My searches found no decent answer. It cant be with ballast tanks. The deepest submarine withstood about 15,750 psi. We aren’t able to pressurize air to anywhere near that.
Usually by dropping weights. The Trieste had two big hoppers full of iron shot which would be released by turning an electromagnet off, for example.
On a similar topic, some (or all) Russian submarines have gas generators (solid rocket motors) in their main ballast tanks to either provide a backup to high-pressure air or for depths great enough that high-pressure air cannot be used for an emergency MBT blow.
The electromagnets were chosen because they would fail safe - they needed to be energized to hold the ballast. So if the sub lost power, the ballast drops and the sub would float to the top powered by physics and buoyancy.
Sucks to be the whale hunting in the deep dark and suddenly getting shot from above!
Good answer. I was thinking something like that. But I couldn’t comprehend a vessel that could withstand 15k psi yet be positively buoyant. Because the amount of material needed to contain the gas for buoyancy.. seems like the container would be greater than the lift it would provide. For instance my scuba tanks can withstand 14,000 psi (during hydrostatic testing) and sink like rocks. Perhaps they use spheres of gas permanently pressurized to 5k (or more if possible) so they can be built to resist 10k pressure instead of 15, reducing their weight to be able to provide buoyancy for the vessel?
Trieste used gasoline as ballast instead of air. So the ballast tanks didn’t have to withstand ocean pressure, the gasoline can be at ocean pressure 30,000 feet down and still be buoyant
Of course duh I should have thought of that. No need for gasses. That just makes it even more vexing as to why Titan was carbon fiber instead of 5 inches of titanium.. when deep ocean ballasts are easy to make if you’re brain isn’t stuck on gasses like mine was.
I think I have all I need to know to make a deep sea sub now! (>Titan anyway 😅)
A titanium hulled pressure cylinder with the same interior volume would weigh about 3.3 more tons that their carbon fibre tube and then require significantly more positive buoyancy adding even more weight. They were trying to cost cut on the ship. A heavier submersible would require a bigger crane and thus a bigger support ship, and hiring ships isn’t cheap. They were already paying about $200k a week.
What scuba tanks do you have? I’ve never seen a scuba tank with a service pressure that would require 14,000 psi hydro. Hydro pressure typically at 1.67 times service pressure.
The source of buoyancy for modern submersibles is syntactic foam: a foam of glass microspheres that are strong enough to withstand the most extreme submergence pressures. As mentioned by another user, in the bathyscaph era a large quantity of gasoline was used to provide floatation. But because its density difference with seawater is not as great as syntactic foam, the bathyscaphs had to have huge "balloons" of gasoline to provide enough buoyancy.
The Mike was a one off SSN that used gas generators. This was required because of its extreme limiting (test) depth of 1000m, which was enabled in part by a titanium hull.
I have also seen references to the Sierra using gas generators for EMBT blow, which makes some sense because it was also made of titanium. There was not as much emphasis on limiting death in the design of Sierra (for example, it has more than one hatch for egress while the Mike only had a single hull opening in the sail), as it was was more of an attempt to make a production SSN using titanium for the pressure hull. The Akula was constructed contemporaneously to a rather similar design, so there is a small chance that gas generators are used on that class as well.
Beyond that, I would doubt if other Russian submarines other than specialized deep submergence vessels use gas generators because they are more complex, expensive, and are not reusable
My recollection, as /u/TwixOps said, is that it is an emergency backup on their "normal" SSNs and SSBNs to the high-pressure air EMBT blows. But I'm not sure which submarines have them.
We do definitely know the Komsomolets had them because air MBT blows at that depth were essentially impossible at her test depth.
You are mistaken. The Project 685 SSN (NATO Mike) had solid-propellant gas generators for EMBT blows (only for the middle group of MBTs). The Russian term is "powder gas generators" (пороховых газогенераторов).
My source is Fire at Sea by D. A. Romanov, a book which covers the sinking of the Komsomolets in considerable technical detail. Romanov was the assistant chief designer of the Project 685 submarine, so you will not find a more authoritative source.
