Thursday, January 5, 2012

Balloon Flight

The following data are from a recent balloon flight. The blue data were recorded from the balloon, and the red and green data were from local airports. The balloon was a 200 g Kaymont, which should burst around 25 km. So the fact that I'm getting over 30 km is strange. I didn't have a gps or altimeter on board, so the altitude is only estimated from the predicted ascent rate. I carefully measured the neck lift and the payload weight before launch. The point where the temperature starts climbing (about 17 km) is consistent with what I have seen in other flights (and the local data) leading me to believe that the the elevation profile is reasonably accurate. Is it possible to reach over 100,000 ft. with a 200 g balloon?

Further Flight Details

The purpose of this flight was to test the capability and range of my make-shift APRS system. The payload was considered "disposable" and consisted of the following:
  • 1 Maxon FRS-214 radio transmitting at 441.1625 MHz
  • 1 arduino nano running Trackuino (reporting temperature only)
  • 3 thermistors
  • 1 resistive heater
  • 2 3V lithium batteries for power
It was all encased in 1 inch foam insulation and the total payload weight was 6.1 oz.

The radio was nominally 500 mW, converted from FRS to ham frequencies. The stock antenna was replaced with a 1/4 wave length of wire with 2 radials. At the furthest distance (about 40 miles), I was still able to hear the packets, but transcription by the TNC was spotty. I assume, now, that with a good Yagi, 60+ miles should be possible. (For this test, the ground station had only a "rubber duck" antenna)

The balloon was a 200 g kaymont. The nozzle lift was 16 oz, so the ascent rate should have been about 900 ft./min. It stayed aloft for just over 2 hours, so the max elevation was probably around 105,000 ft. (that's just a guess, based on the ascent rate calculations, and my initial elevation of 7500 ft.)

In conclusion, the FRS/Ham radio worked great, as did the trackuino. Since package recovery is often out of the question here in the mountain west, this is a great "cheap" way of doing balloon flights. Unfortunately, though, I don't have any pretty pictures from the edge of space.

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