The hydrogen issue is more of a psychological one. It's pretty well
understood now that the Hindenburg thing was more a problem of skin
materials that became extremely flamable when heated (chemical change).
Hydrogen fires generally blow themselves out. With a different skin, maybe
only one or two cells on the Hindenburg would have blown out from the
lightning strike.

Still, anytime anyone mentions using hydrogen as a lifting gas....."......OH
NO!!! NOT ANOTHER HINDENBURG!"

And you're right. What little concern you might have about flamability would
pretty much go away, unless you were using regular air for ballast and there
was potential for mixing (which would probably mostly be gone by the time
you got up pretty high).

"nafod40" wrote in message
...
I am wondering about possibly using Hydrogen. At the extreme altitudes
considered, I'd think the flammability issue would be much less. And
Hydrogen is significantly more bouyant than Helium. Maybe a mix of the
two?