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#21
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"D Schneider" wrote:
Henry Spencer wrote: [...] [...] A quick-donning, one-size-fits-all, lightweight emergency suit is most unlikely to be a high-pressure suit, at least not any time soon. Are the "skin suit" designs a candidate for this? Perhaps with a high-pressure helmet? Skinsuits are decidedly not one-size-fits-all, nor would I expect them to be particularly quick-donning *or* high-pressure. |
#22
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"D Schneider" wrote:
IIRC, previous discussions pointed out that "skin suits" hadn't completely solved the joint problem yet, "Skin Suits" haven't solved *any* of their problems yet. D. -- Touch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL |
#23
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"Henry Spencer" wrote in message
... As Rand says, this is a very old idea. Unfortunately, it turns out that legs are really quite useful in free fall, for holding you in place and maneuvering you around (using foot restraints, of course). The pod concepts mostly date from a time when people thought that working while floating free would be easy, when in fact it's extremely difficult. The idea is not ridiculous, but it's by no means obviously attractive. Considering the dexterity that some people manage with the likes of bicycles, forklifts, even helicopters, I am hopeful that some kind of remote leg, perhaps with prehensile toes, might be workable. At first thought, human legs do not seem that well suited to space, many much longer grappling legs, (perhaps foot operated), might be of some use. Even if this is not as coordinated as a suited leg. The pod concepts do not necessarily have to replace space suits, just supplement them. Designing the space station, or whatever, with such pods in mind might also be sensible. For example, the capacity to externally detach small things and then bring them through an airlock into the pod for onsite fine work without gloves might make some sense. Detaching larger objects and carrying them into a hanger for such fine work also seems highly desirable. A gloved hand is still far inferior to bare hands for fine work. I think such pod approaches should enable you to greatly reduce suit time at little extra cost. Even having a podded person on hand to assist the suited "surgeon" with tools, air, extra eyes, power, heavy grappling, a mobile platform, simple tasks, fine work on detached components, etc., might greatly speed up the operation at little cost. The likes of a quick flyby inspection of the space shuttle tiles would also be possible, not that I am suggesting use of a shuttle. Point being, I suspect such a pod system might be a useful and justified addition to space station operating equipment. Greatly increasing your options and ability to quickly do stuff. Pete. |
#24
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In article opsia5gyicemtzlb@d3h1pn11,
D Schneider wrote: [...] A quick-donning, one-size-fits-all, lightweight emergency suit is most unlikely to be a high-pressure suit... Are the "skin suit" designs a candidate for this? Perhaps with a high-pressure helmet? Nope. Aside from the fact that skinsuits are not yet a proven approach -- the basic concept works, but whether some detailed engineering problems can be adequately solved is unknown, due to lack of funding -- they don't work for this at all. As things stand now, skinsuits most emphatically are *not* quick-donning or one-size-fits-all. Donning is tedious and difficult, to the point that this rates as one of the important unresolved problems. Moreover, they have to be precisely custom-tailored, to the point that the intended wearer has to avoid gaining or losing more than a pound or two if he wants the suit to fit properly. Modern materials might help the tailoring problem, but the donning problem is harder. Finally, all skinsuits made to date are low-pressure. Helmet and body pressures must match; there is a continuous liquid column between the lung capillaries and the skin capillaries, after all. And the one attempt so far at producing an 8psi skinsuit glove was unsuccessful -- techniques and materials which work quite well at 3.5psi don't scale well enough. -- "Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | |
#25
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Henry Spencer wrote:
[...] As things stand now, skinsuits most emphatically are *not* quick-donning or one-size-fits-all. Donning is tedious and difficult, to the point that this rates as one of the important unresolved problems. Moreover, theyhave to be precisely custom-tailored, to the point that the intended wearer has to avoid gaining or losing more than a pound or two if he wants the suit to fit properly. Modern materials might help the tailoring problem, but the donning problem is harder. Dang. Modern materials might include some of the artificial muscle materials, but these aren't going to be ready for *this* application for a while; might as well be unobtanium. However, when the decade dawns that these are the material of choice, they might as well use them to solve the donning problem as well as the tailoring problem. Finally, all skinsuits made to date are low-pressure. Helmet and body pressures must match; there is a continuous liquid column between the lung capillaries and the skin capillaries, after all. And the one attempt so far at producing an 8psi skinsuit glove was unsuccessful -- techniques and materials which work quite well at 3.5psi don't scale well enough. Okay, we rig the transporter to remove nitrogen, and just aim us into the spacesuits. "Careful, Captain...the machine has bin leaving a few wee embolisms of late; we dinna wanna lose ye..." /dps -- Using Opera's revolutionary e-mail client: http://www.opera.com/m2/ |
