[HN Gopher] The bathyscaph Trieste: technological and operationa...
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The bathyscaph Trieste: technological and operational aspects,
1958-1961
Author : pmcjones
Score : 71 points
Date : 2023-06-28 19:40 UTC (3 hours ago)
(HTM) web link (archive.org)
(TXT) w3m dump (archive.org)
| sclarisse wrote:
| - 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.
| eutectic wrote:
| When 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 wrote:
| It could well be both.
| eutectic wrote:
| Well, 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 wrote:
| The 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 wrote:
| The 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.
| sjackso wrote:
| I 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.
| moffkalast wrote:
| > 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.
| Zee2 wrote:
| > athwartships
|
| What a phenomenal word!
| sclarisse wrote:
| Ah! 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.
| b215826 wrote:
| > _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
| elzbardico wrote:
| The 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 wrote:
| Ballast 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 wrote:
| FWIW 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 wrote:
| It'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.
| a4isms wrote:
| You're correct, no "e." Thanks!
|
| The diving in Five Fathoms Marine Park is exquisite, and
| it's a short drive from Lion's Head, which has absolutely
| stellar rock climbing.[1] We've taken the kids on the
| ferry to Manitoulin Island[2], and from there driven over
| to Sudbury.
|
| I recommend trying that ferry at least once, it was a
| lovely experience.
|
| [1]: https://www.thecrag.com/en/climbing/canada/lions-
| head
|
| [2]: https://en.wikipedia.org/wiki/Manitoulin_Island
| babypuncher wrote:
| Some steel shot ballast was jettisoned to slow the descent.
| They didn't want to crash into the floor and damage the
| pressure hull.
| NoraCodes wrote:
| Interesting 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 wrote:
| "The inspiration for Prof. Tournesol" is my favourite tidbit
| about Picard :)
| foobarbecue wrote:
| So 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 wrote:
| At 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.
| dpierce9 wrote:
| General Mills also built Alvin which launched in 1964 and is
| still in service.
|
| [0]https://en.m.wikipedia.org/wiki/DSV_Alvin
| adolph wrote:
| It 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-s...
|
| 1. https://cyberneticzoo.com/teleoperators/1960-minotaur-
| remote...
| pmcjones wrote:
| This was written by Don Walsh, who with Jacques Piccard,
| descended to the bottom of the Challenger Deep in 1960. It
| explains many engineering details.
| rvba wrote:
| How many tons of gasoline has this craft put into the see?
| jaggederest wrote:
| Natural oil seeps leak dozens of tons a day into the ocean.
| (estimated 160,000 ton/year) A little gasoline here and there
| isn't going to be substantial.
| 2b3a51 wrote:
| I 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 wrote:
| Reminds 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_.
| mechhacker wrote:
| Interesting 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/
| babypuncher wrote:
| It 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.
| qwertox wrote:
| What 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 wrote:
| It's an underwater zeppelin (or blimp) and you can't convince
| me otherwise.
| adolph wrote:
| The 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._
| foobarbecue wrote:
| "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 wrote:
| Obligatory "This design is the wurst."
| ant6n wrote:
| This spelling of die Wurst is a turd.
| andrepd wrote:
| Funny, 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 wrote:
| I agree. Modern stuff is childish at times.. and old stuff
| when slightly drifting tended to go toward poetry.
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