oilfield makes giant parts out of exotica all the time, aint cheap but I think that a 5 person 6000psi sub shouldent be cheaply built.

Mild or even normalish high strength steel isnt going to be very appealing since it will have to have a very thick wall and would need some sort of additional buoyancy. Titanium is compelling for the strength / weight /corrosion resistance.

Very high strength steel, stainless, or nickel alloys would probably work ok. It is basically statically loaded in pressure so you can use steel heat treated to within an inch of its life, but gotta watch corrosion. Maybe some 300ksi maraging steel

As an engineering coop student, I worked on and commissioned the worlds largest titanium autoclave (at the time). It was not a lot different in size than that sub.

How do people with unlimited funds (billionaires) opt for a budget trip/vessel to go to the Titanic wreckage? I would have spent any amount necessary to increase my odds of survival if it was something I really wanted to do..

Is Oceangate the only option available to someone with those financial means?

Tragic as it is, those people have probably done more to rekindle ocean curiosity / exploration since Jacque Cousteau's time.

Adhesive for the end cap rings applied by hand with bondo spreaders, and apparently not done in a vacuum chamber and with the assembly spinning in order to evenly distribute the adhesive and lesson air bubbles in it (and with glue being the only fastener used? Wow!)- nutz, considering the intended use of that thing.

He was a real visionary though.....

Yep, ha ha!

Wow, if the info and pics in that vid are true, then the builder/designer decided to raise two tall middles to tried and true best practices, the basics of working with adhesives and carbon fiber, etc. Really incredible to see.

I'm absolutely dumbstruck by the glue application indicated in that vid; anyone who has ever used two part adhesives or resins, applied them in open air by hand (bondo spreader, or similar) and then later broken a cured piece of it off, can see all kinds of air bubble pockets in it, even if care was taken to not stir a bunch of air in during mixing. Had I been on the assembly crew for that submersible, and was handed a hand spreader, intended to be used in the manner the pics in the video indicate, and been told to have at it, I would have laughed and said, "You've gotta be shiitin me, really?".

But it was "designed by an engineer!" :( So anyway we wont really know what happened until they recover the wreckage and complete an investigation.

Coincidentally this failure reminded my of the The Challenger Disaster O-Ring failure. Not the same thing but again designed by engineers.

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

https://youtu.be/vXAyJWeI-f0



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Apologies if this has already been posted (19 hours ago).

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It just astounds me that Stockton Rush was told so many times that the submersible that he was building was unsafe and he didn't listen, he was going to build it his way regardless of what anyone thought. Well, his way was obviously WRONG!!!!

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Apologies in advance but at this point I felt I had to sate the obvious.

"For the love of money is the root of all evil: which while some coveted after, they have erred from the faith, and pierced themselves through with many sorrows."

- Timothy 6:10, King James Version

So who do you want to design the next airplane you get on, lawyers and accountants? or maybe hairstylists?

there are engineers and there are engineers

https://th.bing.com/th?id=OIF.ueVbZ6...id=ImgDet&rs=1https://th.bing.com/th/id/OIP.mV-Bqi...id=ImgDet&rs=1

The problem with the Challenger's SRB joints is more of a management problem than a design problem. NASA management (full of guys with engineering degrees) chose to ignore other engineers warnings of launching on cold days.

Roger Boisjoly (an engineer) is best known for his attempts to stop the launch.

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

Of the two engineers I showed pictures of, both are dead.

The first guy earned a watery grave south of the coast of Newfoundland. The second guy you can go see some of his work at the Temora Aviation Museum. It shouldn't be too far a drive.

https://aviationmuseum.com.au/

https://aviationmuseum.com.au/lockheed-hudson/

as a bonus you may see it flying since its still airworthy

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Otto, You're right "there are engineers and then there are engineers" but do you know what purple font means? (Sarcasm)

Is this better? "designed by an engineer who was only employed because he/she/they ticked all the right boxes".

