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Why isn't Titan classed? (2019)

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

#251

Post by hgsgm »

proggy wrote: post #178
stickfigure wrote: post #73

Earlier quoted context omitted.

The first space shuttle launch was crewed. It ended up with a ~2% failure rate. The Titan made about 50 dives. So, from a reliability perspective, on par with the shuttle. I posit that half the people on HN would volunteer for a hypothetical next shuttle flight without thinking twice.

One of the shuttle missions that resulted in loss of crew was caused by operating the vehicle outside of the rated temperature envelope (for the SSB O-rings). If that requirement was honored, the failure rate could have been halved. 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…

More specifically, mission control management intentionally chose to launch Challenger after being notified that the launch was rejected by engineering.

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.

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

#252

Post by smoyer »

jtriangle wrote: post #203
TeMPOraL wrote: post #195

Earlier quoted context omitted.

As much as I love the show, I'd call it Star Trek's approach to OSHA. I mean, Starfleet officers are so well-trained and perfect that they don't need safeguards such as guardrails on elevators moving engineers up and down a three story high room that ends up shaking at least twice per episode. And let's not even talk about seatbelts.

Well, idk, every time the ship gets hit some console on the bridge shorts out and the arcflash blows some noname ensign across the room. So, star trek probably isn't the example I'd pull from.

You don't need guardrail s on startrek ... You need the right color shirt!

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

#253

Post by Photogrammaton »

This is the Tragedy of Delamination all over again. I coined the phrase half in jest, modeled on a TV-ad phrase (the tragedy of psoriasis, as I recall), after it turned out that a commercial airline flight went down near JFK Airport two months after 9/11 because a carbon-fiber failure allowed its tail to snap off. Now it looks as if a carbon-fiber failure allowed Titan’s pressure hull to implode. Admittedly, we don’t know yet. But a lot of effort will go into finding out, because (as in that plane crash) lives were lost.

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

#254

Post by noduerme »

icegreentea2 wrote: post #204
noduerme wrote: post #139

Earlier quoted context omitted.

One thing I'm curious about, as someone who knows nothing about the engineering of these things... why wouldn't anyone building something like this choose to over-pressure the sub once people were inside it and it began descending? Wouldn't 2 atmospheres inside represent a 50% reduction in the pressure differential on the hull at depth?

Separate from the comments about pressure differential - even 2 atmospheres is probably enough to risk decompression sickness if they just popped the hatch at the end of the dive. So you'd need some way to reduce the pressure gradually. That either needs a way to vent gas out (which means adding a hole in the hull, which you'd really rather avoid having to deal with), or having a compressor inside the hull, or do the…

I'm not sure why it seems intuitive to me that the external to internal pressure ratio would be the measure of force exerted... i.e. that 2psi vs 1 would have the same net force as 100 vs. 50. I guess it's wrong, hence the responses, but it's still bothering me. Like, it seems intuitive that twice the mass in the same volume should exert twice the force on the inside of the container. I don't completely understand my error. Yes there's still 299 more atmospheres outside, but it's only 150x the inner pressure.

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...?

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

#255

Post by marcosdumay »

_yb2s wrote: post #128
learn_more wrote: post #60

Earlier quoted context omitted.

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

Yes, this doesn't make sense to me either. I suppose it could help prevent bucking and crack propagation, because as the walls of the sub started to bend, one side would have to suddenly be in tension? Still, I wonder if a pure plastic/epoxy hull would have actually been stronger than composite in this situation.

From the design they published of it, I do really think they intended to have the carbon fiber tensioned between a pair of titanium rings.

I understand epoxy doesn't deal well with that, but with the right plastic, I believe it could work very well.

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

#256

Post by marcosdumay »

mr_00ff00 wrote: post #41
tverbeure wrote: post #15

Earlier quoted context omitted.

"We don't need to vaccinate against measles because hardly anyone gets measles."

I have a friend who is a professor of history. He jokes that human history is basically us creating systems to solve problems, then time passes and we remove those systems causes “those types of problems never happen.” Rinse repeat

To be fair, as a general rule, removing the systems makes sense. You don't want to accumulate them forever even after they become useless.

But in theory, people are smart, and shouldn't evolve their culture by blind trial and error.

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

#257

Post by nocoiner »

hgsgm wrote: post #251
proggy wrote: post #178

Earlier quoted context omitted.

One of the shuttle missions that resulted in loss of crew was caused by operating the vehicle outside of the rated temperature envelope (for the SSB O-rings). If that requirement was honored, the failure rate could have been halved. 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…

More specifically, mission control management intentionally chose to launch Challenger after being notified that the launch was rejected by engineering. 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.

With Columbia, Mission Control knew there was a potential issue pretty much as soon as the shuttle reached orbit, but because there was basically nothing* that could be done about it, they essentially were going to not worry the crew too much about it and hope for the best. As I recall, they modified the reentry procedure somewhat to possibly reduce stress on the affected wing. Obviously it did not work.

* 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.

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

#258

Post by theoldlove »

Photogrammaton wrote: post #253

This is the Tragedy of Delamination all over again. I coined the phrase half in jest, modeled on a TV-ad phrase (the tragedy of psoriasis, as I recall), after it turned out that a commercial airline flight went down near JFK Airport two months after 9/11 because a carbon-fiber failure allowed its tail to snap off. Now it looks as if a carbon-fiber failure allowed Titan’s pressure hull to implode. Admittedly, we don’t…

Maybe https://en.m.wikipedia.org/wiki/American_Airlines_Flight_587, though the Wikipedia page dismisses concerns about the composite’s strength.

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

#259

Post by nocoiner »

phire wrote: post #244
stickfigure wrote: post #73

Earlier quoted context omitted.

The first space shuttle launch was crewed. It ended up with a ~2% failure rate. The Titan made about 50 dives. So, from a reliability perspective, on par with the shuttle. I posit that half the people on HN would volunteer for a hypothetical next shuttle flight without thinking twice.

First, it did way less than 50 dives. I'm finding it really hard to find any solid numbers, but I've only found reference to only 3 or 4 previous dives to the Titanic, a test dive and a few dives to much shallower depths. That would put the failure rate for dives to this depth closer to 20%. Second, the space shuttle never carried any paying passengers. I'm very much of the opinion that the second you start accepting…

The space shuttle carried politicians, though! The mission that landed right before Challenger carried the now-administrator of NASA and then Florida Congressman Bill Nelson. They also took up a republican rep or senator from Utah (where the SRBs were built).

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).

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

#260

Post by nocoiner »

wcfields wrote: post #228
mustacheemperor wrote: post #165

Earlier quoted context omitted.

>On a vehicle that has no need for weight savings 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.

> the 'titanic tourism carnival ride' business model. 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... https://t.co/0ee7AImRRh

I guess he didn’t know how safety conscious and risk averse the oil and gas industry actually is. You can be at a meeting in a conference room in downtown Houston, and they’ll start the meeting — like, every single one — with a safety minute and directions to the nearest stairwell.

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.

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