Compass interference

[Terry B]

Hi all,

I need some advice on compass placement. I have a BC12, and currently my whiskey compass is mounted right between the two down tubes above the panel, basically its front and center about 2 in from the top of the windscreen nestled right in the angle o the "v". I get a ton of interference there, is is from the steel in the tubes? Is there a better location for it?

Thanks Much!~
Terry

[Hank Jarrett]

Re: Compass interference

When I bought my 45 the compass was locked in one position. Prior owner said he used to always park it faced in the same direction for annuals () He never got caught. He said he never flew where he needed a compass anyway. God protect fools and small children.
Needless to say the first thing I did was pull it down to check it out. As soon as I removed one of the bolts the compass swung right around. I think you could pick up a screw driver with that bolt, so the first thing I would do is take the bolts out and see if the compass works out of the plane.
If the compass still doesn't work, solution's simple, fix or repair the compass.
If the compass works out of the plane you have something magnetic up there and the easiest solution is to get an NDI guy (someone with the equipment for Mag Particle) to degauss the tubes. It's not a big job and with a few passes he should be able to (magnetically) clean you up in Bristol fashion.
Hank

[Hank Jarrett]

Re: Compass interference

Oh yea, it is supposed to be top center. I wouldn't move it. Some have put the compass on top of the glare shield but there really isn't enough structure there to properly support it.
Hank

[Marv]

Re: Compass interference

If you were to mount the compass on the glaresheild, i think you will find that when you move the controls to move the elevaters up and down your compass will deviate back and forth and not be reliable. Marv

[robbie]

Re: Compass interference

My is mounted on top of the instrument panel and has a reinforcement under the metal glare shield.
Been there since I got the plane 27 years ago. Works fine.

[Hank Jarrett]

Re: Compass interference

I know it "can" be mounted on the glare shield (with proper reenforcement) but I guess I am a little anal about not upsetting the feds. I would imagine they would want paperwork to support moving an instrument (not that very many inspectors have any idea what the original configuration was).
Mine works great at the apex.
Hank

[Terry B]

Re: Compass interference

Thanks much guys, I am going to try the degauss route first. Will let you know what happens.

Tailwinds!

Terry

[Larry Lyons]

Re: Compass interference

As I have no knowledge of what I am talking about, I offer this with that caveat. I have an old degauss machine that I got with a TEAC tape player I bought back in the early 70's in Hawaii. It seems to produce a strong magnetic field and I was instructed back then, to run it over the head of my tape player once a month. If that is what we are talking about here I am thinking eBay would have them cheap. Also, if what I have will work it is available for free less shipping if someone knows how to make it work for our situation. Larry

PS: It needs 110V a AC supply.

[NC22211]

Re: Compass interference

The early Model B's had the compass mounted onto the glareshield, in a domed shaped or 1/2 conical housing which ran from the leading edge of the instrument panel, tapering down toward the windshield to a point. It is a pretty impressive structure and was probably necessary to spread the load over the chipboard glareshield. With a thin aluminum brace underneath, it would work OK. NC22211 had its compass moved up top, between the "V" tubes at the top of the windscreen, as were later T-craft with the special Taylorcraft Logo compass from Airpath. It was hung using several aluminum tube clamps and brass screws.

Compass inteference in these old steel tube airplanes is always a problem, and its part of the charm of navigating around the country in them. Most of the inteference can be compensated out, if it is a quality compass. I have a couple of very early ones which were great in their time, but now seem to find mag north in fantastic places having nothing to do with reality. They make great paperweights.

Accepting the fact that you're moving at the speed of slow, using a sectional or Rand McNalley for gross area Nav, the little deviant is just charming. Record it on the compass card, verify it every annual when you swing the compass, and fly on. If you're dead set on making every check point on-time and on-mark, perhaps you'll need the ol' GPS upgrade. There's another 2 cents. Bob

[8708]

Re: Compass interference

I had the same problem with my compass when I got the plane. Turns out there was a tiny screw holding on the compass correction card. Of course it was magnetic! I put the compass back in and turned it on the airport compass rose and it is great! I really like it up in the windshield as opposed to the dash mount.
Good luck!
Jay