If it did implode in multiple pieces it means the experts were right; many said that carbon fiber was a poor choice because while it's light, it breaks like glass, contrary to steel which tends to "open" slowly.
My guess would be that the window wasn't the failure point, assuming that pressure hull was indeed found in many pieces. If the window did go first, the pressure delta on the rest of the hull immediately begins to equalize, so the amount of force the hull is under immediately goes down, making failure of the hull instantly less likely. The inertia of all the water rapidly entering the vessel might do some damage, but that inertia would have to overcome both the pressure of the ocean pressing in on the outside of the hull, and the tensile strength of the carbon fiber, which is stronger in tension than compression. So my guess would be that if the window failed, it would result in mostly just the titanium end caps being blown off rather than a complete destruction of the hull.
If the hull itself failed, however, given the way carbon fiber fails, finding the hull in many pieces seems to be the expected result.
> the submersible was designed to reach depths of 4,000 metres, but Lochridge said the passenger viewpoint (window) was only certified for depths of up to 1,300 metres
Carbon fiber is a lot easier to work with than metal in this case because welding metal creates failure points. I don't think they could afford building a titanium pressure vessel. Weight is a factor too, carbon fiber is lighter so you can make the pressure vessel thicker and still have enough buoyancy to reach the surface(probably a good thing).
From their perspective it kinda made sense even though its not safe at all.
> I don't think they could afford building a titanium pressure vessel
If they could they probably still wouldn't have done so. The founder who was onboard the Titan was known for calling safety regulations unnecessary and a barrier to "innovation", like a window only rated for a depth of 1300m used at 4000m.
No, it’s not easier to work with, unless you consider your work done completely once it’s manufactured without a thought to the ongoing testing and inspection regime required. And even then, laying CF is more niche than welding metal.
Carbon fibre is a ply. Plies are much harder to nondestructively inspect for flaws. That is an immediate, obvious risk in a use case involving cyclic pressure of hundreds of atmospheres. It is also brittle, so strain deformation does not occur nearly as much before fracture.
Welds are a vastly more well-understood feature that is possible to easily design around and - more critically - inspect afterwards. Metals also stretch before snapping, which is why you can go and measure the spacing of links on your bike chain and know when it’s time to replace it. All of this makes through-life maintenance and inspection much easier.
Carbon fibre was an incredibly poor design choice, selected to prioritise cost over safe operation.
Obviously there seem to be some compelling reasons why the choice of a carbon hull was a faulty idea to begin with. The CEO would have been familiar with those critiques and proceeded anyway, presumably because of counter arguments he put more confidence in. Anyone out there familiar with what some of those counter points may have been?
Plain old steel seems to work and I'd imagine would be better given most subs are made of it. The Deepsea Challenger was made with 2.5 inch thick walls and went to 3x the depth. https://en.wikipedia.org/wiki/Deepsea_Challenger
The main problem with steel is that it can only withstand such pressures if it's of spherical shape (i.e. a bathysphere). This usually only leaves enough room for two to three people (e.g. https://en.wikipedia.org/wiki/DSV_Alvin).
So it seems it's more a matter of cost and passenger space than just weight alone.
This quote shines light on his hiring philosophy:
“When I started the business, one of the things you’ll find, there are other sub-operators out there, but they typically have, uh, gentlemen who are ex-military submariners, and they — you’ll see a whole bunch of 50-year-old white guys,” Rush told Teledyne Marine in a resurfaced interview.
“I wanted our team to be younger, to be inspirational and I’m not going to inspire a 16-year-old to go pursue marine technology, but a 25-year-old, uh, you know, who’s a sub pilot or a platform operator or one of our techs can be inspirational,” said Rush.
"50 year old white guys have a lot of experience but would cost a fuck ton of money. I prefer to exploit, er, um, employ, 25 year old white guys and gals because they are about 1/4 the cost."
When you take all the BS justifications out of it, that's really what the guy was saying. Elon Musk school of capitalism. Play stupid games, win stupid prizes.
Ah, I see he's got the 'Elon Musk school of thought' in regards to cutting corners in vehicles carrying people's lives and seeing safety regulations as a nuisance hindering his "visionary progress" that these pesky gray-beard engineers just can't grasp.
Fucking idiot CEO, took 4 innocent people with him. Aero, naval, automotive, all have a a history written in blood, and all those rules and regulations aren't to hinder innovation but to save lives based on what we've learned from all the people who lost their lives in the past.
"Ah, I see he's got the 'Elon Musk school of thought' in regards to cutting corners in vehicles carrying people's lives and seeing safety regulations as a nuisance hindering his "visionary progress" that these pesky gray-beard engineers just can't grasp.
Fucking idiot CEO, took 4 innocent people with him. Aero, naval, automotive, all have a a history written in blood, and all those rules and regulations aren't to hinder innovation but to save lives based on what we've learned from all the people who lost their lives in the past."
I agree, except maybe on the notion of "innocent billionaire". They too usually have a history of blood. Except maybe the 16yo tho. Maybe.
It's the government's job to regulate people not being allowed to pay for trips to the bottom of the ocean in submarines that look like they were built on Linus Tech Tips.
The ship has to be under some countries flag, it's not like international waters are a totally lawless zone where you can loot, murder and rape without consequence.
Sadly, being able to "shop" for a county with minimal safety, inspection, and enforcement standards is a valued feature of the modern ship registration system: https://en.wikipedia.org/wiki/Flag_of_convenience
(And, so long as you keep your rape and murder within your ship - that is also a feature. If you are a crime victim on a cruise ship, and the cruise company feels that looking into what happened to you is not in their own business interest... OTOH, you or your survivors may be able to sue the cruise company for damages in a shore-based court. Google for the obvious if your want to see stories about that.)
