't have a "I heard something under us implode" warning.
https://en.wikipedia.org/wiki/Sonar

I’m a little late to the scene, but is he suggesting that the Titan imploded at 3500 foot depth?

https://www.npr.org/2023/06/23/1183976726/titan-titanic-sub-implosion-navy

From the article:
“The listening system the Navy used to register the noise is believed to be the Sound Surveillance System or SOSUS, according to information shared with NPR by a senior Navy official. SOSUS, an underwater cable system that has been in place for decades, is capable of detecting underwater anomalies that might indicate the presence of foreign submarines.”

Personally, I’m thinking why would the mother ship be any better equipped than the sub-standard vessel.

Perhaps of interest:

https://www.cbsnews.com/news/titanic-submersible-interview-transcript-with-oceangate-ceo-stockton-rush/

"The other thing with carbon fiber is, you can't cut holes in it. It doesn't like that. And so these [cables] go into the titanium, and that's how we get our data in. So that's how you get things in and out of the sub, is through the little port."

"So the key on that one is, we have an acoustic monitoring system. Carbon fiber makes noise. There're millions of fibers there. There are 667 layers of very thin carbon fiber in this five-inch piece.

It makes noise, and it crackles. When the first time you pressurize it, if you think about it, of those million fibers, a couple of 'em are sorta weak. They shouldn't have made the team.

And when it gets pressurized, they snap, and they make a noise. The first time you get to, say, 1,000 meters, it will make a whole bunch of noise. And then you back off, and it won't make any noise until you exceed the last maximum.

And so when, the first time we took it to full pressure, it made a bunch of noise. The second time, it made very little noise.

We have eight acoustic sensors in there, and they're listening for this. So when we get to 1,000 meters, if all of a sudden we hear this thing crackling, it's, like, "Wait, did somebody run a forklift into it? You know, has it had cyclic fatigue? Is there something wrong?"

And you get a huge amount of warning. We've destroyed several structures [in testing], and you get a lotta warning. I mean, 1,500 meters of warning.

It'll start, you'll go, "Oh, this isn't happy." (LAUGH) And then you'll keep doin' it, and then it explodes or implodes. We do it at the University of Washington. It shakes the whole building when you destroy the thing.

So that's our backup for the hull. And we're the only people I know that use continuous monitoring of the hull."

"And as I said, the warning is about 1,500 meters. It's a huge amount of pressure from the point where we'd say, "Oh, the hull's not happy" to when it implodes. And so you got a lotta time to drop your weights, to go back to the surface, and then say, "Okay, let's find out what's wrong."

"Like, over here, we blew this one up. So this is all a one-third scale [model of the Titan]. We were able to blow this up intentionally, to hear what it's like with our acoustic monitoring system. What we wanted to verify was, we can detect the carbon fiber failing way before it happens, so that you can stop your descent and go to the surface.

And that's what we found out here. So we now know what this shape sounds like when it's uncomfortable and right before death.

It's the loudest thing I've ever heard in my life.

When you go beyond 6,000 PSI in the test chamber that we were using at the University of Washington, they have to empty the building. Only essential personnel can be there."

"Well, obviously, the hull is critical. And if the hull being carbon fiber—and being a unique material, and having the potential for things like water intrusion—but if that hull goes, that could kill people.
You wanna make sure it's infrequent and also detectable. And one of the ways to do detection is this acoustic monitoring system.

So we bench-checked it against the system that Boeing uses. We made our own system that was much smaller and more sensitive, actually.

And then we also have strain gauges. So we look at the hull every step of the way.

And so we get to 1,000 meters and the hull's acting differently, the strain gauge goes off, or the acoustic monitoring system is showing a lot of noise, you call off the dive. You come to the surface. You find out what's wrong.

And so that's what we tested with all of these components, taking it to destruction, and also testing at the deep-ocean test facility, the entire sub, and being able to see: What does it sound like on its first dive, and what's it sound like now? And we can keep comparing it and making sure it's still putting out that beautiful sound—of silence."