The Komsomolets certainly had them, but I am not sure about other Russian submarines. It appears from a cursory search that such a system may have been first tested on the Project 611 (Zulu) submarine B-61 in 1963-64. I also found a reference to the Project 671RT (Victor II) submarine K-517 testing the system in 1979, which suggests to me that it was installed on many Soviet submarines.
Yup. No amount of ‘ex’-plosion will fix how incredibly imploded we would be after a 5km dive.
OP, is this a genuine question or just a shit post?
5000m. That’s outlandish.
Hahaha. True.
And here I was thinking I’d found a brotherhood of fellow (current and former) crews of our sleek black messengers of death.
‘Always bet on Black’.
"We aren't able to pressurize air to anywhere near that"
That's why the Trieste (Mariana Trench, 1960) used gasoline, not air, for buoyancy in addition to droppable weights as others have mentioned. Without the droppable weights Trieste was positively buoyant, even at Challenger Deep, because gasoline is essentially incompressable and less dense than water.
Usually by dropping weights. The Trieste had two big hoppers full of iron shot which would be released by turning an electromagnet off, for example.
On a similar topic, some (or all) Russian submarines have gas generators (solid rocket motors) in their main ballast tanks to either provide a backup to high-pressure air or for depths great enough that high-pressure air cannot be used for an emergency MBT blow.
The electromagnets were chosen because they would fail safe - they needed to be energized to hold the ballast. So if the sub lost power, the ballast drops and the sub would float to the top powered by physics and buoyancy.
Sucks to be the whale hunting in the deep dark and suddenly getting shot from above!
Shot from above, I’m in the deep. You give subs a bad name.
As usual coming in with the unique knowledge. Love it
[deleted]
Where do I get it?
Good answer. I was thinking something like that. But I couldn’t comprehend a vessel that could withstand 15k psi yet be positively buoyant. Because the amount of material needed to contain the gas for buoyancy.. seems like the container would be greater than the lift it would provide. For instance my scuba tanks can withstand 14,000 psi (during hydrostatic testing) and sink like rocks. Perhaps they use spheres of gas permanently pressurized to 5k (or more if possible) so they can be built to resist 10k pressure instead of 15, reducing their weight to be able to provide buoyancy for the vessel?
Trieste used gasoline as ballast instead of air. So the ballast tanks didn’t have to withstand ocean pressure, the gasoline can be at ocean pressure 30,000 feet down and still be buoyant
Of course duh I should have thought of that. No need for gasses. That just makes it even more vexing as to why Titan was carbon fiber instead of 5 inches of titanium.. when deep ocean ballasts are easy to make if you’re brain isn’t stuck on gasses like mine was.
I think I have all I need to know to make a deep sea sub now! (>Titan anyway 😅)
A titanium hulled pressure cylinder with the same interior volume would weigh about 3.3 more tons that their carbon fibre tube and then require significantly more positive buoyancy adding even more weight. They were trying to cost cut on the ship. A heavier submersible would require a bigger crane and thus a bigger support ship, and hiring ships isn’t cheap. They were already paying about $200k a week.
What scuba tanks do you have? I’ve never seen a scuba tank with a service pressure that would require 14,000 psi hydro. Hydro pressure typically at 1.67 times service pressure.
The source of buoyancy for modern submersibles is syntactic foam: a foam of glass microspheres that are strong enough to withstand the most extreme submergence pressures. As mentioned by another user, in the bathyscaph era a large quantity of gasoline was used to provide floatation. But because its density difference with seawater is not as great as syntactic foam, the bathyscaphs had to have huge "balloons" of gasoline to provide enough buoyancy.
Could the Russians go that deep, or are we talking Typhoons?
The Mike was a one off SSN that used gas generators. This was required because of its extreme limiting (test) depth of 1000m, which was enabled in part by a titanium hull.
