It seems that all airships leak at least a small quantity of helium. Why can't helium be contained 100%?

Question

I recently got interested in airships as an alternative form of transportation with great environmental potential. There are technological and economic barriers, but they seem to be within reach. One aspect that appears problematic is the high cost of helium gas. This seems compounded by the fact that airships leak, albeit very slowly. However, at $100/cubic meter, I can imagine that this induces substantial operating costs... I cannot find out why there would always be a leak. Of course helium is a very small particle, so I'm guessing that any membrane might be somewhat porous to it... Answer anyone?

Answer 1

Your guess is quite correct.

Answer 2

As you said, helium is a lot smaller than an Oxygen molecule. As such all materials used to contain it have a much larger atomic structure and so porous.

Answer 3

Because a container that would be truly air- and helium-tight would have to be solid, thick, and too heavy to be lifted by the helium it contained.  The best that can be done is to hold the helium in a light material that allows the least seepage/leakage.

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Answer 4

Another problem additionally to the leaking through the fabric is, that all valves, links and seals are not 100% perfect.

The costs caused by leakage are still less as the other maintenance costs, no airship in operations leaks as fast helium as it burns oil or eats pistons.