by Rick von Glahn, N0KKZ
Mike and I left the launch site around 20 to 30 minutes after the
liftoff. We (Mike) had to pack all the launch gear into the car as we did
not anticipate returning to Treynor High School after the flight.
Initially, when we were on the road, it seemed to me that the balloon was
just getting farther and farther away from us. No matter how fast we drove (up
to the speed limit :-) the balloon was still rapidly outpacing us. I
feared that the prediction was going to turn out to be useless and we'd have
to traipse over to Illinois to recover our systems. But, after a little
trouble shooting I discovered our difficulty. As had happened on our previous GPSL experience, we ran into a problem I experience whenever I attempt APRS
with a passenger in the car.
I use a D700 Kenwood to track the balloon. A Garmin Etrex is plugged into this
radio. The flexibility of the physical location of the GPS is severely
constrained by having to be tied into a DB-9 input on the radio and a
cigarette lighter with a fairly short cord. So, it sits on the console between
the driver and passenger. When it's just me in the car obstructing one slice
of the sky to the left of the gps, it manages to capture enough satellites to
get a good solid lock. When someone sits in the passenger seat, the gps is
blocked to the left and right and so is limited to satellites in front,
overhead and behind it. This effectively kills the GPS fix as the receiver can
never (rarely) get enough birds locked up for a good fix. So, I initially
thought that the balloon was tearing down range at a phenomenal rate. But
after checking the GPS, I noted it wasn't locked and then determined that the
range and bearing the Kenwood was giving for the balloon was being calculated
from the last good lockup of the GPS at Treynor High. We were 20 miles east of
that. So instead of the balloon being 45 miles east as I was imagining in my
head and deducing from the range of 25 miles on the Kenwood it was really only
5 miles east of us. Once I discovered this, we started babying the Etrex to
keep it locked up. This restored our confidence in the original prediction and
I abandoned hastily contrived plans and reverted to the original plan to drive
to Grant, IA and capture packets and run a post burst predict from there.
Grant was is a slight valley so we decided to find a high spot by driving
from there to the predicted landing location. We found a very nice high spot
with a good horizon all around us (good for simplex with the rest of the
tracking guys) and parked with Jim, K0TOR, to watch the balloon on APRS and
generate the updated predictions.
Something happened that caused Balloon Track to not receive packets from
the AE0SS-11 system. I haven't really figured this one out yet, but this
failure resulted in my inability to generate any post burst predictions. While
Balloon Track couldn't see the packets from AE0SS-11, it was still seeing all
the other traffic on 144.360 MHz. So, that's the mystery. AE0SS-11 was
probably the closest balloon. It passed almost directly overhead of us and was
spotted visually by me with no problem. And, the Kenwood was getting good
packets from the balloon and providing good direction information as it helped
me determine the azimuth to search for the balloon when I was attempting to
acquire it visually. So, a weirdness to be considered.
Once the balloon moved east of us it burst. We then moved on to County Rd
28 where we watched the parachute pass almost directly
overhead.
When the parachute descended to around 2000 AGL, we started to drive
towards the apparent touchdown site.
Within a minute or two of touchdown we were on the scene. Randy Reynard,
NQ0R, was there first and a couple of others had arrived including one local
resident.
It took approximately one hour to find the land owner and have him escort
us into our landed payloads systems. However, the parachute was visible the
entire time from the southern vantage point.
After recovery, we traveled a few miles west to Grant and had lunch at the
Hayloft restaurant.
Mission accomplished.
