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The Bathyscaph Trieste: Technological and Operational Aspects (1962)
- pmcjones 3y agoThis was written by Don Walsh, who with Jacques Piccard, descended to the bottom of the Challenger Deep in 1960. It explains many engineering details.
- sclarisse 3y ago- Main hull of the craft is a tank filled with gasoline: lighter than water and only a little compressible. It is not a high pressure enclosure. A membrane keeps these two fluids apart mostly, but some maneuvers dump gasoline into the ocean. - Ballast is held in place with magnets. You actually want to drop ballast as you descend, to make up for the added seawater. - Sphere on the bottom holds observer and instruments. This is a high pressure part. - There’s no real propulsion or navigation. You land more or less where you land.
- sjackso 3y agoI recall reading about the craft using gasoline as an incompressible floatation fluid, but I hadn't realized the scale: 100 tons of gasoline, making up 2/3s of the craft's mass.
- bodhi_mind 3y agoBasically the equivalent of a lighter than “air” craft but in a different fluid. I wonder if there’s a word for a craft that controls its buoyancy regardless of medium?
- pvaldes 3y ago> I wonder if there’s a word for a craft that controls its buoyancy regardless of medium sperm whale
- javajosh 3y agoAn Archimedes craft. (I made this up just now).
- gigiggufh 3y agoFluid is a Latin root, so why not "fluidostat" on the model of "aerostat"?
- 4gotunameagain 3y agobecause -stat is a Greek root. merriam-webster borrowed from French aérostat, probably back-formation from aérostatique "of aerostatics," with -stat (after héliostat heliostat) taken as the Greek agentive element -statēs "one who causes to stand" — more at -stat
- deleted 3y ago[deleted]
- moffkalast 3y agoI've never looked at it this way, but it really is literally an underwater blimp lol.
- specialp 3y agoI never knew the scale either. But the book says gasoline has a specific gravity of 0.7. So 100 tons will make roughly 30 tons of buoyancy. The negatively buoyant craft is 50 tons so combined with the air inside that is probably the displacement required to make it positive
- moffkalast 3y ago> The primary 24 volt electrical system of TRIESTE is powered by 56 twelve-volt, 48 ampere-hour, lead-acid batteries located in four aluminium saddle tanks fastened to the top of the float beneath the superstructure. Each of the four battery tanks or boxes is pressure- compensated through the use of transformer oil and, therefore, during submergence the batteries themselves are subjected to full depth pressure.’ Three of the boxes are allotted for powering the craft's five 3-horsepower electrical propulsion motors and for providing power to the lighting systems. > The propulsion system consists of five special General Electric 3-hp de motors. These motors are designed to operate in inert fluid (silicone oil) and are subjected to full ambient pressure during diving operations. > The motors themselves are in five different locations. Two of them provide horizontal motion forward and backward, two provide vertical motion either ascending or descending, and one is installed athwartships for turning. The motors all drive propellers through gear boxes. It actually does have electric thrusters. Interesting that they were able to make the batteries neutrally pressured.
- sclarisse 3y agoAh! I was misled by the general comparison to an unpowered balloon that they make a few times. It’s not much propulsion and they take special care to differentiate it from a submarine that can actually travel the world.
- Zee2 3y ago> athwartships What a phenomenal word!
- HeyLaughingBoy 3y agoIncidentally one of my favorite nautical terms. Just always liked the sound of it :-)
- b215826 3y ago> You actually want to drop ballast as you descend, to make up for the added seawater. The ballast is dropped during the ascension, not the descent. This makes the ascension-step impossible to fail and requires no electricity [1]. Incidentally, I first came to know about the bathyscaphe while reading Peter Watts's Rifters trilogy (which is an amazing hard SF series set in the deep sea). [1] https://en.wikipedia.org/wiki/Bathyscaphe#Mode_of_operation https://en.wikipedia.org/wiki/Bathyscaphe#Mode_of_operation
- elzbardico 3y agoThe document says otherwise. As gasoline is slightly compressible, seawater is admitted in the float during the dive, increasing negative buoyancy, and increasing the rate of descent. So, to control the rate of decent, some ballast is released during diving too.
