[amsat-bb] Questions On Balloons With Amateur Packages

Robert Bruninga bruninga at usna.edu
Fri Dec 30 17:19:53 UTC 2016

```We tried zero pressure balloons (Mylar party balloons) but the max
possible height was just 23,000 feet or so due to the weight of the
balloon itself.  It's a direct calculation.  So we paralleled balloons,
but still, no matter how many balloons you add, the math still comes out
to asymptotically approach the same max altitude due to the mass of the
balloon material itself and its volume.

We did learn one other thing.  With 5 under filled Mylar balloons to reach
a cruise altitude around 23,000 feet (from memory?) we sent the cut-down
command and nothing happened.  (launching from Maryland is a guaranteed
ocean landing unless you can come down in 65 miles or so)...

On recovery, we found one balloon had burst, and so it hung DOWN from the
other 4 and got all wrapped around the payload.  So when we sent the
cut-down command, it worked, but the entangled lines kept everything
together.

But now with only 4 of the 5 balloons providing lift, it came down at a
very slow rate...  about the same as the ascent rate... which means we
chased it TWICE as far as intended.

Oh the fun of discovery!
The event is shown on our web page (Spycam mission starts about 30% down
the page)  http://aprs.org/balloons.html

Bob, Wb4APR

-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Richard
Tejera
Sent: Friday, December 23, 2016 3:08 PM
To: Dave Marthouse; 'AMSAT'
Subject: Re: [amsat-bb] Questions On Balloons With Amateur Packages

Dave,

Knowing the weight of the payload, they will fill it with enough gas to
become neutrally buoyant at the target altitude.

If altitude is the goal, enough gas will be filled to take it to an
altitude that will exceed the Burt diameter.

Rick Tejera K7TEJ
Saguaro Astronomy Club
www.SaguaroAstro.org
Thunderbird Amateur Radio Club
www.w7tbc.org

On December 23, 2016, at 11:01, Dave Marthouse <dmarthouse at gmail.com>
wrote:

I have seen posts from time to time on the BB about balloons with amateur
radio payloads on them.

I've got a question regarding the missions that carry payloads around
the world.  What stops the balloons from going up until they explode do
to the high altitude.  How are the packages kept from doing this to
achieve such long distance flights?

--

Dave Marthouse N2AAM
dmarthouse at gmail.com

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AMSAT-NA.
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Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
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