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yankee-flyer

Well Known Member
OK, I confess that I must not have paid much attention to the compass tape until having some other problems with the D-180 that I'm slowly resolving. Situation is this: if I make a very slow gradual turn. it's pretty easy to stop on the desired heading. If I bank 30 deg or more, the tape seems to lag pretty badly, then when the turn is stopped it will overshoot as much as 50-60 deg, then slowly com back to the heading I'm holding. Sometimes the tape will "stick" and not move, then all of a sudden it will move in almost a blur, overshoot the heading quite a bit, and then come back. Seems to be worse in a left turn than in a right.

Has the Dynon & magnetometer always done this and I just didn't pay attention or has something else in that wonderful black box now gone haywire.

Thanks

Wayne 120241/143WM
 
yankee-flyer said:
OK, I confess that I must not have paid much attention to the compass tape until having some other problems with the D-180 that I'm slowly resolving. Situation is this: if I make a very slow gradual turn. it's pretty easy to stop on the desired heading. If I bank 30 deg or more, the tape seems to lag pretty badly, then when the turn is stopped it will overshoot as much as 50-60 deg, then slowly com back to the heading I'm holding. Sometimes the tape will "stick" and not move, then all of a sudden it will move in almost a blur, overshoot the heading quite a bit, and then come back. Seems to be worse in a left turn than in a right.

Has the Dynon & magnetometer always done this and I just didn't pay attention or has something else in that wonderful black box now gone haywire.

Thanks

Wayne 120241/143WM
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Wayne, what you are seeing is definitely not normal or acceptable.

1) Did you EXACTLY follow the calibration procedure?

2) Did you input your magnetic inclination value?

3) Is the magnetometer mounted level laterally, pointed straight ahead and in the same vertical plane as the instrument panel?

4) Are any moving ferrous objects close to the magnetometer?

5) Is the D-180 "seeing" the remote magnetometer?

If all these items are good, then you need to get in touch with Dynon to have your unit repaired. The heading tape should follow the plane in a turn with no errors and always move smoothly.
 
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I should add

that once everything settles down to steady state the heading is correct, and on the ground headings check OK against a compass rose. Just does this during turns in the air-- ground turns up to 360 deg seem to be OK.

Wayne
 
Sounds normal for a wet compass, which can't compensate for inclination (vertical component of the earth's magnetic field). I'm guessing a magnetometer might behave similarly if inclination was set to zero?
 
yankee-flyer said:
that once everything settles down to steady state the heading is correct, and on the ground headings check OK against a compass rose. Just does this during turns in the air-- ground turns up to 360 deg seem to be OK.

Wayne
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Brian is correct. Call Dynon. The heading should be stabilized.
 
Have you tried recalibrating, per the manual? Sounds sort of similar to the way mine acted when I had intially screwed up the calibration.
 
Solved-- Thanks everyone

With input from you guys and lots of help from Mike at Dynon, the compass tape now behaves like it should. All my fault. Here's what happened.

When the D-180 was originally installed I somehow got bad INC and INT numbers from the NOAA site-- no idea WHAT I did there. I did not complete the calibration process since I thought that was just for tweaking the readout and the compass was within 5 degrees of my home runway headings and we don't have a compass rose. Note that the compass tape worked just fine in the air and on the ground except for the small error.

When I got the repaired D-180 back a few months ago I had to reset the numbers and somehow managed to get the same bad numbers (except for small yearly changes) again. Compass behaved just fine except for small errors.

About 3 weeks ago I was at a field with a compass rose and did the calibration (note I still had bad-- very bad-- numbers). Now the compass readout was right on while on the ground or during steady-state flight but it went bannanas during a turn in the air. Ever see a compass stop during a turn, then turn backwards for 420 degrees to reach the correct heading???

After lots of emails from Mike I input the correct numbers with no change to the compass behavior-- note it's still fine during steady-state flight or on the ground. On Mike's advice this afternoon I want back to the compass rose (ground readings were 5 deg or less off from the rose) and did the full calibration procedure. Compass NOW behaves like it should and runway heading readings are correct.

Hope this long story helps someone else who's a digitally confused as me.

Wayne 143WM
 
Alternative to a compass rose...

If you need to compete a Compass (magnetic heading indicator) calibration and have no access to a compass rose, there is an alternative that works quite well.

Checkout the article on page 8 of THIS old Rvator issue
 
rvbuilder2002 said:
If you need to compete a Compass (magnetic heading indicator) calibration and have no access to a compass rose, there is an alternative that works quite well.

Checkout the article on page 8 of THIS old Rvator issue
Click to expand...

As usual, a good suggestion by Scott. The GPS procedure works great. In fact, I believe it may be even more accurate than using a painted compass rose that was placed there years before by persons unknown. After all, who knows how accurate their compass was!
 
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