Talk-Polywell.org

Posted: **Wed Dec 11, 2013 5:23 am**

Just because it's cool:
http://nextbigfuture.com/2013/12/mit-bi ... -that.html

Posted: **Wed Dec 11, 2013 2:10 pm**

Yes, she's a NIAC recipient. Been on NASA TV several times. I think the idea comes from Cowboy Bebop.

Posted: **Wed Dec 11, 2013 4:47 pm**

GIThruster wrote:Yes, she's a NIAC recipient. Been on NASA TV several times. I think the idea comes from Cowboy Bebop.

According to wikipedia the idea dates back to the 1950's. It was used allot I recall in J.E. Pournelle's stories from the '70's.

http://en.wikipedia.org/wiki/Mechanical_counterpressure

For whatever reason NASA fell in love with the "balloon"/pressure suit model instead.

Posted: **Wed Dec 11, 2013 4:57 pm**

I appreciate that but really, I was joking.

But have you seen those skinny suits in CB?

Posted: **Wed Dec 11, 2013 5:45 pm**

As with engineering in general, there are tradeoffs. One liability of a mechanical counter-pressure suit is the need for a fairly exacting fit. With pressure suites it is possible to fit a range of people with a limited selection of sizes, but movable joints become difficult.

Wondering how much vacuum testing has been done, I found http://en.wikipedia.org/wiki/Space_activity_suit.
Regarding an earlier generation design

A number of problems also turned up, primarily related to the problem of keeping the suit in strong mechanical contact at every point on the body. Concavities or small folds in the fabric could lead to fluid pooling in the gaps; the groin area proved extremely difficult to tailor successfully. To correct this, small pads of polyurethane foam were inserted into concavities and were successful in most problem areas. The suits had to be tailored to each individual, although the same was true of all space suits of the era. The largest difficulty was donning and removing the suit. In order to effectively provide the minimum pressure of 29.6 kilopascals (220 mmHg; 4.3 psi) necessary for human physiology, the suit had to be extremely tight-fitting, making donning and doffing a highly strenuous task.

Posted: **Wed Dec 11, 2013 8:18 pm**

hanelyp wrote:As with engineering in general, there are tradeoffs. One liability of a mechanical counter-pressure suit is the need for a fairly exacting fit. With pressure suites it is possible to fit a range of people with a limited selection of sizes, but movable joints become difficult.

Wondering how much vacuum testing has been done, I found http://en.wikipedia.org/wiki/Space_activity_suit.
Regarding an earlier generation design
A number of problems also turned up, primarily related to the problem of keeping the suit in strong mechanical contact at every point on the body. Concavities or small folds in the fabric could lead to fluid pooling in the gaps; the groin area proved extremely difficult to tailor successfully. To correct this, small pads of polyurethane foam were inserted into concavities and were successful in most problem areas. The suits had to be tailored to each individual, although the same was true of all space suits of the era. The largest difficulty was donning and removing the suit. In order to effectively provide the minimum pressure of 29.6 kilopascals (220 mmHg; 4.3 psi) necessary for human physiology, the suit had to be extremely tight-fitting, making donning and doffing a highly strenuous task.

I can imagine the groin area would be difficult.

Which makes me wonder - maybe a solid 'codpiece/girdle' that seals around the waist and thighs? Probably be uncomfortable as all get out, but it'd keep you from having vacuum hickeys in embarrassing places...

Posted: **Wed Dec 11, 2013 8:28 pm**

As I understand, she has not yet met her pressure goal. It is more conceptual than actual.

Posted: **Thu Dec 12, 2013 5:54 am**

hanelyp wrote:exacting fit.

Is there something inherent to such suits that couldn't allow economies of scale?

A number of problems also turned up, primarily related to the problem of keeping the suit in strong mechanical contact at every point on the body. Concavities or small folds in the fabric could lead to fluid pooling in the gaps; the groin area proved extremely difficult to tailor successfully. To correct this, small pads of polyurethane foam were inserted into concavities and were successful in most problem areas. The suits had to be tailored to each individual, although the same was true of all space suits of the era. The largest difficulty was donning and removing the suit. In order to effectively provide the minimum pressure of 29.6 kilopascals (220 mmHg; 4.3 psi) necessary for human physiology, the suit had to be extremely tight-fitting, making donning and doffing a highly strenuous task.