When the Navy lost the Thresher they theorized that the breach allowed it to fill so fast the hull didn't collapse.

acoustic emissions is a lot of things ... but a fail safe it is not. AE is a chaotic mess, and you dont actually know for certain what is happening.

also they are measuring the "warning buffer" in additional feet of pressure, but if its cracking, than its already failed and is weaker that it was before. ie, a better spec for that buffer would be a combination of time, and cycle count. it might not be 1500 feet of additional pressure (in this case the term would actually be head, but whatever), but if you left it at whatever pressure it was at when it cracked, over time, it would continue to crack likely. and if you removed that pressure, and added the same pressure again, you would see additional damage.

ie, the "warning buffer" he talks about here is a lot more complicated than he says it is. every single AE detection is a weakening of the structure.

EDIT: every interview with rush i read sounds like when elon billionaire-splains second year engineering school concepts like its ground breaking. rush sounds the exact same.

This is a ready good intro on Ocean Acoustics. It is fascinating to me since I lived the dream but will be a sleeping aid to others.

http://stream1.cmatc.cn/pub/comet/MarineMeteorologyOceans/IntroductiontoOceanAcoustics/comet/oceans/acoustics/print.htm

SOSUS has been around for a long time, even predating my time in the Navy.

https://www.csp.navy.mil/cus/About-IUSS/Origins-of-SOSUS/

So, all that said, SONAR is an active sensor, it puts out energy in the water and looks for a return. SONAR doesn't "listen". Passive arrays "listen" for noise in the water.

The difference is in anti-submarine warfare tactics: Active sonar is very critical in high ambient noise tactical scenarios, think inner zone ASW in the fleet. Ships make a lot of noise and active sonar is an imperative because the bad guys are in the hen house.

Once you "ping" they know more about you than you know about them.

Passive detonation is equally important but I'd key cramps writing why.

Lastly, the depth of the Titanic debris field is over two miles down. No tactical submarine in the world goes that deep. My curiosity is why the Titan needed guidance from above.

I agree. Sensor operators and their digital assistants look for anomalies in their "day in the life" analysis. It is fairly rare to have large noise swings in the water.

I have listened to snapping shrimp, whales yap, etc. Great stuff.

I will say, everything is recorded and analyzed. That is how we "hull type" other countries submarine, right down to the hull number.

we are talking about different things. im talking about the safety system in the sub to listen for the hull cracking ... not a hydrophone/passive sonar system.

wiki link: https://en.wikipedia.org/wiki/Acoustic_emission

Imagine if you jumped out of a helicopter two miles high. You have a parachute but its totally dark. Your target is something the size of the titanic. The wind is blowing 7 knots.

How far are you going to drift by the time you reach the ground? The viz is 30 feet and you have a flashlight.

If the mother ship had an active sonar they could ping the submersible and give corrections.

I remember a sonar friend calling a contact a G-U-ELEVEN

(that was a longgg time ago)

I think that was filmed on the USS Blueback. If I ever get off may rear and do a road trip to see friends in Washington I'll stop in Portland to visit it. The last time I saw it was in 91.

Sounds like yhe CEO was trying to be the SpaceX of the sea? Xsub?

Copy. My bad.

I still own 35% of a composites company, not thick composites but the discussion threads on this are very informative. There is a lot more to even simple composites than many can imagine.

When composites became more main stream for aircraft, the scrap rate for even the big manufacturers of thick composites, in my case when I was the IPT lead for the Bell Y/Z helicopters, was very high.

The amount of Destructive and Non-destructive analysis almost killed the program.

We do FAA composite repair work on commercial aircraft parts and the quals, tracking, inspections are brutal but they pay well.

Boeing had to make a couple wings for the X32 in order to get one that was acceptable.

That is what is most interesting to when combined with CP posts: how did they know, without multiple dives and post mission analysis then unmanned to failure with data capture, what was good versus bad noise emissions?

Happy to learn more.