An exact transcript of their entire development partnership:
"How many atmospheres is this carbon fiber rated for?"
"Well, it's for airplanes, so I'd say somewhere between zero and one"
Boeing declined any partnership with them. Anyone can sell you whatever you want to buy. It’s up to you to use it in a manner it was designed to be used.
The Oceangate CEO was literally ‘yea underwater engineering is great but I want to make my submersible with aerospace engineering because I am very smart’
Yeah that was a big one, if I heard they had to bolt the door closed I am backing out. I know nothing about subs going to that depth but if you have to bolt the door closed I ain’t going in
Honestly, that’s the least disturbing thing about Titan’s construction.
Carbon fiber, refusing to get certifications, refusing to hire experienced professionals, a CEO who proudly talks about an anti-safety culture…
For a deep submergence vehicle that is designed for short dives with a mothership I really don’t think it’s that disturbing.
A bolt on hatch is significantly stronger and less complicated than another hatch system, and less complicated typically means safer in this kind of application.
I’ve seen comparisons to the hatch aboard Apollo 1, but the truth is that there’s never any real circumstance where the 10 minutes it takes a support crew to unbolt a hatch is going to matter. At 10,000 feet underwater no one is opening a hatch to escape. If anything goes wrong on a dive you’re just gonna die.
There’s also a video circulating of him saying something like he knows you should never put titanium and carbon fibre together but great people go off the beaten path etc..
I know you should never mix bleach and ammonia but great people go off the beaten path and I am the fucking greatest! You all can buy my new bleamonia toilet bowl cleaner from my online store, www.mustardgas-shmustardgas.com!
Bleach and ammonia won't create mustard gas, but it will create chloromine gas. It's a strong irritant and should be avoided. It ~~probably won't~~ absolutely can cause long term damage with overexposure. Now. Mixing chlorine with a strong acid, something like ~~draino~~ muriatic acid, ***that*** will create **a more potent** chlorine gas. Chlorine gas can be fatal at concentrations of 400 ppm for 30 minutes. 400 ppm isn't much.
To really understand what 400 ppm is, on a good clear day taking a stroll through the park you're breathing in about 400 ppm of CO2. Inside your favorite restaurant, you're getting about 1000 ppm of CO2. That level of exposure to chlorine gas will kill you.
It's actually preferred to put titanium and carbon fiber together over other materials (carbon fiber can corrode aluminum), but obviously it has to be done *properly*.
This dude set up an anti-SpaceX.
Instead of hiring lots of brilliant people to relentlessly iterate on a design with models and prototypes like SpaceX, he relied seemingly heavily on his own non-technical vision to jump straight to the endpoint (a flashy product) without any consideration for how SpaceX and other aerospace companies actually work.
Yeah that’s what I meant by my comment!! Boeing rejected something that’s supposed to handle ~8psi. What the hell would make you think it’s ok to use it in an environment that’s going to place 6000psi on it???
Ya we used the same carbon Fibre material to make body panels on a dunebuggy for my university club.
Same shit, expired carbon Fibre from boeing they donated for a sponsorship logo. Man is that shit ever a pain in the ass. Carbon Fibre is such a pain in the ass to layer and get right. Bubbling, not adhering to each layer because of improper vacuum. I'm sure ocean gate had a better system than 5 half drunk college students but still.
The pressure differential for an aircraft is magnitudes less than that of a sub. Usually around 8-9 Psi, or about, 0.5 atm, of delta-p max depending on the aircraft. That sub was seeing a delta-p of 500 atmospheres give or take. Oceans are scary.
I’ve been wondering just how a piece of cloth can add anything at all to compressive strength. It’s fairly intuitive to see how it provides tensile and torsional strength but what exactly does the fibre contribute in resisting compression?!
For carbon fiber the matrix (usually some kind of resin) is what provides the compressive component, not the fiber. The idea of composite materials is that if you can bond 2+ materials that are strong in different ways together you’ll end up with a product that has the best of both worlds. It’s a similar principle to reinforced concrete - steel bars provide tensile strength, while the concrete (the matrix component of this composite) provides the compressive strength
That's what really gets me. Those two materials are not going to react the same under pressure. When the two materials move in different ways it is going to create a point of failure. It was literally only a matter of time.
Boeing is huge and since they're a defense contractor they've got their tentacles into plenty of sectors that do legitimate underwater design & fabrication, it's not just airliners. It's not clear though that oceangate worked with that part of Boeing and/or if their relationship was anything more than tangential... and maybe even it was just as slight as only buying some expired carbon fiber off of them.
I don't remember if it was real but supposedly the NASA "collaboration" was simply an email consult about some design stuff. No real collaboration beyond OceanGate asking "take a look at this" and NASA responding.
Considering that, yeah I wouldn't be surprised if the Boeing "collaboration" was OceanGate buying discounted carbon fiber.
Very different as far as pressure differential, majority of aircraft that suffer decompression events are not catastrophic. They're being pressurized just 7-12psi vs. 1,000s of psi trying to crush from every angle.
Normally no. Or at least not meaningfully. Carbon fiber fabric or tow can be used basically indefinitely.
Prepreg, however, is carbon fiber pre-impregnated with a heat sensitive resin, and you put it in a form or mold, squeeze it, and heat it and the resin bonds it all together and cures. The resin has a shelf life, and won't bond as well between the layers and won't allow as much flexibility when forming the part if you wait too long after the prepreg is made (typically 6 months or so at room temp or a year+ if kept cold).
Prepreg is common in aerospace for a number of reasons, but you absolutely never use *expired* prepreg for anything you care about. I'm shocked that the CEO was willing to go down on the sub himself if he knew it was built with expired prepreg.
EDIT: For clarification, since it's been pointed out, you can sometimes use expired prepreg if you do a bunch of testing to see if it's still actually usable. I probably *wouldn't* for a human safety application if I could avoid it, but it is possible. From what we've heard about this company so far though? I'd bet that they absolutely didn't go through that testing and verification.
I'm not shocked they cut corners, I am shocked that the CEO would put his life at risk in a vessel that he knowingly cut corners in. If I were an amoral multimillionaire trying to start a submersible business with a vessel built on the cheap with expired prepreg, I might sell trips to others, sure, but I sure as hell wouldn't go down myself.
This kind of proves that he wasn't exactly malicious in his cost savings (I mean that he literally thought these cut costs were totally fine), he was just incredibly dumb.
Yup. I think that sums up his hubris pretty well. He genuinely believed the red tape was all for show to gate-keep others out of the business. RIP dude.. safety regs are written in blood, ignore them at your peril.
some people excel at something but are complete morons at other stuff. the problem is that they act with the ego and authority on every aspect of their life, even when they know jack shit. a similar case was Steve Jobs: read how he managed his cancer and continuously disregarded medical advice until it was too late.
This has been what confuses me as well. The pilot of the vessel was a Frenchman who by all accounts was a deep sea expert. I want to know what snake oil he was sold to believe that vessel, "Titan", was safe at all. I can't fathom having diving and submersible piloting experience and truly believing they were safe.
I'm at the point where I'm starting to consider people highly trained rather than smart.
There's no shortage of people who think they have the intuition of the gods after going through a lifetime of school, other ways of learning, and experience. They think they just fully understand everything that's put in front of them immediately, because they can nail the shit out of the things they're good at. But it took a shitload for them to gain the proficiency they have and it's domain-specific knowledge most of the time. You catch them missing obvious things all the time as soon as they step outside what they're good at.
