I am relying on the fact that Bar Sport allows for 'all sorts of unrelated topics' in order to post it here. Not Arduino related, unless you are doing an Arduino sounding balloon. Here is my question:
Why is helium used over hydrogen for large lighter-than-air balloons? Yeah, I know it was a real, real bad idea for the Hindenburg, but that was an all-weather passenger aircraft with lots of people in suits and no parachutes. Helium is really, really expensive and the world loses whatever it uses. It's bad to waste helium. From a recent article:
But Thompson said on Wednesday the balloons cost several hundred thousand dollars each, and he estimated the team lost $60,000 to $70,000 in helium with the aborted jump.
That's a lot of money. If you are flying on a perfect day, and Felix certainly was, why not use hydrogen? Inflate the balloon remotely. After it is inflated, there really should be no danger that cannot be mitigated. And the dude does have a solid capsule and a parachute if he needs to bail. Maybe I am an idiot, but I would fly this on hydrogen, if the permeation of hydrogen through the balloon membrane isn't so much greater than helium that this is a technical obstacle.