Annoying Questions I'd Like Answered...

DSMatticus · Post by **DSMatticus** » Wed Dec 12, 2012 7:35 am

LargePrime wrote:3) Dump ~20 pounds of air into both

That is approximately seven cubic meters of air (at normal conditions). Are you suggesting that that came through the hose in fifteen seconds? Or that that is how much was in his suit? Or are you suggesting that large amounts of air can significantly change the pressure of small chambers, therefore any amount of air can significantly change the pressure of small chambers? Because all three of those are horribly, horribly wrong.

LargePrime wrote:hard vacuum

You say this term a lot and I don't think you have any idea what it means. Because it doesn't actually mean anything. In the same way that there exists no scientific consensus on how many kilometers per hour something has to be travelling before it is "fast," there exists no scientific consensus on how low a vacuum's pressure must be before it is "hard." It's a very unscientific term, and pretty much used arbitrarily by an author.

Animal testing with vacuums of various extents has been fairly extensive, and it is always hypoxia. Every human anecdote confirms this; the fact that there is nothing to breathe (well, actually, their lungs are working in reverse to give off gases) knocks them out pretty much as soon as the deoxgyenated blood hits the brain. And that takes between five and ten seconds.

Cynic · Post by **Cynic** » Wed Dec 12, 2012 8:17 am

So I've been looking for new movies to watch. Since I've been on such a Hellblazer comics kick, I was wondering if there were any films that are like the comic or the character of Constantine. I'm not at all interested in the Keanu Reeves movie. But if other movies can handle the supernatural or horror in the weird sort of style that Hellblazer does then it would be cool

Any suggestions?

tussock · Post by **tussock** » Wed Dec 12, 2012 12:12 pm

LargePrime wrote:If one has a small hole in there space suit, assuming pressurized to 1 ATM, how long would it take to depressurize to ~0ATM?

Guesstimate: air exits holes toward a vacuum at the speed of sound (give or take). You can assume a suit will empty at

hole-area m^2 x 330 m/s x 1 kg/m^3 = 330 kg/s per 1m^2 area.
Or for a half-inch stable circular hole about .05 kg/s (which is 50 litres, which is a portable chiller, or a keg, 12 gallon for you medievalists, should easily fill a pressure suit).

Under a second then, ignoring drag on a narrow hole, which shouldn't more than double it, plus some to let the air out of his lungs, and other minor complications.

fectin · Post by **fectin** » Wed Dec 12, 2012 2:00 pm

Okay. After a lot of swagging, I get initial air flow = 6ft^3/s per square foot of orifice. Probably that hose had a 3 inch^2 cross-section, so thats roughly 1/8 cf/s initial flow.

But, here's the thing: low pressure makes you pass out because it sucks blood into your extremities and away from your brain. All astronauts were test pilots though, and pilots get training on how to counteract that, because the same thing happens in high-G turns. If they know it's coming, they can compensate.

Regardless, it still comes back to what "safe" means. General anesthesia knocks you right out too, and you recover from it more slowly. a golf clap has a pressure spike large enough to damage your eardrums. Going jogging in Denver can be dangerous to out-of-towners, but trivial for anyone acclimated. Diving has some really severe pressure deltas, and you can die from the bends, but is generally considered "safe". It really does all come back to definitions in this case (for 'pressure' too; spikes, short term, and long term are pretty different).

Prak · Post by **Prak** » Wed Dec 12, 2012 4:26 pm

Cynic wrote:So I've been looking for new movies to watch. Since I've been on such a Hellblazer comics kick, I was wondering if there were any films that are like the comic or the character of Constantine. I'm not at all interested in the Keanu Reeves movie. But if other movies can handle the supernatural or horror in the weird sort of style that Hellblazer does then it would be cool

Any suggestions?

I actually do recommend Constantine. Granted, it's not a Hellblazer movie, more a movie about some guy with the same name who fights demons in America, but it is pretty enjoyable once you make that distinction. I know it's not saying much, but it may be Reeve's best action movie.

