The problems with compass fluid are that is is flammable and that it does not
damp the magnetic compass properly. That is, in turbulent air, that sucker
swings around and is totally worthless for determining what direction you are
headed.
The problem, then, resolves itself to finding a clear viscous ("thick") fluid
that is not flammable.
Several fluids were tried. The most promising to start was mineral oil ("baby
oil") from the drugstore. It was exactly the right viscosity, didn't burn very
well, and damped the compass quite well. Unfortunately, it got real cold here a
couple of weeks ago and the damned compass was beyond viscous -- it took about
ten minutes to come to a heading when making a standard rate 180° turn. I
didn't do any super-scientific measurements, but putting the stuff in the
freezer caused it to freeze solid. Not good.
The freeze problem also held true for corn-sugar based syrups ("Karo") and other
hydrocarbon fluids. I did not try brake fluid (5606) or tranny fluid because of
the color change.
What has worked for the last month or so has been "toner oil" from the local
copy shop. It is actually a silicone based fluid, absolutely nontoxic and
nonflammable, exactly the right viscosity, and has performed exactly as
expected. The CCR tables show it having a freeze point of -40°, and quite
frankly, if the cabin temperature ever gets that low, I'm not much for flying
anyway. The copy shop sold me a pint of it (in my container) for $2.
Yes, it takes almost half a minute for the compass to totally catch up with you
when making a 180° turn. So what? That's what the DG is for. I will take slow
compass reactions for the capability of having a useful instrument when it gets
bumpy.
Like I said, this is all in a dream and would NEVER have made it's way into an
airplane, much less a standard certificated airworthiness airplane. Never, no,
hm'um, unhunh, nope, not here.
Jim
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com j...@rst-engr.com
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This looks like very good info,Jim. Puff Puff , as soon as I blow all
the SMOKE away I'll finish reading it.
Bob Olds RV-4 N1191X
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http://www.sirsproducts.com/page3.html
I've got a compass that's flakey and this looks like a reasonable
replacement.
Another good suggestion for anyone thinking about rebuilding their
automobile compass is the shock oil from R/C trucks. It's silicone based,
and comes in various viscosities. You can basically custom tailor your
compass to your own liking. More bounce but faster adjustment, or less
bounce and slower to come around.
Just a thought,
Kev
This is exactly why lists like this are so DAMN great. Thanks to all
you guys for doing some levelheaded R&D. Only in America !!!!!!
Jim
benf...@aol.com (Ben Haas)
shared these priceless pearls of wisdom:
->> Another good suggestion for anyone thinking about rebuilding their
->> automobile compass is the shock oil from R/C trucks. It's silicone based,
->> and comes in various viscosities. You can basically custom tailor your
->> compass to your own liking. More bounce but faster adjustment, or less
->> bounce and slower to come around.
Yes, R/C is Radio Controlled. Any good hobby store near you should carry it.
Kev
Mike
MU-2
"Kevin M" <kev...@swball.com> wrote in message
news:5yxt9.271$Wf4.13...@newssvr11.news.prodigy.com...
Great tip, Mike (and Jim, and others) -- I never heard of them.
Thanks!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"