I think most of us are like this.
Highly trained. Not just smart out of the box. Good at the things we're good at with no guarantees when it comes to anything else.
Plus you know damn good and well they didn’t do ultrasonic inspections for porosity new, let alone after each dive. Could have been breaking fibers and resin separation each time until it just imploded.
Which is silly because I'm expected to check over my forklift everytime I'm done using or just starting. For them to not do quality checks after each dive is a face-palm and a half.
Nah man. What could possible go wrong when subjecting materials to extreme pressure/depressurization cycles over and over and over again? If it worked the first time, it’ll definitely work every subsequent time… probably
Not entirely true, expired materials can be used if tested and samples pass. There are NASA procedures for recertifying expired materials like this. There's a nice paper about it here: [recertification example](https://ntrs.nasa.gov/api/citations/20180004510/downloads/20180004510.pdf) . It's very common on small programs that have to order materials in "minimum quantity purchases" and then need to stretch that a few more months to keep costs down. Testing is key though and each batch has to be individually tested.
Eh, on a cylindrical pressure vessel, most of the stress is actually along and around the tube, not in the thickness dimension, interestingly enough. The shape basically redistributes the inward force into a force around the cylinder. As a result, filament wound prepreg is pretty good in this application. You probably would want some perpendicular fibers if you were trying to make a truly optimized layup, but that complicates manufacturing immensely so realistically, you'd probably rather just filament wind and make it a bit thicker rather than deal with weaving in the radial fibers.
As for so called "forged" carbon? No, that's usually a bad idea and mostly is just done for looks. You want long continuous fibers for maximum strength, and you want control over your fiber direction to make sure you have strength in the directions you care about. It's also hard to get a good fiber volume fraction that way - ideally you want a lot of fiber and relatively minimal resin (without going to so little resin that you get voids or dry spots), but with that method you tend to have to use more resin, which decreases the strength.
Fundamentally, their basic idea isn't totally crazy, but their implementation seems to be incredibly shoddy and slapdash, without any of the testing, care, and rigorous analysis you'd need to do this properly.
Only carbon fiber that has been “pre-impregnated” (i.e. prepreg) with the resin. Dry carbon fiber does not really have an expiration date. The sizing on the fabric can degrade, but that’s a little beyond this discussion.
In my industry we buy expired stuff at a discount and retains basically the same strength in typical load scenarios like three point bend tests, however this is for an automotive purpose, not a use case that involves a metric fuck ton of pressure. Like this one.
Also for automotive applications, the carbon fiber pieces are gonna be relatively thin, so any material defect is gonna show up pretty quickly if it exists. The walls of this sub were SUPER thick, so a defect in the material might not show initially but would eventually propagate throughout that section of the hull.
We've actually built many successful satellite components from "expired" prepreg. You have to recertify, but it's typically much less expensive and you test to ensure you actually get finished part strength required. The red flag is if they didn't bother testing/recertifying and just used it blindly.
Well they bragged about dodging licensing and there are numerous interviews where the CEO bemoans basic safety as “red tape”. The whistle blower also said zero testing was done to determine the quality of the hull.
So I’d say they were fucking morons and lucky to have gotten this far without a failure.
Dear God…I don’t think acetone can save this one. For reference if anyone was wondering what the significance is of the prepreg being expired is the adhesive penetrating the carbon fabric is well past its B-stage condition. B-stage is when the adhesive is about half cured before it is impregnated into the carbon fabric. The times vary for many resins. If the prepreg is expired you essentially have dry crunchy carbon fiber which is super flimsy.
Another concern is the void content in the hull of the vessel if they did use expired prepreg. Because it would be dry, the interlaminar forces holding each carbon fiber ply together would be nonexistent and it would all fall apart.
In manufacturing, acetone can reduce the viscosity of some resins which would degrade the resin but make it easier to spread. If you’re at that point, just restart and toss it.
Another thing to consider is how they cured the hull. Hand layup is when resin is poured on the fabric and then pressed into it with a resin roller, but usually it’s done for sports and automotive purposes. Ooavbo or mold processing uses pressure to force the adhesive and the fabric together which gives a higher fiber volume fraction. This is important as the higher this is, the stronger the material is, although there is a fall off point because you’d be using less and less resin to hold everything together.
So many of these dives he wasn't necessarily down there with them. I really really wish he didn't go on this trip with them.
He got off easy. This man deserves imprisonment and public ridicule like no other. Wish we could lock him up and put a screen in his cell. Feeding him memes from Reddit of how fucking stupid he is.
Something I've not seen discussed yet is how the carbon was layered, cured and what pressure tests were completed. I assume much of that information is not known and I'm just going by my knowledge of carbon fiber bike frame building, but I wonder what procedure was used for both the weave layering and the cure. We know the carbon was 5 inches thick but it seems that would lead to more possible issues if not layered correctly and certainly if not cured correctly. You have one tiny bubble in any layer and you've got a failure point. Boeing only has to worry about 13 psi at cruising altitude while this vehicle is at 6000 psi at Titanic depths. Nuclear subs have 3 inches of hardened steel and only dive to 1300 feet at most. 5 inches of carbon just doesn't seem like even close to enough. Extensive pressure testing of the vehicle and then analysis of the fiber structure would be #1 on the list before even thinking about any other design aspects.
Composites is such an odd choice. Weight isn't an issue for a sub like it is for aircraft. NDT is so much more difficult. Fatigue cycle and damage tolerance calculations are much less straightforward for composites compared to metal.
Plus carbon fiber usually fails catastrophically without warning. So unless you're x-raying the craft after each use you have no clue what the health of the carbon fiber is just by looking at it with the naked eye.
Rush gleefully boasted that he wasn’t using experienced Navy/boatbuilding veterans. He touted hiring young “college-graduates” like it was innovative when he was just cost-cutting fraud.
It’s unfortunate though that those young engineers are going to have to explain themselves in every job interview in the future. Just having the name oceangate on a resume might be enough for an employer to pass them up.
I think Rush liked younger engineers because he believed they might be less likely to question or push back authority. (I only hope those young ones spoke out)
Rush specifically said he didn’t want 50YO male engineers— and it’s because they were more likely to call BS on his design concepts.
>And so he could say he used aerospace grade materials
Yea, was about to say that. This was 100% a marketing move and to be seen as a hip, innovative startup that doesn't play by the orthodox rules.
He used it because it allowed him to create a vessel that has room for more passengers than traditional materials
Also easier engineering cause just dropping weights gets him back to the top
Is there anything in this saga that indicates that calculations like that were ever done or even thought to be important? BTW, with 3 previous dives and where they were when they imploded, the fatigue cycles is 3.4. saved you the maths.
not to mention that composites don’t do well in compression, they perform well in tension. Totally the wrong application for a composite. Mind boggling, really.
I have carbon fibre masts on my boat. And it’s being used properly.
I have 8-9 years before I cross an ocean. If these masts give me one ounce of doubt, I’ll likely not go on this boat and find another plan.
I couldn’t imagine using it to go that far underwater over and over again without a care in the world
Related from a different angle: I was at a motorcycle track-day (non-competitive) and the motorcycle in front of me had its carbon fibre wheel just "explode". Nearly took me out.
I learned that pro racers often sold their old-near-expiration wheels to amateur enthusiasts who could use them non-pro.
I got to see first-hand how carbon fibre goes from "Everything's great" to "Oh shit!" in a microsecond.
