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Category: 2001
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This flight was a little more of an adventure than some.........

Saturday the 19th dawned with clear skies and calm winds.  Bill N3KKM and I arrived a little after 7am and the rest arrived by 7:30.  We began filling the balloon and measured 14.0 lbs of total lift and 4.0 lbs of positive lift (with the quiet winds we were able to get accurate lift readings).  We launched nearly on time at 1309 UTC (0809 CDT).  The balloon ascended almost vertically for the first 15 minutes, then turned eastward towards Omaha.  In the picture on the left, from top to bottom are the balloon, parachute, camera/simplex repeater payload, and APRS/telemetry payload.

The chase teams headed on the road soon thereafter and proceeded east to I-80.  Most of us went on Hwy 92 to Treynor to wait for the burst.  In the interim, many simplex repeater contacts were made, with one from Sioux City, IA to Springfield, MO, or about 380 miles.  We used 446.100 MHz today and experienced no intermod or other problems with the repeater.  Lots of low-power (500 mW or less) contacts made.

The balloon burst at 1439 UTC (0939 CDT), or 90 minutes after launch.  One of the participants was able to see the burst through binoculars.  The average ascent rate was 1047 ft/min, which was very close to our target of 1000 ft/min.  

About 10 minutes later, I noticed there were no longer any transmissions through the simplex repeater.  I didn't think much about it at the time, because during payload testing I noticed that the cables between the HT and repeater unit were intermittent if the unit was in just the wrong position.  The GPS data still looked good, so we proceed on the chase.

We went east from Treynor to US 59, then south and east a few miles.  We stopped a couple of times and looked for the parachute when it was between 10,000 and 20,000 ft above us, but couldn't see it (and didn't really expect to).  At around 8000 ft the parachute was just visible.  We watched the payload in an open field about 50 yards from the gravel road we were on at 1525 UTC (1025 CDT).  The payload was swinging quite a bit during the terminal descent - I think this was due to the large amount of the balloon left on the load line, plus the gore in the top of the chute may have been too small.  Not much I can do about the balloon, but I'll make the gore a bit larger next time.

One of the farmers in the area was watching us drive up to the payload.  I imagine we looked a strange sight - three vehicles with all sorts of antennas driving, stopping, looking at the sky, driving off again, then chasing down some object parachuting into a field.  He came up behind us just as we were getting out of our vehicles.  After we explained what we were doing, his expression changed from one of concern to one that a parent would get when his child has done something incomprehensible and probably stupid.

As we walked up to the payload, something didn't look right - one of the payloads was missing.  The tracking payload was still attached (of course - we were getting data!), but the package with the simplex repeater and the video camera was gone.  No trace, not even a frayed string to show that it was on in the first place.  Also, about half of the 1200-gram balloon was still attached - this one didn't shred as well as most.  We took the usual pictures, packed everything up, then headed off for a quick search of the area where we thought the payload fell.

Our technique for this attempt wasn't all that detailed.  We knew the repeater worked for at least a minute or two after burst, but had stopped by 15 minutes or so afterwards.  Figuring the winds would have a negligible effect, we went back along the payload's track between burst and landing.  We hoped the simplex repeater would still be functional, so we all set our rigs on maximum power and made periodic transmission from the top of the hills we encountered - something akin to shouting for a lost dog and hoping he'll bark.

We drove around and hit all the county roads in the area close to the track, with no luck.  Since I knew I had a recording of the simplex repeater traffic with good time hacks for each transmission, we figured the best thing was to narrow the search area with the data we had rather than driving about aimlessly.  We went to Perkins in Council Bluffs for lunch and headed home from there.

After I got home, I reviewed the simplex repeater recording and found that the last simplex repeater transmission was at 1450 UTC.  In the graphs of the descent profile, we found a "notch" in the graph about 70,000 ft and 1443 UTC where the descent rate appeared to abruptly change to a lower figure.  This area was about a 3/4-mile-long track from the point where we suspected the camera fell off to where the parachute was 7 minutes later.  I still figured the winds would not have much of an effect on the falling camera, but biased my search area to about 1/3 mile east.

With this search area in mind, Shari and I returned to the area and got permission to search on foot in the fields (Search Area 1 below).  The suspect area was mostly flat and open, with a creek running through the area and hills and hay fields towards the east end.  We spent a bit over an hour walking around, but didn't find anything.

