Why isn't Titan classed? (2019)
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As a former tall ship captain:
No Shit. Ships stopped sinking when we started requiring inspections and design rules around stability and watertight compartments.
We largely eliminated a common failure mode, designer error, through inspections and classing, so now we are left with the harder failure modes: operator error.
I’m curious if the flag state will get involved here. It’s one thing to push the limits with experimental design (happens all the time in boats, airplanes and cars). It’s a while other thing to use experimental designs in commercial applications. There’s a good reason that the FAA doesn’t allow commercial operators to use experimental registered aircraft…
I hope the rescue teams sue the perpetrators' estates and corpos for their costs.
> The vast majority of marine (and aviation) accidents are a result of operator error, not mechanical failure. As a result, simply focusing on classing the vessel does not address the operational risks.
Aka "classing doesn't mitigate all problems, so we're not going to do it at all"
It's a generic pretend argument: You say doing(or not doing) this thing will be risky. So that means you're saying that people who don't do(or do) the thing have perfect lives with no risks and free ice cream?
You're strangling innovation/A coward!
The relative merits differ, and any given thing is debatable, but “it doesn’t solve everything so it’s no better than nothing” is a nakedly dishonest argument.
I can point to some subtle logic bugs that no sane unit test would have caught.
I've found that it's better to think of unit tests as a contract. You don't write them to check your code for bugs, you write them to declare an explicit (though incomplete) contact that's checked in to source control.
Sure. They have some of the highest costs of failure post-deployment of anyone, and they have some solid development practices. I'll cite NASA in this context any time. Feel free to pull in other sources if you don't like them though.
But the constraints, requirements, and priorities for a given project at NASA won't even be the same as every other project there, let alone projects at pretty companies in different fields.
By extension, I would argue that the concept of universally superior development best practices as a whole doesn't make sense.
"Why do we have laws against slavery? It's not like anyone actually owns slaves. Seems pretty superfluous, so let's just get rid of it!"
Technically correct, too. The vast majority of marine and aviation accidents are the result of operator error… because engineering standards are so good and mechanical failures are so rare.
There's probably a name for that fallacy. People take all the issues that have been solved/addresses for granted, and pretend the unsolved issues are the only ones that matter. And because current methods don't fix those, they're clearly worthless and should be thrown out.
To have something properly function you need both a solid build and maintenance. Doing one well doesn't absolve you of doing the other.
> While classing agencies are willing to pursue the certification of new and innovative designs and ideas, they often have a multi-year approval cycle due to a lack of pre-existing standards, especially, for example, in the case of many of OceanGate’s innovations, such as carbon fiber pressure vessels and a real-time (RTM) hull health monitoring system. Bringing an outside entity up to speed on every innovation before it is put into real-world testing is anathema to rapid innovation. For example, Space X, Blue Origin and Virgin Galactic all rely on experienced inside experts to oversee the daily operations, testing, and validation versus bringing in outsiders who need to first be educated before being qualified to ‘validate’ any innovations.
Gamble with money all you want. Don't gamble with people. Things get fixed, people don't. That is quite a hard lesson for inexperienced people to learn.
I'll also recall the sinking of the Herald Of Free Enterprise - a roll on/roll off ferry that departed Zeebrugge and "rolled over" in shallow water due to the bow door being left open - ie stupidity and a lack of monitoring. That wasn't a tall ship but the same general rules apply.
Those are three samples from 400 years of maritime history. The Vasa was a daft design from the outset (meta vs cog), Mary Rose a daft refit after 30 years of service (it was OK for 30 years and then wasn't) and Herald was basically abused by her crew and lacked monitoring.
Now submarines are pretty new. We do have a fairly long history of making pressure hulls from steel and some other materials but they all build upon earlier designs and they have all been tested with a lot of loss of life for failed designs - the history of submarines is pretty sad.
I gather that all very deep sea hulls are basically spherical. The Titan's pressure hull was made of carbon fibre which I gather no one else has used like that. As well as a novel material its shape was elongated to allow more passengers - that's two changes. Finally we also have a viewing port at the front that was actually tested but never rated for 4000m.
