got it backwards

[Mike Arman]

> highly explosive gas (you have seen the
>> > pictures of the Hindenberg explosion?)
>> 
>> The Hindenburg was filled with HELIUM - not Hydrogen - which is what led to
>> her demise! Helium is flammable, and explosive - Hydrogen is safe! VERY
>> SAFE!



Other way around - it is the helium that is inert and safe, the hydrogen
that is explosive.

Historical note - the US has most of the world supply of helium. We
declined to sell it to the Germans in the late 30s because a FEW people
fortunately in the right places in our government had some idea what was
coming. The builders of the Hindenberg wanted to buy helium, but we turned
'em down for "strategic materials" reasons.

Both gasses are difficult to handle. Hydrogen burns with an invisible flame
(see next paragraph), and both the hydrogen atom and the helium atom are so
small that they seep through seals and gaskets even faster than pentosin.
In helium airships, the loss of helium through the envelope can be as much
as one or two percent every day!

Hydrogen is a special problem. The space shuttle uses hydrogen as (one of)
the fuels, and NASA recently issued a request for "a device which can see a
hydrogen flame" - precisely because we can't until it is too late.

The spectacular Hindenburg explosion was actually a combination of
explosions. The final, outer skin of the Hindenburg was fabric, coated with
aircraft dope and finely powdered aluminum. The function of the powdered
aluminum was to protect the fabric from deteriorating from the sunlight.
The powder did two other things - it gave the Hindenburg its distinctive
"aluminum" color, and the POWDER is what burned off with the spectacular
explosion! Finely powdered aluminum is highly flammable, and in fact is
just short of being an explosive all by itself. It is used as a FUEL in
some missiles.

The current theory is that something (lightning, static electricity,
perhaps sabotage) ignited either a very small hydrogen leak or the outer
skin, and once on fire, everything went up all at once. This theory was
developed and confirmed by a researcher just a few years ago, who knew that
a hydrogen flame is invisible, and the Hindenburg explosion was far too
spectacular to have "just" been the hydrogen burning.

The inner details of the Hindenburg were interesting also. The lift cells
which contained the hydrogen were made of the most impermeable substance
available at the time - a celluloid film similar to photographic film, and
this was also highly inflammable.

All in all a spectacular device, but it had a fatal Achilles heel - any
ignition source, even a single match, could destroy it.

Best Regards,

Mike Arman