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Why isn't Titan classed? (2019)

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Re: Why isn't Titan classed? (2019)

#101

Post by cbzoiav »

stickfigure wrote: post #73
cbzoiav wrote: post #16

> The vast majority of marine (and aviation) accidents are a result of operator error, not mechanical failure. Could that be because the vast majority of mechanical designs go through processes designed to validate them and catch flaws? They also use SpaceX as an example. SpaceX ran a large number of unmanned launches to prove out the design before putting people on board. Several of those ended in loss of the vehicl…

The first space shuttle launch was crewed. It ended up with a ~2% failure rate. The Titan made about 50 dives. So, from a reliability perspective, on par with the shuttle. I posit that half the people on HN would volunteer for a hypothetical next shuttle flight without thinking twice.

The shuttle did something nobody had done before and was viewed as a genuine step forward in human capability. It was also over 50 years ago and had to rely on technology of the time - uncrewed tests were much harder to perform.

This wasn't a particularly ground breaking vehicle in terms of capability and was taking paying tourists...

Re: Why isn't Titan classed? (2019)

#102

Post by throw0101a »

foota wrote: post #82
cactusplant7374 wrote: post #72

Earlier quoted context omitted.

It had already been down quite a few times. Do you mean 100's of drops? Although, couldn't they just leave it at the bottom for a month and see if it implodes?

I believe the stresses of the hull going through changing pressures is relevant.

> I believe the stresses of the hull going through changing pressures is relevant.

It certainly does for aircraft, and I doubt the material science would be much different for subs (with the added challenge(s) that (salt) water often brings):

* https://www.smithsonianmag.com/air-space-magazine/what-deter...

* https://simpleflying.com/pressurization-cycles-aircraft-life...

Re: Why isn't Titan classed? (2019)

#103

Post by _yb2s »

pengaru wrote: post #90
cactusplant7374 wrote: post #72

Earlier quoted context omitted.

It had already been down quite a few times. Do you mean 100's of drops? Although, couldn't they just leave it at the bottom for a month and see if it implodes?

> Although, couldn't they just leave it at the bottom for a month and see if it implodes? No, cyclic stresses are a different animal altogether. But considering it's just a matter of attaching ballast to sink it, dropping ballast to raise it, there's nothing preventing cyclic testing vs. static @ max depth over the same duration. It seems obvious to me that you'd want to burn through a few test hulls characterizing t…

This is a really good point... from what I've seen they estimated the strength with Finite Element Analysis in Solidworks, and went for a ~2x margin of safety. There seems to have been no attempt to experimentally determine the expected number of load cycles to failure, they only considered the theoretical case of a perfectly flawless composite with no wear and tear.

Re: Why isn't Titan classed? (2019)

#105

Post by jonathankoren »

swayvil wrote: post #29
dpedu wrote: post #3

Patent for their hull monitoring system: https://patents.google.com/patent/US11119071B1/en

With the right waveform analysis algorithm you could monitor stress, cracks and the progress thereof. Get more warning.

Perhaps in with other materials, but the pressure vessel was made out of carbon fiber, and carbon fiber splinters with almost no warning.

https://youtu.be/DM6J-yw8yjA?t=65

Re: Why isn't Titan classed? (2019)

#106

Post by cbzoiav »

rossjudson wrote: post #96
ajross wrote: post #37

Earlier quoted context omitted.

That's exactly it. If OceanGate had build and dropped a few dozen of these hulls empty, as many times as needed to reach failure, whatever design flaw caused the implosion almost certainly would have been noticed. It's the hubris of diving in what amounts to a prototype that's at issue here, not any fundamental technical mistake.

I think a smaller N number of more dives would yield better results. Down, up, down up...repeat until failure . In parallel do it with another hull at the same time. Or maybe more than one. Compare. Testing to failure is a nice option because it finds certain types of unwelcome surprises. But it's not really complete, either -- there are probably a lot of ways that a submersible can be compromised, and there's no way…

The debris may yield significant clues. Those may then be able to be validated with independent testing rather than requiring a full vehicle.

Re: Why isn't Titan classed? (2019)

#107

Post by quickthrower2 »

lamontcg wrote: post #14
arcticbull wrote: post #6

Earlier quoted context omitted.

Giving them the benefit of the doubt, they're saying the biggest problem with submersibles is operator error. Of course it is, when the classing system effectively eliminates the majority of mechanical failures. That doesn't mean the classing system is failing, on the contrary, it means its working.

Reminds me of some code that I've written which got passed off to other teams who ripped it out because all they saw was the complexity and they didn't recognize what issues it was preventing (Chesterton's Fence).

Code like that needs a 10 ft comment. I have been save by seeing those on otherwise “why the fuck is this needed” code.

If they if ignore the comment, well that is hubris.

Re: Why isn't Titan classed? (2019)

#108

Post by AlbertCory »

advael wrote: post #78

What a profoundly stupid take by a profoundly irresponsible company. This is a great example of why you should consider anything a company says about itself to be marketing, and treat it with commensurate skepticism. "We're so innovative we don't have time for safety regulations" - An idiot, destined to harm someone unless pure dumb luck causes their company to fail first

> We're so innovative

what I'm wondering is: what's the incentive to be "innovative" in the first place? Unless "innovation" is an end in itself.

Is there some great unmet need to send people to extreme depths, especially when unmanned probes can do most necessar work nowadays?

Re: Why isn't Titan classed? (2019)

#109

Post by spencerflem »

stickfigure wrote: post #73
cbzoiav wrote: post #16

> The vast majority of marine (and aviation) accidents are a result of operator error, not mechanical failure. Could that be because the vast majority of mechanical designs go through processes designed to validate them and catch flaws? They also use SpaceX as an example. SpaceX ran a large number of unmanned launches to prove out the design before putting people on board. Several of those ended in loss of the vehicl…

The first space shuttle launch was crewed. It ended up with a ~2% failure rate. The Titan made about 50 dives. So, from a reliability perspective, on par with the shuttle. I posit that half the people on HN would volunteer for a hypothetical next shuttle flight without thinking twice.

Its a big hackernews meme that NASA spends way too much on safety/beurocracy instead of innovation. Plenty of other submarines companies do the same (and get classed).

I don't think this is a very insightful comparison.

Re: Why isn't Titan classed? (2019)

#110

Post by advael »

aleph_minus_one wrote: post #99
advael wrote: post #78

What a profoundly stupid take by a profoundly irresponsible company. This is a great example of why you should consider anything a company says about itself to be marketing, and treat it with commensurate skepticism. "We're so innovative we don't have time for safety regulations" - An idiot, destined to harm someone unless pure dumb luck causes their company to fail first

Rather: for every customer who slightly informs himself, it should be insanely obvious that signing up might be quite dangerous (with a risk that is likely very hard to actually measure - this is a huge red flag for any risk-averse person). So if you neverthess sign up, you are very aware that things might go insanely wrong (and there is actually a very realistic probability of dying). So you really know what you are…

The linked article is very clearly an attempt to persuade its reader that the lack of classing (IE verification of safety by an external auditor) is less of an issue than they might otherwise think. Your advice to a reader of this article is rational here, but I think it's worth also pointing out that the article is meant to persuade said reader to not think that way
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