Half a croissant, on a plate, with a sign in front of it saying '50c'
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Airships of the not falling out of the skies variety

It's all down with sticky tape
  [vote for,

Anyway, while I was working on a hot nitrogen/CO2 balloon (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 create an inner set of firewalls from the graphene sheet produced.

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 knacker the one bit of the outer skin as it burns its way out and so 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 making a choke-point, then (possibly) enough layers of graphene, each laid at a tiny off-set, might be impermeable to hydrogen?

* I still have the scars, and an over-whelming aversion to Camembert.

** Why is "Noel" the same as "Leon" backwards, not even mention "Elon" of the Musk family.

not_morrison_rm, Sep 03 2015

Electric Nose Cheese yada yada Electric_20nose_20cheese_20filter
[not_morrison_rm, Sep 03 2015]

Impermeability of Graphene http://arxiv.org/pdf/0805.3309.pdf
"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 ...
8th of 7, Sep 03 2015

       What if we use ionic hydrogen (so a proton cloud) and positively charge the graphene?
Voice, Sep 03 2015

       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.
sninctown, Sep 03 2015

       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 high speed.
MaxwellBuchanan, Sep 03 2015

       // 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.
8th of 7, Sep 03 2015

       I have. That's why it's so important to hire the best pilots.
MaxwellBuchanan, Sep 03 2015

       //best pilots// best mechanics.
wjt, Sep 05 2015

       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 structure.   

       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.
lurch, Sep 06 2015


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