From: My Mother, although my Father had some small part.
I remember reading about the cargo airships 20 or 30 years ago but nothing has come out of it. I would say that the lightest element (hydrogen) is absolutely necessary to make the airship viable. All later developments have tried to use helium and that is just too heavy to be commercially or practically viable.
Helium weighs 4, while hydrogen weighs 2, but air weighs about 15, so the lift of hydrogen versus helium is only 13 : 11, which is a small, non-essential difference. Basically it is not about the weight of the light gas, but of that of the displaced air.
It's not a non-essesntial differece. Even hydrogen is just barely viable. Airships are huge with a very small carry capacity in comparison.
If helium provided significantly more lifting force it could be feasible. As it is now it is just too rare and expensive.
hydrogen (71 lbf/1000 cu ft)
helium (66 lbf/1000 cu ft)
hydrogen $2 per 1000 cubic feet
helium $86 per 1000 cubic feet
If only we could tap helium from Jupiter or the Suns core...
Wait until we can make it.
Seek peace but keep your gun handy.
I'm not a complete idiot, some parts are missing!
“Illegitemus non carborundum est (“Don’t let the bastards grind you down”).”
― Julia Child