- Cerium 3y agoBallast is dropped during both descent and assent. The linked document explains how the gasoline used for buoyancy is significantly compressible and becomes denser as the bathyscaphe descends. If no ballast was dropped during descent the rate of descent would continue to increase due to the feedback mechanism of increased pressure, leading to increased compression, leading to increased density.
- a4isms 3y agoFWIW you don’t need a bathyscape to experiment with this. When Scuba diving in temperate locations (like Tobermory, Ontario), people with 7mm wet suits and extra vests or jackets experience this as they descend: The neoprene compresses, and if you don’t add small amounts of buoyancy to your BCD, you’ll start to free-fall.
- jacquesm 3y agoIt's Tobermory. Absolutely beautiful area, so many birds. I went camping there several times. It's also pretty much the end of the world, the only way through is by ferry.
- eutectic 3y agoWhen people say 'carbon fiber is weaker under compressive loads', or 'cylinders distribute compressive forces unevenly', these kinds of issues seem like engineering challenges not fatal flaws. I feel like the problem with the Titan submersible was the lack of respect for safety, not any specific design choice.
- jacquesm 3y agoIt could well be both.
- eutectic 3y agoWell, obviously going with a more conventional construction would make it easier to come up with a safe design. But I feel like people are going to take the wrong lesson from this accident.
- jacquesm 3y agoThe people whose lives depend on this sort of thing will definitely be learning the right lessons and the rest doesn't matter. In fact, plenty of them already had learned those lessons, the CEO of that company was a pretty special case (and not in a good sense).
- eutectic 3y agoThe Boeing 787 is primarily made from carbon fiber, including the wings which experience a mix of tensile and compressive loads thousands of times over their design lives. Of course deep sea submersibles occupy a much smaller market where a comparable degree of rigor may not be justified, but I think it's silly that everyone suddenly seems to be a expert in composite and/or submersible design.
- Aeolun 3y agoAirplanes deal with lesser atmospheric pressure though, not more. Flexibility is probably a good thing.
- cratermoon 3y agoIt says at the link, on page 5, "The compressional loss of buoyancy is of such a magnitude that approximately 1 ton of ballast must be dropped for every 3000 feet of descent to maintain equilibrium."
- NoraCodes 3y agoInteresting to note all the discussion of how aviation balloon materials aren't suitable; I presume this is because Picard was most experienced with building balloons for high altitude exploration and applied similar techniques to the Trieste.
- andrepd 3y ago"The inspiration for Prof. Tournesol" is my favourite tidbit about Picard :)
- foobarbecue 3y ago"The float has the shape of a cylinder with tapered ends (sausage)." I love that they aren't afraid to sound "informal." I think there's been a change in technical writing since this period -- technical and academic writers today are more concerned about sounding authoritative and less concerned with communicating clearly.
- moffkalast 3y agoObligatory "This design is the würst."
- ant6n 3y agoThis spelling of die Wurst is a turd.
- andrepd 3y agoFunny, I have exactly the opposite impression: at least in my field old papers are stuffy and obscure, newer papers are more happy to be informal in the discussion sections at least.
- siliconunit 3y agoI agree. Modern stuff is childish at times.. and old stuff when slightly drifting tended to go toward poetry.
- JKCalhoun 3y agoSomething about that "era" in general though. I can't help but feel like the document exudes optimism, engineering know-how ... a kind of spirit of intelligent progress. It was a kind of golden age in my mind.
- foobarbecue 3y agoSo many fascinating things in this report. One was that the robot arm was made by General Mills (today, mostly a parent brand of breakfast cereal companies).
- projektfu 3y agoAt the time, baking products and breakfast cereals were also their main products. Quite a surprise to see them there. That said, they had a history of inventing new machines, like the extruders that make puffy breakfast cereal.
- SAI_Peregrinus 3y agoAnd the design & manufacturing capability to make the machines used for making breakfast cereals (the mills) in-house.
