DM03 - 2018-06-02

Tracker Details

Tracker Type: APRS

Model: PicoTracker1

Powered by 2 AAA batteries

Configuration:

• id[4] = DM03
• callsign[6] = KD2KDD
• transmitCount = 2
• msBetweenTransmits = 3000 (3s, 0m, 0h)
• lhAltFtThreshold = 10000
• hAlt.wakeAndEvaluateMs = 900000 (900s, 15m, 0h)
• lAlt.wakeAndEvaluateMs = 45000 (45s, 0m, 0h)
• lAlt.stickyMs = 10800000 (10800s, 180m, 3h)
• dz.wakeAndEvaluateMs = 1800000 (1800s, 30m, 0h)

Launch Parameters

Balloon and Payload

• 36" Qualatex, unstretched
• 31.2 gram payload
• 3.7 grams free lift

Heat sealed neck.

Predictions

Predicted Internal Pressure: 2.5 kPa

Predicted Altitude: 18,100 ft

Actuals

• Float Altitude - 19,500 ft
• Duration - 14 hours, 26 min
• Distance -344 miles great circle
• Cause of death - Float was steady all along, but got pushed to a higher altitude over Lake Erie and then it popped

Records

• New state flyover - Pennsylvania
• Notable flyover of Lake Erie

General Thoughts / Observations

Great float. Now convinced the lower free lift is the key to not blowing up at altitude.

I think we can go lower in terms of free lift as well. Seemed to rise with no real issue.

There was a slight gradual decrease in altitude over time. Unsure if that is due to colder temperatures due to night and northward travel, or if a slow leak.

Pretty clear that the prediction spreadsheet doesn't give the right altitude figures. Perhaps not on internal pressure either.

The death was surprising. What caused the balloon to rise so much over the lake?

The balloon has gone over ocean before and not been affected in that way.

For the future:

• How to deal with possible lake flyovers, or generally being pushed higher in altitude?
  • Less free lift, meaning less internal pressure at float
  • Double balloon (also another internal pressure mitigation technique)
  • Higher altitude
    • Generally, weather effects, like whatever might have happened due to the lake, are lessened by altitude
      • So if I can float even higher, maybe I won't actually get pushed upward as much
    • This will come with the above