Sun Oct 25, 2009 2:41 am
A2C wrote:
Hi Engguy:
What is the purpose of your idea? Are you trying to create a 50 mile long blow up doll to stop g.w.? If so, pm me on that one. To answer your question about how many C.F. are in 1 gal of helium: 1 gal of helium or any other substance is .134 C.F. That's about 7.5 gal per C.F.
????
I don't think so. 1 gallon of liquid helium is much more than that.
If a cryo liquid gas wasn't condensed like that then there would be no reason to contain it in that form.
I just read a site that said 2700 cubic feet of gaseous helium would fit into
a 26 gallon liquid container.
1 cubic foot of any substanceat standard temp and pressure, uncompressed, is 7.5 gallons.
Sun Oct 25, 2009 5:50 pm
lets see 2700 / 26 = 103.8 cuft per gallon
Your missing the point helium is very very cold when it is a liquid.
Your missing the point helium is very very cold when it is a liquid.
Sun Oct 25, 2009 6:03 pm
Holedigger wrote:What AC had all the wing cavities filled with ping pong balls to make it buoyant in case it went down in the drink?
Never mind, found it, Vultee V1-A
We filled fuel tanks with wiffle balls to stop sloshing of fuel while racing (before fuel cell foam) and it worked great!
unitl the fuel filter became clogged with wiffle ball shavings.... 
Mon Oct 26, 2009 8:44 am
MX304 wrote:Airlift48 wrote:What happens to the lifting properties of helium when you pressurize it? Does it decrease with more pressure?
Helium is still lighter than air no matter how compressed it is. If you could make a cylinder that would hold 2000psi and be light enough, it would float.
No you couldn't! That is so wrong!
In answer to Airlift48's question, that is correct. As it is compressed, its lifting capability is decreased. It is so basic; as it is compressed, it becomes more dense. Static (lighter than air) lift is a matter of relative densities and displacement, not absolute weights - the same way that a 95,000 ton aircraft carrier is able to float in water. The 95,000 tons of steel aircraft carrier takes up more space than the equivalent 95,000 tons of water it is displacing, therefore it is less dense and consequently it floats on the water.
A cubic foot of uncompressed helium is lighter than a cubic foot of regular air, but a cubic foot of compressed helium in a pressurized vessel like an aluminum tank is NOT lighter than the same volume of air. You have to expand or decompress the helium for it to "float" a payload and the differential must be great enough to account for the weight of that payload, too.
Helium has a density (@ 0 degrees C, 101.325 kPa) of 0.1786 grams/liter. Nitrogen, which everyone knows makes up approximately 78% of the Earth's atmosphere, has a density (under the same temperature and pressure conditions) of 1.251 grams/liter. That means that Nitrogen is about 7 times heavier than Helium.
If you compress helium to 2000 psi (roughly 133 times atmospheric pressure), you're putting 133 x 0.1786 grams into each liter of volume = 23.81 grams per liter - which is way more than the same volume of uncompressed dry air (78% Nitrogen and 21% Oxygen, which is about 1.2759 grams per liter).
The result is that even without the pressure cylinder, the "compressed" helium would no longer "float" because it is 18.66 times heavier than the same volume of air.
Mon Oct 26, 2009 9:53 am
you're all full of hot air. 