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.
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..
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.
https://medium.com/@christian.dobbert/the-missing-bullet-hol...