james.d.mulroy at gmail.com
Sun Aug 7 16:29:47 PDT 2011
Hey guys, here are a couple sites you can buy balloons from that aren't 30
American Science & Surplus (you'd have to inquire about how many grams it is
and fill capacity)
Scientific Sales is by far the best bet (my group often bought from them,
then again, our budget wasn't exactly limited as we were government funded).
A bit pricey, but a 1200 gram balloon won't have a problem bringing a 6
pound payload to 80K or 90K feet.
To practice, testing communication equipment, we might try picking up a
couple of the really cheap smaller balloons.
On a side not: if you want to see a 'real' balloon check out
HASP launches balloons that stay up for 20-30 hours. This balloon
fluctuates between 120K and 130K feet, carries about 6K pounds of payload
and several hundred pounds of metal dust as ballast, and when it gets to
altitude it is so big that you can theoretically rotate an entire football
stadium inside of it 360 degrees all around and it won't touch the sides.
This is what NASA considers a "small" balloon compared to the other ones
Also, if you don't already then you should use a burst calculator for
determining how much helium to use. You can also use it to determine where
your balloon will land within 5 miles.
You should aim for an ascent of at least 7 m/s or else you risk that the
balloon will reach altitude and not pop, in which case it will end up in
Greenland in a couple months or something...
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