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Why isn't Titan classed? (2019)

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

#151

Post by quickthrower2 »

noduerme wrote: post #139
aaronscott wrote: post #100

> Another simple risk mitigation step we take, that we believe to be unique to OceanGate is that we draw a small vacuum on the inside of the sub at the start of each dive. This step verifies the integrity of the low-pressure O-ring seal and eliminates the risk of leaks I wonder what that low-pressure o-ring is sealing. I assume the vacuum would only simulate a one atmosphere differential, so that o-ring must not be s…

One thing I'm curious about, as someone who knows nothing about the engineering of these things... why wouldn't anyone building something like this choose to over-pressure the sub once people were inside it and it began descending? Wouldn't 2 atmospheres inside represent a 50% reduction in the pressure differential on the hull at depth?

Not an expert so guessing but that would give you 299 atmospheres differential instead of 300. Also might be uncomfortable for the passengers?

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

#152

Post by cactusplant7374 »

cbzoiav wrote: post #117
pengaru wrote: post #90

Earlier quoted context omitted.

> 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.

So Stockton Rush had a lot of options to make money during extensive testing? He made it sound like the company would go under.

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

#153

Post by cactusplant7374 »

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…

Each time they go down they have to jettison some waste to return to the surface?

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

#154

Post by hadlock »

notreallyauser wrote: post #74
lozenge wrote: post #54

Earlier quoted context omitted.

Titan didn't have a flag, it only operated in international waters. But the surface support vessel has a Canadian flag, and Canada's launching an investigation.

The Guardian is reporting the submersible as registered in the Bahamas

Flag of convenience. Where the country of record allows ships to register under their name as a way of generating revenue from foreigners. Bahamas will not do more than issue a statement, if that. You step foot on a flag of convenience boat with no prior reputation and you are effectively waiving any expectation safety.

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

#155

Post by shadowgovt »

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.

Not me. That thing has a 2% failure rate and I want to live.

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

#156

Post by AlbertCory »

advael wrote: post #113
AlbertCory wrote: post #108

Earlier quoted context omitted.

> 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

Exactly. One could make the same claim about space tourism, but that one has some rational justification at least. I don't see a great benefit in having cheaper deep-water subs.

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

#157

Post by Sporktacular »

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…

That's spot on - it's like survivorship bias. If the majority of fighter planes returned with bullet holes on their tops, Oceangate would have armoured the tops.

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

#158

Post by hadlock »

ajross wrote: post #37
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…

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.

The design flaw was that they used a construction material strong in tension, but weak in compression. For a task that is almost entirely compression. On a vehicle that has no need for weight savings. Also in a couple photos looks like they have drilled and screwed a monitor mount directly into the pressure vessel, creating future failure points, rather than gluing a piece of plywood to the hull and screwing into that, which is standard procedure.

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

#159

Post by brookst »

rossjudson wrote: post #130
spencerflem wrote: post #109

Earlier quoted context omitted.

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.

I have rarely seen large groups of humans be accused of excessive consistency over time when it comes to matters of fact and science.

Consistency isn’t possible at a sufficient level of context.

I mean, I light campfires and I put them out. At a level of reductionism very common in online conversations, I am totally hypocritical about whether I want a fire or not.

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