degausing fabric for dry compasses

[Dave Krall CFII SEL SES]

I've heard a number of complaints of difficulties getting both dry and wet compasses to be accurate in Highlanders. Anybody used degausing fabric (I think it's called) made of nickel to shield the compass from everything that interferes in the panel avionics, engine compartment, and airframe tubing?

[scubarider2]

Mounted my compass on top of the panel.  No problems.  
Dennis

[fiferphil]

HI Dave

OOOOOh! Do I have an interesting (horror!) story about whiskey compasses!, but I'll save that for another posting.  Every rag and tube airplane I have owned except for the Super Decathlon has had the problem of magnetic compasses with huge deviation errors on some headings. Even careful swinging of the compasses on these birds did not reduce the deviation error to an acceptable level.

I've seen in Aircraft Spruce some sort of material that is supposed to act as a shield tp prevent  magnetic interference playing havoc on compasses. On the 1979 model Super Decathlon, there was a metel plate of some sort, maybe nickel, that was mounted underneath the glare shield, right under the glare shield mounted compass. That airplane had a full stack of avionics, plus the steel tubing structure, but still gave good heading information (no more then + or - 2 degress of deviation on any given heading.) I don't know what that metal plate was, but it seemed to work.

I've thought about mounting mine on the wind screen as far from any tubing that I can get it -- but I'm a long way from that point. I might even give American Champion Aircraft a call and ask them if they do anything special installing the compasses in today's Citabrias.

I,  too, am keenly interested in solving this problem, and will publish on this forum any data that I can dig up that offers a solution.

[KevinC]

I mounted mine on the windscreen and have huge error - like not useable error.  Good thing I have good eyesight and can read road signs.

K

[fiferphil]

Yeah, Kevin, it looks like you've got it awfully close to that huge carry-thru tube. One thing I plan to do is to take a compass in my hand and start moving toward a cluster of tubing and notice how close I can get before I start seeing the compass card deflecting. There's gotta be an optimal place to mount that thing, and still be able to read it. Maybe right on top of the instriment panel glare shield as Dennis did will be the ticket.

[rmullins]

I'm glad to hear that I'm not totally inept. I mounted mine on top of the dash in the center and like Kevin, in certain directions I have huge discrepancies. I have twiddled with that thing for hours and just cannot get it usable. I'll be very interested in the solution you guys come up with.

[Dave Krall CFII SEL SES]

I searched "Mu metal" compass degausing and found foils, fabric and plates made of mostly either Cobalt or Nickel. I like the foil for light weight but am calling a few companies tomorrow to get more info before I order anything.

[stede52]

I've tried some of that Spruce material for my vertical indash compass and it did nothing.  You need to wrap the part with the material which also needs to be at least 3-4" away from the compass it self because the material has magnetic qualities.  In my case it was impossible to be that far away from the problem.  My compass is also worthless in my panel.

Steve

[Dave Krall CFII SEL SES]

I've tried some of that Spruce material for my vertical indash compass and it did nothing.  You need to wrap the part with the material which also needs to be at least 3-4" away from the compass it self because the material has magnetic qualities.  In my case it was impossible to be that far away from the problem.  My compass is also worthless in my panel.

Steve

I'm considering lightweight Mu cobalt foil radiating from the panel mounted dry compass combined with wrapping all the airframe tubes in the area with Mu cobalt foil tape. Have to talk with some more people first though.

[Dave Krall CFII SEL SES]

I've tried some of that Spruce material for my vertical indash compass and it did nothing.  You need to wrap the part with the material which also needs to be at least 3-4" away from the compass it self because the material has magnetic qualities.  In my case it was impossible to be that far away from the problem.  My compass is also worthless in my panel.

Steve

I'm considering lightweight Mu cobalt foil radiating from the panel mounted dry compass combined with wrapping all the airframe tubes in the area with Mu cobalt foil tape. Have to talk with some more people first though.

I talked with a few companies and some A&Ps and it sounds like shielding for a magnetic compass just doesn't work.

I'm encouraged by initial experiments with 1 or 2 small "satellite" magnets placed on the panel or behind it in such a way as to correct for large errors, but my amphib is suspended from a beam in the hangar and can't be swung through the compass rose just now.

First I tried a magnetic business card but it wasn't powerful enough. Then I tried about a 1/2 inch round metal magnet and it immediately brought my dry vertical card compass to the known heading when placed about 6 inches from the compass in about the "8 o'clock" position (the plane is heading 253 degrees as it hangs). I'll try others when I can swing the plane.