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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

#601

Post by jacquesm »

fastball wrote: post #521
manarth wrote: post #455

Earlier quoted context omitted.

Standard scuba cylinders are typically pressurised to around 230 bar, with a small proportion taking 300 bar as their standard working pressure (with margin for over-pressure). It's not too much of a leap from there to the 380 bar pressure at Titanic's depth.

Indeed, this company[1] seems to sell COPV's that are rated for 414 bar, so my assumptions were wrong in this case. As such, I will revise my theory, and posit that the actual issue with this strategy at Titanic depths is keeping the water out of the ballast tanks once you've evacuated them. This seems plausible given that the hatch must be bolted on from the outside. If they had a method to keep 382 bar of water dyn…

Big difference between pressure from inside the vessel or from outside of the vessel.

Re: Titanic tourist submersible goes missing with search under way

#602

Post by jacquesm »

lb1lf wrote: post #509
malshe wrote: post #233

Earlier quoted context omitted.

This is great info! Can you please point me to any write up that explains this in more details?

I went to sleep, time zones being what they are, but see that user jacquesm posted a link to a most impressive rabbit hole of engineering porn. As an aside, one of the first field jobs I attended after graduating was commissioning some equipment fitted onto the R/V Knorr, the very ship which was used for finding the Titanic. For a Titanic buff, that was a great experience - doubly so when the project manager at the W…

I've done some work for a company in this domain, it is incredibly interesting and you could easily lose several lifetimes on all of the engineering details.

Re: Titanic tourist submersible goes missing with search under way

#604

Post by jacquesm »

spadros wrote: post #571
wnc3141 wrote: post #463

After hearing about the experimental nature of the firm (see: https://www.youtube.com/watch?v=29co_Hksk6o&t=203s ), does anyone have any perspective on the firm's ethics or responsibilities for unknown dangers? How does this compare to say astronauts or experimental aircraft pilots?

Seems like they’re going to get sued if the passengers and crew aren’t saved. Possibly even if they are saved. Maybe the contract they get people to sign is tight enough, but everything I’ve read so far seems like they were a bit reckless. They don’t have to inspect their hull for issues every dive; they have real time monitoring of the health at all times! We just pop them back up when we discover an issue… But what…

By the time their monitor tells them they 'have an issue' the only use that will have is forensics, I doubt anybody will be saved.

Re: Titanic tourist submersible goes missing with search under way

#605

Post by jacquesm »

ciguy wrote: post #99

This section from their website is interesting: "Real-Time Health Monitoring The most significant innovation is the proprietary real-time hull health monitoring (RTM) system. Titan is the only manned submersible to employ an integrated real-time health monitoring system. Utilizing co-located acoustic sensors and strain gauges throughout the pressure boundary, the RTM system makes it possible to analyze the effects of…

It tells you when your crew and passengers are dead. There is not going to be any lag between 'RTM system says there is a problem' to 'sub lost'.

Re: Titanic tourist submersible goes missing with search under way

#606

Post by jacquesm »

johnwalkr wrote: post #477
Avlin67 wrote: post #350

let me be naive : carbon fiber composite is about tensile stength, not compression strength ? what happens in the ocean ? compression...

Individual fibres, yes. But the composite material is fibres and resin. Plus the vessel is surely pressurized.

With a pressure differential of 399 atmospheres I don't think that the vessel being pressurized is going to be much of a factor. It might as well be vacuum.

Re: Titanic tourist submersible goes missing with search under way

#607

Post by hkchad »

Vecr wrote: post #579
hkchad wrote: post #551

Earlier quoted context omitted.

Personally I do it because it's the closest I will ever get to feeling like a space explorer. You are neutrally buoyant (weightless) completely relying on your equipment for survival and able to see places IN the earth very few people will ever experience, plus I love a challenge. When most people think of cave diving they imagine really small holes and limited visibility. Sure, that can be it if you want or you can…

I guess you might be saying that, but it's probably not actually true. "I feel less safe driving to some of the caves than I do diving them" see https://www.dg-aviation.de/en/library/safety-comes-first and https://chessintheair.com/the-risk-of-dying-doing-what-we-lo...

So the places we drive to are pretty remote and not in 'safe' spots. So I could sit at the hotel/resort and have no issues or get out on the road to the dive site. Every trip has had a story, not all good ones, but every dive has been worth it.

Re: Titanic tourist submersible goes missing with search under way

#608

Post by aaron74 »

beowulfey wrote: post #524
ciguy wrote: post #99

This section from their website is interesting: "Real-Time Health Monitoring The most significant innovation is the proprietary real-time hull health monitoring (RTM) system. Titan is the only manned submersible to employ an integrated real-time health monitoring system. Utilizing co-located acoustic sensors and strain gauges throughout the pressure boundary, the RTM system makes it possible to analyze the effects of…

> "No other submersible currently utilizes real-time monitoring to monitor hull health during a dive. We want to know why. Classed subs are only required to undergo depth validation every three years, whereas our RTM system validates the integrity of the hull on each and every dive." [1] I suspect your intuition may be why RTM is not really used. Failures happen too quickly for them to give useful preventative data,…

Aviation cross-country flight training maxim: 'If you don't know where you are, you're lost."

Manned Underwater Submersible maxim: "If you must constantly check your hull integrity, your hull isn't safe."

Re: Titanic tourist submersible goes missing with search under way

#609

Post by stickfigure »

jacquesm wrote: post #595
Miraste wrote: post #590

Earlier quoted context omitted.

This is usually done with a plug hatch and it's not that complex. The Alvin submersible has one and it's from 1964.

Exactly. There are so many lessons learned already when designing a device like this there is no point in re-learning them the hard way, just adopt a tried and true design.

That's what they did? Alvin is an outlier; other bathyscaphes used the (tried-and-true) bolt-in method.

Assuming they're out there near the surface bouncing around in 6' waves and whitecaps, what they need isn't a door they can open and drown themselves with. Seems like what they need is a more effective location broadcast.

We don't actually know that they don't have good ways of being found. If they do, it makes it all the more likely that the sub is on the bottom :-(

Re: Titanic tourist submersible goes missing with search under way

#610

Post by boppo1 »

justsid wrote: post #580
venusenvy47 wrote: post #535

Earlier quoted context omitted.

And literally steered with a cheap game controller. There's a YouTube video from CBS of their reporter taking a trip on this thing. It's almost comical how cheap it seems.

What’s wrong with game controllers? They are built to be ergonomic and in use for extended periods of time. Also a lot of people are already familiar with how to use them. Not saying we should replace every bespoke interface with a game controller, but using a game controller isn’t necessarily bad either.

>What’s wrong with game controllers?

I saw a video where he said they used the controllers' built-in bluetooth. Bluetooth is anything but mission-critical. Imagine a disconnect when you're trying to decelerate.

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