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hams use coax to transfer high frequency electromagnetic energy between antennae and receivers and transmitters
Jan 19, 2007
(an archived page, this may contain outdated or broken links)
filling a balloon @ UAH
The University of Alabama Huntsville Space Hardware Club prepares a balloon for launch.

ARHAB logo
How did I get here ?


I have recently taken interest again in the sport of Ballooning. Not with party balloons or huge hot air balloons, but the ones decked out with student/hobby payloads that use GPS and Amateur Radio to provide flight telemetry and tracking information. I was involved in the startup of the well known EOSS group in Denver in 1990, but moved back to Tennessee before they got famous. None the less, the bug had bitten, and the "poor-mans satellite" always found a way into my diet of radioactivity. Periodically one of Bill (WB8ELK) Brown's balloons would come floating by and some of us would help provide tracking feedback, or on a lucky day - be close enough to a landing site to help with recovery. I guess I hadn't been paying attention, then all of a sudden Bill lives just around the corner about a mile away ! Then I find myself approaching New Years Eve listening on 20meters for a PSK31 beacon from an Arizona balloon launched by ANSR, and talking with Jack (WA7JLC) via IRLP... I hadn't talked with Jack since I left Denver.

So much for my trip down memory lane... Turns out that the UAH Space Hardware Club has been launching some balloons recently and has one coming up (scheduled for this coming Sat, Jan 20 @ 0900).  I've been messing with APRS recently and wanted to participate in the tracking. Of course it is so much easier nowadays, what with APRS-IS and findU.com. The mapping is much better as well and I wanted some practice first, so I dug up a TNC log file of a previous UAH balloon flight. From what I can tell this was launched in November 2005 - and was called "HALO". I sliced and diced the data and came up with a few interesting graphics.

red ballDoesn't this look like fun ?

Post-flight Review - HALO


First, just a peek at the raw data log - not going into that just now...
raw aprs data log

I took data points about 5 min apart, to see how high it went.
altitude graph
The same data points show how fast it went up and came down. It appears to fall really fast before the atmosphere gets thick enough for the parachute to have enough to grab onto.
velocity graph
So, put these on a map, and show where it went.

mapgen thanks to tiger.census.gov

- a little closer view of the burst at ~86,678 feet

mapgen thanks to tiger.census.gov

Well, that was fun - but turned out to be a fair amount of work.
Thanks to tiger.census.gov for the map generation.

So this next flight was postponed last week, expecting poor weather - hopefully this week will not be too windy. It must be tricky trying to figure out how much gas, how much weight you can handle, how high it will go before burst, which way and how hard the wind will blow at different elevations, etc... One website has rolled a bunch of this together to help 'Balloonatics' predict various possible flight plans Visit www.nearspaceventures.com and try it yourself. The primary flight calculations are by way of Bill Brown's early programs originally written in Basic. The Google Map output is just icing on the cake. This painlessly integrates the forecasted wind profiles from NOAA. The  estimate I got via email today from Bill was based upon a 1000 fpm ascent and a 1300 fpm descent, so I ran a few passes with slightly slower rates to see how much that would affect the touchdown. I also ran an earlier and a later launch time to see how different the wind conditions might be. I'm sure that there are a lot of factors I'm not considering, but it sure gives me a better idea of what goes into this. I'll just drop these graphics in here for comparison. Hopefully I'll have more about all this (with external links) in a future page. If you can't wait, and need more links, check my Blog for January's research links. Come back after the flight, and find out what happened.

red ballPrevious page was /2006/20061120.html
red ballNew 'Nearly Live APRS' Project pages.
predicted track

- again, but with a slower descent
predicted track

- again, but with a slower ascent and slower descent
predicted track

* So, for a closer landing we need less wind,
will that be earlier or later in the day ?
predicted track

predicted track

Hummm, kinda like rocket-science . . .
It's almost beyond comprehension, to imagine the balloons that NASA uses for their high altitude research. Those can carry hundreds of pounds of payload...
73 for now   /;^)


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