That's why they cancelled their dives earlier this year: The weather didn't cooperate.Stat Monitor Repairman said:
That seems dangerous from the stand point that there's got to be a maximum sea state to recover that sub.
So if the sub is down for an extended period of time and resurfaces to a heightened sea state, the submersible could become unrecoverable and the people trapped inside. They might not be able to get it back on deck. They'd have to send people onto the barge to unbolt the end cap in an emergency situation.
I could see people getting trapped in the sub due to deteriorating weather on the surface.
Just launching and recovering the sub seems really dangerous. You'd have to really confident in your weather window. Seems like they'd have been better off chartering a vessel with a moon pool. some sort of dive support vessel specially designed for that.
Adventure to the Titanic goes terribly wrong [Staff Warning in OP]
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Last: 4 mo ago by Stat Monitor Repairman
That seems a little…basic?
Again, I don't know what the norm would be.
Obviously, this guy cut corners wherever he could. But damn.
As a passive observer, it seems like if one were taking a vessel miles under the ocean, one would use something more intense than a cordless drill to seal the vessel shut.
At this point, it seems like this guy was trying to see how absurd he could make every aspect of this piece of junk.
Again, I don't know what the norm would be.
Obviously, this guy cut corners wherever he could. But damn.
As a passive observer, it seems like if one were taking a vessel miles under the ocean, one would use something more intense than a cordless drill to seal the vessel shut.
At this point, it seems like this guy was trying to see how absurd he could make every aspect of this piece of junk.
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I'm treating this "potential human remains" the same as "noises detected every 30 minutes". One goomba can make a tweet and our very thorough and professional journalist pool runs with it.
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The pressure should help push the hatch in and seal it, if it's designed properly...
I've seen pictures of the Alvin and the Triton and the hatch design is very different. They have hatches on the top of their sphere pressure vessel.
I've seen pictures of the Alvin and the Triton and the hatch design is very different. They have hatches on the top of their sphere pressure vessel.
MarathonAg12 said:
The videos I have seen is using a torque wrench and hand tools
Probably a non calibrated torque wrench from Harbor Freight
they did use a torque wrench after they tightened them all.TexasAggie_02 said:
They used cordless drills in the videos. I would hope that they used a torque wrench in the final tightening....
Looking at that hatch, it looks Ike it would work, if it were trying to hold pressure in from the inside.
There does not appear to be any interlocking mating surfaces between the two pieces, looks like it is just two flat surfaces. That is less than ideal when the bolts are subjected to shearing forces.
There does not appear to be any interlocking mating surfaces between the two pieces, looks like it is just two flat surfaces. That is less than ideal when the bolts are subjected to shearing forces.
There may have been some holes in the hull undiscovered
Bonus Hole said:
There may have been some holes in the hull undiscovered
User name checks out
The cylindrical design of the pressure vessel and thus the hatch I feel like are more examples of Rush trying to be "innovative" instead of safe. Just being different for the sake of it without justification is ridiculous.
A cylinder was likely easier and less expensive than a sphere.chase128 said:
The cylindrical design of the pressure vessel and thus the hatch I feel like are more examples of Rush trying to be "innovative" instead of safe. Just being different for the sake of it without justification is ridiculous.
Yep. I think he liked to try and pass off easy as innovative or thinking outside the box.
They routinely twist maximum allowable tourqeage using a Craftsman Model 1019 Laboratory Edition Signature Series torque wrench, the kind used by CalTech high energy physicists and NASA engineers.aggieforester05 said:MarathonAg12 said:
The videos I have seen is using a torque wrench and hand tools
Probably a non calibrated torque wrench from Harbor Freight
Was it dead-on balls accurate?
Quote:
The pressure should help push the hatch in and seal it, if it's designed properly...
There is more than one reason why the hatches on other submersibles are not bolted on from the outside.
And how many knucklehead mechanics have you seen run a bolt down with an impact or electric driver, then click it with a torque wrench without turning the bolt and say it's good?Quote:
they did use a torque wrench after they tightened them all
techno-ag said:A cylinder was likely easier and less expensive than a sphere.chase128 said:
The cylindrical design of the pressure vessel and thus the hatch I feel like are more examples of Rush trying to be "innovative" instead of safe. Just being different for the sake of it without justification is ridiculous.
