5 ms·

Saw this today. https://www.youtube.com/watch?v=0mSq6ibKKXQ https://www.youtube.com/watch?v=0mSq6ibKKXQ

ARandomerDude 3y ago
That’s pretty wild. The operator was able to tell when they were going deeper based on the sound of the carbon fibers cracking in the hull.
- Alupis 3y ago
  These sort of sounds occur even in metal (steel/titanium) submersibles.
  - TheCondor 3y ago
    True. Those metals have flex and recovery to them though, not nearly as rigid as carbon fiber FWIW, archers tap or attempt to flex arrows and listen to them to tell if the carbon has cracked. An intact arrow will flex a little, silently where damaged ones will crackle and sometimes splinter or shatter.
    - Gwypaas 3y ago
      Which is why the aviation industry is extremely careful. The limit for steel is like 80% for it to recover while for aluminum it is 20-30%. Not including micro cracks. Thus you need to carefully control the number of cycles, which the aviation industry is extremely diligent about.
  - mrguyorama 3y ago
    Navy subs literally deform while diving. If you tie a string tight from one bulkhead to another (from left to right, not front to back), as you dive, the string will go slack and you can tug on it. Destin (smarter every day) demonstrates this in one of his submarine videos.
  - _yb2s 3y ago
    I would say that is different. A steel part will make sounds as it rapidly flexes under pressure or temperature cycling, but those sudden movements can be within the "endurance limit" of the material, and not lead to fatigue or failure. The hull sounds they were hearing in Titan were likely snapping of carbon fibers (based on the linked video above), which means a permanent reduction in strength each time it happens. DeepFlight Challenger, the unused submarine that pioneered this type of design, was intended only for single use: "But the company that built DeepFlight Challenger has told The Telegraph it refused to back the project, insisting the submarine was suitable for only one dive and could not be reused because of the pressure on its structure at such depths." "The problem is the strength of the vessel does decrease after each dive. It is strongest on the first dive.” https://www.telegraph.co.uk/news/science/science-news/11291994/Sir-Richard-Branson-quietly-shelves-Virgin-submarine-plan.html https://www.telegraph.co.uk/news/science/science-news/112919...
  - mechhacker 3y ago
    Yep I think there's plenty of growth/shrinkage creaking from small gaps opening and closing and from structures sliding around on normal metallic subs. But, I bet this sounded different and more terrifying, and was fibers/matrix breaking and cracking. And amplified by the total lack of acoustic materials inside the sub. I thought about this last night and it kept me up a bit. Most of my experience now with carbon, after a little work on structural analysis of layups, has been masts for windsurfing. I've had a couple high performance carbon masts that use 90% carbon and 10% glass break on me. The outer glass is to help against impacts. I've had a case where I heard a little cracking noise then pow, the mast totally collapses into two pieces and I'm in the water. The consequences are usually much much lower when you're on a board floating in water than when underwater thousands of feet down, but the sound in that thing must have been horrible. I want to see his video though.
- RajT88 3y ago
  Holy Shitballs. Cracking noises! Things which you never want to hear on a submersible! (insert "this is fine" meme)
  - deleted 3y ago
    [deleted]
  - lb1lf 3y ago
    You hear those in conventional subs, too, as you go deeper the hull makes all sorts of worrying creaks. (During a sea trial, I had to be aboard a sub from $NAVY diving to 900 feet and change - the crew assured me the sounds were normal...)
mustacheemperor 3y ago
Interesting, he says the theory he currently finds most plausible and has heard from other experts is that water was able to penetrate the flange connecting the titanium caps to the pressure hull. So the hull itself may not have been the first to go. But of course that failure is intrinsically connected to the carbon fiber nature of the sub.

That’s pretty wild. The operator was able to tell when they were going deeper based on the sound of the carbon fibers cracking in the hull.

Alupis 3y ago
These sort of sounds occur even in metal (steel/titanium) submersibles.
- TheCondor 3y ago
  True. Those metals have flex and recovery to them though, not nearly as rigid as carbon fiber FWIW, archers tap or attempt to flex arrows and listen to them to tell if the carbon has cracked. An intact arrow will flex a little, silently where damaged ones will crackle and sometimes splinter or shatter.
  - Gwypaas 3y ago
    Which is why the aviation industry is extremely careful. The limit for steel is like 80% for it to recover while for aluminum it is 20-30%. Not including micro cracks. Thus you need to carefully control the number of cycles, which the aviation industry is extremely diligent about.
- mrguyorama 3y ago
  Navy subs literally deform while diving. If you tie a string tight from one bulkhead to another (from left to right, not front to back), as you dive, the string will go slack and you can tug on it. Destin (smarter every day) demonstrates this in one of his submarine videos.
- _yb2s 3y ago
  I would say that is different. A steel part will make sounds as it rapidly flexes under pressure or temperature cycling, but those sudden movements can be within the "endurance limit" of the material, and not lead to fatigue or failure. The hull sounds they were hearing in Titan were likely snapping of carbon fibers (based on the linked video above), which means a permanent reduction in strength each time it happens. DeepFlight Challenger, the unused submarine that pioneered this type of design, was intended only for single use: "But the company that built DeepFlight Challenger has told The Telegraph it refused to back the project, insisting the submarine was suitable for only one dive and could not be reused because of the pressure on its structure at such depths." "The problem is the strength of the vessel does decrease after each dive. It is strongest on the first dive.” https://www.telegraph.co.uk/news/science/science-news/11291994/Sir-Richard-Branson-quietly-shelves-Virgin-submarine-plan.html https://www.telegraph.co.uk/news/science/science-news/112919...
- mechhacker 3y ago
  Yep I think there's plenty of growth/shrinkage creaking from small gaps opening and closing and from structures sliding around on normal metallic subs. But, I bet this sounded different and more terrifying, and was fibers/matrix breaking and cracking. And amplified by the total lack of acoustic materials inside the sub. I thought about this last night and it kept me up a bit. Most of my experience now with carbon, after a little work on structural analysis of layups, has been masts for windsurfing. I've had a couple high performance carbon masts that use 90% carbon and 10% glass break on me. The outer glass is to help against impacts. I've had a case where I heard a little cracking noise then pow, the mast totally collapses into two pieces and I'm in the water. The consequences are usually much much lower when you're on a board floating in water than when underwater thousands of feet down, but the sound in that thing must have been horrible. I want to see his video though.
RajT88 3y ago
Holy Shitballs. Cracking noises! Things which you never want to hear on a submersible! (insert "this is fine" meme)
- deleted 3y ago
  [deleted]
- lb1lf 3y ago
  You hear those in conventional subs, too, as you go deeper the hull makes all sorts of worrying creaks. (During a sea trial, I had to be aboard a sub from $NAVY diving to 900 feet and change - the crew assured me the sounds were normal...)

mustacheemperor 3y ago

Interesting, he says the theory he currently finds most plausible and has heard from other experts is that water was able to penetrate the flange connecting the titanium caps to the pressure hull. So the hull itself may not have been the first to go. But of course that failure is intrinsically connected to the carbon fiber nature of the sub.