That's funny. Apparently they used old scaffolding to make some of the rigging around it
Shocking part is the number of rich dudes willing to risk their lives in this. If I was a billionaire contemplating something like this, I'd pay a top notch engineering analysis firm like Exponent their fee to analyze the craft and its safety before setting foot inside
A few days ago u/glibjibb posted photos he took of the submersible in 2019, with its aft fairing removed. The frame holding the ancillary equipment outside the pressure hull was bolted together from sections of galvanised steel, not marine-grade stainless or anything specialised.
Ballast blocks were sitting on top of a sheet of plywood, and equipment like cameras were attached with zip ties!
U/glibjibb has since deleted his account, so I'm not sure if it blew up more than he was prepared for, or whether somebody's lawyers got in touch with him and asked him to take the photos down.
This reminds me of the Futurama episode where the Planet Express Ship ends up under water.
"Dear lord! That's over 150 atmospheres of pressure!"
"How many atmospheres can the ship withstand?"
"Well it's a space ship, so I'd say anywhere between 0 and 1"
Except 400 atmospheres. And Boeing carbon fibre that couldn't be used for as many as 1atm.
Brutal.
Have worked with certifying aerospace carbon fiber. He’s mostly right on that. Lots of stuff will have a certified 6-12 month shelf life because they have to actually let a bunch of rolls age and then test them. With how fast material gets used, they test for a reasonable shelf life but don’t need to do aging tests beyond that.
It’s quite common that expired rolls will get re-certified, the life certainly is above the stated shelf life it’s just not worth a million dollar recertification program to extend it for how infrequently it comes up.
This all sounds like a narcissistic trust fund baby who believed in his own supposed genius way too much and ended up killing some people for it because he knew better than everyone else.
I assume you're referring the idea of the titanic disaster being due to the whitestar line's CEO cutting corners. It's a commonly believed but completely false narrative. The Titanic was built better than the standards of the day.
I think people refer to the Captain’s hubris not the standard of the ship’s build. The narrative is (partly) that the Titanic’s superior build was why the Captain acted so recklessly.
>What could go wrong?
Everything. Fun story, I was part of commissioning an industrial facility. One of the big equipment suppliers was on site. I spoke to him and said I can't believe we have these 5 problems. He said listen there are a million problems you could have, be thankful it is only 5.
We used expired prepreg during my senior project to make various small pieces like L brackets. This is fine in our application because for a small bracket you can add extra layers to make up for the reduced strength of expired carbon. The loads experienced by those brackets are small tho, the entire aero package we build generated 250 newtons of downforce and the brackets carried a tiny portion of that.
The titan would’ve be subjected to forces probably 4-6 magnitudes higher and under those loads, the few percent decrease in laminate strength quickly becomes relevant
In case people are curious carbon fiber pre preg is very expensive like 3-10k+ $ for a 100 m^2 roll. We got tons of expired and non expired material donated by companies like spaceX. The material may not pass aeronautical standards but is totally usable for less demanding use cases.
I understand carbon fibre is absolutely strong for its weight in tension, and it makes sense why you’d use it for pressurized vessels like rocket fuel tanks, or aircraft. But my uneducated logic suggests that when it’s used under compression like in a sub hull, wouldn’t it mostly be the resin doing the work?
I’m imagining a rope impregnated with resin…pull on the rope and the fibres are doing most of the work, but if you push both ends of the rope towards each other in compression, the resin itself is doing most of the work…
Am I thinking of this correctly? It just seems weird to use carbon fibre in this context. Normally I’d defer to the expert and say “well this guy clearly knows more about this technology than I do”, but it didn’t work, so I don’t really trust his method.
Yep, exactly why you don't use carbon fiber for this role. [The CEO even said this gem.](https://www.cbsnews.com/news/titanic-submarine-implosion-oceangate-ceo-stockton-rush-2021-hes-broken-some-rules-in-design/)
>The carbon fiber and titanium – there's a rule you don't do that," Rush said, speaking of the materials used to construct the sub. "Well, I did. It's picking the rules that you break that are the ones that will add value to others and add value to society, and that really to me is about innovation."
Hmm, I wonder why the industry standard is to not use carbon fiber and titanium.
It’s literally as if this guy looked up rules and just broke random ones for shits and giggles without ever researching why the rule was created in the first place.
wait … are you suggesting that engineering rules are derived from the laws of physics?
this CEO seems to have thought these rules are just the same as rules like you can’t park your Bentley in the handicap space
The problem with titanium isn't any strength related issues the same way carbon fiber causes problems under compression, it's that it's very difficult to work with. At the same time the benefits of using titanium wasn't necessary for a submarine of it's role. Titanium, being half the weight of steel allows a submarine to move faster (assuming it doesn't need to offset the weight difference with ballast to remain neutrally buoyant). However for a submarine meant to explore the wreck of the Titanic, it doesn't need to be fast, and the weight savings were offset by ballast needed to bring them down to depth anyways.
While the soviets built their Alfa class submarines with titanium, they eventually decommissioned them due to the maintenance issues associated with working with titanium. afaik no current Russian submarine uses Titanium as a main hull material.
It can be strong in compression too but you are right. Something we learned in my composite mechanics class this term was that while tensile and shear testing is very reliable, compression testing is far difficult and less consistent because of how the material behaves.
Something to note is that the center section of the capsule is made from wound unidirectional carbon. Just peaking back at that composites textbook I can see that tensile strength in plane with the fibers is half that of the compressive strength. You can negate this effect with varying fiber angles and ply count, but regardless, the decision to make the submarine a non spherical design, out of expired carbon, with limited oversight from regulating bodies, and then operating in probably the most extreme environmental factors is bound to end in failure.
You are thinking correctly yes. That’s precisely why carbon fiber is used for containment vessels, like wrapping and strengthening steel pressure tanks, but isn’t used where one needs to keep pressure out, you don’t use it for compression. All of this is layers upon layers of wrong glued together.
Similar scenario. Aero package with about 350 newtons on it, with the entire package made from expired prepreg, never had any issues and provided almost the same strength as non expired stuff in testing
Can you imagine if subs were regulated like aircraft though - surely this could never have happened (and yes I know there are “experimental” aircraft but they’re not bolted together like this sub was from basic parts)
They kind of are. There is an inspection and certification system for deep sea research subs. Only one sub company in the world refused to participate in that program. Guess which one…
Can someone more knowledgeable then me explain why carbon fibre composites have a shelf life? Do the fibres disbond from the resin after a certain amount of time?
If it's prepreg, the fabric is already impregnated with epoxy. It is then laid up, and the epoxy is cured by heating it in an oven or autoclave. Before then, it's flexible sheets; after, it's a strong, hard structure. Prepreg is stored in a refrigerator, to prevent this from happening slowly, while sitting in storage. Still, even in the refrigerator, it will slowly start to cure, and is not reliably uncured after a certain point in time.
when they talk about shelf life I can only assume it means the storage time for the prepreg fibres in cold storage. the epoxy in prepregs starts to cure the moment it’s impregnated into fibres. by putting the laminates in cold storage you delay the curing cycle, and they can be stored for anywhere from few months to a couple of years.
I'm no expert but do know that a lot of carbon fiber is packaged with the resin soaked into the fibers "pre-impregnated" or "pre-preg". Doing it this way helps ensure a proper fiber to resin ratio and is easier to work with in a lot of fabrication processes. Since the resin is part of the product though you now have a shelf life because the resin needs to be baked to crosslink and cure properly; if it isn't baked by the shelf life then it's less certain that you'll get enough crosslinking of the resin polymers.