- dpierce9 3y agoGeneral Mills also built Alvin which launched in 1964 and is still in service. [0]https://en.m.wikipedia.org/wiki/DSV_Alvin https://en.m.wikipedia.org/wiki/DSV_Alvin
- adolph 3y agoIt is kinda hard to find more information about the arm. The below site has some Trieste pictures [0] and how the same model of arm was used at Los Alamos [1] for working with radioactive material. 0. https://cyberneticzoo.com/underwater-robotics/1961-trieste-submersible-harold-froehlich-american/ https://cyberneticzoo.com/underwater-robotics/1961-trieste-s... 1. https://cyberneticzoo.com/teleoperators/1960-minotaur-remote-manipulator-general-mills-american/ https://cyberneticzoo.com/teleoperators/1960-minotaur-remote...
- JKCalhoun 3y agoI love the linked site, BTW. It is exhaustive (in a good way).
- runlevel1 3y ago
- rvba 3y agoHow many tons of gasoline has this craft put into the see?
- 2b3a51 3y agoI understand your concern but at around the same period as this expedition it was routine to flush ships bunker tanks in maintenance docks now and again - probably a few tonnes each time. I grew up on a spit of land between two estuaries and I can remember the globs of bunker oil and the slight film on the water. I suspect that the Trieste itself added little to the general mess.
- jiggawatts 3y agoReminds me of a few rabid "activists" trying to stop any further development of SpaceX Starship because of a few chunks of concrete a single test launch scattered on a beach. In their minds, all human scientific progress should just stop dead if it makes a mess.
- 100k 3y agoSpaceX deliberately decided not to use a flame diverter for that launch site, which is a few hundred feet from an endangered bird nesting area. It's clear they could have done more to avoid damage to nearby wildlife and property and it's a travesty that they were given a permit to launch without using standard practices.
- jiggawatts 3y agoHow many birds died? Did any of the activist bother to count? No, seriously: What's the actual, measured impact on wildlife instead of "what if" scenarios cooked up by people who've never set foot in the area? Did anyone compare the impact to hurricanes that regular hit that area?
- scotty79 3y ago
- mechhacker 3y agoInteresting that the overall concept of the Trieste is very similar to the Limiting Factor. The main difference being instead of using gasoline as bouyancy, they use syntactic foam. It seems like that made the overall vessel smaller. But the fundamentals of the pressure vessel is very similar, with modern tech wrapped around inside and outside. And LF using Ti vs. the Trieste's Steel vessel. https://lynceans.org/tag/syntactic-foam/ https://lynceans.org/tag/syntactic-foam/
- babypuncher 3y agoIt turns out after 60 years, a sphere is still the strongest three dimensional shape we can make. There are in fact some basic engineering truths that cannot really be improved upon further.
- dtgriscom 3y agoIn another 60 years, a sphere will still be the strongest three-dimensional shape.
- qwertox 3y agoWhat a beautiful submission. Yesterday I was reading about the Trieste in the Wikipedia. I had already seen an image of it years ago, but just yesterday I realized that only the small sphere was the place where the crew was in while the remainder was for navigation.
- bombcar 3y agoIt’s an underwater zeppelin (or blimp) and you can’t convince me otherwise.
- adolph 3y agoThe last paragraph of Operating Principles talks about just that. Finally, it must be remembered that the bathyscaph is not a submarine. It has neither the mobility nor the controllability of a submarine. Whereas a submarine may be regarded as analogous to a dirigible or a blimp, the bathyscaph may be considered to be a lighter-than-water free balloon. The craft is at the mercy of currents and is limited mostly to "elevator" type operations, such as investigations of the water column from the surface to the sea floor and detailed studies of the sea floor at the base of the water column. The bathyscaph type of configuration does not lend itself to survey work.
- 100k 3y agoWikipedia: "After passing 9,000 metres (30,000 ft), one of the outer Plexiglas window panes cracked, shaking the entire vessel." If anyone else is curious about why the cracked window didn't cause an implosion, I found the answer in an interview: it was a plexiglass window on the entrance tunnel, not the viewport that was part of the sphere. "A Plexiglas window in the flooded entrance tunnel had cracked under the pressure. But Walsh and Piccard were safe inside their cabin, separated from the tunnel by a thick steel hatch." https://spectrum.ieee.org/don-walsh-describes-the-trip-to-the-bottom-of-the-mariana-trench https://spectrum.ieee.org/don-walsh-describes-the-trip-to-th...
