[islandlabs] I have an antenna for the balloon in my office...
Thu Dec 17 17:51:01 EST 2009
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.
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:
> 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?
> *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
> I see, the person must have been mistaken. Or maybe they were talking about
> industrial tanks of larger size.
> 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
> 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.
>> On Thu, Dec 17, 2009 at 15:13, John Teddy <masterjediyoda at gmail.com>
>> > 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
>> > 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
>> > bring this antenna and see if it fits.
>> > I believe the remaining parts we need are: parachute and helium (and
>> > 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
>> > explained to me yesterday, the large helium tank can weigh up to 500
>> > So this is exceedingly difficult to carry around. If anyone can crunch
>> > numbers and figure out how much helium we would need, and how much each
>> > tank can hold.. that would be helpful.
>> > -John
>> > _______________________________________________
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