No one really knows what happens to carbon fibre pressure hulls when they go from one atmosphere to 180 and back again, repeatedly, then they are picked up out of the water - more stress and strain. Also, no one really knows what happens at the interface of a "window" to carbon fibre at 180 atmospheres.
There are lots more questions to be answered but frankly I see a company trying to run a submarine with DevOps attitude (move fast and break things) rather than proper maritime grade engineering. At 180 times atmospheric pressure, you die within seconds. No ifs and no buts.
I absolutely stand with you guys in insisting on standards for this sort of thing. It isn't the same as running up Everest or going into space. Deep sea is way, way more dangerous.
Discount, too-old-for-aircraft-use carbon fiber, apparently:
https://www.insider.com/oceangate-ceo-said-titan-made-old-ma...
That doesn't seem right to me. Deep sea and space seem equally dangerous
Without any real justification, I invite you to imagine an elephant pirouetting on top of your skull. Hmmm, nice image, does it stack up:
180 atmos is 186 kg/cm^2 according to random online calculator. That's 2645 psi in old money, according to Google calc. An adult african elephant is about 5-6 tonnes according to several sites (max 6.8 tonnes). So 6000/186 = 32 cm^2. root 32 is about 5.7cm. I really did pluck the elephant thing out of the air and it does seem to work out (please check my 'rithmetic).
Imagine that every 5.7cm^2 of your body/vessel/submarine has an adult african elephant's weight bearing on it.
Now in space we have a bit of a problem with keeping everything in, instead of out but we can lower the internal atmospheric pressure and up the oxygen content (fire risk - procedures!) and other tricks and we have to scrub the CO2 (and so below surface). We also have to worry about very, very fast moving anything, radiation and other issues.
But in space you do not have an elephant's weight crushing each 2.5" square of your body, all the time! That's why deep sea is far more dangerous than space (which is also very dangerous).
[1]: https://en.wikipedia.org/wiki/Soyuz_11#Re-entry_and_death
DevOps is, in part, about using repeatable methods of automation and extensive testing throughout the software development lifecycle to try and make sure that the software you deliver in production will do exactly what it should do and nothing else, and so long as it is properly designed, should be able to withstand significant scaling stress but just getting slower and slower but not less reliable.
From what I can tell regarding the Titan incident, there was no part of a proper DevOps mindset or approach that those people adopted. They people in charge were just damn stupid cowboys out to make a fast Buck from people who were too stupid to know how much in danger they were of losing their lives.
Could that be because the vast majority of mechanical designs go through processes designed to validate them and catch flaws?
They also use SpaceX as an example. SpaceX ran a large number of unmanned launches to prove out the design before putting people on board. Several of those ended in loss of the vehicle and the data from that was used to refine.
It wasn't rated for the depth. In fact, I think it was rated for 1000 meters less than the target depth.
It certainly does for aircraft, and I doubt the material science would be much different for subs (with the added challenge(s) that (salt) water often brings):
* https://www.smithsonianmag.com/air-space-magazine/what-deter...
* https://simpleflying.com/pressurization-cycles-aircraft-life...
Titanic depths are around 380 atmospheres pressure. So equivalent to the difference of about 133,700 feet and sea level.
No, cyclic stresses are a different animal altogether.
But considering it's just a matter of attaching ballast to sink it, dropping ballast to raise it, there's nothing preventing cyclic testing vs. static @ max depth over the same duration.
It seems obvious to me that you'd want to burn through a few test hulls characterizing the fatigue limits and verifying they are at least consistent hull-to-hull with a deterministic failure point you can plan for retiring before approaching.
You just need resources to burn on destroying enough hulls for the data.
And there's a rub there; as you inform the process via destructive iteration, odds are you'll first find the manufacturing process isn't even controlled/consistent enough to make progress on answering the "so how many cycles before go boom boom?" question until you've gone through a good chunk of runway figuring out how to even make it properly multiple times.