Sounds like a good application for 3D printed, disposable/recyclable even, jockstrap like groin interfaces with the suit. Scan groin and print gradually flatter & more rigid layers.

ladajo wrote:As I understand, she has not yet met her pressure goal. It is more conceptual than actual.

This particular research project on this suit scheme was already featured a few years ago. Visually almost identical suit prototype then as the one in above article. So is it safe to assume they're still around because they've made some progress? It wasn't just 2-3 years ago IIRC. More like the better part of a decade.

Posted: **Thu Dec 12, 2013 6:13 pm**

Betruger wrote:
hanelyp wrote:exacting fit.
Is there something inherent to such suits that couldn't allow economies of scale?

I see it as analogous to buying a jacket off the rack vs. custom tailored. The latter fits better, but will always cost more because of the unique construction, as opposed to umpteen interchangeable pieces. Mass production typically lends itself to methods that trade an increased tooling cost for lower unit cost. Automated scan and fabrication can reduce costs, but each suit is still a custom job.

Posted: **Thu Dec 12, 2013 8:08 pm**

hanelyp wrote:
Betruger wrote:
hanelyp wrote:exacting fit.
Is there something inherent to such suits that couldn't allow economies of scale?
I see it as analogous to buying a jacket off the rack vs. custom tailored. The latter fits better, but will always cost more because of the unique construction, as opposed to umpteen interchangeable pieces. Mass production typically lends itself to methods that trade an increased tooling cost for lower unit cost. Automated scan and fabrication can reduce costs, but each suit is still a custom job.

I don't think much will happen, for whatever reason NASA seems to be enraptured with their 4 million dollar puncture prone "balloon" suits. Hate to see how one of those will fare with the abrasive wind-borne sands on Mars for instance. But what if the Bigelow inflatable habitat Space X space tourism starts happening? Sure the millionaire enjoying his orbital vacation will want to take a spacewalk. Even with lots of bells and whistles, hard to believe a mechanical counter pressure suit will cost anywhere near 4 million bucks. Probably more like tens of thousands of dollars, and if space tourism takes off, there will be economies of scale lowering price more.

Posted: **Fri Dec 13, 2013 1:28 pm**

each suit is still a custom job.

Shrink wrap?

Posted: **Fri Dec 13, 2013 4:22 pm**

mvanwink5 wrote:
each suit is still a custom job.
Shrink wrap?

Something that was pulled on loose then contracted to fit would answer at least one of the major difficulties of mechanical counter pressure suites, getting it on. Getting the suit to shrink the correct amount would be an engineering challenge. There's also the point that shrink wrap materials I know of aren't high tensile strength. A material, if it can be engineered, that stretches like a wet-suit to put it on then loses stretch on command might make this practical. I've also seen spray on fabrics that might be useful if they had the tensile properties needed.

Posted: **Mon Dec 16, 2013 1:35 am**

If the pressure is 4.3 pounds, it must be pure oxygen. Static generated sparks would be bad.

Sounds like a rebreather is order, where N2 is admitted at 4.3psi at low volumes to toes/fingertips, and oxygen kept concentrated by a membrane separator in the vicinity of the nose/mouth.

Posted: **Mon Dec 16, 2013 2:11 am**

The point of a mechanical counterpressure suit is it doesn't contain gas pressure except for the helmet section, which is why the exact fit is critical. Though come to think of it, a minimum pressure suit that fit as closely on the limbs might bend almost as easily while allowing fit margin for some sensitive areas around the torso.

Posted: **Mon Dec 16, 2013 7:46 am**

I sort of remember a material that shrank when a electric current was passed through it. They talked about it for musles for robots. I wonder how much pressure you could get from that material.
I have found it
Electroactive polymers, or EAPs, are polymers that exhibit a change in size or shape when stimulated by an electric field. The most common applications of this type of material are in actuators and sensors. A typical characteristic property of an EAP is that they will undergo a large amount of deformation while sustaining large forces.
http://en.wikipedia.org/wiki/Electroactive_polymers

The idea being a looser fitting suit that get smaller when voltage is applied becoming form fitting.
sometimes I amaze myself

Talk-Polywell.org

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Sapce suit you can just wear

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