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xkcd #3279: Main Span
(thelemmy.club)
Title text:
Wind stress? Don't be silly. When has wind stress ever been a problem for a suspension bridge?
Transcript:
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Source: https://xkcd.com/3279/
At 99°C (210°F) the lift power of hot air balloon is 0.25 kg per m³. Pillars supporting a four kilometre long suspension bridge section are under 200 MN vertical load, or 20 million kg. The air balloon would have to be 80 million m³ large, or 534 m (⅓mi) in diameter.
So you're saying its possible.
Doesn't even sound that unrealistic to be honest.
Does that mass include the containment and support structure for the balloon itself?
Surface area is 895844 m², Dycron weights 4 ounces per sailsmakers yard, or 0.171 kg per m². 153458 kg, so additional 38365 m³ required, supports should also be relatively light. Quite negligible compared to, for instance, cars weight.