[islandlabs] How Much Helium

John Teddy masterjediyoda
Thu Dec 17 18:20:37 EST 2009


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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