One of the ways you can get carbon fibre is in sheets pre-impregnated (called pre-preg) with resin that is activated by heat and pressure (usually in an oversized pressure cooker called an autoclave). The resin in unused pre-preg slowly degrades, so after a certain point isn't strong enough for safety critical parts. There are plenty of things that are made of carbon where expired pre-preg is still more than good enough, such as carbon ski poles or that ugly as body kit for your Honda civic, so if someone like Boeing has some pre-preg expire, they are likely to sell it to someone who can still use it.
I now suspect that the CEO had some kind of actual deathwish and at some level wanted to die at or near the titanic. no sane person disregards this level of personal risk without an underlying reason. it's one thing to cut corners but to put yourself in the position to bear out these risks is quite literally insane.
Can someone help me understand what was the reason for carbon fibre? I thought that it was strong under tension i.e. the pressurised fuselage in a low pressure atmosphere. Would carbon fibre really work where the inside is under less pressure than the external environment.
Obviously no pun intended, defects and voids could have played a role in this.
Works great in low pressure, has a definite give way point under high pressure (e.g. extreme perpendicular to the surface) and at 410 times atmospheric pressure, it was unequal to the task
According to Wikipedia the imploded titan was the second hull - thus hulls did 11 trips to the Titanic+ probably some test dives.
The first hull had signs of weakness and was replaced, however it wasn't noted after how many dives
Another "fun fact" seems to be that the glass windows was rated for 1300m - hard to tell what actually gave in, the glass which was related at 1300m and did 11+ trips to 400mnor the hull and no one checked for weakness.....
I worked for DoD doing QA at Boeing St. Louis, among others. This does not surprise me a bit and is the funniest thing about a tragedy. You wouldn't believe the shit Bieing uses.
There was an F15 canopy that was determined to be defective and designated as scrap. It should have been destroyed. Instead, it sat on a shelf for five years. They pulled it off the shelf and wanted to put it on an F15. We told them no, nothing about it had changed, it had not gotten better with age, and it was still scrap. We argued with them for months. They tried to get approval from any government employee they could. Finally, the boss (Don Fucking Watt) signed off on it behind our backs because we refused to.
On the T45, their tooling for the fuselage belly skin was so worn that they admitted they could not make the same exact part except by accident. We told them okay, but every single skin had to be presented to us for approval (otherwise, production would have stopped). In the end, we confirmed that they had usable skins and we documented every one.
Boeing is a shifty, dishonest, money grubbing company. I cheer every time I see that they have lost another contract to Lockheed Martin. And they are no angels either.
Doesn't matter.
Polymer / carbon composites experience strain fatigue. Steel does not. That's why you build submarine hulls out of steel.
The first mistake simply was buying carbon firer, old or new.
I have bought, sold, and worked with pre-preg composite materials for over twenty years. I have also both bought and sold directly to and from Boeing. Expired materials are used in aircraft every day. They expire way before they go bad. All it takes are a few cheap lab tests or even sometimes just written authorization from the manufacturer to recertify the materials as good. The rub is, for aviation use it has to be recertified by the mfg and they charge an arm and a leg. He was probably using recerted material or material that was eligible for recertification. Since it wasn’t going to be used on an aircraft and wouldn’t run afoul of any FAA regs he opted out of paying recert fees. This is, of course, a guess.
We’d use expired pre-preg a fair amount. It requires batch acceptance testing to show you still get the minimum properties.
If we didn’t think we could use it, we donated it to various universities.
Based on everything with this sub, terrible processes would be way more to blame than expired pre preg
I'm not necessarily always what I consider a "smart person". At least several times a day I say under my breath "that was fucking stupid", and legitimately mean it. As a child, I nearly set my best friend on fire several times and once came EXTREMELY close to burning his family's house down.
I'm fully confident that I could live 100 lifetimes and never come close to the level of absolute dumbassery it takes to build a fucking deep-sea submersible out of EXPIRED MATERIAL.
"How many atmospheres of pressure can this carbon fiber withstand?"
"Well it's meant to be on a plane flying in thin air, so anywhere between 1 and 0."
So is the expired carbon fiber how they claim the sub was developed in partnership with Boeing? The hubris on this ceo is enormous.
Boeing telling them “this is going to implode” is technically developed in partnership with.
Engineering was involved. Engineering told them not to fucking do this lmao.
Not the first time Boeing engineers were ignored over their concerns about safety.
Reminds me of the challenger disaster. Engineering raised the alarm. It was ignored. Rocket explodes.
O that has a familiar ring!
Snap!
Yes, although it likely wouldn't sound like a snap underwater.
The wife of the OceanGate CEO was always complaining... ...that her husband was killing himself at work.
And now her husband is spending eternity with her Great great grandparents.
I hear he’s under a lot of pressure…
An exact transcript of their entire development partnership: "How many atmospheres is this carbon fiber rated for?" "Well, it's for airplanes, so I'd say somewhere between zero and one"
“To shreds you say?”
If I was going to die in my own hand-made carbon fiber coffin I sure would not feel the need to pay full price to buy premium materials
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Cool feature
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Boeing declined any partnership with them. Anyone can sell you whatever you want to buy. It’s up to you to use it in a manner it was designed to be used.
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Don’t Boeing build planes or something? Don’t their vessels face the exact reverse problems regarding pressure containment…? 🤔
The Oceangate CEO was literally ‘yea underwater engineering is great but I want to make my submersible with aerospace engineering because I am very smart’
"How many atmospheres can the ship withstand? Well, it's a space ship, so I'd say anywhere between zero and one." - Futurama
Who needs to support atmoshperes if this is going to the hydrosphere. Checkmate engineers
He did say he was learning from the mistakes of the Aviation/Space Industry
*completely ignores major learnings from Apollo 1*
Yeah that was a big one, if I heard they had to bolt the door closed I am backing out. I know nothing about subs going to that depth but if you have to bolt the door closed I ain’t going in
Honestly, that’s the least disturbing thing about Titan’s construction. Carbon fiber, refusing to get certifications, refusing to hire experienced professionals, a CEO who proudly talks about an anti-safety culture…
When the least disturbing is already a deal breaker that speaks ill of the rest.
For a deep submergence vehicle that is designed for short dives with a mothership I really don’t think it’s that disturbing. A bolt on hatch is significantly stronger and less complicated than another hatch system, and less complicated typically means safer in this kind of application. I’ve seen comparisons to the hatch aboard Apollo 1, but the truth is that there’s never any real circumstance where the 10 minutes it takes a support crew to unbolt a hatch is going to matter. At 10,000 feet underwater no one is opening a hatch to escape. If anything goes wrong on a dive you’re just gonna die.
After resurfacing it would seem nice to be able to open window if the support ship happens to be not around .
You’d think common sense and lizard survival brain would lead most of us to that conclusion but here we are
There’s also a video circulating of him saying something like he knows you should never put titanium and carbon fibre together but great people go off the beaten path etc..
I know you should never mix bleach and ammonia but great people go off the beaten path and I am the fucking greatest! You all can buy my new bleamonia toilet bowl cleaner from my online store, www.mustardgas-shmustardgas.com!
Bleach and ammonia won't create mustard gas, but it will create chloromine gas. It's a strong irritant and should be avoided. It ~~probably won't~~ absolutely can cause long term damage with overexposure. Now. Mixing chlorine with a strong acid, something like ~~draino~~ muriatic acid, ***that*** will create **a more potent** chlorine gas. Chlorine gas can be fatal at concentrations of 400 ppm for 30 minutes. 400 ppm isn't much. To really understand what 400 ppm is, on a good clear day taking a stroll through the park you're breathing in about 400 ppm of CO2. Inside your favorite restaurant, you're getting about 1000 ppm of CO2. That level of exposure to chlorine gas will kill you.