Now that I've said that... All good and I appreciate your content in this thread!

hmm. sarcasm doesn't translate well with color codes

I can't seem to sleep now that I'm retired/retarded

I crunched some numbers. I hope our authorities fish the wreck bits off the ocean floor and do an investigation. I would like to know how the hull failed of the Titan.

Composite pressure vessles are usually in tension like a SCUBA tank. Carbon fiber TOW is wound around an aluminum liner. The aluminum doesn't provide structure just the form for the fiber to be wound on. Some of the windings are circular and we call these hoops and some of the windings are diagonal. The hoops take the radial loads and the diagonals take the axial loads.

https://th.bing.com/th/id/R.d2bb49e6...pid=ImgRaw&r=0

Now this submersible is loaded in compression. Carbon fiber/fiberglass/kevlar are very strong in tension and not great in compression.

Concrete is the other way around; great in compression and lousy in tension

I'm actually somewhat sympathetic to Stockton Rush because I can see how he may have went down the path of a composite hull. Its light, cheaper to manufacture than a metallic hull and you can get the neutral bouancy without resorting to tanks of gasoline like the Triest had.

So..since I can't sleep I was thinking about how much pressure is on the hull along the axis. I used these numbers

6000 PSI sea pressure

2.8 meters hull diameter or 110" for those of us who live in a country that put a man on the moon :cool:

hull thickness 5"

these are numbers I got off the internet somewhere, the sea pressure is really the only one I can be somewhat confident in

and I got 34500 psi in compression

This is within a good carbon fiber strength but that is when the fibers are lined in the direction of the load and that is not the case with this pressure hull.

The fibers in the hull are mostly hoops so the this load is 90 deg to the fibers. I don't think any of the fibers are alinged with the axis of the hull. The resin is taking much of the load along the axis and the strengths of resins vary.

Room temp cure resins are around 9000 psi tension and resins that need heat to cure are significantly stronger but nowhere near 34.5 ksi

If I had a time machine and could talk to Stockton Rush a couple years ago I would suggest that he build two hulls (or more) and have it fully instrumented and take it some place truely deep, like the Marianas Trench and lower it on a cable and see at what depth does the hull fail. Then take the other hull to the Titanic and lower and raise the hull at least 100 times.

Rush made the mistake of taking short cuts and if I can quote JRR Tolkien; Short Cuts Make Long Delays

Most of our bodies are essentually fluid or fluid filled. Except for our lungs and throat which are full of air, wouldn't we be essentially liquid and therefore not likely to compress much? Granted, I think our lungs and throat would do something traumatic and unfortunate. The big thing is that the pressure would be universal. Your example of an SUV focused on a 1" steel rod creates a picture for us, but I think the mental image that is created for most of us centers around that weight only being one that one spot. As you said, if we were completely covered in those steel rods on ever spot from every direction, there wouldn't be any direction for anything to squish.

I wouldn't think the event would be pretty, but I also don't think that it would turn a body to paste. I think our skin would do a pretty good job of holding us together.

I thought it was universally agreed that green would be used for sarcasm @ PPOT.
I haven't watched the various videos posted in this thread about the sub or its construction, but I thought I'd read that the sub had been down at least a few times before. And based on discussion here (and it makes sense to me, but then I don't have expertise in c/f or materials science. It sounds like a big part of the problem may not have been a single trip down, but that repeated trips, multiple pressure cycles could have caused tiny flaws to create issues that increased/multiplied over time.

For instance, maybe if every trip down was a brand new sub, it would have been (relatively) safe, but taking the same sub down multiple times was destined for failure.

Clearly, there were lots of issues with the thinking/design/implementation, and I wouldn't want to be in the thing at any depth (what's the point with 1 tiny view port).

At the risk of being truly macabre....yes our skin would unless it gets pierced by fragmented debris. Then...well... I do hope that it was as near to instantaneous as would avoid that pain.