[EMAIL PROTECTED] wrote:
From Stephen A. Lawrence
...
Hydrogen has more lift, it's cheaper, and it's easier to contain
(molecule's roughly twice as big, doesn't slip through the pores so
quickly). Helium's a very poor second choice, except for the
flammability issue.
OTOH hydrogen is explosive in certain circumstances, so you might be
suspected of terrorist activities if it got around that you were making
large amounts of it.
I cast my lot with those who tend to think the main reason helium is
being chosen in this intriguing design is due to an overly skewed
perception of the dangers that hydrogen pose. The Hindenburg
disaster still haunts our minds, and the irony is that hydrogen's
flammability issue was the least of the problems that actually
caused so much death and destruction when the airship finally
crashed to the ground. Unfortunately, hydrogen continues to be
unfairly blamed as the reason for so much death and destruction.
I believe a recent NOVA TV program installment showed convincing
evidence to back up the theory that the highly flammable skin
properties of the Hindenburg's fuselage, as well as diesel fuel,
were the actual causes for so much death and destruction. Film of
the Hindenburg disaster show hydrogen combusting with the
surrounding air as an orange ball that quickly goes upwards and AWAY
from the air ship.
There is something peculiar here. Hydrogen burns with an invisible
flame. An _orange_ fireball had to be due to something else then,
right? Or is it possible that there was enough crud mixed with the
hydrogen to color the flame? (Orange flame typically means sodium, at
least in a typical kitchen.)
Besides, I thought the footage of the Hindenberg was all black and
white? (But maybe that's just because I grew up with a B&W television
set, and the first place I saw those newsreels was on that set.)
Meanwhile, the film footage clearly shows the
highly flammable skin of the airship catching fire and spreading
like wildfire throughout the entire skeletal structure as it crashes
to the ground.
Again, on the side of the "hydrogen bad" advocates, if the fire were
spread in whole or in part by burning hydrogen escaping from one or more
ruptured bags, you would probably not see that part at all in the film
because its light is all UV. You would just see the flames from the
(secondary) fires on the skin, and it would appear that only the skin
was burning -- which is indeed how it appeared.
But, then again, B&W film from that time was UV sensitive ... but then,
again _again_, it's been common since just about forever to use filters
to cut the UV when filming, 'cause otherwise everything looks rather
hazy. So the UV light from the the hydrogen flames would again most
likely have been filtered out and not have been recorded on the film.
This is followed by explosions from on-board diesel
fuel rupturing.
Nova was fortunate enough to have obtained a small sample of
original skin from the airship. They analyzed its properties. If
memory serves me correctly, they finally set part of the skin on
fire. It burned as if it was the equivalent of a solid fuel
propellant.
Had helium been substituted I suspect the Hindenburg would still
have caught fire and crashed to the ground. There still would have
been a major disaster with probably many lives lost. Hydrogen,
however, would not have been blamed for the cause. The most likely
cause was due to an unfortunate (and very common) static charge
buildup that would likely have ignited the airship's flammable
skin.
That's sure what I heard when I was growing up -- it was believed to
have been a static charge, which resulted in a small lightning bolt
jumping from the mooring tower to the dirigible.
I realize there still exist conspiratorial theories suggesting
actual sabotage had been involved, but Occam's razor suggests (a
least to me) that Mother Nature was the most likely guilty party.
This prejudice, unfortunately, is probably adding unnecessarily to
the costs to the intriguing rotary generator. I would therefore
agree with those who suggest hydrogen is likely to be a better
alternative than more expensive helium. I think the benefits would
far outweigh the dangers. It seems to me that if lightening were to
strike the rotary design while in operation and fatally rip the
fabric apart the structure would crash to the ground regardless of
whether it had been filled with helium or hydrogen.
Regards,
Steven Vincent Johnson
www.OrionWorks.com