I did see that DeepFlight Challenger, Steve Fossett's unused/untested carbon fiber sub which used the same basic design as Titan, was only built to a 1.5x margin of safety. Experimental tests suggested it was only safe for a one time use, and shouldn't be used for multiple dives.
But yeah for stuff like bridges you're probably looking at something closer to 20x
Unmanned submersibles have plenty of market value. You may still be losing money, but you can strap sensors and cameras to the thing / undercut on price for research missions and substantially reduce the cash burn while building investor confidence.
I think submarines use ballast tanks they flood with sea water and empty with pumps to vary their buoyancy. Titan had none of that complexity AIUI, and multiple articles I read mentioned dropping "ascent weights".
So you really only care about their structural integrity at the surface.
Your data will be all over the place from surplus to surplus sale.
[1] https://www.insider.com/oceangate-ceo-said-titan-made-old-ma...
In parallel do it with another hull at the same time. Or maybe more than one. Compare.
Testing to failure is a nice option because it finds certain types of unwelcome surprises.
But it's not really complete, either -- there are probably a lot of ways that a submersible can be compromised, and there's no way to be sure what caused this particular failure.
Most deep sea submersibles only seat a couple people, which wouldn't work for the 'titanic tourism carnival ride' business model. I would guess the weight savings were intended to enable a sub with more capacity that could still be winched on and off the support ship without more complex/expensive heavy lifting equipment.
That was more marketing; the main biz model was to create enough buzz with the oil/gas industry to get bootstrapped and produce a product fleet of cheap subs for independent contractors to use for oil rigs.
https://www.fastcompany.com/40406673/the-man-who-wants-to-se...
The operators with the kind of risk tolerance to support this kind of, uh, venture can’t afford to do deepwater exploration - that’s solely the domain of the industry mega-giants, which are the most safety conscious and risk averse of all. The odds of getting a contract with, say, Exxon for anything resembling that piece of shit submarine are just vanishingly small. I actually don’t think the accident makes that prospect any less likely - it was already about as close to 0 as you can get.
A modern DSV for Challenger Deep (2x the pressure) used Isofloat to save weight and improve buoyancy.
I posit that half the people on HN would volunteer for a hypothetical next shuttle flight without thinking twice.
There's no way in hell I'm getting on one of virgin galactic's death traps, that looks 10 times worse than the space shuttle.
This wasn't a particularly ground breaking vehicle in terms of capability and was taking paying tourists...
NASA actually had a strong focus on safety. They just went about it the wrong way, calculating safety ratings backwards.
Considering the pressure vessel of this sub was only meant to handle 1300m as per another article, the way it survived 50 dives at 4000m is pretty amazing though.
There seems to be a lot of confusion around this, let me try to clear it up.
The 1300m limit of the glass number comes from an interview with the "whistleblower" in 2018. That would mean it refers to the Cyclops 1 vehicle they had then. A couple years later they built the Cyclops 2, which has the 5" thick hull, titanium bells, and first dove in 2021. That's the ill-fated Titan.
If you pay close attention to the videos floating around you'll notice two visibly distinct subs - one with a large transparent dome in front (v1) and one with the titanium bell and tiny porthole (v2).
EDIT: This video (taken from a commenter on this page) includes film of the previous sub, playing next to the guy talking:
https://storage.courtlistener.com/recap/gov.uscourts.wawd.26...
Put spy satellites into orbit and then later retrieve them? That's not to be critical, but we could have done much of the scientific and space station work with a different platform and likely had a much lower mission failure rate. The design of the shuttle wasn't solely about this criteria, though.
I don't think this is a very insightful comparison.
I mean, I light campfires and I put them out. At a level of reductionism very common in online conversations, I am totally hypocritical about whether I want a fire or not.
Which incidentally was exactly what the engineering studies predicted while it was being designed. Which really says something about the quality of engineering analysis which went into creating the Shuttle.
