Vacuum Airship

True, but we were talking about something that
actually exists, as opposed to a containment shell
lighter than hydrogen yet still strong enough to
resist collapsing under 14.7 lbs pressure per square
inch.

Too bad H2 is so reactive. It's about as perfect a
lifting gas as we're likely to get. Still there are
cheap alternatives, such as H2O at 400 degrees F, with
a molecular weight of about 18, as opposed to the
average of air of about 29, hot H2O would therefore
have 1/3 greater lift than an equivelant volume of air
at that temperature and is chemically inert,,,ie,
"safe".

Gary 7