OceanGate Expeditions Titan DSV loss

That is well worth watching, and DSV Limiting factor is another example of deep-sea vehicles done right. This one is designed for full ocean depth (Challenger Deep).
 
Arjen said:
It depends on what you're used to. I grew up with the metric system and the Celsius scale - any temperature below zero means imminent danger of iced up roads (danger! danger!) as well as a decent chance of skating (yay!). Win some, lose some. 37 degrees centigrade was hammered into my brain as normal body temperature - any weather hotter than that is, as you put it, 'stupidly hot'. 100 degrees centigrade is dead easy to remember as the boiling point of water at sea level.
The beauty of SI - (pedant warning!) which, by the way, uses the Kelvin scale - is the interconnectedness of its units, which spares any astronomer/physicist/biologist/chemist/engineer/mechanic the need to use endless arbitrary conversion constants to calculate what reality is likely to throw their way.
But, again, it's mostly whatever you're used to. Like those antique monetary units of twelve pence to the shilling, twenty shillings to the pound, guineas, crowns et cetera et cetera...

Remind me - how many Ningi go into a Triganic Pu?
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Well, its the other way round, Kelvin uses the Celsius Scala. When temperature was new defined (of course, it is no longer the boiling water), the Kelvin scala was choosen to ease calculations from Celsius to Kelvin. At the time when the Celsius scala was introduced, now none newed there was a minimal temperature of -273° C.
 
(full pedant-mode) From wiki:
Historically, the Kelvin scale was developed from the Celsius scale, such that 273.16 K was 0 °C (the approximate melting point of ice) and a change of one kelvin was exactly equal to a change of one degree Celsius.
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They are two different scales, the difference being that the Kelvin scale has its zero at absolute zero, unlike the Celsius scale's zero which is at 273.16 K - the point where water freezes at sea level. The magnitude of the one degree increment is identical in both scales.

The Kelvin scale is used in SI.
The Celsius scale isn't, although you could argue the Celsius degree increment is still in use in SI.
(/full pedant-mode)
 
What I really hate is when your physicists work exclusively in metric and your technicians work exclusively in imperial and you the engineer are stuck in the middle with a design thats in metric using imperial fasteners... And thats before getting to the absolute cluster that is working with pressure units...
 
Desertfox said:
What I really hate is when your physicists work exclusively in metric and your technicians work exclusively in imperial and you the engineer are stuck in the middle with a design thats in metric using imperial fasteners... And thats before getting to the absolute cluster that is working with pressure units...
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That's probably one of the easiest ones. Round hole size up to next drill bit size from the imperial->metric conversion.

The one I always hated was fractional versus numbered drill bits.
 
Scott Kenny said:
That's probably one of the easiest ones. Round hole size up to next drill bit size from the imperial->metric conversion.

The one I always hated was fractional versus numbered drill bits.
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Fractional, numbered, and letter drills.

And let's not get started on the different wire and sheet metal gauges. It's a rabbit hole almost as bad as turtle evolution.
 
1635yankee said:
Fractional, numbered, and letter drills.

And let's not get started on the different wire and sheet metal gauges. It's a rabbit hole almost as bad as turtle evolution.
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Lettered drills are part of the same sequence as numbers in my mind.

And gauges as a measure of diameter or thickness can go DIAF.
 
Nicknick said:
somthing intresting about carbon fibre, especially regarding compression loading:

View: https://www.youtube.com/watch?v=8b2EgTu9_GU&ab_channel=DarkAero%2CInc
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I don't think that video really covered the use of composites in externally compressed structures, though.

"Carbon Fiber fails without warning" may be a myth, but it's also a useful rule of thumb because there's no plastic deformation to warn you that you're exceeding the yield strength.

assuming a sufficiently quiet environment, you absolutely can hear the resin crackling before it fails. Wasn't there a report that Titan was on the way back up after hearing a bunch of crackling before she imploded?
 
Nicknick said:
I don't care, Cabron...
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Perhaps you can elucidate on your use of the word "cabron" please? There being more than one definition.
Scott Kenny said:
I don't think that video really covered the use of composites in externally compressed structures, though.

"Carbon Fiber fails without warning" may be a myth, but it's also a useful rule of thumb because there's no plastic deformation to warn you that you're exceeding the yield strength.

assuming a sufficiently quiet environment, you absolutely can hear the resin crackling before it fails. Wasn't there a report that Titan was on the way back up after hearing a bunch of crackling before she imploded?
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I can remember there being a suggestion noises were heard from the rear of the hull before they started their ascent but not sure if the noise was described as cracking or what.
 
Nicknick said:
Hi, don't take it too personal, in Spanish everyone can be called "cabron"....
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Not taking anything personal mate, if I do not understand I ask, simples. Have a great day mate.

If I were taking it personal like I could have reacted differently but language is a multi faceted thing after all and changes with generations.
 
So I leave it up to you :)

About the noise, yes I read the same, they heard some cracking but than it was allready too late...
 
Nicknick said:
About the noise, yes I read the same, they heard some cracking but than it was allready too late...
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Exactly.

Each crack sound is the creation of a void, a delamination. Each void is a weakness. At some point pretty quickly, the material strength will drop below the level of force being applied to it. And because each void is in an unpredictable location, the catastrophic failure point is also unpredictable.
 
Given the basic properties of materials and structures, any damage incurred under sustained load is progressive and exponential, not linear.
 
Scott Kenny said:
Exactly.

