[Discuss] Near space: Gas

Ben Hallert EMAIL HIDDEN
Tue Jan 24 13:47:50 PST 2012


Parties to Go quoted me $172 for the same size tank of Helium, and
that's per day.

- Ben



On Tue, Jan 24, 2012 at 1:34 PM, Rick Osgood <EMAIL HIDDEN> wrote:
> All good points.  Can we get helium from another supplier?  Party store?
>  That's where we rented helium from in the past.
>
>
> On Tue, Jan 24, 2012 at 1:17 PM, Laura Harris <EMAIL HIDDEN> wrote:
>>
>> Except that the hydrogen flame is invisible in daylight :P
>>
>> The minimum energy for spark ignition [of hydrogen] at atmospheric
>> pressure is about 0.02 millijoules. (via wikipedia)
>>
>> This is really low- cell phones can generate sparks at this level, so
>> we'll need to be careful about such things as well as making sure all
>> electronics in the capsule are turned off while inflating, the use of
>> anything metallic or capable of making sparks close to or inside the
>> balloon, and being careful to avoid any static discharges (esp. if the air
>> is dry). Non-sparking wrenches for attaching hoses, etc. will be required
>> (e.g., brass wrenches). Metallic tools coming in contact with hydrogen
>> lines, fill ports, and valving should all be grounded. And so on.
>>
>> Yes, I'm paranoid about this- if we had an explosion, aside from the
>> potential for physical harm, the press would be merciless (assuming they
>> found out) and that in turn could create PR problems for other NS projects.
>>
>> ________________________________
>> From: Rick Osgood <EMAIL HIDDEN>
>> To: James Hukill <EMAIL HIDDEN>
>> Cc: Laura Harris <EMAIL HIDDEN>; Ben Hallert - Vipmail
>> <EMAIL HIDDEN>; "EMAIL HIDDEN Maker Space"
>> <EMAIL HIDDEN>
>> Sent: Tuesday, January 24, 2012 12:45 PM
>>
>> Subject: Re: [Discuss] Near space: Gas
>>
>> We can also use James' "cut down" mechanism idea to visually locate the
>> payload at peak altitude. ;)
>>
>> On Tue, Jan 24, 2012 at 12:23 PM, James Hukill <EMAIL HIDDEN> wrote:
>>
>> Other upside, much easier to have an emergency down option.
>> Small spark in the balloon and it will decelerate
>>
>> ;-)
>>
>>
>> On Tue, Jan 24, 2012 at 12:20 PM, Laura Harris <EMAIL HIDDEN> wrote:
>>
>> 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 <EMAIL HIDDEN>
>> To: Rick Osgood <EMAIL HIDDEN>
>> Cc: "EMAIL HIDDEN Maker Space"
>> <EMAIL HIDDEN>
>> 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 <EMAIL HIDDEN>
>> wrote:
>>
>> Thanks Ben.  Do you know what size tank that is?
>>
>> Rick
>>
>> On Mon, Jan 23, 2012 at 8:45 AM, Ben Hallert - Vipmail <EMAIL HIDDEN>
>> 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.
>>
>> Regards,
>>
>> - Ben
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