Submersible missing while visiting Titanic wreck

[MrMobodies]

At 10:47:27 a.m. (local), the TITAN messaged, “dropped two wts”. The depth of the TITAN was approximately 3341 M. This was the last message that was sent from the TITAN.

6 seconds later at 10:47:33 a.m. (local), the TITAN was pinged for the final time. The TITAN’s location was 41.73441N; -49.9424E. The depth of the TITAN was 3346 M.

As well as going down 5 meters I wonder could the dropping of the weights have in any way helped contribute to the breakup.

[floobydust]

The debris field (CG-103) huge, about a  edit: chart scale is wrong 20km strip and 8km wide. That must have been brutal to search such a wide area by Pelagic Research Services ROV. Never saw any interior items in ROV vids.

Anyone remember their ChemE thermodynamics? Napkin calc I looked at one simple number - how much was the air volume inside Titan compressed?
It blowed up at 328 bar, so ideal gas law would say squished to 1/328 of the vessel's roughly 4.41m³ net volume... that's down to 0.0135m³ or about 1/2 cu. ft. total... and you are all squished like a bug.
I did not look at the Steam Tables to see what happened to the air- temperature, density and phase if it goes superheated etc.

[Mr.B]

The debris field (CG-103) huge, about a 20km strip and 8km wide. ...

I am not convinced the scales shown on those charts are correct.
The first chart has a circle centered on the St Johns Lighthouse, that is marked 68000m (68km), but the scale does not match that by a long shot.
The second chart has a circle centered on the LAST KNOWN POSITION TITAN, that is marked 200m. The scale appears to be correct.
The third chart shows part of that same circle, but the scale appears way off.
Going by the second chart, the debris field appears to be about 350m long, not 20km.

I may be wrong, but I doubt the search debris rectangle was 160km2. That to too big an area to search in the time they spent and the small articles of debris found.
~350m X ~150m would be more realistic.


Edit: To correct search to debris.

[nctnico]

The debris field (CG-103) huge, about a 20km strip and 8km wide. ...

I am not convinced the scales shown on those charts are correct.
The first chart has a circle centered on the St Johns Lighthouse, that is marked 68000m (68km), but the scale does not match that by a long shot.
The second chart has a circle centered on the LAST KNOWN POSITION TITAN, that is marked 200m. The scale appears to be correct.
The third chart shows part of that same circle, but the scale appears way off.
Going by the second chart, the debris field appears to be about 350m long, not 20km.

I may be wrong, but I doubt the search debris rectangle was 160km2. That to too big an area to search in the time they spent and the small articles of debris found.
~350m X ~150m would be more realistic.


Edit: To correct search to debris.

The size of the circle on page 2 (200 meters ) to indicate the size of the search area shows you are about right.

[Phil1977]

There is one thing we just don't know that heavily influences the way this thing imploded.

Just for explanation, here are the two extremes:
a) Super quick destabilisation of the carbon fibre hull leading to a cavitation-like implosion bubble. In that case I wouldn't be surprised if some of Stockton Rushes very personal hydrogen atoms are helium now.
b) A sealing failure that let high pressure water ingress into the sub before the hull imploded. In that case there would be less destruction. E.g. a failure in a pressure feed through could have filled the sub with water and killed its crew without any big destruction around.

The released videos clearly show truth is between a) and b) - but I really can't estimate the implosion power by looking at the residues.

[tom66]

If it was (b), wouldn't the hull be mostly intact with dead occupants inside?  Instead, we see damage along the lines of a catastrophic failure of the hull, which has delaminated into the individual one-inch layers of carbon fibre and adhesive.

[floobydust]

Titan was 431m/1414ft above seafloor and I have no idea of ocean currents at that depth, to carry debris around.
I wasn't sure to trust that PPT slide for the scale- but they are incorrect, post fixed.

My interest was finding dimensions for the submersible, and what happened to the oxygen cylinders inside. I've never seen that wreckage. The tanks were under the floorboard. Wondering if they breached and there was a msec combustion? Did it light up?
Because the scale of things here is mind boggling. Everything inside completely disintegrated it seems.

[Phil1977]

If it was (b), wouldn't the hull be mostly intact with dead occupants inside?  Instead, we see damage along the lines of a catastrophic failure of the hull, which has delaminated into the individual one-inch layers of carbon fibre and adhesive.

