[LINK] Scientists offered cash to dispute climate study

[Stewart Fist]

Stig coughs apologetically:
> 
> Ahem! Perhaps you mean the change in density, or buoyancy, or size... If
> clouds can change mass, we can skip this entire discussion of fuels and
> energy forever! ;)

No, my clumsy sentence actually means weight of the airship.

When you've got a airship the size of a football field, carefully balanced
to be neutral bouyancy at the chosen flying altitute (which meant dropping
water ballast, and compressing the air in airbags called canonettes (from
memory), then you had to be very particular about accumulating or loosing
extra weight.  

If you weren't, you'd quickly lose all your adjustment ballast and then have
to vent hydrogen to remain neutral

When a non-aluminiumised airbag flew through a cloud, it could easily pick
up enough moisture to double its envelope weight.  Then some of ballast
would need to be dumped.  Then ten minutes later you'd be out in the sun,
and it would be dry and hydrogen would need to be vented.  These ships flew
around the world in about a month, so they needed to be very particular
about their hydrogen reserves and ballast.

Some of the bigger rigid airships did have a motor driven air-condensater
which could extract water from moist air and exhaust fumes and be used to
rebalance.

I once looked into all this, with the idea of making a travel documentary
television series, tentative entitled "The world from the air".

Eventually we settled on a Catalina flying boat. But nothing came of either.



-- 
Stewart Fist, writer, journalist, film-maker
70 Middle Harbour Road, LINDFIELD, 2070, NSW, Australia
Ph +61 (2) 9416 7458