I also read that it had to be designed in that shape because it had to hold 5 people to make economic sense. If they made it spherical they wouldn't be able to accommodate enough people.
Can you imagine being cooped up in that thing for 12 hours, you make it back to the support vessel (by the grace of God), only to find out one of the idiots tightening the 17 bolts fouled the threads and you are stuck?
"It was hard to reach"
It's an industry toim.TexasRebel said:
Was it dead-on balls accurate?
Okay here's my POV after working 5 years designing deep sea robotic vehicles for Nauticus Robotics. My experience includes a trip to WHOI to study their latest ROVs and apply to our vehicles. Our last vehicle was rated to 3000m. There were not humans involved, precisely because designing ANY deep sea vehicle is hard. It's a more challenging environment than space, and as such, we're trying to replace humans deep sea because of the cost and risk.
All of our vehicles were flooded, and only specialized electronics were placed in very expensive titanium pressure housings using American material stock, fabricated in America, with high quality metals. All were machined from single stock of material, pipe or billet. Why? Because any void can cause an immediate failure.
Any electronics with pressure-rated components were flooded with oil, and pressure compensated. Slightly positive pressure ensures oil is pushed out of the system so that no seawater gets into the electronics. We place water sensors in all electronics so that if they get wet, the computer will immediately know and bring the sub to surface before housing is completely flooded.
Most housings are pressure-assisted seals, and only need enough fastener preload to set the seal. After that, water pressure assists the seal until the metal flanges compress and transfer the load.
The pressure-assisted front "hatch" on Titan isn't the big issue. That's typical and a low risk item. The acrylic window is the higher risk item, as plastics creep, age, and change more with time, pressure and UV exposure than most metals. The biggest issue is the composites...which also have plastic involved.
We use composites for our unmanned subsea vehicle, but only as unpressurized vehicle structure. I've never seen any one use composites for a subsea pressure housing. That applies to ROVs and AUVs. Making a human-rated composite pressure vessel is unheard of.
Even using them for internal pressure, such as COPV, they typically have a metal liner to prevent leaks and are still leak-before-burst designs. You can't get that with external pressure, as any leak in the structural walls typically is catastrophic.
The mating seal between the Ti end caps and the composite cylinder is an adhesive bond, which isn't a big deal as it looks like the end cap has a flange that transmits axially load into the cylinder and the adhesive isn't that structural. However, the issue with this design is, any uneven loading on that flange can cause localized failures, ripples, and delamination of the composite, most likely internally due to the pressure distribution. This results in high stress regions that will avalanche since it's in compression.
My guess is that's what happened. After a few cycles, the internal flange lip of the composite cylinder wall delaminated due to higher-stress from the dome. Depending on post-dive inspections (if they did any), the delamination might not have even been detected at STP due to relaxing of the joint.
I'm curious what kind of NDE they did after fabrication and every dive, and what areas of the sub they inspected. I'm also curious if they did any leak monitoring or stress measurements during missions at high criticality regions.
All of our vehicles were flooded, and only specialized electronics were placed in very expensive titanium pressure housings using American material stock, fabricated in America, with high quality metals. All were machined from single stock of material, pipe or billet. Why? Because any void can cause an immediate failure.
Any electronics with pressure-rated components were flooded with oil, and pressure compensated. Slightly positive pressure ensures oil is pushed out of the system so that no seawater gets into the electronics. We place water sensors in all electronics so that if they get wet, the computer will immediately know and bring the sub to surface before housing is completely flooded.
Most housings are pressure-assisted seals, and only need enough fastener preload to set the seal. After that, water pressure assists the seal until the metal flanges compress and transfer the load.
The pressure-assisted front "hatch" on Titan isn't the big issue. That's typical and a low risk item. The acrylic window is the higher risk item, as plastics creep, age, and change more with time, pressure and UV exposure than most metals. The biggest issue is the composites...which also have plastic involved.
We use composites for our unmanned subsea vehicle, but only as unpressurized vehicle structure. I've never seen any one use composites for a subsea pressure housing. That applies to ROVs and AUVs. Making a human-rated composite pressure vessel is unheard of.