LargePrime · Post by **LargePrime** » Wed Dec 12, 2012 6:19 pm

DSMatticus wrote:
LargePrime wrote:3) Dump ~20 pounds of air into both
That is approximately seven cubic meters of air (at normal conditions). Are you suggesting that that came through the hose in fifteen seconds? Or that that is how much was in his suit? Or are you suggesting that large amounts of air can significantly change the pressure of small chambers, therefore any amount of air can significantly change the pressure of small chambers? Because all three of those are horribly, horribly wrong.

None of the above. Did you actually read my post?

DSMatticus wrote:
LargePrime wrote:hard vacuum
You say this term a lot and I don't think you have any idea what it means. Because it doesn't actually mean anything.

It Does. A hard vacuum means a vacuum created for the purpose of maximum vacuum, as opposed to vacuum created to simply be a lower pressure. Yes it is more of a term of art, as one scenarios "Hard Vacuum" is insufficient for another. But given that we havent changed scenarios...

DSMatticus wrote:Animal testing with vacuums of various extents has been fairly extensive, and it is always hypoxia.

You have a source for this?

I would like to point out that there were 3 sources of air entering the vacuum chamber
1) small cache of air in his suit
2) the External air feed line
3) the External air return line
As he was exercising he needed both a air supply and removal, which went through the wall of the chamber into whatever supply system they had to his suit.
We don't know which hose failed. When the hose failed, his suit was still being 'supplied' by either the back flowing "exhaust" line or the supply line, which ever was intact. It it so hard to say that that supply did to limit the amount of vacuum he was exposed to.

Chamomile · Post by **Chamomile** » Thu Dec 13, 2012 1:33 am

This isn't so much a question as an observation that I didn't think deserved its own thread: The Wish and the Word describes a team-up between a gods-defying superman who murders everything that gets close on the one hand, and on the other hand...Timmy Turner.

tussock · Post by **tussock** » Thu Dec 13, 2012 8:41 am

A hard vacuum means a vacuum created for the purpose of maximum vacuum

No. There is no maximum vacuum. You can always spend more money to get more molecules out. A "hard" vacuum might mean you're at the point of batting individual air molecules out of your chamber, when the fans don't work any more, because most molecules are making it wall-to-wall without collision and so can't respond to pressure changes.

More importantly, how much of a vacuum it was doesn't matter. Not even slightly. Getting water to boil at body temperature shows it was below 0.07 atm inside his mouth and lungs. That's plenty of vacuum.

Prak · Post by **Prak** » Thu Dec 13, 2012 11:46 am

So, I'm basically a caffeine freak, and the coffee at school is expensive and shitty. I've been wanting to put together a portable coffee kit for a while (originally just carrying a french press and some ground coffee, a friend showed me an air press that I now want even more).

The problem has been heating water portably and in-obtrusively. I mean, sure, I can carry around an electric kettle in a giant bag, and seek out an outlet, and have this whole big thing going on my desk in the back of the room, but I'd... rather not?

Does anyone have a suggestion for a way heat water, preferably without an outlet, and without turning making a cup of coffee on the go a huge, attention grabbing production?

Ancient History · Post by **Ancient History** » Thu Dec 13, 2012 12:10 pm

Heating pack from an MRE.

LargePrime · Post by **LargePrime** » Thu Dec 13, 2012 12:45 pm

Prak_Anima wrote:Does anyone have a suggestion for a way heat water, preferably without an outlet, and without turning making a cup of coffee on the go a huge, attention grabbing production?

Does the cafeteria sell tea?
Usually that's a bag and you add hot water from a coffee caldron that has no coffee.
Get the hot water there.
Now just Social engineer access...
off the top suggestion
If anyone asks tell them you are allergic to the tea they sell, so you brought your own.
Don't brew your coffee near your free hot water.