For reference you can nerd out on the following awsome books:
"Space Shuttle Decision, 1965-1972 (History of the Space Shuttle, Volume 1)"
"Development of the Space Shuttle, 1972-1981 (History of the Space Shuttle, Volume 2)"
The other loss of crew was caused by a genuine oversight in the design of the system, in that the orbiter was always susceptible to strikes from insulating foam falling from the external tank.
Unlike Titan, neither one of these failures were due to the inevitable cyclic wear of the primary pressure vessel. They were both devils hiding in the details, neither one the result of reckless hubris.
OceanGate full on admitted that its carbon fiber hull, a major red flag component at the center of its design, was highly experimental and did not know exactly when it would fail. They foolishly thought that strain gauges would detect issues well in advance of failure, while completely ignoring how immediately and catastrophically composite structures are known to fail. They recklessly sold tickets to fund their experimental craft, inviting people aboard who were definitely not made fully aware of just how flawed the design was up front. These were not all members of the Explorers Club — a former head writer for the Simpsons went on a dive, for goodness’ sake.
So to return back to your point, I’d rather take a shuttle after a few dozen flights than get inside a Titan II after a few dozen dives.
Same as Titan -- Management intentionally launched into catastrophe. At least Rush bet his own life on it, not only innocent victims.
I'm not sure about Colombia.
* There were a handful of high-risk options that in all probability would have resulted in one or more dead astronauts. One plan would have been to send the Columbia crew on a spacewalk to try to fashion whatever kind of shield they could jerry-rig to cover the ceramic tiles - like bags of frozen water. The most glorious plan would have been putting the Columbia crew on a minimal sustenance/activity schedule right away and then rushing the next orbiter scheduled to fly (Atlantis, I think it was) into orbit on a rescue mission. I get chills even thinking about that kind of mission, but the shuttle was obviously a temperamental vehicle, and if NASA had cut the normal months of prep time into a handful of weeks, who knows what could have gone wrong with that launch. I have no doubt you would have had 100 or more volunteers among the past and present astronaut corps to fly it though.
Second, the space shuttle never carried any paying passengers.
I'm very much of the opinion that the second you start accepting paying passengers, the safety standards should massively go up. Consumers have an expectation that if a company is offering a service to the general public, that service will meet a minimum level of safety. Companies shouldn't be able to hide behind liability wavers (well, not for a ~2% risk and absolutely not for a 20% risk) as even with a waver explictly stating death is an option, they will under estimate it.
Third, NASA engineers actually quantified the risk all the way back in the design stage and had it at ~2%, remarkably accurate in retrospect. NASA decided that was an acceptable level of risk for their mission profile and went ahead (it would have been way safer if the air force hadn't put insane mission profiles on it)
With everything we now know, there is no way in hell that OceanGate had any level of risk calculation. They were denying any risk at all, asserting that their real-time monitoring procedures would catch any failures before they became critical.
That’s pretty much the NASA equivalent of “paying customers.”
I actually don’t disagree with your point at all, it’s just funny to look back at the teacher in space and who preceeded McAuliffe and who would have been next if Challenger hadn’t blown up (probably Walter Cronkite or Dan Rather).
According to https://metro.co.uk/2023/06/22/how-many-times-has-the-titan-...
"OceanGate has stated that the Titan completed over 50 test dives, including to depths similar to those of the Titanic, both in waters around the Bahamas as well as in a pressure chamber."
Other articles mention 200 dives among three subs. So overall it's hard to know exactly.
I don't see what paying passengers have to do with it. If you could get a space shuttle ride for a few thousand bucks, half of HN would put nonrefundable deposits in today and happily accept a 2% risk of death.
I think the real difference is that more people romanticize space than the deep ocean. That's fine, but don't be smug about it.
A) I expect many HN readers are familiar with how stupid and bureaucratic the shuttle program was and would never agree to fly in one
B) comparing the shuttle to titan is a pretty obvious false equivalence
Boeing max, theranos..
https://medium.com/@christian.dobbert/the-missing-bullet-hol...