- jojobas 3y agoSo the tunnel was flooded, but not permanently connected to the outside? Otherwise why would it crack?
- hadlock 3y agoIt was a weird, early design. 90% of that "submarine" is a giant bladder that held gasoline, with a tube through the middle, and then a sphere at the bottom. There's a window at the top of the tube, and then a steel hatch separating the sphere from the tube. It's a weird design, that's just how they decided to do it back then.
- implements 3y agoIt’s not really “weird” - the design allowed the crew to leave the submersible unassisted when it was on the surface, which would be optimal for safety. The tunnel provided a route from the crew sphere to the top of the float. During the dive it was used as a ballast tank and filled with water. Compressed air was carried to blow the water out at the end of the dive. The original design had an open conning tower, but it was found that waves could break over it and potentially flood the diving bell if its hatch was open - hence a door was fitted. The tower was supposed to be pressure equalised, so why the door’s plexiglass cracked is a puzzle - perhaps a thin sheet will crack when exposed to a very large static pressure?
- 3y ago
- puzzledobserver 3y agoBasically, regular submarines blow compressed air into the ballast tanks when they need to surface. Because the Trieste goes so deep, compressed air wouldn't work. It uses fine steel shot instead. But at this point, to make it neutrally buoyant, one needs a large amount of material that is only slightly lighter than water. It also has to be mostly incompressible, so aviation gasoline it is. The Trieste effectively becomes an underwater airship. Or a watership, if you will.
- cratermoon 3y agoDid anyone ever yell "Watership Down!" when it submerged?
- jakedata 3y agoSlightly obligatory Futurama quote: Leela: Depth at 45 hundred feet, 48 hundred, 50 hundred! 5000 feet! Farnsworth: Dear Lord, that's over 150 atmospheres of pressure. Fry: How many atmospheres can this ship withstand? Farnsworth: Well it's a spaceship, so I'd say anywhere between zero and one.
- sacnoradhq 3y agoFNRS III/DSV-0/DSV-1 were engineered for fail-safe, elegant simplicity over cost and bulk. Power failure or operator opens the shot releases, and positive buoyancy is assured. There's nothing in the buoyancy filler (gasoline "balloons") that is ever not equalized with external pressure or could be crushed. Archimède was a French Navy contemporary of the Trieste class but weighing 60% less. Deepsea Challenger and Limiting Factor do away with 92% of 150 t of Trieste class mass to roughly 12 t each. HeavensGate& did away with another 2 t but couldn't take half the pressure using unsound design, testing, and manufacturing processes and unproven materials in a rush to cash-in on commercial adventure experiences. & I meant OceansGate. Darwin Award engineering failures are best syncretized as an admixture of derision of crackpot approaches but with the seriousness of regulatory safety investigation failure chain analysis translated into an oft-repeated undergrad engineering case study. It also seems apparent to not overlook the breadth and depth of human factors extending into a myriad of areas including design, engineering, manufacturing, maintenance, rework, and testing regimes far beyond just operation. After blameless data gathering for exhaustive contributing factor analysis, final findings uncovering evidence of negligence should be severely punished by regulators (if there's anyone still living to sue or foreclose on). https://www.faa.gov/aircraft/air_cert/design_approvals/human_factors https://www.faa.gov/aircraft/air_cert/design_approvals/human...
- snowwrestler 3y agoA somewhat silly detail of the Trieste's Challenger Deep dive is that there was a Rolex watch strapped to the outside of the vehicle. It survived. https://www.rolex.org/perpetual/trieste-the-deepest-dive https://www.rolex.org/perpetual/trieste-the-deepest-dive
- p-e-w 3y agoThat watch was custom-made for the dive, though. It was not a regular Rolex diving watch. I think the strongest commercially available diving watches are rated for 1000 meters – less than 10% of the depth of the Challenger Deep. Which is of course itself ridiculous, since the deepest any human has ever dived was 534 meters, and even professional divers very rarely go deeper than 200 meters.