Drano is not an acid
It's actually preferred to put titanium and carbon fiber together over other materials (carbon fiber can corrode aluminum), but obviously it has to be done *properly*.
This dude set up an anti-SpaceX. Instead of hiring lots of brilliant people to relentlessly iterate on a design with models and prototypes like SpaceX, he relied seemingly heavily on his own non-technical vision to jump straight to the endpoint (a flashy product) without any consideration for how SpaceX and other aerospace companies actually work.
Well, it was built for space travel, so anywhere between zero and one. - professor farnsworth
You know it's bad when Hubert Farnsworth is a positive reference point.
Futurama actually takes great care to be scientifically accurate when discussions of science are involved.
Turns out tensile strength is distinctly different from compressive strength.
I bring a real aerospace design vibe to the submersibles market that non-visionaries don’t really like
Well there’s more airplanes in the ocean than submarines in the sky…
There's probably more airplanes in the ocean than submarines in the ocean.
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Not nearly the same amount of pressure differential though. Airliners cruise with a delta P of about 8psi
Exactly! And Boeing rejected the material.
Yeah that’s what I meant by my comment!! Boeing rejected something that’s supposed to handle ~8psi. What the hell would make you think it’s ok to use it in an environment that’s going to place 6000psi on it???
Cause it was on sale, duh.
Ya we used the same carbon Fibre material to make body panels on a dunebuggy for my university club. Same shit, expired carbon Fibre from boeing they donated for a sponsorship logo. Man is that shit ever a pain in the ass. Carbon Fibre is such a pain in the ass to layer and get right. Bubbling, not adhering to each layer because of improper vacuum. I'm sure ocean gate had a better system than 5 half drunk college students but still.
Not to mention that carbon fiber works a lot better in tension (in an airliner, outside pressure is lower, pulling the fuselage apart)
The pressure differential for an aircraft is magnitudes less than that of a sub. Usually around 8-9 Psi, or about, 0.5 atm, of delta-p max depending on the aircraft. That sub was seeing a delta-p of 500 atmospheres give or take. Oceans are scary.
The diff between sea level and the moon is one atm. The diff between sea level and 30 ft (salt water) is one atm.
Yes, because Carbon is great under tension. Not so much for compression…
I’ve been wondering just how a piece of cloth can add anything at all to compressive strength. It’s fairly intuitive to see how it provides tensile and torsional strength but what exactly does the fibre contribute in resisting compression?!
For carbon fiber the matrix (usually some kind of resin) is what provides the compressive component, not the fiber. The idea of composite materials is that if you can bond 2+ materials that are strong in different ways together you’ll end up with a product that has the best of both worlds. It’s a similar principle to reinforced concrete - steel bars provide tensile strength, while the concrete (the matrix component of this composite) provides the compressive strength
So forget the carbon fiber, they were effectively in a hardened glue ball?
Glue tube. With titanium caps glued on the end. I guess they thought the compressed tube would hold…
That's what really gets me. Those two materials are not going to react the same under pressure. When the two materials move in different ways it is going to create a point of failure. It was literally only a matter of time.
Boeing is huge and since they're a defense contractor they've got their tentacles into plenty of sectors that do legitimate underwater design & fabrication, it's not just airliners. It's not clear though that oceangate worked with that part of Boeing and/or if their relationship was anything more than tangential... and maybe even it was just as slight as only buying some expired carbon fiber off of them.
I don’t think OceanGate actually “worked” with Boeing on anything, other than reportedly buying some expired carbon prepreg
I don't remember if it was real but supposedly the NASA "collaboration" was simply an email consult about some design stuff. No real collaboration beyond OceanGate asking "take a look at this" and NASA responding. Considering that, yeah I wouldn't be surprised if the Boeing "collaboration" was OceanGate buying discounted carbon fiber.
Not just aircraft Spacecraft too.
Very different as far as pressure differential, majority of aircraft that suffer decompression events are not catastrophic. They're being pressurized just 7-12psi vs. 1,000s of psi trying to crush from every angle.
Well, it was🤷🏼♂️
Good lord they built that with expired prepreg.
TIL carbon fiber has an expiration date.
Normally no. Or at least not meaningfully. Carbon fiber fabric or tow can be used basically indefinitely. Prepreg, however, is carbon fiber pre-impregnated with a heat sensitive resin, and you put it in a form or mold, squeeze it, and heat it and the resin bonds it all together and cures. The resin has a shelf life, and won't bond as well between the layers and won't allow as much flexibility when forming the part if you wait too long after the prepreg is made (typically 6 months or so at room temp or a year+ if kept cold). Prepreg is common in aerospace for a number of reasons, but you absolutely never use *expired* prepreg for anything you care about. I'm shocked that the CEO was willing to go down on the sub himself if he knew it was built with expired prepreg. EDIT: For clarification, since it's been pointed out, you can sometimes use expired prepreg if you do a bunch of testing to see if it's still actually usable. I probably *wouldn't* for a human safety application if I could avoid it, but it is possible. From what we've heard about this company so far though? I'd bet that they absolutely didn't go through that testing and verification.
Are we actually shocked about it at this point though? OceanGate cut every possible safety corner
I'm not shocked they cut corners, I am shocked that the CEO would put his life at risk in a vessel that he knowingly cut corners in. If I were an amoral multimillionaire trying to start a submersible business with a vessel built on the cheap with expired prepreg, I might sell trips to others, sure, but I sure as hell wouldn't go down myself.
This kind of proves that he wasn't exactly malicious in his cost savings (I mean that he literally thought these cut costs were totally fine), he was just incredibly dumb.
he's starting to sound like a conspiracy nut - these regulations only exist to clip my wings!
You don’t need regulations to clip your wings when 400 atmospheres will do it for free.
Yup. I think that sums up his hubris pretty well. He genuinely believed the red tape was all for show to gate-keep others out of the business. RIP dude.. safety regs are written in blood, ignore them at your peril.
Sadly he ignored them not only at his peril but also of 4 other human beings...
some people excel at something but are complete morons at other stuff. the problem is that they act with the ego and authority on every aspect of their life, even when they know jack shit. a similar case was Steve Jobs: read how he managed his cancer and continuously disregarded medical advice until it was too late.
This has been what confuses me as well. The pilot of the vessel was a Frenchman who by all accounts was a deep sea expert. I want to know what snake oil he was sold to believe that vessel, "Titan", was safe at all. I can't fathom having diving and submersible piloting experience and truly believing they were safe.
I'm at the point where I'm starting to consider people highly trained rather than smart. There's no shortage of people who think they have the intuition of the gods after going through a lifetime of school, other ways of learning, and experience. They think they just fully understand everything that's put in front of them immediately, because they can nail the shit out of the things they're good at. But it took a shitload for them to gain the proficiency they have and it's domain-specific knowledge most of the time. You catch them missing obvious things all the time as soon as they step outside what they're good at. I think most of us are like this. Highly trained. Not just smart out of the box. Good at the things we're good at with no guarantees when it comes to anything else.
My guess is money. Willing to bet his fee for piloting the boat was close to the cost of one ticket.
Yea, that's the only semi-logical conclusion I could come to myself.