> No other submersible currently utilizes real-time monitoring to monitor hull health during a dive. We want to know why. Classed subs are only required to undergo depth validation every three years, whereas our RTM system validates the integrity of the hull on each and every dive.
Completely, completely bizarro in my opinion. I'll take the hull that is proven to actually withstand the pressures it was designed for over some system that gives me a heads up before I get crushed to death.
Related question for those more knowledgeable. I always thought the primary benefit of carbon fiber was tensile strength. I don't even understand how it could sufficiently resist the compressive pressures at the bottom of the ocean - it is a fiber after all. Edit: After seeing the comments below about James Cameron, apparently I'm not alone. From James Cameron's Wikipedia page: "He was also critical of the use of carbon-fiber composite in the company’s Titan submersible, stating that the material has “no strength in external compression” when withstanding the pressure in deep sea environments."
Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses.
Exactly, that's my point. I didn't realize that (this present catastrophe notwithstanding) that carbon fiber could even begin to have such compressive strength. How is the fiber formed in such a way to maintain that strength?
or if sea water degrades the glue, or if the carbon fiber degrades after each trip and eventually isn't strong enough any more, etc.
Tensile strength would make sense in that scenario, but I don't see how it would apply when the cylinder is empty and being crushed by outside forces.
Specifically, the failure mode was delamination.
I can't vouch for how credible this all is - but, given how much disregard the OceanGate team had for safety, it doesn't seem too far fetched.
While it may still be an entirely unsuitable material for 4km, not being suitable for 10km doesn't prove that.
So, sure, it was launched before and recovered, but it never experienced the same conditions which caused the failure.
(At least twice, and probably more times).
Seems like we already found out the answer is “no”. The overall ship design failed.
I'm not arguing in favor of the classification system, but, I think if you went to them and framed things as simply as they are here "you require validation every 3 years, we're doing it on every single dive" they would say "that's more than once per 3 years, APPROVED!" so the situation is clearly far more complicated than they are indicating.
Carbon fiber, however, is not known to gradually fail.
James Cameron said it looks like they had dropped their emergency ascent ballast before the implosion, so they may have gotten enough warning to take action. But I would guess that system was never tested to failure in real life.
It will be interesting to see which of the novel innovations supposedly enabling this unconventional design failed, if it can be determined. Rush also lampshaded the fact that his company had "successfully" bonded the titanium endcaps to carbon fiber despite that being contradictory to conventional materials science wisdom, reading the patent for the monitoring system it looks like it may have been intended to provide warning about those bonds failing too.
I understand epoxy doesn't deal well with that, but with the right plastic, I believe it could work very well.
Even under tension, you need the epoxy to transmit loads between fibres, or else the carbon fibre is pretty useless which is why the finished material CFRP (carbon fibre reinforced plastic) is used. Unlike metals which are generally equal strength in compression and tension, CFRP is roughly half as strong in compression. But it's very light so from a strength point of view it's not automatically the worst material choice. I get Cameron's point but if it really had "no strength in external compression" then it would be a useless material in general.
Regardless of material the main failure mode of a tube with external pressure is buckling, so the strength in compression is much lower than what you expect from a hand calculation that doesn't consider buckling anyway[1]. But CFRP is a risky choice for at least 4 reasons: analysis is not as straight-forward/easy-to-trust, signs of fatigue are harder to detect, delamination is difficult to control[2], and interface to other materials is tricky, especially when temperature changes and water are involved.
[1] You can use hand calculations to check buckling as well but they depend on analytical models which, if they even exist for CFRP, would be quite difficult to trust because there are so many more variables compared to metals.
[2] Delamination must be really nasty when coupled with buckling. Local weaknesses greatly affect buckling, and a even a small void between plys is a local weakness where the plys don't transmit load to each other.
It doesn't matter into which page you scroll, all things you get to read are related to concerns of the security of the sub. Ok, it basically starts at page 9, all before it is legalese bootstrapping.
