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Why isn't Titan classed? (2019)

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

#111

Post by rossjudson »

blamazon wrote: post #80

Related reading - "Vigor's Black Box Theory" [1] [1]: https://www.usps.org/durham/Bullhorns/vigor.htm

Interesting. I'd say that for systems, defense-in-depth usually relies on various forms of maintenance, and consistent effort to maintain functional parity in redundancies. In other words, just having a redundancy or secondary system is not enough. There's a lot of care and feeding when a secondary uses a different method of achieving the same ends as the primary. That requires effort -- which is all too often skipped or falls out of common knowledge.

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

#112

Post by paulddraper »

quickthrower2 wrote: post #86
TazeTSchnitzel wrote: post #70

It's not classed because nobody would have signed off on it with the level of testing they had done. Carbon fibre reinforced polymers don't have a defined fatigue limit, so stress cycle failure can't be ruled out, and it's difficult to estimate how much a design based around that material can endure. To get certified, OceanGate would have had to do destructive endurance testing on a replica hull, but they only proved…

Having read enough plain crash stories, first thing I though of was material fatigue. Like in the early days fan blades snapping off jet engines causing catastrophic failure after so many takeoffs. Now they have to inspect these closely in manufacturing and during maintenance cycles. Wouldn’t surprise me if they use ML now as it seemed a difficult human observation task. The stress/unstress cycle of a vessel going th…

I recall first learning of "material fatigue" though the fictional movie No Highway in the Sky (1951) [1]

[1] https://en.wikipedia.org/wiki/No_Highway_in_the_Sky

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

#113

Post by advael »

AlbertCory wrote: post #108
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?

The only "unmet needs" such an endeavor need care about is convincing a deep-pocketed investor

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

#114

Post by qwertox »

OceanGate vs Lochridge [0] is an interesting lawsuit which may interest some of the readers here.

It doesn't matter into which page you scroll, all things you get to read are related to concerns of the security of the sub. Ok, it basically starts at page 9, all before it is legalese bootstrapping.

> Defendant David Lochridge has extensive background as a submarine pilot and training of the same [...] Underwater Inspector, and trained to recognize flaw and points out failure in subsea equipment

> May 2015 [...] began working with OceanGate as an independent contractor

> As a part of his job duties, Lochridge was the Director of Marine Operations and was tasked with "ensuring the safety of all crew and clients during submesible and surface operations."

> Issues of quality control with the new submersible Titan were raised, as there were evident flaws throughout the build process [...]

> Lochridge worked on his report and requested paperword [...] was met with hostility and denial of access to the necessary documentation.

> Lochridge first expressed verbal concerns over the safety and quality control issues regarding the Titan to OceanGate executive management. These verbal communications were ignored.

And so on.

[0] https://www.documentcloud.org/documents/23854184-oceangate-v...

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

#115

Post by jonathankoren »

erik_seaberg wrote: post #87
deelowe wrote: post #77

Earlier quoted context omitted.

I thought the deepest it had gone was 3000 meters and there's no evidence of it even having been tested to 4k.

They had two successful trips to Titanic, and other tests in the Bahamas.

So just enough times to weaken the hull through stress fractures.

It wasn't rated for the depth. In fact, I think it was rated for 1000 meters less than the target depth.

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

#116

Post by LeftHandPath »

JohnMakin wrote: post #49

This is such a clear fallacy right from the get go. "This thing doesn't completely solve the problem, therefore, we will not do it." So many people fall for this or talk in such terms like it's perfectly reasonable and it always baffles me. You see it in political discussion a lot.

See the nirvana fallacy: https://en.wikipedia.org/wiki/Nirvana_fallacy

It happens a lot. I think it's one of the big reasons that hyped-up video games and movies always disappoint.

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

#117

Post by cbzoiav »

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…

> You just need resources to burn on destroying enough hulls for the data.

Unmanned submersibles have plenty of market value. You may still be losing money, but you can strap sensors and cameras to the thing / undercut on price for research missions and substantially reduce the cash burn while building investor confidence.

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

#119

Post by _yb2s »

AdamJacobMuller wrote: post #58
hn_throwaway_99 wrote: post #22

> OceanGate’s submersibles are the only known vessels to use real-time (RTM) hull health monitoring. With this RTM system, we can determine if the hull is compromised well before situations become life-threatening, and safely return to the surface. This innovative safety system is not currently covered by any classing agency. > No other submersible currently utilizes real-time monitoring to monitor hull health during…

Truly bizarre. Failures like this happen in milliseconds, it doesn't matter how realtime your realtime monitoring is. I'm not arguing in favor of the classification system, but, I think if you went to them and framed things as simply as they are here "you require validation every 3 years, we're doing it on every single dive" they would say "that's more than once per 3 years, APPROVED!" so the situation is clearly far…

Yes, I don't understand this acoustic monitoring concept... I'm curious what the logic behind it was. It just doesn't seem like there would be enough time to take action once the monitor starts to detect failure.

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

#120

Post by rossjudson »

fredgrott wrote: post #95

One should note that carbon composites are not for external pressure situations since they delaminate...in shorts words they were playing a dice rolling game and lost on damn stupidity. The whole reason they were not classed is that carbon composites would not pass any class certifications due to the limits indicated above.

I'm still trying to understand why they wanted to use carbon composites. Cost to manufacture? Low mass? I read somewhere that the carbon pressure vessel was about five inches thick. I'm not sure how thick a comparable titanium vessel would be, or how much that would cost.
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