[islandlabs] How Much Helium

John Teddy masterjediyoda
Fri Dec 18 17:15:28 EST 2009


http://www.srcf.ucam.org/~cuspaceflight/calc/

http://ukhas.org.uk/guides:balloon_data

http://ukhas.org.uk/



2009/12/17 John Teddy <masterjediyoda at gmail.com>

> One we have the phone, we will put everything on a scale and measure the
> weight and we can start to whittle down to a closer degree the calculations.
>
> Does anyone have a scale they can bring to Wednesday's meeting?
>
>
> 2009/12/17 Burns, William <burns at cshl.edu>
>
>>  I made some assumptions... but I'm sticking w/ my 113 cubic feet figure
>> for now. (I think our requirement is half of your figure)
>> Unless the formula in the e-mail is wrong, or we start using some other
>> method/variables for estimating the helium required?
>> (what's our actual payload weight?)
>>
>> -Bill
>>
>>  ------------------------------
>> *From:* list-bounces at islandlabs.org [mailto:list-bounces at islandlabs.org]
>> *On Behalf Of *John Teddy
>> *Sent:* Thursday, December 17, 2009 5:57 PM
>> *To:* Island Labs main mailing list
>> *Subject:* Re: [islandlabs] I have an antenna for the balloon in my
>> office...
>>
>> Someone look at my figures and tell me if it makes any sense, or am I way
>> off.
>>
>> 2009/12/17 John Teddy <masterjediyoda at gmail.com>
>>
>>> Since we already spent $65, it looks like our project total cost is going
>>> to be around ~$150 at least. So roughly the same as MIT. They got some stuff
>>> gratis which we did not. Maybe if we call some engineering / tech school in
>>> the Jersey area and ask one of the professors if they want to give us helium
>>> at no cost.
>>>
>>> 2009/12/17 John Teddy <masterjediyoda at gmail.com>
>>>
>>> So if I squish Bill and my email together, we need
>>>>  *65.5 * 3.3 = 216.15*216 cubic feet of helium.
>>>>
>>>>
>>>> http://bit.ly/7Z4v6A .. I called this guy on ebay, that tank is 244
>>>> cubic feet. He said it weighs 150 pounds full. ANd he said it could be
>>>> rented for $84.99. But he is in Florida. This gives us a rough idea of
>>>> prices though. he said to rent it and use all the helium in it, is $84.99
>>>> can it can be returned after a few days or whatever.
>>>>
>>>> -John
>>>>
>>>> 2009/12/17 Burns, William <burns at cshl.edu>
>>>>
>>>>  Applying the given formula: (4/3*pi*R^3)
>>>>> Excel says: 65.5 cubic feet for a 5-ft diameter balloon.
>>>>>
>>>>> According to the Kaymont figures:
>>>>> http://www.kaymont.com/pages/sounding-balloons.cfm
>>>>>
>>>>> The launch diameter of a kaymont 350 (used by MIT) should have been 125
>>>>> cm if their payload was 250grams.
>>>>> The launch diameter of a kaymont 800 (used by I.L.) should be 150cm if
>>>>> our payload is 250grams.
>>>>>
>>>>> Scaling-up a 5-ft balloon by the same ratio gives us a 6-ft balloon...
>>>>> So (ballpark) our balloon should contain 113 cubic feet of helium.
>>>>>
>>>>> Who knows what size tank might contain that much helium?
>>>>>
>>>>> -Bill
>>>>>
>>>>>  ------------------------------
>>>>> *From:* list-bounces at islandlabs.org [mailto:
>>>>> list-bounces at islandlabs.org] *On Behalf Of *John Teddy
>>>>> *Sent:* Thursday, December 17, 2009 5:04 PM
>>>>> *To:* Island Labs main mailing list
>>>>> *Subject:* Re: [islandlabs] I have an antenna for the balloon in my
>>>>> office...
>>>>>
>>>>>   I see, the person must have been mistaken. Or maybe they were
>>>>> talking about industrial tanks of larger size.
>>>>>
>>>>>
>>>>> http://www.target.com/gp/detail.html/185-8901296-2975720?ASIN=B000PGQ63O&AFID=Froogle&LNM=B000PGQ63O|Disposable_Helium_Tank&ci_src=14110944&ci_sku=B000PGQ63O&ref=tgt_adv_XSG10001<http://www.target.com/gp/detail.html/185-8901296-2975720?ASIN=B000PGQ63O&AFID=Froogle&LNM=B000PGQ63O%7CDisposable_Helium_Tank&ci_src=14110944&ci_sku=B000PGQ63O&ref=tgt_adv_XSG10001>
>>>>>
>>>>> This is a 12lb tank, and holds 15 cubic feet of helium. It only costs
