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Post by fish on Jun 27, 2023 11:01:12 GMT 12
What a load of crock. Pressure increase is absolutely linear. In your world either the water some how magically becomes less dense the deeper you go and somehow the water above doesn't compress it. Or gravity decreases the deeper you go or maybe both. At 10m the pressure is 2 atm. At 20m it's 3atm At 50m it's 6atm At 1000m it's 101atm On the surface it's 1atm P = ρgh If density (ρ) and gravitational force (h) are constants then the only variable is height. For every 10m you descend the pressure increases by 1atm. It's the very definition of linear. Nb: give or take small variances in density of the water due to salinity and temperature these differences are infinitesimally small and don't even factor into the maths... eg 1.025kg/L @ 20degC vs 1.0kg/L at 4deg C You're confusing pressure with Boyles Law which states the volume of gas is inversely proportional to the pressure. So in the first 10m of diving you will see the greatest change in air volume which is why equalization is so critical in the first 10m and why decompression stops happen in the last 10m. The greatest change in air volume occurs in the first 10m which is why you experience the need to equalise in the first 10m and after that it becomes easier. So at 2atm (10m) the air volume in your ears had halved. At 3atm (20m) the volume of air is 1/3, at 4atm (30m) 1/4th. The pressure is linear but the volume of air is inversely proportional to the pressure. This is also why the first 10m are the hardest to get down, cause in the first 10m you are pushing half the air out of your wetsuit. Duckmaster my good man, did you read what I wrote? You are sounding like Stockton himself and thinking you have understood all of the phenomena when you haven't. Your explanation of Boyles law is good, and close to what I am on about. What is is the percentage change of pressure when descending 10m from the surface, and descending the last 10m to settle on the bottom at 3,800m? The first is a 100% change, the second is a 0.23% change. Why is that important? It relates to change in force (delta force). If there is any elastic modulus in any component of the sub, it affects the rate of expansion / compression on that component. As far as I know, the steel / titanium used on subs like the Trieste and James Cameron's one are non-compressible / non-elastic. The acrylic viewing hatch on Titan was most definitely elastic, cause they measure the deflection the deeper they go. Something like 3/4 of an inch? A key assumption mistake was probably assuming the carbon tube did not have an elastic behaviour. It is a flexible compound and it most definitely has elastic behaviour. Its just that it is so thick that it is hard to measure the deflection / elasticity. Now, think of the example of blowing up a balloon or pumping up a tyre. In the real world I do this with polyethylene pipelines for pressure tests. When you start pumping there is the greatest delta P and delta F. The elastic material absorbs energy and deflects. In these examples it expands. In the sub there is going to be a slight compression. What we find with pipeline tests is we get to 80% of target super quick, then sit there for hours trying to get the last 20% or so up to the target pressure. As you have correctly stated, the pressure increase is linear. Pressure is force, so the force / energy is increasing linearly. The adsorption of force by an elastic material is non-linear. The closer the material gets to its breaking point the less energy it can adsorb. The problem for Stockton came about because he was using the fibre's pinging to monitor and predict a catastrophic failure. I posit that the fibres were pinging due to deflection (a function of elastic behaviour) and not of total energy (force) This means that the rate of pinging is going to slow down just before a catastrophic failure, not increase. He fairly much said this himself, that all the pinging occurs in the first 1,500m of descent. Basically, its like trying to blow up a balloon as big as you can (to win a competition) and knowing when to stop before it bursts. When you start blowing it up, it gets bigger with each breath. When it is almost as big as it will get, each breath makes very little difference to the size. Then, BOOM!
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Post by DuckMaster on Jun 27, 2023 12:20:57 GMT 12
Pressure is linear. I don't know what thing you are referring to but if it doesn't increase linearly then it isn't Pressure. If you want to talk about something else that increases at a different rate proportional to Pressure then call by its proper name, whatever you think it is...? Personally I don't know what this thing you're talking about is, but it isn't Pressure. The pressure on the sub increases linearly with depth. End of story. There might well be some other relevant unit of measure that increases logarithmically and is somehow related to pressure, by all means tell me what that is. Your comment was: There are soo many assumptions he is making in that interview: 1) that pressure increases lineally as depth increases (I've no idea if it does or doesn't, but the rate of change of pressure sure isn't going to be linear). Pressure increases linearly. For every metre you go down the pressure increases by exactly the same amount. If there is some other force or action or thing happening to the sub as a result of the linear increase of pressure then by all means talk about that thing and call it by its scientific name. Whatever it is. But don't call it Pressure.
