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Why isn't Titan classed? (2019)

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

#221

Post by actionfromafar »

cbzoiav wrote: post #101
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.

The shuttle did something nobody had done before and was viewed as a genuine step forward in human capability. It was also over 50 years ago and had to rely on technology of the time - uncrewed tests were much harder to perform. This wasn't a particularly ground breaking vehicle in terms of capability and was taking paying tourists...

Interestingly, the first Soviet shuttle flight was uncrewed.

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

#222

Post by mcv »

teeray wrote: post #216
mcv wrote: post #212

TLDR: "The entire shipping industry is doing it wrong, so we're doing it differently." 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.…

It’s possible that it did work flawlessly, but the signal that the hull was compromised failed to change the pixel color on a monitor before the monitor was destroyed by the imploding hull.

Yeah, but that's not "well before". Detecting a problem when it's too late to do anything about it is not quite as useful.

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

#223

Post by zarzavat »

Alupis wrote: post #55
jackmott42 wrote: post #51

Earlier quoted context omitted.

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...

It’s a dumb idea for numerous reasons. The titanium and carbon fibre will expand and contract in relation to temperature and pressure at different rates, they are two different materials with totally different material properties. So you’ve added a second force on the vehicle which is the pulling and pushing of the carbon fiber and titanium from one another. And all you have to hold that together is fancy glue, the glue is taking all that force. A 5 year old could do better.

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

#224

Post by Gwypaas »

TheCondor wrote: post #122
Alupis wrote: post #44

Earlier quoted context omitted.

These sort of sounds occur even in metal (steel/titanium) submersibles.

True. Those metals have flex and recovery to them though, not nearly as rigid as carbon fiber 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.

Which is why the aviation industry is extremely careful. The limit for steel is like 80% for it to recover while for aluminum it is 20-30%. Not including micro cracks.

Thus you need to carefully control the number of cycles, which the aviation industry is extremely diligent about.

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

#225

Post by jsjohnst »

throw0101a wrote: post #102
foota wrote: post #82

Earlier quoted context omitted.

I believe the stresses of the hull going through changing pressures is relevant.

> I believe the stresses of the hull going through changing pressures is relevant. 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...

Pressure at 330ft (aka 100m, way way shallower than Titanic depths) is 10 atmospheres higher than what it is at the surface. Even at 50k feet (higher than most planes operate) air pressure is still > 0.1 atmospheres.

Titanic depths are around 380 atmospheres pressure. So equivalent to the difference of about 133,700 feet and sea level.

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

#228

Post by wcfields »

mustacheemperor wrote: post #165
hadlock wrote: post #158

Earlier quoted context omitted.

The design flaw was that they used a construction material strong in tension, but weak in compression. For a task that is almost entirely compression. On a vehicle that has no need for weight savings. Also in a couple photos looks like they have drilled and screwed a monitor mount directly into the pressure vessel, creating future failure points, rather than gluing a piece of plywood to the hull and screwing into tha…

>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

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

#230

Post by vardump »

foota wrote: post #81
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.

Why go on the shuttle when you can go on the dragon?

One big reason is they weren't contemporary.
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