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There were no survivors
It’s more John Carpenter than James Cameron 
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From the discussed Twitter thread:
Carbon fiber is the worst material to make submarines from. You get fatigue that’s difficult to detect and repair from the stress and then suddenly hull failure
And that closely echos Cameron’s comments, and he goes further saying you can’t do determine it’s properties nor do Finite Element Analysis on this material.
Folks here are obviously bright-and I’m a fan of Cameron’s and his movies-but this “carbon fiber makes for a terrible pressure vessel,” seems rash and, well, misguided. I mean they’ve been making commercial jet hulls from this stuff for more that a decade and nary a one has done a Comet.
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Commercial jet hulls do not experience dozens of levels of atmospheric pressure in the same way.
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south park is already working on that
/s it wouldn’t actually surprise me if they really were though, a good plot element would be james cameron having to defend all the backwards completely wrong science presented in “The Abyss” , throughout the episode.
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Commercial jet hulls do not experience dozens of levels of atmospheric pressure in the same way.
Hmm. Please elaborate.
If not, why did airline investigators end up using a giant bathtub on the Comet to determine the cause of the unexpected hull failures (which ended up being due to cracks forming from the edges of the square windows).
Maybe there some nuance I’m missing, but it seems to me like pressure is pressure, either coming from the outside in or inside out.
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Every 33ft is 1 ATM of pressure with sea water. The exponential difference is a factor.
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Pressure coming from the inside puts the pressure vessel in tension; coming from the outside puts it in compression. Some materials don’t mind as much; fiber composites tend to be more graceful under tension.
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It’s been said elsewhere but that’s a totally different application.
When used to contain internal pressure a pressure vessel is put under tension, which is what carbon fiber is good at. But even then, there are limits. Composite CNG fuel tanks have legally-defined expiration dates because you can’t easily inspect them and determine what the damage is from repeated high pressure cycles.
A submarine hull is put under tremendous compression, not tension, so the carbon fiber doesn’t do much to help you and you’re basically getting all the compressive strength from the epoxy binder. It has almost nothing in common with the forces on a composite aircraft.
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Some materials don’t mind as much; fiber composites tend to be more graceful under tension.
Ah interesting. I can buy that. The TIL I get from this board are awesome. 
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Every 33ft is 1 ATM of pressure with sea water. The exponential difference is a factor.
Agreed there’s a huge difference in pressure.
But to Cameron’s overall point of “carbon fiber + subs = bad” (e.g. it’s inscrutable as you’re unable to do FEA on it) just seem incorrect. For example I just found this interesting paper that appears to be be a suitable material upon which you can use FEA just fine.
The obtained experimental values were used for the static and dynamic crash analysis of the bow, stern and foil through Finite Element Analysis (FEA)
Overall it seems like it can be a good submarine material. For example, it is nice and light, but you just need to do the proper engineering around it. Again, from the paper:
The present study investigated the suitability of S-Glass/Carbon fibers reinforced polymer composite for design of submarine hull that can travel up to 7000 m of sea depth. Experimental investigation revealed that the composite material exhibited combination of strength, stiffness and density that is comparable to many composites or metals at lower density (i.e.higher specific strength and stiffness).
…
it was concluded that S-Glass/Carbon fibers reinforced polymer composites are mechanically stable to withstand the hydrostatic and impact loads.
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A balloon is great at holding its shape as long as the pressure is from the inside …
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The giant bathtub was used to accelerate the fatigue process. It was a means to get the testing done in a reasonable time to identify the root cause and lift the grounding order.
Carbon fibre (and almost all fibers). Great on tension, bad in compression.
Difference in change in pressure going from sea level to 35,000 feet is about 10psig (pushing outward). Difference in pressure going from sea level to 3,000 meters underground is about 5000 psig (pushing inward).
All aircraft have an inspection schedule based on time and/or cycles. Certain areas of the aircraft are inspected more than others. Engineers have determined where the areas of particular need for inspection are and set the maintenance schedule. There are also scheduled overhauls and NDI done on key areas. The aircraft is designed with a high safety factor and multiple redundancies. These submarine operators were not doing any preventive maintenance on an experimental vessel that seems to have had no safety factors in the design and was operating beyond the limits of the materials (clearly).
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… once again, we’re not talking about aircraft
Saving weight is not helpful at all in a submarine, much less a priority — they have to take on ballast because they’re not heavy enough
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Welcome to BoingBoing!
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I saw an interview on TV where the person interviewed tried to give an illustration of how fast the hull collapse was. IIRC she said the human brain takes 2.8 milliseconds to sense something but the hull collapse at those depths would take just over a millisecond. She mentioned a collapse at 1500 mph, so that’s about a Mach 2 implosion speed.
Carbon fiber in most aviation, automotive, bicycles and other applications is built up to relatively thin amounts. It’s pretty easy to test 1 to 5mm thicknesses for voids and delamination vs. a 125mm thickness.
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All this talk about carbon fiber & compression vs. tension forces and the physics involved at depth is irrelevent to the fact that those people are dead because Joe Biden isn’t enough of a leader, or something…
At least, according to this guy:
…the Republican lawmaker claimed the international search effort appeared to be a case of “epic failure in leadership,” possibly stretching into the White House and upper echelons of the Coast Guard and Navy.
This goober is now my Representative in Congress, thanks to redistricting.
As if Ted Cruz isn’t enough…
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I mean, he has a point. If only Dark Brandon had cared enough about teh billionairz to zip on down there 90 minutes after they started their dive and pull them out of the sub to safety just before it imploded, they’d still be alive today, hoarding money and brib…er… donating to Republican politicians and Supreme Court judges.
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Stated this way, then this incident was a good thing.
Talk about a moral dilemma…
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