Yeah, I did this whole "what fluid to use" thing about four years ago on
this same newsgroup. No, kerosene isn't the optimum choice, but that's what
Lindy had to use going across the Big Pond, and the FAA has proceeded little
from that point.

Mineral oil freezes at a fairly high temperature. Damned few sailboats out
on the water when it freezes, so that isn't a problem for them. It is for
us.

The viscous fluid of choice for compasses is copy machine fuser oil. Good
from boiling to freezing and well past. Thick enough not to ooze past
slightly dried out seals. Not to be used except in experimental aircraft
and aviation quality (ahem) "boat" compasses.

Jim

--
"Life is not a journey to the grave with the intention of arriving safely in
a pretty and well preserved body, but rather to skid in broadside,
thoroughly used up, totally worn out, with chocolate in one hand and wine in
the other, loudly proclaiming 'WOO HOO What a Ride!'"
--Unknown


"Morgans" wrote in message
...


In sailboats, I was told the reason for using mineral oil was to dampen
the movements, with the more viscous fluid doing that function.

I would think that airplanes would need the same characteristics of the
dampened movement, but yet, people are saying that the thinner kerosene is
the fluid of choice to use in the compass.