Even using them for internal pressure, such as COPV, they typically have a metal liner to prevent leaks and are still leak-before-burst designs. You can't get that with external pressure, as any leak in the structural walls typically is catastrophic.
The mating seal between the Ti end caps and the composite cylinder is an adhesive bond, which isn't a big deal as it looks like the end cap has a flange that transmits axially load into the cylinder and the adhesive isn't that structural. However, the issue with this design is, any uneven loading on that flange can cause localized failures, ripples, and delamination of the composite, most likely internally due to the pressure distribution. This results in high stress regions that will avalanche since it's in compression.
My guess is that's what happened. After a few cycles, the internal flange lip of the composite cylinder wall delaminated due to higher-stress from the dome. Depending on post-dive inspections (if they did any), the delamination might not have even been detected at STP due to relaxing of the joint.
I'm curious what kind of NDE they did after fabrication and every dive, and what areas of the sub they inspected. I'm also curious if they did any leak monitoring or stress measurements during missions at high criticality regions.
Mike Shaw - Class of '03
We are making composite panels for our manned submersibles and running tests on them now but not for extraordinary depths. Of course these are just panels on a steel hull.
Username checks out
So you don't even trust composite materials to protect electronics in unmanned vessels going to great depths, yet they were using composites with human beings.NASAg03 said:
Okay here's my POV after working 5 years designing deep sea robotic vehicles for Nauticus Robotics. My experience includes a trip to WHOI to study their latest ROVs and apply to our vehicles. Our last vehicle was rated to 3000m. There were not humans involved, precisely because designing ANY deep sea vehicle is hard. It's a more challenging environment than space, and as such, we're trying to replace humans deep sea because of the cost and risk.
All of our vehicles were flooded, and only specialized electronics were placed in very expensive titanium pressure housings using American material stock, fabricated in America, with high quality metals. All were machined from single stock of material, pipe or billet. Why? Because any void can cause an immediate failure.
Any electronics with pressure-rated components were flooded with oil, and pressure compensated. Slightly positive pressure ensures oil is pushed out of the system so that no seawater gets into the electronics. We place water sensors in all electronics so that if they get wet, the computer will immediately know and bring the sub to surface before housing is completely flooded.
Most housings are pressure-assisted seals, and only need enough fastener preload to set the seal. After that, water pressure assists the seal until the metal flanges compress and transfer the load.
The pressure-assisted front "hatch" on Titan isn't the big issue. That's typical and a low risk item. The acrylic window is the higher risk item, as plastics creep, age, and change more with time, pressure and UV exposure than most metals. The biggest issue is the composites...which also have plastic involved.
We use composites for our unmanned subsea vehicle, but only as unpressurized vehicle structure. I've never seen any one use composites for a subsea pressure housing. That applies to ROVs and AUVs. Making a human-rated composite pressure vessel is unheard of.
Even using them for internal pressure, such as COPV, they typically have a metal liner to prevent leaks and are still leak-before-burst designs. You can't get that with external pressure, as any leak in the structural walls typically is catastrophic.
The mating seal between the Ti end caps and the composite cylinder is an adhesive bond, which isn't a big deal as it looks like the end cap has a flange that transmits axially load into the cylinder and the adhesive isn't that structural. However, the issue with this design is, any uneven loading on that flange can cause localized failures, ripples, and delamination of the composite, most likely internally due to the pressure distribution. This results in high stress regions that will avalanche since it's in compression.
My guess is that's what happened. After a few cycles, the internal flange lip of the composite cylinder wall delaminated due to higher-stress from the dome. Depending on post-dive inspections (if they did any), the delamination might not have even been detected at STP due to relaxing of the joint.
I'm curious what kind of NDE they did after fabrication and every dive, and what areas of the sub they inspected. I'm also curious if they did any leak monitoring or stress measurements during missions at high criticality regions.
Knowing what we all know about Stockton Rush and OceanGate, does this surprise you?
Not at all. He sued his former employee saying the hull was messed up and they weren't doing enough inspections.
