Saturday, July 2, 2016

Flight: wisp1c_4

Flight wisp1c_4

My new 0.8mm boards came in from Hackvana.  I did my testing, and two flights on my OSHpark RevB boards.  RevC changes were all cosmetic - cleaning up traces, etc.  I was confident enough that I just went ahead and ordered the slightly modified boards in bulk for flights.

First step: Make a batch of boards

I ordered them in panels of 3.

Finished product, out of the oven.

Nice and light!

Prepping for flight

Testing went smoothly.  I had to clean up some solder bridges on the processors, and one bridge on a solar chip.  Once that was fixed, all 3 boards passed all diagnostic checks with flying colors.  I numbered the boards 4-6, and prepped number 4 for flight.

Without antennas and tape, it comes in at 10.6 grams.

I built an antenna and counterpoise, as i had in the past with thread and 36ga wire.  I attached them to small lengths of guitar wire for strain relief.

I implemented an "elegant solution" (ok, kludge!) to keep the counterpoise away from the GPS chip antenna.  The two lines going to the tracker near the chip are just thread.  The thread/wire counterpoise line is secured above and away a bit.

Kapton tape FTW.  I put a bunch of strain relief on the wire connections to keep them from being stressed and flexed near the attachment points,

The twin balloon assembly looks like this.  I used Tyvek tape to attach the upper to the lower balloon.

These two balloon pictures aren't from this flight, but give an idea of what the balloons look like when assembled.


 It was a gorgeous day with clear skies and 5mph winds.  The tracker floated straight up from release and hovered nearby as it climbed.  I nearly forgot to take a picture.  It's off in the distance here.  If you zoom in, you can make out the tracker 17 feet below the balloons, and the antenna dangles below that.  There is a small square of tape at the bottom of the antenna.  You can just barely see it when zoomed in.

Flight: Day 1

 The first day of flight followed the predictions nicely.  The zigs and zags are from missed telemetry packets.  The envelope reached float at around 29,500 feet.  Near the end of the day, the balloons stretched a little, and opened up to around 30,000 feet.

Flight: Day 2

 The tracker woke up on schedule.  It was a nail-biter as it was flying right into the storm below.  On top of that, the bands were awful.  Propagation sucked all day, so very few packets came in until about 4:00pm.

The day ended with the tracker starting to make the curve southward.  By this point, the balloon was fairly consistently over 30,000 feet.  It was traveling at over 100mph.  The weather looked clear.  It looked optimistic for Day 3.

Flight: Day 3

We awoke over France, as scheduled.  That's a new Personal Best for me!  :-)  It was still right on the predicted track.  The balloons stretched a bit more.  The balloon peaked at 34,000 feet for much of the day.  Speeds seemed to hold around 30-40 mph.

As the day wound down, it flew into a pretty large storm.  The dramatic tension will be high as I wait until tomorrow morning to see if we're still there!

Flight: Day 4

Balloon down!   I awoke this morning to find beacons coming from the balloon at nearly ground level.  

The last pair of packets BOTH received were on 30m.
Jul 03 04:16:13 [INFO] 2016-07-03 08:14 KD2EAT 10.140153 JO83 +0 SM0EPX/RX2 30m
Jul 03 04:16:13 [INFO] 14/16/18/KD2EAT JO83 0 0
Jul 03 04:19:14 [INFO] 2016-07-03 08:16 QU6VKY 10.140151 JO83 +23 SM0EPX/RX2 30m
Jul 03 04:19:14 [INFO] 16/QU6VKY 23
Jul 03 04:19:14 [INFO] 16 KD2EAT JO83VK 6 0.6 5 5 0 0 0
Jul 03 04:22:15 [INFO] KD2EAT-14>APRS,TCPIP*,qAS,KD2EAT-1:!/3LhZR{;wO!!Y/A=000000 0 QU6VKY 23 30m|"zWw'W?U!'!!!!|

This telemetry data decodes as follows:
Grid Square: JO83vk
Altitude: 0m  (between 0-111 meters)
Satellites: 6
Solar volts: 0.6v
Battery volts: 4.80
Temperature: 5c (really means 5c or ABOVE.  This is max temp we report.)

We subsequently received one more telemetry packet, without the first packet.  It was identical.

Looking at the elevation in that area, it appears it's 138m.  So, we're very close to ground level in that vicinity.  

This is the satellite view of the landing area.

The data is a little curious.  We started receiving packets at 07:14 UTC.  Given the daylight overlay I saw on, I would have assumed the tracker would have had daylight a good bit earlier.

Given that it came down, the big question is "why?".  We had significant weather in Germany the night before, but it didn't go down "hard", or it wouldn't have traveled as far as it did.  My guess is either a catastrophic balloon failure on one of the envelopes, or perhaps the upper envelope simply came off.

Local hams have been contacted via a Balloon forum, and they may attempt a recovery.  In the meantime, here is the final track we followed, beside the original prediction made on launch day. That's pretty darn good, for 4 days out!

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