#26
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In article opsicy53faemtzlb@d3h1pn11,
D Schneider wrote: Modern materials might help the tailoring problem, but the donning problem is harder. Dang. Modern materials might include some of the artificial muscle materials, but these aren't going to be ready for *this* application for a while; might as well be unobtanium... You don't need to get quite that drastic. :-) Skinsuits benefit a lot from materials with a non-linear stress-strain curve, and some of those already exist. With a normal elastic material, if you want to stretch it twice as far, you have to apply about twice as much force. But there are some materials, Spandex being one of them if I recall correctly, which are different. They start out the normal way, but when you reach a particular amount of stretch, the curve flattens out: the material stretches, and stretches more, and stretches still more, with only the most minute increase of force. Eventually the required force starts rising again, but there's a wide flat section in the middle of the curve. This is exactly what's wanted for a skinsuit: essentially constant force over a wide range of stretch. Not only does this accommodate flexing of the body, but if that range is wide enough, it can also accommodate some discrepancy between the design size and the actual size of the body. But at donning time, you're still trying to put on something that's squeezing hard all the time. What's needed is a way to turn that off and on, either on command or automatically in response to ambient pressure (a fabric that shrinks in vacuum). Not simple. -- "Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | |
#27
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Henry Spencer wrote:
[...] But at donning time, you're still trying to put on something that's squeezing hard all the time. What's needed is a way to turn that off and on, either on command or automatically in response to ambient pressure (a fabric that shrinks in vacuum). Not simple. Well, that's what I was thinking of the muscle fabric for...to take up the slack you need for donning. Slip on your "Incredibles" suit, getting your legs in nice spacious openings (like Slates, not Levis), and push a button to cinch things up. But even as promising as the Sci Am article was, it will still be a while.... /dps -- Using Opera's revolutionary e-mail client: http://www.opera.com/m2/ |
#28
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D Schneider wrote:
Well, that's what I was thinking of the muscle fabric for...to take up the slack you need for donning. Slip on your "Incredibles" suit, getting your legs in nice spacious openings (like Slates, not Levis), and push a button to cinch things up. This will be developped. The documentary Back to the Future (2 I think) showed such garments in action, including shoes. More likely would be some sort of "heat shrink" fabric which, upon encountering a catalyst, shrink to fit. (catalyst could be some spray of a chemical for instance). One would also need to have a reverse chemical reaction to make the fabric expand again so you can egress the suit. Nut again, this is not needed for emergency return to earth since the human will not need mobility while in space, and will automatically regain mobility once differential pressure is reduced as altitude decreases. |
#29
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(Henry Spencer) wrote
Nope. Aside from the fact that skinsuits are not yet a proven approach -- the basic concept works, but whether some detailed engineering problems can be adequately solved is unknown, due to lack of funding -- they don't work for this at all. As Fate, Serendipity, Jungian Synchronicity and Morphic Resonance would have it, I was just doing some deep diving in Google Groups and found http://tinyurl.com/63cts from 1982. I'm not sure whether I prefer "skinsuit" to "space leotard" or not. |
#30
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"Henry Spencer" wrote in message ... With a normal elastic material, if you want to stretch it twice as far, you have to apply about twice as much force. But there are some materials, Spandex being one of them if I recall correctly, which are different. They start out the normal way, but when you reach a particular amount of stretch, the curve flattens out: the material stretches, and stretches more, and stretches still more, with only the most minute increase of force. Eventually the required force starts rising again, but there's a wide flat section in the middle of the curve. This is exactly what's wanted for a skinsuit: essentially constant force over a wide range of stretch. Not only does this accommodate flexing of the body, but if that range is wide enough, it can also accommodate some discrepancy between the design size and the actual size of the body. But at donning time, you're still trying to put on something that's squeezing hard all the time. What's needed is a way to turn that off and on, either on command or automatically in response to ambient pressure (a fabric that shrinks in vacuum). Not simple. No, something simpler. Something that reacts to a piezoelectric force. Done a nice loose fitting suit, plug in the battery, bamm... skin tight. -- "Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | |
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