> Defendant David Lochridge has extensive background as a submarine pilot and training of the same [...] Underwater Inspector, and trained to recognize flaw and points out failure in subsea equipment
> May 2015 [...] began working with OceanGate as an independent contractor
> As a part of his job duties, Lochridge was the Director of Marine Operations and was tasked with "ensuring the safety of all crew and clients during submesible and surface operations."
> Issues of quality control with the new submersible Titan were raised, as there were evident flaws throughout the build process [...]
> Lochridge worked on his report and requested paperword [...] was met with hostility and denial of access to the necessary documentation.
> Lochridge first expressed verbal concerns over the safety and quality control issues regarding the Titan to OceanGate executive management. These verbal communications were ignored.
And so on.
[0] https://www.documentcloud.org/documents/23854184-oceangate-v...
plane_with_red_dots.jpeg
This sounds an awful lot like survivorship bias.
If they if ignore the comment, well that is hubris.
Rinse repeat
> Chesterton’s Fence is a principle that says change should not be made until the reasoning behind the current state of affairs is understood. It says the rash move, upon coming across a fence, would be to tear it down without understanding why it was put up.
But in theory, people are smart, and shouldn't evolve their culture by blind trial and error.
So many people fall for this or talk in such terms like it's perfectly reasonable and it always baffles me. You see it in political discussion a lot.
In political discussions, it's because that's what people do when they don't want to plainly state their real reasons for opposition.
It happens a lot. I think it's one of the big reasons that hyped-up video games and movies always disappoint.
A typo laden with prophecy.
https://www.forbes.com/sites/katherinehamilton/2023/06/21/oc...
>Lochridge also questioned OceanGate’s plans to install a monitoring system on the vessel to detect the start of hull breakdown. His court filing argued “this type of acoustic analysis would only show when a component is about to fail—often milliseconds before an implosion—and would not detect any existing flaws prior to putting pressure onto the hull.”
It's been in most media on the past few days.
And yes, one has to wonder about a warning system that does not warm in advance and which operates in situations where no-one can do anything about it, anyway...
[1] https://www.forbes.com/sites/katherinehamilton/2023/06/21/oc...
Edit: oh dear flood of replies!
There wasn't even an "Uh-oh", as far as we know.
None of this validates using the audio sensor as a warning system because whether you have milliseconds or as much as a couple of minutes warning prior to rapid decompression makes no difference at the depth it occurred, but it does suggest the passengers knew they were doomed prior to the actual decompression.
Do you mean rapid compression (i e. implosion)? The internal pressure in such subs is kept at roughly 1 atmosphere at all depths. The massive pressure difference at depth is why hull integrity is of the utmost importance, if it's compromised, things go south rapidly.
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.
Thus you need to carefully control the number of cycles, which the aviation industry is extremely diligent about.
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/112919...
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.
(insert "this is fine" meme)
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.
It’s the same for the bond between the titanium and carbon composite bits. These things deform differently and at different rates. Stress monitoring is much more difficult than in a single piece.
The acoustic signature predictive of a material compromise or potential
failure may include a large magnitude, high frequency acoustic burst followed by a
sustained interval of acoustic signals of slightly lower magnitude and high frequency,
but still well above a predetermined healthy structure condition.
> However, this does not mean that OceanGate does meet standards where they apply, but it does mean that innovation often falls outside of the existing industry paradigm.
in particular:
> ... this does not mean that OceanGate does meet standards where they apply ...
"...and although that approach is perfectly reasonable from an engineering standpoint, our commercial model can't accommodate it."
The whole reason they were not classed is that carbon composites would not pass any class certifications due to the limits indicated above.