Yeah, that´s what I´ve meant with the truth is somewhere between (a) and (b), probably near (a). It´s definitely not (b) because of the described destructions, but we don't know if the destruction comes from the worst possible implosion (the total hull collapsed at once) or if e.g. the front collapsed first. But I also think both cases are fast enough to be painless 

[floobydust]

To fill'er up my math is 1,165 gallons of water/4,413 L at 4,750 psi - not sure how long that takes including the time for a CF crack to build.

[nctnico]

Titan was 431m/1414ft above seafloor and I have no idea of ocean currents at that depth, to carry debris around.
I wasn't sure to trust that PPT slide for the scale- but they are incorrect, post fixed.

My interest was finding dimensions for the submersible, and what happened to the oxygen cylinders inside. I've never seen that wreckage. The tanks were under the floorboard. Wondering if they breached and there was a msec combustion? Did it light up?

That is a good point. There was way more oxygen onboard than just the contents of the hull. Only question is whether they used pure oxygen or compressed air. Compressed air is simpler to acquire and easy to handle but pure oxygen would take less space at the cost of risk with dealing with pure oxygen leaks. And there had to be some way to get rid of exess air as well. Still, CO2 scrubbing is far more important compared to getting extra oxygen. In a closed space, you'll die of CO2 poisoning first, not by lack of oxygen.

Either way, as (dive) air and oxygen tanks are typically operated at pressures from 200 to 300 bar, it is possible these tanks got crushed by the water pressure while heating up the contents inside. Pure oxygen could ignite / burn the metal tank it is in.

[floobydust]

They might have been scuba air tanks? - but these are filled with compressed air to 3,000psi and not liquid. I remember seeing small green tanks under the floorboards.
I'm not sure what was in the tanks to get that purported 96 hour spec. for five people. I thought lox but that needs heaters. Not sure what a scrubber extends that.

James Fisher and Sons plc has many commercial products for subs including scrubbers.
Stockton's Home Depot special ala Apollo 13-style CO₂ scrubber didn't quite cut it so he likely bought something commercial.
Even with this life-support system, have to wonder if he did it on the cheap as well, nobody seems to look at its design as further shoddiness.

After the hearing I guess we wait for the Coast Guard final report and then I imagine lawsuits galore. OSHA cannot be sued as a gov't agency.
]https://www.wired.com/story/titan-submersible-hearings-end-oceangate-coast-guard-heres-what-comes-next/]

[nctnico]

They might have been scuba air tanks? - but these are filled with compressed air to 3,000psi and not liquid. I remember seeing small green tanks under the floorboards.

The color for oxygen tanks is typically green. So if the tanks where green, they would very likely contain pure oxygen.

[vad]

To fill'er up my math is 1,165 gallons of water/4,413 L at 4,750 psi - not sure how long that takes including the time for a CF crack to build.

The energy released by the implosion is about 140 MJ, equivalent to 75 pounds of TNT - more than the explosive content of a typical 155 mm artillery shell (30-60 pounds).

[dietert1]

I checked the numbers as follows: Imagine a cylinder of variable length, a monster syringe if you want so. Start with length 0 m and pull out to 4 m. The force needed is 1 m² * 3500 m * 1 t/m³ = 3.5E7 N, where 3500 t is the weight of a 3500 m high water column with 1 m² area. This constant force acting along 4 m works 3.5E7 N * 4 m = 1.4E8 J as 1 J = 1 Nm. That energy gets released by the implosion. Imagine 3500 t falling down from a height of 4 m. By the way that takes about 1 second.
The energy released by exploding TNT is assumed to be 4.184E6 J/kg on average. Division gives 1.4E8 J / 4.184E6 J/kg = 33.46 kg.
Part of the energy smashed the hull. Another part was emission of sound (a load bang). Some part gets dissipated as thermal energy - a slight temperature increase of surrounding water. The water volume affected was at least the same 4 m³ = 4000 Liter where the submersible was before implosion. Divide 1.4E8 J / (4000 L) / (4190 J/(L*K)) = 8.35 K, as an overall estimate for the heating of water.

Regards, Dieter

[vad]

Slightly easier estimation:

E ~= P * deltaV

Delta V is 4.4 cubic meters. External pressure at the depth of 3200 meters is approximately 320 atmospheres (roughly 1 atmosphere per 10 meters of depth), or 32 MPa (1 atmosphere is approximately 100 kPa):

E = 32 MPa * 4.4 m3 = 140.8 MJ

The energy released by explosion of 1 kg of TNT is 4.18 MJ. So the Titan’s implosion is equivalent to explosion of 140.8 MJ / 4.18 MJ/kg = 33.7 kg of TNT, or 74 pounds.

