Airships are pretty dang cool. Airplanes need a continuous expenditure of energy to stay in the air, but if you just fill a bag with a light gas, you can stay up in the air with no energy expenditure at all. The two lightest gases are hydrogen and helium. Though the hydrogen atom is 4 times lighter than helium, hydrogen gas is made of two hydrogen atoms bonded together, so it's only twice as light as helium gas. The difference in lifting power is even more minor: What matters for lifting power of a gas is the difference between its density and that of ordinary air. Hydrogen and helium are both much lighter than air, so the lifting power of either gas is nearly equal to the density of air.

Hydrogen and helium both have problems as lifting gases. Helium's problem is that it's very expensive. Helium comes [...]

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Narrated by TYPE III AUDIO.