h a l f b a k e r y
I didn't say you were on to something, I said you were on something.
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Anyway, while I was working on a hot nitrogen/CO2
(wonderful for growing tomatoes in) I decided it was a
silly, silly, silly idea.
Hydrogen airships have the tendency to do the 'fall from
the skies in flames' bit, which does tend to put a damper
on the trips. So, by using an enormous
pencil lead and a
gargantuan roll of sticky tape NMRM Enterprises will
an inner set of firewalls from the graphene sheet
Presumably the best way would be like the cardboard
divider in a box holding multiple wine bottles. If the
hydrogen in that cell decides to catch fire, it'll only
the one bit of the outer skin as it burns its way out and
the rest of the crash should be survivable.
The really nice way would be to have fire-walls and an
external skin of graphene.
Learning from my experience* with the electric nose
cheese filter, that two layers of something, with little
pores in it, can be made to overlap each other, so
a choke-point, then (possibly) enough layers of
each laid at a tiny off-set, might be impermeable to
* I still have the scars, and an over-whelming aversion to
** Why is "Noel" the same as "Leon" backwards, not even
mention "Elon" of the Musk family.
Electric Nose Cheese yada yada
[not_morrison_rm, Sep 03 2015]
Impermeability of Graphene
"We therefore conclude that the graphene layer is essentially perfect and for all intents and purposes impermeable to all standard gases, including He." [lurch, Sep 06 2015]
||// (possibly) enough layers of graphene, each laid at a tiny off-set, might be impermeable to hydrogen? //
||Hydrogen under modest pressure will diffuse through several millimetres of molybdenum steel (and many other dense, tough materials) at a disconcertingly high rate. After all, it's mainy just protons.
||Good luck with your graphene ...
||What if we use ionic hydrogen (so a proton cloud) and
positively charge the
||Just make the airship out of thin stainless steel sheet and
vent hydrogen through small holes in the surface, thus
allowing the entire airship to be continuously on fire.
||I'm pretty sure that hydrogen airships can be made
perfectly safe. After all, we fly around in thin
aluminium shells carrying tons of flammable liquid at
||// thin aluminium shells carrying tons of flammable liquid at high speed //
||Yes ... read that back to yourself and then think really, really hard about the implications.
||I have. That's why it's so important to hire the best
||//best pilots// best mechanics.
||Number of graphene layers needed: One.
||Pursuant to [8th]'s plaint about molybdenum steel, it will
be instructive to note that such case actually involves
hydrogen atoms dissociating from each other, and
dissolving into the metal. This is facilitated by the
electrons moving into the conduction bands of the metal
ions' electronic orbitals. Graphene does not promote
dissociation, leaving the hydrogen molecules intact; these
are too large to penetrate the gaps in the graphene
||Note that molecular hydrogen is actually a larger entity
than (noble, therefore mono-atomic) helium.
||As far as multiple layering, the electronic structure of the
carbon pi-orbitals in the graphene will interlock between
the two layers, causing the holes in the lattice to align. It
is possible to offset the orientation of two adjacent
sheets by a few degrees, such that not all holes can align;
however, such an orientation is "not energetically
favorable" (this term would describe, for example, ball
point pens stored, unsupported, balanced on their tips)
and could lead to a failure in one or more of the sheets.