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Post by fish on Jun 27, 2023 13:15:28 GMT 12
Pressure is linear. I don't know what thing you are referring to but if it doesn't increase linearly then it isn't Pressure. If you want to talk about something else that increases at a different rate proportional to Pressure then call by its proper name, whatever you think it is...? Personally I don't know what this thing you're talking about is, but it isn't Pressure. The pressure on the sub increases linearly with depth. End of story. There might well be some other relevant unit of measure that increases logarithmically and is somehow related to pressure, by all means tell me what that is. Your comment was: There are soo many assumptions he is making in that interview: 1) that pressure increases lineally as depth increases (I've no idea if it does or doesn't, but the rate of change of pressure sure isn't going to be linear). Pressure increases linearly. For every metre you go down the pressure increases by exactly the same amount. If there is some other force or action or thing happening to the sub as a result of the linear increase of pressure then by all means talk about that thing and call it by its scientific name. Whatever it is. But don't call it Pressure. Yes, OK, pressure increases linearly. We can agree on that. What I am talking about (meant to talk about, acknowledging my unclear earlier statement) is energy. Elastic energy. Energy in an elastic structure does not increase linearly. It is the energy in the structure (the carbon tube) that causes it to implode. Or, that the Stockton was monitoring the elastic energy via the fibre pings, which is not related to total pressure (force) on the tube. The point of confusion is that the energy is derived from the pressure. The points of contention are that the carbon tube is an elastic structure. I posit that it is. It is likely that Stockton assumed it behaved as a solid, such as the metal materials. And therefore ignored consideration of elastic energy. He could clearly see it and measure it with the acrylic dome, because he could measure the deformation. He would not have been able to measure deformation in the carbon tube. He deliberately made it to look and behave like a solid structure. That doesn't mean its not absorbing elastic energy though. Ignoring that, or confusing it and the cause of the fibre pings he was using to measure carbon degradation likely lead to the over-estimation of the ability of the tube to not implode.
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Post by harrytom on Jun 27, 2023 13:24:17 GMT 12
Interesting carbon fibre cloth unused only has a 1 month shelf life.
What is the shelf life of carbon fabric? Carbon fiber prepreg needs to be stored at low temperature. At room temperature (25°C), the storage period is only 1 month; at -5°C to 0°C, the storage period can be extended to 3 months; if the temperature is lower than -18°C , the storage period can be increased to more than 6 months.22/04/2022
Do you know the storage temperature of carbon fiber prepreg? - Tanchain
tchaintech.com
Now the mother is saying she gave her seat to the son who wanted to go,but media reports say son didnt want to go?
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Post by Fogg on Jun 27, 2023 15:41:36 GMT 12
Anyone know what they build military subs out of?
Or any other v deep submersibles?
Why the interest in using carbon - I’m no engineer but I think of carbon when you need strength + lightness. But surely weight is less of an issue in a submersible. So what’s wrong with less exotic but heavier construction?
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Post by Bleh on Jun 27, 2023 16:03:31 GMT 12
Why the interest in using carbon - I’m no engineer but I think of carbon when you need strength + lightness. But surely weight is less of an issue in a submersible. So what’s wrong with less exotic but heavier construction? I don't understand the physics of using carbon fibre at all. I can't see how it has any strength at all under compression. Here's two experiments:1. Take a basket ball, wrap it in continuous length of carbon fibre ( without epoxy), that basketball will not be able to expand, the carbon fibre will never let it. Deflate the basket ball and the carbon fibre will crumple - carbon fibre has no ability to withstand compression. 2. Take a basket ball, wrap it in continuous length of carbon fibre ( WITH epoxy), that basketball will not be able to expand, the carbon fibre will never let it. Deflate the basket ball and the carbon fibre will NOT collapse = but what is stopping the carbon fibre from collapsing - it sure isn't the carbon fibre - it's the strength and quality of the epoxy... Carbon fibre is like a rope, it is super strong under expansion but has absolutely zero strength under compression. Carbon fibre for a submarine makes absolutely zero sense to me. Anyone know what they build military subs out of? Or any other v deep submersibles? Steel and Titanium. There are also some places building them out of acrylic.
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Post by Fogg on Jun 27, 2023 16:51:22 GMT 12
That’s a good analogy to explain the strength & weakness (literally) of carbon.
I think if I was in a position to build a sub to take tourists (plus myself) to the bottom of the ocean, I would be hiring ex-naval submarine architects and telling them to over-engineer it.
