Will a magnetic compass work well in a semi truck?

From all my reading I get the idea that people don't shoot off in sundry directions in the Sahara. They stay on the beaten path :-) I got the compass in my truck after I turned right instead of left at an unmarked intersection and didn't discover my mistake until I got to the next town. It is sort of embarrassing to ask someone where Bangkok is and they point back the way you came :-)

The Sahara once held the most isolated tree on earth, 400 km from any other tree.

In 1973 a truck hit it.

-jsw

As Joe saw they can calibrate out the effect of the vehicle, although I suspect there is a limit. I had a compass in a Camry years ago, My trip to work took me across a

And his IQ "false positive".

I'm an excellent lumberjack. Did I ever tell you my story about the Sahara Forest?

Have you ever driven in the "trakless desert"? Where the track the last guy made 5 hours ago is now under 5 inches of blown sand???

Trust me, you need a GOOD compass, or better yet a GPS or you may miss the only water stop or fuel cache for 100 milles by several miles and not even know it.

I collect fighter pilots' memoirs. You haven't a prayer of matching them.

-jsw

snipped-for-privacy@rahul.net (Edward A. Falk) fired this volley in news:mcj8nr$h2o$3 @blue-new.rahul.net:

As it will any time there's a substantial current flowing in a line close to the compass.

Magnetic compasses are tricky bastids, but they can be got a lot closer than one-two-three-deviation adjustment procedures... just depends on how much time (and fuel or trolly-hauling) you want to do.

Flux-gate compasses can also be fooled by mains busses. They don't measure attraction, but fields... but they do measure ANY field, and even can be made in error by 'bending' of clean fields by large masses of ferro-magnetic materials!

Lloyd

"Lloyd E. Sponenburgh" fired this volley in news:XnsA44BD27C32251lloydspmindspringcom@216.168.4.170:

I should have said, "D.C. current...."

LLoyd

You're supposed to say "What forest? The Sahara is a desert." to which I reply "See what I mean?" My dad and a friend of his wrote a book with WWII fighter and bomber pilot stories, including Dad's drop into France and the German Stalag resort. _To Rule The Sky_ if you're interested. Louis Jaques, Jr. and Bill Leet.

Ever see "The Gods Must Be Crazy"? The sequel was almost as good, too.

I Don't use a compass. when lost, I simply look for the nearest tv satellite dish. They all point kinda south. Ivan Vegvary

On Tuesday, February 24, 2015 at 8:41:31 PM UTC-5, Lloyd E. Sponenburgh wro te:

Retired from it now since last year, but I did many compass calibrations on airliners. We had a compass rose on the field where I worked, and ships u sed to be scheduled through for compass cals. Had to be done when you repl aced the whiskey compass if the calibration card had been lost. If I rememb er it correctly, there were certain electrical loads that had to be drawing current before the cal. If it was a cal. for a gyro compass, always must check to see if somebody had put a steel screw on the cover of the flux val ve at the wingtips. That was a common problem. You could align one gyro com pass to the other system, but the compass system had to be cal. checked on a compass rose within 30 days. Gyro compasses a thing of the past now, with the Inertial ref. systems. Pretty much useless information nowadays.

Try googling 'Flinders Bar' and 'Flinders Balls' for more about how it used to be done on shipboard.

Jim H.

Jim Hornaday fired this volley in news: snipped-for-privacy@googlegroups.com:

Again, not to belabor the point, but to make it clear. All you're doing with those _nearby_ lumps of iron is making the attraction load of more distant 'lumps' of iron equal in all directions. Then the only thing left is the attraction of the magnetic pole.

It's not magic, but might be non-intuitive to someone who's never actually calibrated a compass.

Lloyd

And on an aluminum plane you don't have magnetized steel structure like in a rag and tube, which may require degaussing - not a trivial endeavour. A magnetized fuselage is more likely with a mig welded fuselage than with a gas welded one. (particularly if welded with a DC welder)

snipped-for-privacy@snyder.on.ca fired this volley in news: snipped-for-privacy@4ax.com:

Eh... magnetization has little to do with it. This method was perfected in the day of riveted iron vessels, not welded.

The simple matter is that the compass pointer itself is THE magnet, attracted to whatever iron masses may be near enough.

Make those _apparent_ masses equal in all directions, and the pointer would be equally attracted in all directions, leaving only the earth's magnetic pole to control its pointing.

And... where have you found a _powered_ aluminum aircraft that did not have sizable masses of ferrous metal inside and around the engine(s) (aluminum blocks/heads nothwithstanding)? And, at least in single-engine planes, that those masses weren't pretty close (relatively) to the dashboard, console, or windshield where the compass was mounted?

LLoyd

snipped-for-privacy@rahul.net (Edward A. Falk) fired this volley in news:mcoh57$lm3$1 @blue-new.rahul.net:

Or of the 'moss' growing on brains! Lloyd

And hot rivets are magnetized too. The proximity of iron, magnetized or not, will have some effect on the compass, but magnetized iron or steel has a whole lot more effect.

And the magnetized roll cage on an RV8 causes the compass to be off by

Google " degauss roll cage "

The attraction of the compass needle to unmagnetized ferrous metals is insignifficant compared to the attraction/repulsion of a magnetized ferrous metalfuselage (or even a small portion of the fuselage, as in the RV8 windsheild hoop, or roll cage.

Clare Snyder, technical director Recrational Aircraft Association of Canada (RAA)

snipped-for-privacy@snyder.on.ca fired this volley in news: snipped-for-privacy@4ax.com:

Ok, so, talking to a pilot, now -- you're claiming that the engine mass has no significant effect on an aircraft's magnetic compass. That only steel tube welded fuse frames are to fault. Right?

And, you're saying that aluminum fuselages with iron-bearing engines don't suffer from that, because they're not 'magnetic' in character?

And, that any of this has anything whatsoever to do with using a magnetic compass in a semi truck-trailer combo?

Right?

Are you sure you don't work for the US FAA?

(I know of a Super Viking owner who might argue your points, unless spruce and mahogany have become magnetic during my inattention)

Lloyd