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I don't think it means that you take the underwater parts and use them in space - it means that it was possible to make it work in adverse environments at cheap

I don't think it means that you take the underwater parts and use them in space - it means that it was possible to make it work in adverse environments at cheaper than NASA prices.

ahartmetz 5y ago
Space is probably harder just because there is less experience and it's much more difficult to get it. Temperature extremes and lubricants seem to be obvious difficulies.
h2odragon 5y ago
I'm trying to conceive a vacuum capable hydraulic cylinder. As someone who has used backhoes to dig in water then helped refurb the cylinders afterwards. I'm not seeing any happy possibilities, myself. I agree that it should be possible to make things work at cheaper prices than NASA, but that's still a long way from "easy" or "Commercial off the Shelf"
- s1artibartfast 5y ago
  I'm curious in what ways a industrial cylinder wouldn't be vacuum capable. Pressure shouldn't be a concern. they operate at 5-10,000 PSI above the ambient environment, so an additional 14 PSI differential shouldn't matter. I'm guessing operating temperatures would be a big concern What failed in water?
  - h2odragon 5y ago
    Corrosion is a concern, all over but especially on the inner cylinder that has to seal. The seals are probably OK but they're important and redo them anyway when its open. The fluid will pick up some water and thats a whole hydraulic system flush, once you get "too much". Then you've got bearings and grease ports and channels that not only don't necessarily like water; but you're not operating in clean water either and that compounds all the problems. Noting almost total ignorance of the realities: I forsee vacuum hydraulics problems including keeping seals tight, the inevitable oil coating on cylinders boiling off and getting polymerized residue buildup. Double enclose all the actuators and have another seal system so you can have a moving thing poking out of a hull, as is done for boats, will probably be necessary... and that'll have its own problems at the actuation points i bet.
  - twic 5y ago
    I am very much not a rocket scientist. But off the top of my head: Cooling. In space there's no ambient cooling by air. If you want to cool something, you have to pump heat out of it and into a radiator. And since that is energy-intensive, you want to minimise heat production as far as you can. Volatiles. In a vacuum those will boil off and not come back. All sorts of polymers, possibly including those used in seals and bearings, suffer from this. Electrostatic build up. Again, there's no route for this to escape into the air, so you need to make sure that anywhere it can build up is grounded, i suppose. Maintenance. Depending on where you're going to use it, you might not be able to depend on some guy with a socket set and ungloved fingers being able to fiddle with it whenever necessary. Gravity. I don't know much about hydraulics, but all sorts of machinery is designed around an unstated assumption that liquid will drip downwards given a chance (sumps etc). Some of these problems go away on the moon (which has gravity, and potentially pressurised garages for maintenance) or Mars (which has the above, and also some atmosphere).
    - Ekaros 5y ago
      To add to list vacuum welding. Which happens in hard vacuum. Making it somewhat complicated to test and solve for on Earth. Specially if we talk about large scale machinery. Then I suppose large scale hard vacuum will be solved by hyperloop...

I don't think it means that you take the underwater parts and use them in space - it means that it was possible to make it work in adverse environments at cheaper than NASA prices.

ahartmetz 5y ago

Space is probably harder just because there is less experience and it's much more difficult to get it. Temperature extremes and lubricants seem to be obvious difficulies.

h2odragon 5y ago

I'm trying to conceive a vacuum capable hydraulic cylinder. As someone who has used backhoes to dig in water then helped refurb the cylinders afterwards. I'm not seeing any happy possibilities, myself. I agree that it should be possible to make things work at cheaper prices than NASA, but that's still a long way from "easy" or "Commercial off the Shelf"

s1artibartfast 5y ago
I'm curious in what ways a industrial cylinder wouldn't be vacuum capable. Pressure shouldn't be a concern. they operate at 5-10,000 PSI above the ambient environment, so an additional 14 PSI differential shouldn't matter. I'm guessing operating temperatures would be a big concern What failed in water?
- h2odragon 5y ago
  Corrosion is a concern, all over but especially on the inner cylinder that has to seal. The seals are probably OK but they're important and redo them anyway when its open. The fluid will pick up some water and thats a whole hydraulic system flush, once you get "too much". Then you've got bearings and grease ports and channels that not only don't necessarily like water; but you're not operating in clean water either and that compounds all the problems. Noting almost total ignorance of the realities: I forsee vacuum hydraulics problems including keeping seals tight, the inevitable oil coating on cylinders boiling off and getting polymerized residue buildup. Double enclose all the actuators and have another seal system so you can have a moving thing poking out of a hull, as is done for boats, will probably be necessary... and that'll have its own problems at the actuation points i bet.
- twic 5y ago
  I am very much not a rocket scientist. But off the top of my head: Cooling. In space there's no ambient cooling by air. If you want to cool something, you have to pump heat out of it and into a radiator. And since that is energy-intensive, you want to minimise heat production as far as you can. Volatiles. In a vacuum those will boil off and not come back. All sorts of polymers, possibly including those used in seals and bearings, suffer from this. Electrostatic build up. Again, there's no route for this to escape into the air, so you need to make sure that anywhere it can build up is grounded, i suppose. Maintenance. Depending on where you're going to use it, you might not be able to depend on some guy with a socket set and ungloved fingers being able to fiddle with it whenever necessary. Gravity. I don't know much about hydraulics, but all sorts of machinery is designed around an unstated assumption that liquid will drip downwards given a chance (sumps etc). Some of these problems go away on the moon (which has gravity, and potentially pressurised garages for maintenance) or Mars (which has the above, and also some atmosphere).
  - Ekaros 5y ago
    To add to list vacuum welding. Which happens in hard vacuum. Making it somewhat complicated to test and solve for on Earth. Specially if we talk about large scale machinery. Then I suppose large scale hard vacuum will be solved by hyperloop...