Vehicle: Aircraft: Balloon
road heated hot air balloon booster   (+3)  [vote for, against]
Use air from top of boiling road or top of boiling sand to fill balloon

Fan run by bicycle (or electric fan if available) sits on hot road or sand and fills the balloon.
-- pashute, Nov 06 2011

I get why you'd want to use air from the hot road to fill a balloon, but why sand?

Also, you might not need the fan. Just hold the balloon open over the hot road and wait. A fan would pull air in faster than it can be heated, and you'd wind up with a tepid balloon.

I like the idea. It would be quite fun to take an enormously large sheet of transparent plastic, weight it at the edges, and lay it on a road before the sun came up.

Traffic would be an issue.
-- MaxwellBuchanan, Nov 06 2011


Collecting the hot air would also be an issue. You could make a (slightly raised) hole in the centre of [Max]'s sheet of plastic, from which the air would issue, and squat the balloon over it. Or provide an inverted funnel of film beneath the balloon to act as a scoop; that way you could periodically refuel by hovering over a road.

Logic suggests that, short of a large expanse of plastic covering the road (like a solar tower with only a stub of a tower), you will only be able to harvest energy from an area about equal to that of the balloon; this would then be less effective than a solar hot air balloon, which can collect heat continuously, rather than only prior to take-off or at very low altitudes. It might therefore be best as a booster for a solar balloon.
-- spidermother, Nov 06 2011


correcting according to [spider mother]'s suggestion.

Max's anno is because originally the idea read: Use air from top of boiling road or sand to fill balloon.

Why fill a balloon with sand? Good question.

I don't think traffic would be a problem. You can always find a large empty parking lot or unused dead end road outside town during the heat of day.
-- pashute, Nov 06 2011


I have been sterilising a patch of ground using black plastic covered with sheets of glass, with a small air gap between glass and plastic. I've measured the temperature of the plastic at about 98ºC, when the general air temperature was only in the high 20s; and I didn't even bother getting everything nicely flat and sealed at the edges. That's easily hot enough to float a hot air balloon. Moral: this idea seems feasible.
-- spidermother, Nov 06 2011



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