Each crack sound is the creation of a void, a delamination. Each void is a weakness. At some point pretty quickly, the material strength will drop below the level of force being applied to it. And because each void is in an unpredictable location, the catastrophic failure point is also unpredictable.
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Yes, but I was just the guy who linked that video and didnt produce it myself... Still, here ist was more related to cracking noises during inspection and less so during operation. The other aspect is the compression strength of carbon fibre, which isnt bad at all under the right circumstances.
 
Nicknick said:
Yes, but I was just the guy who linked that video and didnt produce it myself...
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While I replied to you, I'm really challenging the statements on the video.


Nicknick said:
Still, here ist was more related to cracking noises during inspection and less so during operation. The other aspect is the compression strength of carbon fibre, which isnt bad at all under the right circumstances.
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And a basic cylinder without even CF endcaps is NOT the right circumstances.
 
As said before, I believe, the tangential load on the cylinder wasnt the problem, but the connection to the endcaps. It allway depend how you apply the compression load on the carbon fibre, you should not press on the endings on the fibres directly, which makes it hard to find a proper solution for the longitudenal loads in the sub.

BTW; I dont agree to every point in the video, steel is still the best material when it comes to fatigue, it can have a virtual ivinite live when you keep the strain under a certain limit. There is hardly any other material which can do that, not even carbon fibre or titanium. Valve springs are a perfect example, they do see a very high load everytime a valve is fully open (even at idle) but they keep on working reliably for the whole engine life, sometimes a million miles...
 
www.independent.co.uk

Billionaire building $20m sub to prove Titanic wreck site can be visited safely

The billionaire wants to prove Titanic can be visited safely
www.independent.co.uk www.independent.co.uk
nypost.com

Ohio billionaire Larry Connor plans to take $20M sub to Titanic site to prove industry’s safer after OceanGate implosion

An Ohio billionaire is planning to take a deep sea submersible to Titanic wreckage-level depths to prove the industry is safer in the wake of the doomed OceanGate sub that imploded last year.
nypost.com nypost.com
https://twitter.com/x/status/1795384274226692444
View: https://x.com/Schizointel/status/1795384274226692444
 
Well let's give him a chance. Stockton Rush was an arrogant asshole who felt smarter than anybody else and would not left safety rules get in the way, because bureaucracy. Mercifully, that moron died (unfortunately taking a few good people with him). Good riddance.
But SpaceX is proof that a high-tech, dangerous-business, private company can do pretty good aerospace vehicles, even with a moron at the helm. It is a matter of insulating from the said moron - Gwynne Shotwell, how we appreciate you.
If that millionaire is not another Stockton Rush or if he just let engineers doing a good job, then, indeed, a safe submarine could be build to dive at Titanic depth. It is not as if that broke any rule of physics.
One way of doing it: make a copy of the French Nautile, or of the russian submarines (Mir) used by James Cameron.
 
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You 'prove' safety through careful analysis of requirements, proper stress calculations, a thorough understanding of materials and structures and test, test, test. I would pressure test the hull to a pressure substantially in excess of the requirements and test for a significant number pressure cycles.
Performing one successful dive is not a 'proof' that the design is safe.
 
OliverSedlacek said:
You 'prove' safety through careful analysis of requirements, proper stress calculations, a thorough understanding of materials and structures and test, test, test. I would pressure test the hull to a pressure substantially in excess of the requirements and test for a significant number pressure cycles.
Performing one successful dive is not a 'proof' that the design is safe.
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Triton did that with Limiting Factor. They used a pressure chamber in Russia, the only chamber capable of generating enough pressure to simulate an 11 km dive.
Their design was certified by an independent standards body for full ocean depth dives.
 
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I just caught this 60 Minutes (Australia) segment about this tragedy. It reveals that US sources knew on the first day that the craft had imploded, due to detection of (apparently a sound) anomaly near the wreck of the Titanic. James Cameron reveals this (via a US Navy source who told him this), and this is confirmed by a US Coast Guard person interviewed in the segment as well. (The US Coast Guard person claims it was not definitive information, and because it was classified, could not be shared with the public.)

View: https://www.youtube.com/watch?v=Cb9uqlr7b4Q
 
greenmartian2017 said:
I just caught this 60 Minutes (Australia) segment about this tragedy. It reveals that US sources knew on the first day that the craft had imploded, due to detection of (apparently a sound) anomaly near the wreck of the Titanic. James Cameron reveals this (via a US Navy source who told him this), and this is confirmed by a US Coast Guard person interviewed in the segment as well. (The US Coast Guard person claims it was not definitive information, and because it was classified, could not be shared with the public.)

View: https://www.youtube.com/watch?v=Cb9uqlr7b4Q
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SOSUS is an incredibly long-ranged sensor system. Even the early 1960s arrays across the Greenland-Iceland-UK gaps were able to hear Thresher off the coast of Massachusetts and Scorpion off the Azores.

And sadly, an implosion is LOUD.
 
There was an article in this week's Sunday Times where the agenda was quite clear, "Relatives are still searching for answers." Very poor IMO as all the answers are well known by now.
 
OliverSedlacek said:
There was an article in this week's Sunday Times where the agenda was quite clear, "Relatives are still searching for answers." Very poor IMO as all the answers are well known by now.
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I suspect that the answers they're looking for are to questions like "why was this deathtrap allowed to submerge at all?"

Edit: because I cannot believe that any insurance company would underwrite this design.
 
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