HSMM and balloons
wb5mmb at pobox.com
Sat Oct 20 23:32:01 CDT 2012
I have known a couple of people who worked with H2 at chemical plants
and they hated the stuff. One even showed me his scars. The big
things seem to be ease of ignition and burning with no visible flame.
That being said I don't think it is that much worse than acetylene.
At 10:49 PM 10/20/2012, Doug Gentges wrote:
>Here in Denver, our local high altitude balloon group EOSS was
>paying over $300 for a He 300 ( about 260 SCF) until mid summer,
>when we were told it was no longer available at any price. We're
>now paying $18 for a similar sized bottle of H2.
>It does wonders for the budget, although we have a small number of
>members who want nothing to do with H2. We call that the Hindenburg effect.
>I saw that the Red Bull jump needed 180,000 SCF of He for their fill.
>On Oct 20, 2012 7:38 PM, "Robert E. Seastrom"
><<mailto:rs at seastrom.com>rs at seastrom.com> wrote:
>Louis Mamakos <<mailto:louie at transsys.com>louie at transsys.com> writes:
> > Not if you're using 802.11 Wi-Fi radios at 2.4GHz.
>Hidden node doesn't mean it won't work; it just won't work well. When
>people suggest playing with mesh networks for moving any non-trivial
>amount of data, I go with the assumption that they already discarded
>the notion that they will work "well" long ago. Remember that 1200
>baud packet suffers from the hidden node problem too, yet somehow it
>manages to "work".
>I think the number for pure-Aloha mode throughput is 18.4% of
>available channel bandwidth.
>On a related note, I buy helium periodically (in 60 cubic foot "owner
>tanks" - $78.87 each for the fill last time I picked one up). Helium
>is in short supply and expensive like whoa these days, to the extent
>that grocery stores are not handing out free balloons to kids anymore.
>Had a conversation with the guys at Arcet a while back. One can get
>(4 9s pure grade which is the cheapest stuff they've got) hydrogen for
>a fraction of the cost (4x volume tank for same price plus rental;
>they don't do owner tanks for H2), but for some reason they're weird
>about selling hydrogen to the general public. Maybe someone read up
>on the H-Bomb and didn't realize they're selling the wrong isotope or
>that you need a little nuke to light it off. But I digress. Kind of
>ironic considering that they sell acetylene which is some fairly nasty
>stuff to all sorts of dodgy characters with no questions asked.
>So, if AMRAD gets at all interested in doing balloon stuff let me know
>and I'll see what I can do about filling out the paperwork and talking
>to anyone who calls from ATF and wants to know what's going down. I
>even have a place to store the tanks where I don't think they
>represent a hazard to anyone.
> > On Oct 20, 2012, at 4:47 PM, Martin
> <<mailto:dcmk1mr2 at gmail.com>dcmk1mr2 at gmail.com> wrote:
> >> There was talk over tacos today of using a balloon to get a mesh
> >> router to some altitude.
> >> Federal and local regulations apply to balloon operations. There is
> >> FAR 101 that limits moored balloon operations to an altitude of 500 ft
> >> with many restrictions. A FAA NOTAM issued in 2009 forbids moored
> >> balloon operations within the DC FRZ. I believe these restrictions
> >> can be violated with a waiver from the FAA and coordination with local
> >> ATC. A local business routinely gets waivers to fly a large balloon
> >> in the area for photographic purposes
> >> Chloroprene rubber balloons are used for advertising and such. They
> >> will outlast a plain latex balloon and should last several days if
> >> needed. They go for about $30. A WRT54GL runs for about four hours
> >> on a set of eight "AA" NiCads. A WRT54GL weighs about 14 oz and the
> >> batteries weigh about 8 oz. That takes a 5' balloon and about 40
> >> cu-ft of He.
> >> It sounds like a fun experiment in the right setting.
> >> Martin
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