>>>>> $50.
>>>>>
>>>>> I don't think 15 cubic feet of helium be nearly enough.
>>>>>
>>>>> The MIT balloon was 5 feet diameter at launch, and 20 feet at burst. So
>>>>> ours will be under 10 feet diamater at launch, and under 40 feet diamater at
>>>>> burst. My figures are off, need the sphere formula. 4/3*?*radius3
>>>>>
>>>>> I don't know what the weight in the balloon (we have 800gram balloon,
>>>>> they used 350 gram right?), translates to as far as diameter and cubic feet
>>>>> of helium.
>>>>>
>>>>> From the guide:          "each cubic foot of helium can lift 28g" and
>>>>> "each pound of free lift would me 300feet per minute of ascension"
>>>>>
>>>>>
>>>>>
>>>>> http://www.balloonsandhelium.net/heliumtanksforsale.html <--- they are
>>>>> way to expensive to buy. Rent or launch at a party store are the only
>>>>> options. And the weight should definitely be under 100 pounds as you said
>>>>> Mark.
>>>>>
>>>>>
>>>>> They don't actually say in the guide how much helium they use I
>>>>> believe. Does anyone see a figure on how much helium the MIT guys used? They
>>>>> use an example of "61 cubic feet of helium" to describe an example for a
>>>>> formula, but that doesn't mean that is how much they used. If we need 61
>>>>> cubic feet of helium this target tank is not nearly big enough.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> As far as the antenna goes, it was bought with a cellphone modem, it's
>>>>> designed to be used for cell phones. It's omni-directional, long, and
>>>>> quality. And it has the wire connector we need which attaches to the phone
>>>>> already I believe, so no soldering.
>>>>>
>>>>>
>>>>>
>>>>> On Thu, Dec 17, 2009 at 3:30 PM, Mark Drago <markdrago at gmail.com>wrote:
>>>>>
>>>>>> Unless the large helium tank is obscenely large, it's not 500 pounds.
>>>>>> I worked at a party store that rented tanks in 3 sizes (small, medium,
>>>>>> large) and had a fourth size for our own uses (jumbo).  The jumbo
>>>>>> tanks were easy for one person to roll around on their edge, but were
>>>>>> too heavy to really pick up and carry.  I would say they were easily
>>>>>> under 100 pounds, probably closer to 60 or 70.  This is a rough guess
>>>>>> as it has been 10 years since I moved one.  But I can definitely say
>>>>>> they were not 500 pounds.
>>>>>>
>>>>>> Mark.
>>>>>>
>>>>>> On Thu, Dec 17, 2009 at 15:13, John Teddy <masterjediyoda at gmail.com>
>>>>>> wrote:
>>>>>> > http://i45.tinypic.com/riaop5.jpg and
>>>>>> http://i50.tinypic.com/1htb15.jpg
>>>>>> >
>>>>>> > This antenna is already rigged to connect to a usb cellular modem,
>>>>>> that is
>>>>>> > able the size of a large thumb drive. So I believe this connector
>>>>>> should
>>>>>> > work with a lot of cell phones also. When the phone comes we
>>>>>> ordered, I will
>>>>>> > bring this antenna and see if it fits.
>>>>>> >
>>>>>> > I believe the remaining parts we need are: parachute and helium (and
>>>>>> some
>>>>>> > string/rope to connect it all, and other little things which are
>>>>>> easy to
>>>>>> > get).
>>>>>> >
>>>>>> >
>>>>>> > We need to calculate how much helium we will need for the baloon. As
>>>>>> it was
>>>>>> > explained to me yesterday, the large helium tank can weigh up to 500
>>>>>> pounds.
>>>>>> > So this is exceedingly difficult to carry around. If anyone can
>>>>>> crunch the
>>>>>> > numbers and figure out how much helium we would need, and how much
>>>>>> each size
>>>>>> > tank can hold.. that would be helpful.
>>>>>> >
>>>>>> > -John
>>>>>> >
>>>>>> > _______________________________________________
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>>>>>> >
>>>>>> >
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>>>>>
>>>>>
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>>>>
>>>
>>
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