Username17 · Post by **Username17** » Thu Dec 13, 2012 1:06 pm

For fuck's sake guys, just go to Scientific American or something. They have NASA on speed dial and answer these sorts of questions for a living.

In near zero pressure environments, you go unconscious in less than 15 seconds but you don't actually explode. Death comes in a number of minutes, but you may end up with torn lungs or frozen eyeballs even if you're rescued. For D&D purposes, being dumped into space gives you two rounds to get back into a pressurized environment.

-Username17

LargePrime · Post by **LargePrime** » Thu Dec 13, 2012 1:07 pm

tussock wrote:
A hard vacuum means a vacuum created for the purpose of maximum vacuum
No. There is no maximum vacuum. You can always spend more money to get more molecules out.

OK but we are talking about NASA making a vacuum chamber to test shit going into space. As opposed to a vacuum chamber to do high altitude flight aerodynamics experiments at a fractional atmosphere.
So i am going with NASAs SPACE VACUUM Chamber as having a hard vacuum. Well right up until an accident starts dumping air into it.

tussock wrote:More importantly, how much of a vacuum it was doesn't matter. Not even slightly. Getting water to boil at body temperature shows it was below 0.07 atm inside his mouth and lungs. That's plenty of vacuum.

Right, cause as I posted, that's ~.1 ATM. I added a bit due to assumed velocity/humidity effects.
But if a human tongue/face/body is exposed to .07 ATM does it not swell? Joe Kittingers hand over doubled in size.

How do you rationalize exposure to this vacuum but no observed swelling?

P.S. Also .07 ATM is not enough vacuum when you NASA sending shit into space. Thats just soft vacuum

Prak · Post by **Prak** » Thu Dec 13, 2012 2:46 pm

Ancient History wrote:Heating pack from an MRE.

Awesome, thank you. I'll try to source those (there's a local army surplus store) and pass the idea on to my friend who showed me the air press.

@LargePrime: the idea of procuring from the cafeteria came to mind, but the cafeteria is typically out of my way, and most of the staff are unionized first Gen Russian immigrants who have amazing job security, poor English and customer service skills and have no reason to not be a pain in the ass to work with, so they are.

shadzar · Post by **shadzar** » Thu Dec 13, 2012 4:18 pm

Prak_Anima wrote:So, I'm basically a caffeine freak, and the coffee at school is expensive and shitty. I've been wanting to put together a portable coffee kit for a while (originally just carrying a french press and some ground coffee, a friend showed me an air press that I now want even more).

The problem has been heating water portably and in-obtrusively. I mean, sure, I can carry around an electric kettle in a giant bag, and seek out an outlet, and have this whole big thing going on my desk in the back of the room, but I'd... rather not?

Does anyone have a suggestion for a way heat water, preferably without an outlet, and without turning making a cup of coffee on the go a huge, attention grabbing production?

in ye olden days, people had a container which would let you maintain a warm liquid at a semi constant temperature for a long period of time. they would make the liquid substance at home and carry it to work or wherever they were going. one company has the genericized name for the product as a brand name, Thermos.

Ted the Flayer · Post by **Ted the Flayer** » Thu Dec 13, 2012 4:18 pm

I worked in a cafeteria with a lot of Russian immigrants a while back. I got written up because of my habit to swear in Norwegian. Turns out that it's more likely for a Russian to speak Norwegian than an American.

Prak · Post by **Prak** » Thu Dec 13, 2012 5:05 pm

shadzar wrote:
Prak_Anima wrote:So, I'm basically a caffeine freak, and the coffee at school is expensive and shitty. I've been wanting to put together a portable coffee kit for a while (originally just carrying a french press and some ground coffee, a friend showed me an air press that I now want even more).

The problem has been heating water portably and in-obtrusively. I mean, sure, I can carry around an electric kettle in a giant bag, and seek out an outlet, and have this whole big thing going on my desk in the back of the room, but I'd... rather not?

