WB9SBD, Forget the naysayers they seem to come out of the woodwork whenever.
I have a question about heat, could a small pilot light sized alcohol lamp be used to add heat that size flame is close to a 60 watt bulb in heat output.
On the heat topic (Hot Air Ballon) Charcoal Fuel in metal tube lit at the top.
Do you and/or your ballon group have access to a Vacuum Chamber to test equipment in?
I know that you are trying in the 30 meter band but at that altitude VHF (think Tiny Trak) might have a footprint as big as the ISS.
Good Luck, I hope to catch a signal at my QTH.
;) From The QTH of The Extra Light (KC8YHW) ;)