Using the hydrostatic pressure formula:
Pressure = Density of water × Acceleration due to gravity × Depth
Assuming the same density of water (1,000 kg/m³) and acceleration due to gravity (9.8 m/s²):
Pressure = 1,000 kg/m³ × 9.8 m/s² × 4,000 m Pressure = 39,200,000 Pascal (Pa)
Converting to atmospheres:
Pressure in atmospheres = 39,200,000 Pa / 101,325 Pa/atm Pressure in atmospheres ≈ 387 atm
Considering a safety factor of 2, as before, we can calculate the required thickness:
Required thickness = Pressure / (Tensile strength × Safety factor) Required thickness = 387 atm × 101,325 Pa/atm / (434 MPa × 2)
Converting units:
Required thickness ≈ 39,200,000 Pa / (434 × 10^6 Pa × 2) Required thickness ≈ 0.045 meters or 1.48 inches
Therefore, at a depth of 4,000 meters, the titanium walls of the submersible sphere with a 10 ft diameter would need to be approximately 1.48 inches thick to resist implosion, assuming a safety factor of 2. Again, please note that this estimation may vary based on the design, shape, and structural considerations of the submersible sphere. Consulting with experts is essential for accurate calculations and safety assessments.
As for amount of titanium required:
First, let's convert the wall thickness to meters. Since 1 inch is approximately 0.0254 meters, the wall thickness of 1.5 inches would be approximately 0.0381 meters.
Now, let's calculate the internal volume of the sphere by subtracting the volume of the inner sphere (10 ft diameter minus 2 times the wall thickness) from the volume of the outer sphere (10 ft diameter):
Inner radius = Radius of the sphere - Wall thickness Inner radius = 1.524 meters - 0.0381 meters Inner radius = 1.4869 meters
Inner volume = (4/3) * π * (Inner radius)^3 Inner volume ≈ 14.012 cubic meters
Outer volume = (4/3) * π * (1.524 meters)^3 Outer volume ≈ 14.137 cubic meters
Now, we can calculate the volume of the titanium walls by subtracting the inner volume from the outer volume:
Titanium wall volume = Outer volume - Inner volume Titanium wall volume ≈ 14.137 cubic meters - 14.012 cubic meters Titanium wall volume ≈ 0.125 cubic meters
Finally, we can calculate the mass of titanium using the density of titanium (4,506 kg/m³):
Mass of titanium = Titanium wall volume * Density of titanium Mass of titanium ≈ 0.125 cubic meters * 4,506 kg/m³ Mass of titanium ≈ 563.25 kg
Therefore, with a wall thickness of 1.5 inches, the approximate amount of titanium required for the walls of the submersible sphere with a 10 ft diameter would be approximately 563.25 kilograms.
Titanium is currently around $6/kg, so ~$3.4k for just the titanium that made up the wall.
This ain't the innovative win they thought it was. In fact, it's a self-own.
I recently saw a material scientist that specializes in carbon say there wasn't enough money in the world to get her to ride inside a carbon fiber submarine. Why? Carbon fiber has a very high tensile (i.e. stretching) strength. However, it's quite weak when under compression.
Guess which strength is important when operating in a high pressure environment?
Submarines, including deep submersibles, are kind of a solved problem. That doesn't mean there aren't risks involved, but when was the last time a submarine imploded above it's intended operating depth? The 1950s?
The stress/unstress cycle of a vessel going that deep must be immense.
I wonder what that low-pressure o-ring is sealing. I assume the vacuum would only simulate a one atmosphere differential, so that o-ring must not be sealing something exposed to the external pressures at the depths they go down to.
I'm not willing to concede this yet, I'll need to watch some youtube demos of why I'm a dumbass. hah.
As far as decompressing the hull on ascent, I was imagining that if they were testing it by pulling vacuum in it (as mentioned above) there must be some kind of auxiliary air release port...?
The materials must resist the net pressure, which is a vector addition, not division of vector's magnitudes one by another.
That is going to come back and bite them.
It's also worthwhile to be able to experiment with breaking the rules. All said, as someone who jumps from bridges and rides his motorcycle, I support the right of people to take risks and die in the process. Even Russian roulette! Do as you will with your life. You are a pure free agent. Things will happen as a consequence, but that is for you to account for.
