"Bret Ludwig" wrote in message ups.com...

LNG, as used in the Beech system (Beech Aircraft really did the
pioneering work on LNG, of course it went nowhere....) was stored at
very low temperature at approximately atmospheric pressure in a dewar
type insulated tank. It's important to understand that methane-natural
gas- is an incondensible gas for all intents and purposes, like oxygen
and nitrogen but unlike propane, nitrous oxide, carbon dioxide, ammonia
which can be stored at human-habitable ambient temperatures at
pressures feasible for storage tanks.

Methane and propane can be burned in an IC engine in similar fashion
once they are a gas, but at very different fuel-air mixtures. Methane
is approximately 108 octane and propane is in the 103-106 range
depending on exactly what's in it (LP motor fuel is nothing like
reagent grade and contains methane, butane, methanol, and lots of
other junk).

LNG would be practical but the cost of distribution would be high and
the fuel system is fairly complex, at least in the Beech system. CNG
has no range to speak of. LPG is very practical for all sort of ground
vehicles and has been done successfully in helicopters, but large
volume storage in fixed wing aircraft is problematic. A fixed wing
aircraft designed around a fuselage LP tank as a stressed member might
make some sense.


For those of you who have not yet decided that this guy Ludwig is a dufus and / or a troll.... natural gas is not
methane. Although methane makes up approximately 96% of the local natural gas here, there are many other
constituents. Several of the products that he says are stored at human habitable temperatures... well lets just say
that he is wrong at least on the ones that I am most familiar with. For instance, ammonia is stored at temperatures
around -28 degrees f. As a matter of fact, nitrogen, carbon dioxide, and ammonia are all cryogenically stored. BTW,
we condense methane at -282 degrees f. at my work place 24 hours a day as a step in recovery hydrogen for reuse.

Joe Schneider
N8437R



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