Tourist mini sub missing off titanic

[berettafan]

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.

[Zeke]

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.

[Captain Ahab Jr]

Originally Posted by Alan A

I can speculate with the best of them…

It failed because it wasn’t overbuilt sufficiently and with enough redundancy to withstand whatever happened to it between the design studio and the ocean floor.

Engineers tend to be cautious. Salesmen tend to look for quick, imperfect results.

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

[Rawknees'Turbo]

^^^

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.

[Bill Douglas]

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

[Alan A]

Originally Posted by Bill Douglas

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…

[stevej37]

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

[The Synergizer]

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...

[fisher22]

^^^
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.

[pwd72s]

[Captain Ahab Jr]

Originally Posted by Bill Douglas

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

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

[herr_oberst]

Originally Posted by Captain Ahab Jr

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

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.

[Superman]

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.

[Mahler9th]

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.

[Mahler9th]

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.

[Bill Douglas]

Originally Posted by Captain Ahab Jr

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

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

[Mahler9th]

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.

[Mahler9th]

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.



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

[Mahler9th]

[jyl]

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