Removed chimney, closed bottom, painted side black.heliostats produced enough temperature, wind blowing hard.
windy. tested weight of paper & plastic. Paper= 5 X plastic, Heated plastic bag with 8 mirrors 15x15cm.weighed "balloon" after 15 min.Weighed same.ill try&get black plastic.
Windy. No black trashbags. Tomorrow buy.
Trashbag too heavy. Idea: inflate black baloon and measure time difference heating up with or without heliostats. This should work.
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