Sunday the 20th had rain most of the day, some of it quite heavy, so that didn't lend itself to additional searching.  On Monday I had to leave town for a conference in Boulder.  While I was at the conference we consolidated log files and Ralph W0RPK made additional predictions using Balloon Track's descent profiler.  This moved the target area farther east by about a mile from where I was searching on the 19th - the calculations indicated more wind effect than I had accounted for previously.  I also began making arrangements for an aerial search of the target area for the Memorial Day weekend. 

On Friday the 25th I returned from the conference and got permission to search some fields in the new target area.  I spent a couple of hours walking around some soft ground (it had rained a lot that week) and up and down some hills and came back with nothing but muddy boots and tired legs.  Saturday the 26th also had rain off and on which was not helpful for either aerial or ground searches.

With improving weather expected for Sunday, I made final arrangements for an aerial search and to have someone with a radio on the ground that we could direct to the camera if we spotted it (it was in a bright red nylon lunch cooler).  At 7pm on Saturday I got a call from a teacher who lived in the search area.  He asked me if I was an amateur radio operator.  When I said yes, he said he had something that probably belonged to me.  I got his address and hopped in the car for the drive over.

After I arrived, we chatted a few minutes about how the camera was lost and then found again.  Surprisingly, he wasn't too concerned about the fact I had dropped a five-pound package on his land from 13 miles up without a parachute.  He took me out to where it landed so I could get a GPS fix.  The package landed in a small open area amongst a grove of trees near a creek.  Had he not found it, it may have been rather difficult to spot from the air.  Fortunately he was planning to do some work on that bit of ground over the summer, so he went in there frequently.  We talked some more about the balloon project and he was very interested in having me come to one of his classes at the Glenwood school system in the fall.

Once I got home, I disassembled the package and did an inspection of the contents.  Not surprisingly, the package was a bit damp on the inside - over 3 inches of rain had fallen while it was outdoors.  I took everything apart and found the following:

The primary cause of the failure was the snap swivel used to attach the payload to the parachute spreader ring.  It appears the G forces likely pulled the wire out of the catch.  In any case, I won't use snap swivels on future flights.  A nylon wire tie use to control the load line to the lower package also had to have failed to allow the package to go free.

Once again, we had problems with lens fogging.  This time, however, the atmosphere was fairly dry.  I think the condensation occurred between the lens and the filter, so on the next flight I'll leave the filter off.  The fog/frost became noticeable about 20,000 ft, but fortunately began to come off above 85,000 ft and we had clear video for a couple of minutes before burst.  At burst, the camera tips up so that the latex shards from the balloon are visible.  The violence during the descent is quite evident, as the telemetry payload and the parachute come into the frame at times.  The camera stayed with the parachute from burst at 1439 to when it fell off four minutes later at 14:43:25 UTC, or about 72,000 ft.  Impact was at 14:50:16 UTC, or 6 minutes and 51 seconds later at 41 deg 09.570 min N, 95 deg 38.186 min W.  The last simplex repeater transmission ended at 14:50:00, about 16 seconds before impact.  The videotape shows the payload rotating at 3-4x per second, and the resulting signal flutter can be heard in this Real Audio clip.  The signal fade as it went over the radio horizon from my home station can be heard in this clip.

Callsigns heard on the simplex repeater during this flight:

N9XTNN3KKMKA0ON0UJQN0UQZ
K5LBSKE0XQKC0FDCKC0HZVN0LGU
KC0HFLKB0STNKC0AXKN7BTCKC0JQY
N0DYBN0VJK0CBAKC0JVZWV0S
WA0JRJKC0EMKWB6AMYK9AMZN0ORU

The QSO between KC0HFL and KC0AXK was a 2nd-place distance record of 344 miles at the time

Even though the camera was found without benefit of Ralph's efforts at prediction, it was a worthwhile exercise because it does give us confidence that in the future we can use data from the main payload to give us clues as to where a detached payload might go.  Ralph use two methods to come up with his estimates:

  1. The camera payload has the equivalent drag to that of a 12" parachute based on the payload's dimension.  Using the morning 12Z sounding from Omaha/Valley NWS, he used Balloon Track to compute Prediction 1 in the map above. 

  2. The main payload went about 25% farther than Balloon Track predicted, even knowing the sea-level descent rate.  Adding 25% to the original distance prediction and taking it the same direction of travel as the main payload resulted in Prediction 2.

As always, thanks to the chase team and to Ralph for his assistance with the prediction.  For a more detailed explanation of the analysis and recovery predictions, see Ralph's web page.