It takes all kinds to make this world, and just as we learned from the guys who shoved their head in particle beams, and who over-reflected the demon core, and who mishandled FOOF, and from Carrion's disease, we will learn from this - yep Chesterton's fence was there for a reason.
And on the other side we've got cardiac catheterization, a cure for h. pylori, neurotrophic electrodes. People tried in all cases to tell people not to do things and they keep doing them! I love it. Personally, I, as my part in the human composite organism do all sorts of dangerous things, and it's just part of the process of humanity learning and growing.
> Depth Validating
> As an interim step in the path to classification, we are working with a premier classing agency to validate Titan’s dive test plan. A licensed marine surveyor will witness a successful dive to 4000 meters, inspect the vessel before and after the dive, and provide a Statement of Fact attesting to the completion of the dive test plan.
They clearly did not do this. Simply lowering the thing to the ocean bottom uncrewed would have found this problem. It would not have prevented them from experimenting with crazy designs. It would not have significantly impacted their ability to iterate and move fast. It wouldn't have cost that much to do in the grand scheme of things. I would argue that doing de-risked testing at depth would have expanded their ability to be more radical in their design and overall could have sped up their design iteration. Look at how SpaceX does this, they move fast and break things but make sure that the risk is levered to the reward. The first Falcon rockets did not have commercial payloads at all, nor did the first falcon heavy, Falcon did not fly humans until it was a well-proven rocket. Starship is "failing" constantly but they are doing it in a way which means the impact is minimal and they are learning lots each time.
The really sad part of this is that this probably sets back any innovation in submarine exploration decades. Nobody is going to experiment with carbon composite subs, nobody is going to set out to build a sub with the goal of reducing the per-trip cost by 90% or 99%.
Things, overall, could easily have been so different. Very sad.
It had made several trips to Titanic depth already. A more serious testing and classification probably would have prevented disaster but let’s not pretend this is trivial
It is already of high value to know whether the number is more like 10 or 10,000.
> And that number would be different if you built a second ship.
That is why you build the second ship either as similar as possible to the first one or in a way for which there exists evidence that it will have an improved integrity over the first.
> witness a successful dive to 4000 meters, inspect the vessel before and after the dive, and provide a Statement of Fact attesting to the completion of the dive test plan
And there's absolutely nothing wrong either with the decision making process of the engineers thinking that was a good (and fun) idea.
Also:
> OceanGate’s submersibles are the only known vessels to use real-time (RTM) hull health monitoring. With this RTM system, we can determine if the hull is compromised well before situations become life-threatening, and safely return to the surface. This innovative safety system is not currently covered by any classing agency.
So I guess that system didn't work? All the accounts I've heard suggest that the hull collapsed instantly.
"We're so innovative we don't have time for safety regulations" - An idiot, destined to harm someone unless pure dumb luck causes their company to fail first
So if you neverthess sign up, you are very aware that things might go insanely wrong (and there is actually a very realistic probability of dying). So you really know what you are up to.
> "We're so innovative we don't have time for safety regulations"
reads like "to offer an innovative service which would otherwise not possible, we exchanged known risks (what safety regulations are for to capture and mitigate) for much more unknown risks".
As I wrote: "risks that are likely very hard to actually measure are a huge red flag for any risk-averse person" (and most people are risk-averse), so every customer should be perfectly aware for what he signs up.
This is like a financial adviser who offers a highly innovative finance product with a risk profile that is hard to measure because of its novelty, which the advisor clearly tells. There do exist customers for which such a product is a good choice (say risk-affine, novelty-seeking ones), but such customers are perfectly aware what they are up to.
what I'm wondering is: what's the incentive to be "innovative" in the first place? Unless "innovation" is an end in itself.
Is there some great unmet need to send people to extreme depths, especially when unmanned probes can do most necessar work nowadays?
You can argue, but it won't be with me on the other side. I don't have a dog in that fight.
Two reasons: 1) they had plenty of paying customers, so there was a demand
2) the CEO wanted to be remembered as an innovator, views this as being an explorer, and wanted to inspire people (he said so in interviews)
And see what happens?