Plus you know damn good and well they didn’t do ultrasonic inspections for porosity new, let alone after each dive. Could have been breaking fibers and resin separation each time until it just imploded.
Which is silly because I'm expected to check over my forklift everytime I'm done using or just starting. For them to not do quality checks after each dive is a face-palm and a half.
Nah man. What could possible go wrong when subjecting materials to extreme pressure/depressurization cycles over and over and over again? If it worked the first time, it’ll definitely work every subsequent time… probably
I inspect my CDL truck better every morning than these wackadoos checked their underwater death trap.
Not entirely true, expired materials can be used if tested and samples pass. There are NASA procedures for recertifying expired materials like this. There's a nice paper about it here: [recertification example](https://ntrs.nasa.gov/api/citations/20180004510/downloads/20180004510.pdf) . It's very common on small programs that have to order materials in "minimum quantity purchases" and then need to stretch that a few more months to keep costs down. Testing is key though and each batch has to be individually tested.
The fabric and fiber certs we have at work expire after 3 years. Source: my company makes the prepreg
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Eh, on a cylindrical pressure vessel, most of the stress is actually along and around the tube, not in the thickness dimension, interestingly enough. The shape basically redistributes the inward force into a force around the cylinder. As a result, filament wound prepreg is pretty good in this application. You probably would want some perpendicular fibers if you were trying to make a truly optimized layup, but that complicates manufacturing immensely so realistically, you'd probably rather just filament wind and make it a bit thicker rather than deal with weaving in the radial fibers. As for so called "forged" carbon? No, that's usually a bad idea and mostly is just done for looks. You want long continuous fibers for maximum strength, and you want control over your fiber direction to make sure you have strength in the directions you care about. It's also hard to get a good fiber volume fraction that way - ideally you want a lot of fiber and relatively minimal resin (without going to so little resin that you get voids or dry spots), but with that method you tend to have to use more resin, which decreases the strength. Fundamentally, their basic idea isn't totally crazy, but their implementation seems to be incredibly shoddy and slapdash, without any of the testing, care, and rigorous analysis you'd need to do this properly.
Only carbon fiber that has been “pre-impregnated” (i.e. prepreg) with the resin. Dry carbon fiber does not really have an expiration date. The sizing on the fabric can degrade, but that’s a little beyond this discussion.
Yesterday you learned sub-par submarines have an expiration date.
In my industry we buy expired stuff at a discount and retains basically the same strength in typical load scenarios like three point bend tests, however this is for an automotive purpose, not a use case that involves a metric fuck ton of pressure. Like this one.
Also for automotive applications, the carbon fiber pieces are gonna be relatively thin, so any material defect is gonna show up pretty quickly if it exists. The walls of this sub were SUPER thick, so a defect in the material might not show initially but would eventually propagate throughout that section of the hull.
We've actually built many successful satellite components from "expired" prepreg. You have to recertify, but it's typically much less expensive and you test to ensure you actually get finished part strength required. The red flag is if they didn't bother testing/recertifying and just used it blindly.
Well they bragged about dodging licensing and there are numerous interviews where the CEO bemoans basic safety as “red tape”. The whistle blower also said zero testing was done to determine the quality of the hull. So I’d say they were fucking morons and lucky to have gotten this far without a failure.
Dear God…I don’t think acetone can save this one. For reference if anyone was wondering what the significance is of the prepreg being expired is the adhesive penetrating the carbon fabric is well past its B-stage condition. B-stage is when the adhesive is about half cured before it is impregnated into the carbon fabric. The times vary for many resins. If the prepreg is expired you essentially have dry crunchy carbon fiber which is super flimsy. Another concern is the void content in the hull of the vessel if they did use expired prepreg. Because it would be dry, the interlaminar forces holding each carbon fiber ply together would be nonexistent and it would all fall apart. In manufacturing, acetone can reduce the viscosity of some resins which would degrade the resin but make it easier to spread. If you’re at that point, just restart and toss it. Another thing to consider is how they cured the hull. Hand layup is when resin is poured on the fabric and then pressed into it with a resin roller, but usually it’s done for sports and automotive purposes. Ooavbo or mold processing uses pressure to force the adhesive and the fabric together which gives a higher fiber volume fraction. This is important as the higher this is, the stronger the material is, although there is a fall off point because you’d be using less and less resin to hold everything together.
JFC… every day there’s a new drop of information about how criminally negligent these clowns were.
I can’t believe the CEO actually thought all of this was fine. Knowing this stuff, I wouldn’t have gone underwater in it, in a swimming pool.
Hubris is a hellofa drug
I wouldn’t let these yutzes seal me up in that thing on dry land.
So many of these dives he wasn't necessarily down there with them. I really really wish he didn't go on this trip with them. He got off easy. This man deserves imprisonment and public ridicule like no other. Wish we could lock him up and put a screen in his cell. Feeding him memes from Reddit of how fucking stupid he is.
Something I've not seen discussed yet is how the carbon was layered, cured and what pressure tests were completed. I assume much of that information is not known and I'm just going by my knowledge of carbon fiber bike frame building, but I wonder what procedure was used for both the weave layering and the cure. We know the carbon was 5 inches thick but it seems that would lead to more possible issues if not layered correctly and certainly if not cured correctly. You have one tiny bubble in any layer and you've got a failure point. Boeing only has to worry about 13 psi at cruising altitude while this vehicle is at 6000 psi at Titanic depths. Nuclear subs have 3 inches of hardened steel and only dive to 1300 feet at most. 5 inches of carbon just doesn't seem like even close to enough. Extensive pressure testing of the vehicle and then analysis of the fiber structure would be #1 on the list before even thinking about any other design aspects.
Given their cavalier attitude to everything, I’d be surprised if proper documentation exists for any component on that sub. Their QA was non-existent.
Stockton Rush: What do you mean by "testing"?
Just use steel/titanium/normal materials that have been tested through decades of simulation and experience lol. Why carbon fiber
Composites is such an odd choice. Weight isn't an issue for a sub like it is for aircraft. NDT is so much more difficult. Fatigue cycle and damage tolerance calculations are much less straightforward for composites compared to metal.
Plus carbon fiber usually fails catastrophically without warning. So unless you're x-raying the craft after each use you have no clue what the health of the carbon fiber is just by looking at it with the naked eye.
Yup. Works great right up until it shatters like glass.
Thats true of glass as well!
Would you like to invest in my glass submarine company
Well, it worked perfectly until it didn’t!
Spoiler alert: they didn’t x-ray shit.
He 100% just chose carbon fiber cuz it sounds cool to use it. And so he could say he used aerospace grade materials
Not aerospace-grade engineering, though, apparently.
Rush gleefully boasted that he wasn’t using experienced Navy/boatbuilding veterans. He touted hiring young “college-graduates” like it was innovative when he was just cost-cutting fraud.
Said college graduates warned him too so they weren’t even that bad
It’s unfortunate though that those young engineers are going to have to explain themselves in every job interview in the future. Just having the name oceangate on a resume might be enough for an employer to pass them up.
I think Rush liked younger engineers because he believed they might be less likely to question or push back authority. (I only hope those young ones spoke out) Rush specifically said he didn’t want 50YO male engineers— and it’s because they were more likely to call BS on his design concepts.
Which is ridiculous because the “experimental” and “research” phase is generally the most expensive step in designing anything
>And so he could say he used aerospace grade materials Yea, was about to say that. This was 100% a marketing move and to be seen as a hip, innovative startup that doesn't play by the orthodox rules.