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Post by eri on Jun 27, 2023 18:48:46 GMT 12
watch the james cameron videos he seems to have had a history of hating titan's carbon fibre for the same reasons fish gives and as the most successful? of a very small group of undersea explorers he; - knows more about the engineering challenges in the field than any other talking head - seems to have been fully in the loop from even before the accident - is rich enough and enraged enough to publicly speak his mind on the subject before the inquiry has even started not saying that makes him 100% right
but it's the closest to 100% right that mugs like us will hear until the inquiry releases its findings in 3? years time
www.youtube.com/watch?v=5XIyin68vEE
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Post by GO30 on Jun 27, 2023 19:11:44 GMT 12
Interesting carbon fibre cloth unused only has a 1 month shelf life. What is the shelf life of carbon fabric? Carbon fiber prepreg needs to be stored at low temperature. At room temperature (25°C), the storage period is only 1 month; at -5°C to 0°C, the storage period can be extended to 3 months; if the temperature is lower than -18°C , the storage period can be increased to more than 6 months.22/04/2022 Do you know the storage temperature of carbon fiber prepreg? - Tanchain tchaintech.com Now the mother is saying she gave her seat to the son who wanted to go,but media reports say son didnt want to go? Plain carbon cloth lasts well, stored properly of course.
Add things to make it pre-preg for example and then time limits kick in.
There is also the varying grades/options that means some could have varying time limits.
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Post by DuckMaster on Jun 27, 2023 19:11:56 GMT 12
If there even is one.
They are struggling to figure out how to proceed.
The sub was registered in the Bahamas. The mothership in Canada. The staff were private contractors and the company is registered in America.
And the incident happened in international waters.
You couldn't find a more complicated jurisdictional fuckwittery if you tried.
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Post by eri on Jun 28, 2023 7:24:31 GMT 12
Chief investigator Jason Neubauer said the US Coast Guard will receive help from Canada, France and the United Kingdom. He said authorities had already mapped the accident site, and the inquiry will aim to address several questions, including:
what may have happened to cause the implosion? how can safety be improved for future submersible voyages? what civil or criminal charges should be laid in relation to the events, if any? Recovery operations in remote parts of the ocean are painstakingly complex, with myriad variables to consider.
The same vessel that identified the initial debris – a deep-sea ROV called Odysseus 6K – is reportedly also being used to look for the vessel’s remaining parts.
an ROV will be able to reliably and quickly transmit data back to a support vessel or onshore facility, since real-time data transfer is often needed to make important decisions on the fly.
That said, even if Odysseus 6K delivers on this, some parts of the Titan may never be found. They may have disintegrated during the implosion, drifted too far away from the search area, or be obscured by other debris.
Underwater hazards, harsh weather and strong currents all add to the challenge – especially by limiting visibility. In the deep ocean, turbidity (haziness) and the absence of natural light means visibility is close to zero. Here, only sonar technology (which uses sound waves) may be used for navigation, mapping and locating objects of interest.
Any debris recovered will undoubtedly be valuable. Debris is physical evidence of the implosion, so analysing it will provide information (such as damage patterns and fractures) that can be used to infer the source of the implosion and the forces involved.
Experts can also conduct chemical analyses of the residue on the wreckage. However, this is affected by seawater, so a prompt recovery will be important. eveningreport.nz/2023/06/27/the-titan-sub-disaster-investigation-has-begun-heres-what-might-happen-next-208464/
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Post by GO30 on Jun 28, 2023 17:03:51 GMT 12
Chief investigator Jason Neubauer said the US Coast Guard will receive help from Canada, France and the United Kingdom. He said authorities had already mapped the accident site, and the inquiry will aim to address several questions, including:
what may have happened to cause the implosion? how can safety be improved for future submersible voyages? what civil or criminal charges should be laid in relation to the events, if any? Recovery operations in remote parts of the ocean are painstakingly complex, with myriad variables to consider. Stockton will be found at fault. The incident will be used to introduce more expansive and compulsory regulations. The target of lawsuits but they won't happen as he's not here no longer and the company will go tits up in a week or 2 so can't be got at either.
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Post by em on Jun 28, 2023 19:17:29 GMT 12
Chief investigator Jason Neubauer said the US Coast Guard will receive help from Canada, France and the United Kingdom. He said authorities had already mapped the accident site, and the inquiry will aim to address several questions, including:
what may have happened to cause the implosion? how can safety be improved for future submersible voyages? what civil or criminal charges should be laid in relation to the events, if any? Recovery operations in remote parts of the ocean are painstakingly complex, with myriad variables to consider. Stockton will be found at fault. The incident will be used to introduce more expansive and compulsory regulations. The target of lawsuits but they won't happen as he's not here no longer and the company will go tits up in a week or 2 so can't be got at either.
Meanwhile the owners of Odysseus 6k are laughing all the way to bank .
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Post by GO30 on Jun 30, 2023 13:30:59 GMT 12
Sounds like some of the crew have made it back up. They look to have recovered a fair whack of it so they should get a good idea of what happened.
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Post by eri on Jul 5, 2023 13:16:15 GMT 12
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