My understanding of the airship is that the problem becomes ballast. If you dump 20 tonnes or 50 tonnes, then of course you have to either load it up or recompress your buoyancy gas. So it's probably not without a lot of flaws, and it has taken a long time. Of course, hydrogen, which is relatively easy to produce, didn't do so well in the Hindenburg, but helium is a pretty scarce commodity too and not as readily available as hydrogen, by any stretch. Actually, Cumberland were looking at that when they looked at that Meadowbank site. They were thinking about using that, but it wasn't far enough along.
On December 5th, 2011. See this statement in context.