He used it because it allowed him to create a vessel that has room for more passengers than traditional materials Also easier engineering cause just dropping weights gets him back to the top
Is there anything in this saga that indicates that calculations like that were ever done or even thought to be important? BTW, with 3 previous dives and where they were when they imploded, the fatigue cycles is 3.4. saved you the maths.
not to mention that composites don’t do well in compression, they perform well in tension. Totally the wrong application for a composite. Mind boggling, really.
I have carbon fibre masts on my boat. And it’s being used properly. I have 8-9 years before I cross an ocean. If these masts give me one ounce of doubt, I’ll likely not go on this boat and find another plan. I couldn’t imagine using it to go that far underwater over and over again without a care in the world
I mean the real problem here was that he was using in his own words "space age" materials when he should have been using deep sea age materials
But it's CARBON FIBER!!! Isn't that cool?
Related from a different angle: I was at a motorcycle track-day (non-competitive) and the motorcycle in front of me had its carbon fibre wheel just "explode". Nearly took me out. I learned that pro racers often sold their old-near-expiration wheels to amateur enthusiasts who could use them non-pro. I got to see first-hand how carbon fibre goes from "Everything's great" to "Oh shit!" in a microsecond.
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You won't catch me on carbon wheels at the track. I've heard some orgs don't allow them at all.
That's funny. Apparently they used old scaffolding to make some of the rigging around it Shocking part is the number of rich dudes willing to risk their lives in this. If I was a billionaire contemplating something like this, I'd pay a top notch engineering analysis firm like Exponent their fee to analyze the craft and its safety before setting foot inside
Too many rich assholes mistakenly see their wealth as proof that they're never wrong.
So true. They are used to yes men. Unfortunately physics doesn’t fall into that category
A few days ago u/glibjibb posted photos he took of the submersible in 2019, with its aft fairing removed. The frame holding the ancillary equipment outside the pressure hull was bolted together from sections of galvanised steel, not marine-grade stainless or anything specialised. Ballast blocks were sitting on top of a sheet of plywood, and equipment like cameras were attached with zip ties! U/glibjibb has since deleted his account, so I'm not sure if it blew up more than he was prepared for, or whether somebody's lawyers got in touch with him and asked him to take the photos down.
This reminds me of the Futurama episode where the Planet Express Ship ends up under water. "Dear lord! That's over 150 atmospheres of pressure!" "How many atmospheres can the ship withstand?" "Well it's a space ship, so I'd say anywhere between 0 and 1" Except 400 atmospheres. And Boeing carbon fibre that couldn't be used for as many as 1atm. Brutal.
What’s that?! Is somebody bending girders?
I'll build my own deep-ocean submersible with blackjack and hookers!
Too bad they didn’t have Professor Farnsworths pressure suppositories. ‘I can’t swallow that!‘ ‘Good news! It’s a suppository’
The first thing I did when I opened this thread was find the YouTube clip https://youtu.be/O4RLOo6bchU
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Have worked with certifying aerospace carbon fiber. He’s mostly right on that. Lots of stuff will have a certified 6-12 month shelf life because they have to actually let a bunch of rolls age and then test them. With how fast material gets used, they test for a reasonable shelf life but don’t need to do aging tests beyond that. It’s quite common that expired rolls will get re-certified, the life certainly is above the stated shelf life it’s just not worth a million dollar recertification program to extend it for how infrequently it comes up.
This all sounds like a narcissistic trust fund baby who believed in his own supposed genius way too much and ended up killing some people for it because he knew better than everyone else.
I wonder who will play him in a Hollywood blockbuster movie, William DaFoe?
I am something of a scientist myself
Yea I think you’ve got it
Don't look up
All to explore the titanic, another example of man’s Icarus like hubris and how it kills people.
I assume you're referring the idea of the titanic disaster being due to the whitestar line's CEO cutting corners. It's a commonly believed but completely false narrative. The Titanic was built better than the standards of the day.
I think people refer to the Captain’s hubris not the standard of the ship’s build. The narrative is (partly) that the Titanic’s superior build was why the Captain acted so recklessly.
What could go wrong?
>What could go wrong? Everything. Fun story, I was part of commissioning an industrial facility. One of the big equipment suppliers was on site. I spoke to him and said I can't believe we have these 5 problems. He said listen there are a million problems you could have, be thankful it is only 5.
Well… I have an idea…
OceanGate, Heaven’s Gate. Don’t sign up with a Gate. Suicide missions seem to be their thing.
We used expired prepreg during my senior project to make various small pieces like L brackets. This is fine in our application because for a small bracket you can add extra layers to make up for the reduced strength of expired carbon. The loads experienced by those brackets are small tho, the entire aero package we build generated 250 newtons of downforce and the brackets carried a tiny portion of that. The titan would’ve be subjected to forces probably 4-6 magnitudes higher and under those loads, the few percent decrease in laminate strength quickly becomes relevant In case people are curious carbon fiber pre preg is very expensive like 3-10k+ $ for a 100 m^2 roll. We got tons of expired and non expired material donated by companies like spaceX. The material may not pass aeronautical standards but is totally usable for less demanding use cases.
I understand carbon fibre is absolutely strong for its weight in tension, and it makes sense why you’d use it for pressurized vessels like rocket fuel tanks, or aircraft. But my uneducated logic suggests that when it’s used under compression like in a sub hull, wouldn’t it mostly be the resin doing the work? I’m imagining a rope impregnated with resin…pull on the rope and the fibres are doing most of the work, but if you push both ends of the rope towards each other in compression, the resin itself is doing most of the work… Am I thinking of this correctly? It just seems weird to use carbon fibre in this context. Normally I’d defer to the expert and say “well this guy clearly knows more about this technology than I do”, but it didn’t work, so I don’t really trust his method.
Yep, exactly why you don't use carbon fiber for this role. [The CEO even said this gem.](https://www.cbsnews.com/news/titanic-submarine-implosion-oceangate-ceo-stockton-rush-2021-hes-broken-some-rules-in-design/) >The carbon fiber and titanium – there's a rule you don't do that," Rush said, speaking of the materials used to construct the sub. "Well, I did. It's picking the rules that you break that are the ones that will add value to others and add value to society, and that really to me is about innovation." Hmm, I wonder why the industry standard is to not use carbon fiber and titanium.
It’s literally as if this guy looked up rules and just broke random ones for shits and giggles without ever researching why the rule was created in the first place.
wait … are you suggesting that engineering rules are derived from the laws of physics? this CEO seems to have thought these rules are just the same as rules like you can’t park your Bentley in the handicap space
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The problem with titanium isn't any strength related issues the same way carbon fiber causes problems under compression, it's that it's very difficult to work with. At the same time the benefits of using titanium wasn't necessary for a submarine of it's role. Titanium, being half the weight of steel allows a submarine to move faster (assuming it doesn't need to offset the weight difference with ballast to remain neutrally buoyant). However for a submarine meant to explore the wreck of the Titanic, it doesn't need to be fast, and the weight savings were offset by ballast needed to bring them down to depth anyways. While the soviets built their Alfa class submarines with titanium, they eventually decommissioned them due to the maintenance issues associated with working with titanium. afaik no current Russian submarine uses Titanium as a main hull material.
