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.