Does anyone have a suggestion for a way heat water, preferably without an outlet, and without turning making a cup of coffee on the go a huge, attention grabbing production?
in ye olden days, people had a container which would let you maintain a warm liquid at a semi constant temperature for a long period of time. they would make the liquid substance at home and carry it to work or wherever they were going. one company has the genericized name for the product as a brand name, Thermos.

Large Thermoses are expensive-ish, and the small one we have runs out in about twenty minutes.

tussock · Post by **tussock** » Fri Dec 14, 2012 5:18 am

LargePrime wrote:But if a human tongue/face/body is exposed to .07 ATM does it not swell? Joe Kittingers hand over doubled in size.

How do you rationalize exposure to this vacuum but no observed swelling?

Kittinger's hand expanded for the same reason people get sucked out of aeroplanes when they de-pressurise: the pressure on the other side. Joe's body was pressurised, so that pressure gradually forces blood into the hand against it's elastic response, but won't let it back out of the hand because the hand is at lower pressure.

P.S. Also .07 ATM is not enough vacuum when you NASA sending shit into space. Thats just soft vacuum

I'm just saying, that's the upper limit on what he experienced, and that's plenty to get the job done. There's no real physiological differences, other than surface water on mucus membranes boiling off slightly faster for more localised freezing effects. Close your eyes.

Maj · Post by **Maj** » Fri Dec 14, 2012 5:19 am

I think perhaps you are underestimating thermoses, Prak. I'd poke around online and find one with good reviews. I know that they even make coffee press thermoses for just under $30. We have this one, and it's great. It's also the same cost as a month or so of MRE heaters, but will last significantly longer than that.

Cynic · Post by **Cynic** » Fri Dec 14, 2012 8:34 pm

And then there is this as well.

It's pretty easy to get a nice size cheap thermos that lasts for a long time.

Prak · Post by **Prak** » Fri Dec 14, 2012 9:30 pm

Crazy as it seems, I'd honestly rather carry around a shelf stable 8 oz box of milk, a travel mug a brewer, and a couple Mrs heating packs, that can all collapse down to an easily stowed size, than carry around a fairly large Thermos that takes up a hand (I hate carrying stuff in my hands when I'm out, and I don't have a car), or means I have to use my old, ratty backpack instead of ne of my messenger bags.

shadzar · Post by **shadzar** » Fri Dec 14, 2012 10:10 pm

Prak_Anima wrote:Crazy as it seems, I'd honestly rather carry around a shelf stable 8 oz box of milk, a travel mug a brewer, and a couple Mrs heating packs, that can all collapse down to an easily stowed size, than carry around a fairly large Thermos that takes up a hand (I hate carrying stuff in my hands when I'm out, and I don't have a car), or means I have to use my old, ratty backpack instead of ne of my messenger bags.

get the thermos, and your messenger bag, and with a couple of carabiners...the clips rock climbers use, but they make cheap versions for keychains now that either screw or flex to open, and attach the thermos to the messenger bag straps.

Prak · Post by **Prak** » Fri Dec 14, 2012 10:41 pm

And get the shit beaten out of my torso.

Korgan0 · Post by **Korgan0** » Fri Dec 14, 2012 10:50 pm

Prak_Anima wrote:And get the shit beaten out of my torso.

Builds character.

shadzar · Post by **shadzar** » Sat Dec 15, 2012 12:22 am

Prak_Anima wrote:And get the shit beaten out of my torso.

how are you carrying your messenger bag? slung on the back, on the front, or the side?

does it have both low and high point to connect the strap? can you strap a thermos to one high and the other side low point so that it is straddled across the bag and on the outside of you?

just feed the thermos with carabiners through the strap so the thermos is on top of the bag?

there is so many ways to make it work. i just tried a few with a messenger bag and laptop bag, and had no problems with either in any slung position.