Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why isn't Titan classed? (2019)

web.archive.org

Post reply on HN
Print view View original

51–60 of 302 posts

Re: Why isn't Titan classed? (2019)

#51

Post by jackmott42 »

hn_throwaway_99 wrote: post #40
cbzoiav wrote: post #26

Earlier quoted context omitted.

The craft survived several launches - that proved it can do it. Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses.

> The craft survived several launches - that proved it can do it. 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?

align layers of fibers in different directions and you can get strength in different directions. But it is tricky! The glue holding the metal end caps to the carbon tube is also a possible failure point. Imagine a metal ring slid over a carbon tube held on with glue. If pressure deforms the metal differently than the carbon, you get a gap at the interface and BOOM

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.

Re: Why isn't Titan classed? (2019)

#53

Post by AdamJacobMuller »

cbzoiav wrote: post #26
hn_throwaway_99 wrote: post #22

> 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. > No other submersible currently utilizes real-time monitoring to monitor hull health during…

The craft survived several launches - that proved it can do it. Whether it can do it reliably / survive fatigue accross repeated cycles is a different question. Imagine we'll find out as the investigation progresses.

As far as I'm aware, and please correct me if I'm wrong, they had never dove to this depth before.

So, sure, it was launched before and recovered, but it never experienced the same conditions which caused the failure.

Re: Why isn't Titan classed? (2019)

#54

Post by lozenge »

dghlsakjg wrote: post #43

> They [inspections] do not ensure that operators adhere to proper operating procedures and decision-making processes – two areas that are much more important for mitigating risks at sea. 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…

Titan didn't have a flag, it only operated in international waters. But the surface support vessel has a Canadian flag, and Canada's launching an investigation.

Re: Why isn't Titan classed? (2019)

#55

Post by Alupis »

jackmott42 wrote: post #51
hn_throwaway_99 wrote: post #40

Earlier quoted context omitted.

> The craft survived several launches - that proved it can do it. 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?

align layers of fibers in different directions and you can get strength in different directions. But it is tricky! The glue holding the metal end caps to the carbon tube is also a possible failure point. Imagine a metal ring slid over a carbon tube held on with glue. If pressure deforms the metal differently than the carbon, you get a gap at the interface and BOOM or if sea water degrades the glue, or if the carbon f…

A point raised by James Cameron (and others) was the titanium bands mated to the carbon fiber hull. Apparently in the material science community, that's a huge no-no, and a well known one to boot. Galvanic corrosion or something like that...

Re: Why isn't Titan classed? (2019)

#56

Post by DeRock »

dghlsakjg wrote: post #43

> They [inspections] do not ensure that operators adhere to proper operating procedures and decision-making processes – two areas that are much more important for mitigating risks at sea. 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…

Their reasoning is fundamentally flawed.

> 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"

Re: Why isn't Titan classed? (2019)

#57

Post by bmurray7jhu »

dpedu wrote: post #3

Patent for their hull monitoring system: https://patents.google.com/patent/US11119071B1/en

  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.
The patent concedes that a structural failure may be presaged by a "large magnitude ... burst", but does contemplate thst such a burst may be unsurvivable.

Re: Why isn't Titan classed? (2019)

#58

Post by AdamJacobMuller »

hn_throwaway_99 wrote: post #22

> 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. > No other submersible currently utilizes real-time monitoring to monitor hull health during…

Truly bizarre. Failures like this happen in milliseconds, it doesn't matter how realtime your realtime monitoring is.

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.

Re: Why isn't Titan classed? (2019)

#59

Post by justrealist »

gilney wrote: post #36
cbzoiav wrote: post #16

> The vast majority of marine (and aviation) accidents are a result of operator error, not mechanical failure. 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 vehicl…

https://xkcd.com/1827/

I think the point is that while SpaceX had a lot of explosions, they fundamentally approached rocket development very responsibly as regards to human risk. It's not about observation bias.

Re: Why isn't Titan classed? (2019)

#60

Post by learn_more »

hn_throwaway_99 wrote: post #22

> 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. > No other submersible currently utilizes real-time monitoring to monitor hull health during…

I too am perplexed. Perhaps the compressive strength is all derived from the epoxy not from the carbon fiber.
Post reply on HN