NASAg03: Outside of Aggie athletics, posts like this are the reason I subscribe to TexAgs. Please post more.
MarathonAg12 said:
Not at all. He sued his former employee saying the hull was messed up and they weren't doing enough inspections.
And after that insisted on only hiring people that did not have the technical knowledge to question what he was doing.
Exactly. Composites do work great underwater, but only when there's equal pressure on both sides. They are challenging to seal because of all the leak paths, and that's exacerbated as a compressed pressure vessel due to delamination causing new flow paths.BQ78 said:
We are making composite panels for our manned submersibles and running tests on them now but not for extraordinary depths. Of course these are just panels on a steel hull.
Composite fibers are challenging in compression, as each long fiber has a low buckling stress. The fabrication videos of their cylindrical segment show hoop winding. I'm wondering what their layup was axially and 45 for torsion. You need all of then to react hoop, axial, and torsion stresses.
In tension, the walls will compress and the fibers can close voids, but in compression you get localized buckling and delamination.
There are also issues with galvanic corrosion between Ti and C, and significant CTE mismatches. That's a large diameter changing from baking in the summer sun to freezing subsea. If the Ti shrinks much more than the carbon fiber composite, you could get a gap at that bore seal interface, and under pressure that could further cause delamination as the Ti end cap drags against the edge of the CFRP cylinder face.
Mike Shaw - Class of '03
This article talks about some of what they were up to from a composites perspectiveNASAg03 said:Exactly. Composites do work great underwater, but only when there's equal pressure on both sides. They are challenging to seal because of all the leak paths, and that's exacerbated as a compressed pressure vessel due to delamination causing new flow paths.BQ78 said:
We are making composite panels for our manned submersibles and running tests on them now but not for extraordinary depths. Of course these are just panels on a steel hull.
Composite fibers are challenging in compression, as each long fiber has a low buckling stress. The fabrication videos of their cylindrical segment show hoop winding. I'm wondering what their layup was axially and 45 for torsion. You need all of then to react hoop, axial, and torsion stresses.
In tension, the walls will compress and the fibers can close voids, but in compression you get localized buckling and delamination.
There are also issues with galvanic corrosion between Ti and C, and significant CTE mismatches. That's a large diameter changing from baking in the summer sun to freezing subsea. If the Ti shrinks much more than the carbon fiber composite, you could get a gap at that bore seal interface, and under pressure that could further cause delamination as the Ti end cap drags against the edge of the CFRP cylinder face.
https://www.compositesworld.com/articles/composite-submersibles-under-pressure-in-deep-deep-waters
The biggest challenge, Spencer reports, was developing a manufacturable design that "would produce a consistent part with no wrinkles, voids or delaminations." And without use of an autoclave. Spencer opted for a layup strategy that combines alternating placement of prepreg carbon fiber/epoxy unidirectional fabrics in the axial direction, with wet winding of carbon fiber/epoxy in the hoop direction, for a total of 480 plies. The carbon fiber is standard-modulus Grafil 37-800 (30K tow), supplied by Mitsubishi Chemical Carbon Fiber & Composites Inc.(Irvine, CA, US). Prepreg was supplied by Irvine-based Newport Composites, now part of Mitsubishi Chemical Carbon Fiber & Composites Inc. The wet-winding epoxy is Epon Resin 682 from Hexion Inc. (Columbus, OH, US). The curing agent is Lindride LS-81K frLindau Chemicals Inc.cals (Columbia, SC, US).
They don't mention any helical/45 degree layup.
Thats another huge issue in a marine environment. I'm curious to know the composition of the 17-bolts that they were using to mate the titanium end cap with titanium ring plate.Quote:
There are also issues with galvanic corrosion between Ti and C, and significant CTE mismatches.
Stat Monitor Repairman said:Thats another huge issue in a marine environment. I'm curious to know the composition of the 17-bolts that they were using to mate the titanium end cap with titanium ring plate.Quote:
There are also issues with galvanic corrosion between Ti and C, and significant CTE mismatches.
Grade 8. You can tighten them SOBs down real tight
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PA24 said:
Doesn't take a genius to become a billionaire.
That's my problem. I'm just too damn smart to be a billionaire
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