[aprssig] Balloon- clear package keeps warm

[Robert Bruninga]

Instead of heavy foam insulation for Balloons, consider using clear plastic
bottles.

They are smaller and lighter and have no thermal issues..



See http://aprs.org/balloons.html



We have been using this technique since 1991 and the payloads stay at room
temperature.  We now have the data up to 70,000 feet..



Triple layered plastic went no lower than 15 C (60F)

Dual layered plastic went no lower than – 15 C (5 F)

Single layered plastic went no lower than -27 C (-17 F)

While the outside temperature went to -60 C (-76F)



Actually, I guess the triple layer is more like 4 layers since the internal
layer was bubble wrap.



Remember, no matter how cloudy it is on the ground, there is plenty of sun
where the balloon is going.



Bob, WB4APR
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