I thought I'd read somewhere that the only supply of Helium was in yankeeland and it was running low.
If true, surely the Americans would either make it prohibitively expensive or simply keep it for themselves.
Hasn't technology advanced sufficiently since the R101 and Hindenburg era to allow safe usage of hydrogen with it's greater lifting power?
I wonder how much an aluminium piano would cost nowadays?
A lot does come from the USA - it is actually a by product of oil exploration/production. At one time it came out of the ground so fast, it was necessary to fit silencers to the He vents.
However, we get most of our LHe - liquid Helium - via our suppliers who get it from Algeria. Even so, you are right, it isn't getting any more common and its price has risen steeply over the years I been using it.
LHe is weird stuff and even though I have used hundreds of thousands of litres, I have never seen it. It never comes out of the end of the pipe, only as vapour. It has incredibly high surface tension and will climb the walls of any container to an extraordinary degree. It can also boil locally, that is to say, unlike water where the whole volume of water must be raised to 100C before it will boil, Liquid helium can boil in one small part of its volume. This will usually cascade into a generalised state of boiling if the pressure is not maintained.
It goes without saying that if is incredibly cold - about 4K or -269 C.
Roger.