magnetic compass

[hallschuch]

Hi Guys,
on my series 7 I find the magnetic compass is disturbed by the airframe resulting in the impression that I'm always headed west -- what solutions are out there?
thanks,
Karl

[109JB]

Never tried it but:

https://www.aircraftspruce.com/catal...passshield.php

[Dave S]

Karl,

I originally installed a used vertical card compass mounted in the center-top of the cockpit off the carry through tube. Swinging the compass resulted in the best setting to be at least 165 degrees off reality or worse at any direction. Worse than worthless.

Its the magnetic flux the fuselage has developed. I suspect this is hard or impossible to avoid with electric welding.

So, got some sage wisdom from John Mc Bean......who suggested I get a SIRS compass which has a far better adjustment mechanism than the previous century's VC compass; and, if it is good enough for Boeing, it could be good enough for a Kitfox.

Next - with a good compass in hand, I experimented with placement. Turned out, the center of the cockpit over the glareshield is the place that is most infected with magnetic voodoo - at least on our plane. The best place which avoided most of the voodoo was on the left corner of the glareshield and on right corner of the glareshield. I mounted the compass on the top of the glareshield just to the left of the pilot's view out the front window. That position resulted in very minimal adjustments to get the compass right; and, my correction card has correction values of 2 degrees or less all the way around.

Happy as can be with the SIRS compass.

[Dave S]

See entry #5 under "Show us your panel" for my compass placement.

[109JB]

BTW:

On my Kitfox 4 rebuild I will not even have a wet compass installed. A "magnetic direction indicator" is only required for night or IFR flight, and on top of that the "magnetic direction indicator" doesn't have to be a wet compass. Since my airplane will have a Garmin G5, I bought the GMU11 magnetometer with it and the GMU11 will satisfy the requirements for a magnetic direction indicator. Note that a GPS direction doesn't satisfy the requirements. This was verified by talking to a FSDO maintenance inspector I know.

[alexM]

91.205 still contains magnetic direction finder for day VFR

[n85ae]

I have a SIRS as well, and it has a wide range of adjustment, but lacking facilities to Degauss my airframe I never was able
to get it to where I was happy with the alignment. It is still in there, but it's good for rough cardinal headings only. Probably
on the order of +/- 20 degrees depending on heading. I use runway heading, or GPS track 99.999% of the time.

I think the SIRS is a very nice compass, more the point is that alignment in our airframe is a huge challenge. Probably if
mag heading is really important something remote mounted in the wing would be a much better solution.

I did try degaussing my airframe as much as possible with a big mag tape demagnetizer, but not sure that it really did
anything. I recall I spent a lot of time trying to get it adjusted, but in the end accepted what I worked out as "close enough"

I put mine in the MOST "voodoo infected" location, dead center in the middle of the glareshield, and this is probably why
I suffered so much. (Dave did you ever consider having an exorcism done on you plane? It just occurred to me that this
might have been a solution).

Jeff

So, got some sage wisdom from John Mc Bean......who suggested I get a SIRS compass which has a far better adjustment mechanism than the previous century's VC compass; and, if it is good enough for Boeing, it could be good enough for a Kitfox.

Next - with a good compass in hand, I experimented with placement. Turned out, the center of the cockpit over the glareshield is the place that is most infected with magnetic voodoo - at least on our plane. The best place which avoided most of the voodoo was on the left corner of the glareshield and on right corner of the glareshield. I mounted the compass on the top of the glareshield just to the left of the pilot's view out the front window. That position resulted in very minimal adjustments to get the compass right; and, my correction card has correction values of 2 degrees or less all the way around.

Happy as can be with the SIRS compass.

[Dave S]

Quote......
I put mine in the MOST "voodoo infected" location, dead center in the middle of the glareshield, and this is probably why
I suffered so much. (Dave did you ever consider having an exorcism done on you plane? It just occurred to me that this
might have been a solution).
Unquote.....

Jeff,

Originally, after chasing ghosts for so long trying to figure this out, I did consider exorcism as a possible solution! How'd you know that!

[patrick.hvac]

Paperweight or not, in Canada you must have a compass:
"a magnetic compass or a magnetic direction indicator that operates independently of the aircraft electrical generating system"
I always wondered if a battery backup G5 or something would satisfy but I have heard of no-one who has gotten away with it.

[jiott]

In my SS7 I am using a Falcon vertical card compass, mounted high in the exact center of my panel, just under the glare shield. After tweaking with the built-in adjustments My error in any direction does not exceed 2-3 degrees.

I am not familiar with it, but I have heard that there is degaussing equipment that will remove much of the residual magnetic effects from a steel tube airframe. If you know a person or shop with this equipment it may be worth a try; can't cost too much.