EDC-10A calibraion in flight

[arowley]

Is it possible to use the in-flight calibration described for the internal compass for the remote compass?

I am installing a D10A and was comparing notes with the owner of a D6.

He had calibrated his remote compass on the ground, but found it was significantly different in the air. He suspects it is because he has an air driven alternator that only spins up in flight, which alters the magnetic field of the aircraft.

He was planning to use the EDC-10A calibration process in flight, by holding compass headings and going through the north, south, east, west calibration.

I was thinking that the internal calibration process might give better results, because it is designed to be performed in flight - if it can be used for the EDC-10A.

Is this possible?

Thanks,

Andrew Rowley

 

[Dynon]

Unfortunately it isn't. But the EDC-D10A should be located well-away from things that can produce a variable magnetic field though, whether it's a motor, current-carrying wires, or another moving ferrous part (like retractable gear parts, for example). Note that the WIRES that go to the EDC-D10A carry digital data, and their proximity to offending sources won't affect the heading.

 

[arowley]

Thanks, that is what I concluded after a better read of the manual. I have now completed my own installation, and my initial testing shows that my results are also not very good. I will be making another attempt to calibrate in the next few days.

I have found that while installing the EDC-D10A would be easy during building, finding a good and accessible location in a completed aircraft can be difficult.

We have been playing around with a spreadsheet that calculates wind, true airspeed and heading from 3 GPS tracks and ground speeds. One feature that would be really nice is if the D10A could do its compass calibration in flight using input from the GPS and flying e.g. N, S, E, W headings. Essentially it could do the wind calculation in reverse, then adjust the headings used for the calibration to match the calculations instead of exactly 0, 90, 180, 270.

 

[arowley]

I'm interested in trying the release candidate mentioned here:
http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1398763333

I did my not entirely successful first calibration with the tail down. I'm assuming tail down and engine running is probably better than tail up and engine off.

Are there any risks updating with the release candidate code? I'm mainly concerned with the update process itself - as long as I can go back to an older version I'm not too concerned about bugs in the software.

Is the calibration preserved through software updates? Could I use the new code for calibration, and switch back to the stable release afterwards, preserving the calibration information?

 

[arowley]

I had another go at calibration today, as accurately as I possibly could. Testing in flight using the 3 GPS track method, I found that north and south were spot on, but east and west were both out by about 12 degrees (90 indicated = actual heading 102, 270 indicated = actual heading 258, calculated wind 072 @ 6 knots). Southern hemisphere, if that makes a difference.

Any suggestions of a likely cause or resolution?

I think I will try another calibration wth the tail up, and see if that is better.

After this calibration with the aircraft still pointing west the heading did settle on 270 after it performed the calculations. I suppose one test would be to set the aircraft on the ground to an indicated heading of 270 and see whether that still agrees with the compass, and see whether it changes when the tail is lifted.

Thanks for any suggestions.

 

[Dynon]

Have you set your magnetic inclination and intensity for your calibration location before you did the cal? Where are you and what were the values you used?

 

[arowley]

Yes, I have set the inclination and intensity. I am in Ballarat, Australia and the values I used were -68.5 and 59940.

I repeated the calibration on the weekend with the engine off and tail up, and now East and West are only about 3 degrees out. That is probably proportional to the amount I was able to raise the tail - about 3/4 of the way to flying attitude.

3 degrees is probably tolerable, relative to the accuracy I can fly the aircraft and accuracy of forecast winds etc.

However, if the attitude makes that much difference, I wonder about the change between climb and cruise etc. Is this consistent with the bug mentioned in the other post? Is that update likely to improve the accuracy?

 

[Dynon]

Your values look good for you location.

It's hard to say if your cal results will get better with the beta software update, but it couldn't hurt to try and definitely won't make anything worse. Though it's technically not an official release at this point, it's been pretty well-tested by other people in the field with no reports of any issues so far.

 

[arowley]

Thanks.
The link in the other post no longer works - is there an updated link?

 

[Dynon]

Try this.