Golly, how many times do we have to repeat this business about compass calibration? Just asking.
Thanks msinger for posting the thread once again and to ianwood for compiling it. My only quibble with it is that ianwood says beach sand contains iron which will throw your compass off if you take off from a beach. I tested this assertion and concluded that even the most iron-rich sands I could find have NO effect on the compass and flight performance*.
RCRobman: If you live in the western U.S. (
Poleeze indicate in your profile where you are located), then the latitudinal (east-west) change in magnetic declination with distance is small (the lines of equal magnetic declination are far apart - see this chart
http://maps.ngdc.noaa.gov/viewers/historical_declination/, but not so in the midwestern US, South America, and northern Canada where the lines are close together. There you would be wise to re-calibrate if you shift east-west position even 20 miles or so.
Steve Mann says:
Also, don't wear a watch while calibrating the compass.
My Swiss Army watch has NO effect on a compass. A mechanical pencil and a big belt buckle disturb a compass much more than a watch.
Incidentally, forum friends, this chart
http://maps.ngdc.noaa.gov/viewers/historical_declination/ is really cool in the way that it shows how the magnetic declination changes over time. You'll see it isn't much from year to year, but check it out over centuries! We should all live so long to fly our Phantoms under such different conditions.
*I used a couple analog compasses to test some sand dunes with so much magnetite that several attempts have been made over the years to mine and extract the magnetite for profit. The sand is black with magnetite, but it had no effect on any of the compasses I tried, nor on my Phantom when I took off from the dunes.