I have also seen references to the Sierra using gas generators for EMBT blow, which makes some sense because it was also made of titanium. There was not as much emphasis on limiting death in the design of Sierra (for example, it has more than one hatch for egress while the Mike only had a single hull opening in the sail), as it was was more of an attempt to make a production SSN using titanium for the pressure hull. The Akula was constructed contemporaneously to a rather similar design, so there is a small chance that gas generators are used on that class as well.
Beyond that, I would doubt if other Russian submarines other than specialized deep submergence vessels use gas generators because they are more complex, expensive, and are not reusable
Wow, 1km? Inconceivable!
Great thoughts there.
No. It’s about deep submersibles.
My recollection, as /u/TwixOps said, is that it is an emergency backup on their "normal" SSNs and SSBNs to the high-pressure air EMBT blows. But I'm not sure which submarines have them.
We do definitely know the Komsomolets had them because air MBT blows at that depth were essentially impossible at her test depth.
Holy shit the gas generator is a good idea. Would've saved the Thresher. RIP
Where did you get that from- an AI bot?
I have never and will never use generative AI. I hate it with a burning passion.
I have no idea why you would think my comment was written by AI.
Because Russian subs have never had SRM in the ballast tanks. Where did you source that from ?
You are mistaken. The Project 685 SSN (NATO Mike) had solid-propellant gas generators for EMBT blows (only for the middle group of MBTs). The Russian term is "powder gas generators" (пороховых газогенераторов).
My source is Fire at Sea by D. A. Romanov, a book which covers the sinking of the Komsomolets in considerable technical detail. Romanov was the assistant chief designer of the Project 685 submarine, so you will not find a more authoritative source.
The Komsomolets certainly had them, but I am not sure about other Russian submarines. It appears from a cursory search that such a system may have been first tested on the Project 611 (Zulu) submarine B-61 in 1963-64. I also found a reference to the Project 671RT (Victor II) submarine K-517 testing the system in 1979, which suggests to me that it was installed on many Soviet submarines.
Those deep sea diving submarines? They drop ballast and up they go.
For submersibles, they drop weights. Like steel or lead shot to surface.
Or old pieces of sewer pipe? :)
Drop like to the sea floor?
Yep.
Huh interesting, if they do that how would it be able to submerge itself several times, or is it just not able to?
You use cheap ballast so that you can replace it for every dive.
Drop weights.
Huh? 5000 meters?? Over 15,000 ft?? Hmmm. Only a few subs in the world can do that… and they do it very carefully.
No. They stay imploded.
Yup. No amount of ‘ex’-plosion will fix how incredibly imploded we would be after a 5km dive. OP, is this a genuine question or just a shit post? 5000m. That’s outlandish.
There are a number of subs, 5 perhaps 6, that can go that depth or more. OP asked a reasonable question.
No crewed ‘military’ submarines can, or ever have gone anywhere near 5000m.
OP must be researching commercial exploration or ROV’s. Failing to make that distinction on a ‘submarines’ thread was confusing.
From the subreddit description:
Dedicated to every machine under the water.
Fair enough. I made an error. Thanks for the massive amounts of downvotes.
Eh...those are amateur numbers. Gotta gaslight all of reddit like EA to put up some serious numbers :)
Hahaha. True. And here I was thinking I’d found a brotherhood of fellow (current and former) crews of our sleek black messengers of death. ‘Always bet on Black’.
And yet, these vessels are indeed submarines. Which sub would be more appropriate?
I think OP is referring to the research submersible, which I believe are kept on a line and hauled up after submerging, but I could be wrong.
Fair enough. OP, if you’re researching submersibles as Beakerguy has kindly pointed out. Perhaps do a bit more research?
Have you researched the sidebar of this sub?
"We aren't able to pressurize air to anywhere near that"
That's why the Trieste (Mariana Trench, 1960) used gasoline, not air, for buoyancy in addition to droppable weights as others have mentioned. Without the droppable weights Trieste was positively buoyant, even at Challenger Deep, because gasoline is essentially incompressable and less dense than water.
The Titanic even has a designated spot where the ballast is dropped to allow the submarine to rise.
By going up