[dietert1]

I asked myself: How can the submersible lift 3500 t of water by 4 m when it descends? Its weight needs to be more than 4 t, otherwise it won't descend. While it descends, its weight force is working over a distance of 3500 m. Different process, yet same energy amount as before. Imagine the submersible free-falling from a height of 3500 m and you have another image for the violence of the implosion.
My 1 second time estimate above isn't the most likely result. If the submersible collapsed on its side, a water column of 4 m² or 14 000 t of water would move over a distance of only 1 m to fill the volume, and the delay from inertia would be only about 0.45 second. I'd guess the truth is in between.
Another consideration regarding the safety factor: If one assumes delamination of the outer 1" layer of carbon fiber this weakened the hull by about 20 % and reduced their 1.09 safety factor to 0.87. Failure was expected to happen, and roughly at the depth where it finally occurred.

Regards, Dieter

[johansen]

The implosion happens at approximately the speed at which an object would fall if dropped in a vacuum from the surface. 830 feet per second.

As for the hull, the principal issue was the kink bands concentrating expansive forces inside the hull at random locations. Eventually enough delamination occured and buckled somewhere

[johansen]

The energy needed to push the sub down to depth is equal to the energy stored in the compressibility of the submarine (assuming its neutral buoyant at depth and floats at the surface)

Once it implodes you have to lift 4400kg back to the surface.

[BILLPOD]

Hmmmmmm.........anyone hear what the biggest piece of human body found in the wreckage?   I'm guessing all the bones and even skulls disintegrated.

[tom66]

I suspect when they say "suspected human remains" they found some pink goo and it tested positive for DNA of one or more of the occupants.   

No chance of anything recognisable.     

[SiliconWizard]

Yes everything must have been disintegrated and the resulting remains must have been dissolved in water within a few hours. Maybe they found traces of stuff indeed on parts of the submersible.

[floobydust]

They did find some "presumed human" remains and were sent for DNA analysis. A fake pic was out there but there is one of a... boot. I would say everyone became an instant pancake or hamburger.

There are some sea animals - eels, worms, giant sea spiders down there. They would have had some dinner possibly.
One news story mentioned a shark seen in the background of an ROV video. I thought this is hogwash, it's too deep and pretty cold near freezing.

I don't think you use the vessel's mass 9,525 kg (21,000 lbs) for energy calcs. Wouldn't it be the water displaced?

[Bud]

One news story mentioned a shark seen in the background of an ROV video. I thought this is hogwash, it's too deep and pretty cold near freezing

There. The poor creature was like  "WTF...?"

[nctnico]

It is interesting how ductape is used & survives in any environment. 

They did find some "presumed human" remains and were sent for DNA analysis. A fake pic was out there but there is one of a... boot. I would say everyone became an instant pancake or hamburger.

I read a quote somewhere saying a human body acts pretty much like a liquid at such high pressures.

I don't think you use the vessel's mass 9,525 kg (21,000 lbs) for energy calcs. Wouldn't it be the water displaced?

Agreed. It is about water displacement where it comes to energy buildup from water pressure.

[vad]

I don't think you use the vessel's mass 9,525 kg (21,000 lbs) for energy calcs. Wouldn't it be the water displaced?

Agreed. It is about water displacement where it comes to energy buildup from water pressure.

For energy calculation, we only need to account for the volume of the air bubble inside the habitable chamber of the submersible, as this is the volume that collapsed during the implosion. This volume is different from the submersible’s displacement volume, which also includes the volume of construction materials, equipment (both internal and external), the syntactic foam mounted on the exterior, and the tissue volume of the passengers.

The volume of the habitable chamber can be calculated using the dimensions listed on Wikipedia: a 2.4-meter-long cylinder with an internal diameter of 142 cm, and two half-domes of the same diameter.

V = pi * R^2 * L + pi * 4/3 * R^3
V = pi * 0.71^2 * 2.4 + pi * 4/3 * 0.71^3 = 5.3 cubic meters

From this, we subtract the tissue volume of the victims (about 0.35 cubic meters, estimated from an average adult weight of 75 kg), and lets say 250 kg of interior liners, tanks, and other equipment - approximately another 0.05 cubic meters, assuming an average specific weight of materials of 5000 kg/m3.

Thus, the volume of the imploded air bubble was approximately 4.9 cubic meters, about half of the submersible’s displacement volume.