[Discuss] Near space: Gas

Laura Harris tektryx at yahoo.com
Tue Jan 24 12:20:38 PST 2012

Here are the relative boyancies:

	* Gross buoyant lift of hydrogen: 1.1399 Kg/m^3, 

	* Helium is 1.0565 Kg/m^3. 

	* The difference is 10 grams (~.35 oz) more lift per cubic meter of gas. Another way to look at it is that it takes about 8% less hydrogen than helium to lift the same weight. 

The diffusion rate through solids for helium is about 65% of that for hydrogen. IOW, hydrogen 'leaks' about 35% more quickly than helium, all other things being equal. Shouldn't be an issue for our short flight- we can also add a tad more to make up the difference if we want to be really sure.

 From: Ben Hallert - Vipmail <ben at hallert.net>
To: Rick Osgood <rick at eugenemakerspace.com> 
Cc: "Discuss at eugenemakerspace.com Maker Space" <Discuss at eugenemakerspace.com> 
Sent: Monday, January 23, 2012 9:48 AM
Subject: Re: [Discuss] Near space: Gas

Standard welding tank, prolly 250ft^3 I guess?  Whoops!  Forgot to ask, heh.

- Ben

On Jan 23, 2012, at 9:14 AM, Rick Osgood <rick at eugenemakerspace.com> wrote:

Thanks Ben.  Do you know what size tank that is?  
>On Mon, Jan 23, 2012 at 8:45 AM, Ben Hallert - Vipmail <ben at hallert.net> wrote:
>I called IWSI about lift gas and got done quotes:
>>Tank rental is $5 a month
>>Helium is not currently available (because of the shortage, might not get too much better soon)
>>Hydrogen fill is $45.
>>- Ben
>>Discuss mailing list
>>Discuss at eugenemakerspace.com
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