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Titanic tourist submersible goes missing with search under way

bbc.com

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Re: Titanic tourist submersible goes missing with search under way

#61

Post by zabzonk »

scarnz wrote: post #30

This appears to be the vessel in question: https://oceangate.com/our-subs/titan-submersible.html Pressure hull made from titanium and carbon fiber, capable of diving to 4000m (13,000 ft). I recall that one reason SpaceX switched from carbon fiber to stainless steel pressure vessels (fuel tanks) was the difficulty of detecting structural flaws. Can any engineers comment on whether that task is easier for a vessel expo…

> 13,000 ft

titanic is at about 12500, according to wkikipedia - a bit close?

Re: Titanic tourist submersible goes missing with search under way

#62

Post by rwmj »

ralphhughes wrote: post #40

Skimming the website, I assume this submersible is using electromagnetically attached drop-weights so that if anything goes wrong and power is lost, the weights drop off and the submersible floats up to the surface again? And 96 hours of life support sounds good, but unless there is another submersible nearby that can dive down, find them AND attach a line, the number of hours of life support will be irrelevant. Of c…

Wouldn't the sub have a tether to the surface, or is that not practical for some reason?

Re: Titanic tourist submersible goes missing with search under way

#63

Post by noirbot »

paganel wrote: post #50
engineer_22 wrote: post #48

Earlier quoted context omitted.

That's a particularly crass thing to say about someone while their life is in jeopardy. >Did it not occur to anyone that it might be a bad idea? It's hard to be sympathetic in the face of such arrogance The company advertises the safety of their submersible and an active suite of sensors to detect and prevent failures.

Crass but maybe other rich people will also get hold of this sentiment and will avoid doing stupid stuff like this in the future. Also, they were there visiting a place filled with dead and probably long decomposed people, can’t say I’m very sympathetic.

Isn't visiting places filled with dead and decomposing people a fairly normal tourist activity? Various catacombs, graveyards, temples, battlefields, memorials, Pompeii...

I've got no real thoughts on the "stupidity" of doing this, but visiting the wreck of a famous ship doesn't seem an obviously unsympathetic thing to do compared to visiting the ruins of a city.

Re: Titanic tourist submersible goes missing with search under way

#64

Post by riversflow »

SV_BubbleTime wrote: post #51
rodface wrote: post #39

It's worth contrasting the design of this vehicle with what is ostensibly the world standard for deep-sea research submersibles, Alvin of Woods Hole Oceanographic Institution. https://www.whoi.edu/what-we-do/explore/underwater-vehicles/...

There’s a strange sense of scale on that thing. You wouldn’t immediately look at it and say that two people can fit inside for 30 days. EDIT: 30 days between maintenance. I’m a dirty skimmer.

What?

> Alvin enables in-situ data collection and observation by two scientists to depths reaching 6,500 meters, during dives lasting up to ten hours.

Maybe you misskimmed:

> Alvin is a proven and reliable platform capable of diving for up to 30 days in a row before requiring a single scheduled maintenance day

Re: Titanic tourist submersible goes missing with search under way

#65

Post by floxy »

rwmj wrote: post #62
ralphhughes wrote: post #40

Skimming the website, I assume this submersible is using electromagnetically attached drop-weights so that if anything goes wrong and power is lost, the weights drop off and the submersible floats up to the surface again? And 96 hours of life support sounds good, but unless there is another submersible nearby that can dive down, find them AND attach a line, the number of hours of life support will be irrelevant. Of c…

Wouldn't the sub have a tether to the surface, or is that not practical for some reason?

~2.5 miles of tether might be an obstacle.

Re: Titanic tourist submersible goes missing with search under way

#66

Post by sixQuarks »

jiveturkey wrote: post #56
ralphhughes wrote: post #40

Skimming the website, I assume this submersible is using electromagnetically attached drop-weights so that if anything goes wrong and power is lost, the weights drop off and the submersible floats up to the surface again? And 96 hours of life support sounds good, but unless there is another submersible nearby that can dive down, find them AND attach a line, the number of hours of life support will be irrelevant. Of c…

> mercilessly quickly mercifully quickly?

Huge implosion at very high pressure. Would happen in milliseconds

Re: Titanic tourist submersible goes missing with search under way

#67

Post by ghaff »

zabzonk wrote: post #61
scarnz wrote: post #30

This appears to be the vessel in question: https://oceangate.com/our-subs/titan-submersible.html Pressure hull made from titanium and carbon fiber, capable of diving to 4000m (13,000 ft). I recall that one reason SpaceX switched from carbon fiber to stainless steel pressure vessels (fuel tanks) was the difficulty of detecting structural flaws. Can any engineers comment on whether that task is easier for a vessel expo…

> 13,000 ft titanic is at about 12500, according to wkikipedia - a bit close?

Not really. Numbers like that have some safety margin built in.

Re: Titanic tourist submersible goes missing with search under way

#68

Post by readams »

kortex wrote: post #47
scarnz wrote: post #30

This appears to be the vessel in question: https://oceangate.com/our-subs/titan-submersible.html Pressure hull made from titanium and carbon fiber, capable of diving to 4000m (13,000 ft). I recall that one reason SpaceX switched from carbon fiber to stainless steel pressure vessels (fuel tanks) was the difficulty of detecting structural flaws. Can any engineers comment on whether that task is easier for a vessel expo…

I'm not really an engineer (general hobbyist, former chemist) but I have built and worked with pressure and vacuum vessels. Positive pressure (tank vs exterior) is much easier to deal with than negative pressure (vacuum vessel at 1 atm, or bathyscape with 1 atm inside and high pressure exterior). In positive pressure, your stress is mostly in the hoop mode, which is stable. This is why aluminum cans can be so thin. I…

Also space pressure difference is much less. A fuel tank might have just a few atmospheres inside, and of course a human pressure vessel will have a bit under 1 atmosphere inside, compared to the outside which is at ~0 atm.

At 4000m, the outside pressure is _400_ atmospheres compared to just one inside. It's way, way harder.

Re: Titanic tourist submersible goes missing with search under way

#69

Post by ghaff »

noirbot wrote: post #63
paganel wrote: post #50

Earlier quoted context omitted.

Crass but maybe other rich people will also get hold of this sentiment and will avoid doing stupid stuff like this in the future. Also, they were there visiting a place filled with dead and probably long decomposed people, can’t say I’m very sympathetic.

Isn't visiting places filled with dead and decomposing people a fairly normal tourist activity? Various catacombs, graveyards, temples, battlefields, memorials, Pompeii... I've got no real thoughts on the "stupidity" of doing this, but visiting the wreck of a famous ship doesn't seem an obviously unsympathetic thing to do compared to visiting the ruins of a city.

Or the Arizona Memorial at Pearl Harbor.

Re: Titanic tourist submersible goes missing with search under way

#70

Post by meepmorp »

SV_BubbleTime wrote: post #51
rodface wrote: post #39

It's worth contrasting the design of this vehicle with what is ostensibly the world standard for deep-sea research submersibles, Alvin of Woods Hole Oceanographic Institution. https://www.whoi.edu/what-we-do/explore/underwater-vehicles/...

There’s a strange sense of scale on that thing. You wouldn’t immediately look at it and say that two people can fit inside for 30 days. EDIT: 30 days between maintenance. I’m a dirty skimmer.

I think it's 30 days of diving, not 30 continuous days submerged. You can use it a whole month before you need to take a maintenance day.

There's a 3d panorama view of the interior of the sphere linked from the article - I doubt anyone's spending more than a day in there at a go, let alone with someone else.

Edit: apparently, it's 3 people - the pilot and 2 scientists.

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