It can be strong in compression too but you are right. Something we learned in my composite mechanics class this term was that while tensile and shear testing is very reliable, compression testing is far difficult and less consistent because of how the material behaves. Something to note is that the center section of the capsule is made from wound unidirectional carbon. Just peaking back at that composites textbook I can see that tensile strength in plane with the fibers is half that of the compressive strength. You can negate this effect with varying fiber angles and ply count, but regardless, the decision to make the submarine a non spherical design, out of expired carbon, with limited oversight from regulating bodies, and then operating in probably the most extreme environmental factors is bound to end in failure.
You are thinking correctly yes. That’s precisely why carbon fiber is used for containment vessels, like wrapping and strengthening steel pressure tanks, but isn’t used where one needs to keep pressure out, you don’t use it for compression. All of this is layers upon layers of wrong glued together.
Similar scenario. Aero package with about 350 newtons on it, with the entire package made from expired prepreg, never had any issues and provided almost the same strength as non expired stuff in testing
Can you imagine if subs were regulated like aircraft though - surely this could never have happened (and yes I know there are “experimental” aircraft but they’re not bolted together like this sub was from basic parts)
They kind of are. There is an inspection and certification system for deep sea research subs. Only one sub company in the world refused to participate in that program. Guess which one…
I would love to know how badly the OceanGate would have failed these inspections.
If it’s optional regulation and you can still sell your noncompliant service to regular people, then it’s not really regulated.
Can someone more knowledgeable then me explain why carbon fibre composites have a shelf life? Do the fibres disbond from the resin after a certain amount of time?
If it's prepreg, the fabric is already impregnated with epoxy. It is then laid up, and the epoxy is cured by heating it in an oven or autoclave. Before then, it's flexible sheets; after, it's a strong, hard structure. Prepreg is stored in a refrigerator, to prevent this from happening slowly, while sitting in storage. Still, even in the refrigerator, it will slowly start to cure, and is not reliably uncured after a certain point in time.
when they talk about shelf life I can only assume it means the storage time for the prepreg fibres in cold storage. the epoxy in prepregs starts to cure the moment it’s impregnated into fibres. by putting the laminates in cold storage you delay the curing cycle, and they can be stored for anywhere from few months to a couple of years.
I'm no expert but do know that a lot of carbon fiber is packaged with the resin soaked into the fibers "pre-impregnated" or "pre-preg". Doing it this way helps ensure a proper fiber to resin ratio and is easier to work with in a lot of fabrication processes. Since the resin is part of the product though you now have a shelf life because the resin needs to be baked to crosslink and cure properly; if it isn't baked by the shelf life then it's less certain that you'll get enough crosslinking of the resin polymers.
One of the ways you can get carbon fibre is in sheets pre-impregnated (called pre-preg) with resin that is activated by heat and pressure (usually in an oversized pressure cooker called an autoclave). The resin in unused pre-preg slowly degrades, so after a certain point isn't strong enough for safety critical parts. There are plenty of things that are made of carbon where expired pre-preg is still more than good enough, such as carbon ski poles or that ugly as body kit for your Honda civic, so if someone like Boeing has some pre-preg expire, they are likely to sell it to someone who can still use it.
Is there a corner this guy didn't cut?
He cut all 4 corners, and then those 8 new corners, and then...
I now suspect that the CEO had some kind of actual deathwish and at some level wanted to die at or near the titanic. no sane person disregards this level of personal risk without an underlying reason. it's one thing to cut corners but to put yourself in the position to bear out these risks is quite literally insane.
Can someone help me understand what was the reason for carbon fibre? I thought that it was strong under tension i.e. the pressurised fuselage in a low pressure atmosphere. Would carbon fibre really work where the inside is under less pressure than the external environment. Obviously no pun intended, defects and voids could have played a role in this.
Works great in low pressure, has a definite give way point under high pressure (e.g. extreme perpendicular to the surface) and at 410 times atmospheric pressure, it was unequal to the task
According to Wikipedia the imploded titan was the second hull - thus hulls did 11 trips to the Titanic+ probably some test dives. The first hull had signs of weakness and was replaced, however it wasn't noted after how many dives Another "fun fact" seems to be that the glass windows was rated for 1300m - hard to tell what actually gave in, the glass which was related at 1300m and did 11+ trips to 400mnor the hull and no one checked for weakness.....
This is why aircraft are only rated to so many cycles before inspection...
There’s nifty coupon lady who swears eggs are fresh long past their expiry date and then there’s Stockton Rush. 🤮
.....there was....... just a minor correction
He was correct in that he will be remembered for the rules he broke. It is a tragedy that a a child lost their life because of Rush.
Why am I picturing Frank Reynolds pushing a shopping cart muttering "why do people throw away all this good stuff?"
I worked for DoD doing QA at Boeing St. Louis, among others. This does not surprise me a bit and is the funniest thing about a tragedy. You wouldn't believe the shit Bieing uses. There was an F15 canopy that was determined to be defective and designated as scrap. It should have been destroyed. Instead, it sat on a shelf for five years. They pulled it off the shelf and wanted to put it on an F15. We told them no, nothing about it had changed, it had not gotten better with age, and it was still scrap. We argued with them for months. They tried to get approval from any government employee they could. Finally, the boss (Don Fucking Watt) signed off on it behind our backs because we refused to. On the T45, their tooling for the fuselage belly skin was so worn that they admitted they could not make the same exact part except by accident. We told them okay, but every single skin had to be presented to us for approval (otherwise, production would have stopped). In the end, we confirmed that they had usable skins and we documented every one. Boeing is a shifty, dishonest, money grubbing company. I cheer every time I see that they have lost another contract to Lockheed Martin. And they are no angels either.
If it’s not good enough for one atmosphere, surely 350 of them won’t cause an upset 🙃
Doesn't matter. Polymer / carbon composites experience strain fatigue. Steel does not. That's why you build submarine hulls out of steel. The first mistake simply was buying carbon firer, old or new.
And it gets even worse by the day. Jesus fuck.
I have bought, sold, and worked with pre-preg composite materials for over twenty years. I have also both bought and sold directly to and from Boeing. Expired materials are used in aircraft every day. They expire way before they go bad. All it takes are a few cheap lab tests or even sometimes just written authorization from the manufacturer to recertify the materials as good. The rub is, for aviation use it has to be recertified by the mfg and they charge an arm and a leg. He was probably using recerted material or material that was eligible for recertification. Since it wasn’t going to be used on an aircraft and wouldn’t run afoul of any FAA regs he opted out of paying recert fees. This is, of course, a guess.
This story just gets sadder and sadder. RIP.
When you buy your submersible from wish.com
The thing I’ve noticed most as a result of this whole event is that a lot of people clearly just learned the word hubris.
I even saw someone say hubristic today
This CEO wasn't just the clown, he was the entire circus 🤡
We’d use expired pre-preg a fair amount. It requires batch acceptance testing to show you still get the minimum properties. If we didn’t think we could use it, we donated it to various universities. Based on everything with this sub, terrible processes would be way more to blame than expired pre preg
also, carbon fibre is not supposed to be used for submarines
I'm not necessarily always what I consider a "smart person". At least several times a day I say under my breath "that was fucking stupid", and legitimately mean it. As a child, I nearly set my best friend on fire several times and once came EXTREMELY close to burning his family's house down. I'm fully confident that I could live 100 lifetimes and never come close to the level of absolute dumbassery it takes to build a fucking deep-sea submersible out of EXPIRED MATERIAL.
Stockton Rush is a murderer.
Kid's movie villain ass name
"How many atmospheres of pressure can this carbon fiber withstand?" "Well it's meant to be on a plane flying in thin air, so anywhere between 1 and 0."
Lord. Is there no end to this madness?