ADAHRS

[wirejock]

Dynon ADAHRS
Manual says to align it to the airplane within a degree in pitch, roll & yaw. Pitch and roll are no problem. I got within a tenth with a few washers as shims.
Yaw is tricky. My phone has a compass, but it flip flops one degree constantly. I could be off be 1 degree just in device error.
I have a super duper compass but looking at it accurately is pretty difficult. My ADAHRS shelf is in front of F707 up between the stringers under the turtle deck. Difficult to get a device in there to measure deviation. I could probably point a borescope at it.
Laser level could work but measuring to a laser line isn't accurate to a degree over a small box. One degree over a 4" square is not much.
I should be able to loosen hardware and move it a degree or two without enlarging holes. I just need a reliable way to measure.
None of this is fun laying in the tail cone.
Maybe I'm over thinking it.
Any tips appreciated.

Edit...
I found a more stable phone app. Im only off one degree. I should be able to get dead nuts by loosening the hardware.

 

[PaulvS]

If a compass is accurate to within 1 degree then that is probably better than many that are flying.
I think that the calibration process at the airport compass rose should also give an indication of the ADAHRS/remote compass fitting and if it is not happy it will let you know.

 

[Carl Froehlich]

Compass cal for the SkyView is not as rigorous as you list. Get the ADAHRS aligned with the airframe, not compass direction. Move the plane out of the hangar and start the calibration. I use a standard Boy Scout compass out on the wing. Follow the SkyView compass cal instructions (data point taken at the four points) as your buddy turns the plane. This completes the ground phase and is more than accurate enough to get you in the air.

After flying you refine the calibration in the air, again following the instructions.

I’ve done this on four installs and it is amazingly accurate.

BTW - phone compasses are not what you should use.

Carl

 

[MacCool]

Aligning the Dynon ADAHRS in 3 axes with the airframe was straightforward for me in my RV-9A, simplified by Van's OP-60 bracket behind the luggage compartment (part number F-00149 for RV 7/9). Automatically provides correct alignment. I just riveted it in, screwed the ADAHRS down (with non-magnetic screws). My EFIS is an Advanced Flight 5000-series using the Skyview network. After install and before flight, I calibrated the compass using the airport's compass rose and confirmed with the compass on my iPhone. Only issue when calibration kept failing, which was resolved with a phone call, was that Rob Hickman informed me that it won't calibrate with the (slider) canopy open. DOH!

 

[sahrens]

Close enough

The AFS installation manual states "should" be within one degree. I put my ADAHRS in the same location as you and tried to get within one degree. I believe I am pretty close. In the end it calibrated without any issues.

Get as close as possible and check the calibration. I think you will be happy with the results.

 

[wirejock]

Phone compass

Compass cal for the SkyView is not as rigorous as you list. Get the ADAHRS aligned with the airframe, not compass direction. Move the plane out of the hangar and start the calibration. I use a standard Boy Scout compass out on the wing. Follow the SkyView compass cal instructions (data point taken at the four points) as your buddy turns the plane. This completes the ground phase and is more than accurate enough to get you in the air.

After flying you refine the calibration in the air, again following the instructions.

I’ve done this on four installs and it is amazingly accurate.

BTW - phone compasses are not what you should use.

Carl

To be clear, I'm not using the phone compass to do any calibrating. I am using it to get the box aligned to the airframe. I took several readings off the airframe to get the longitudinal center reading.
Then I moved the box so it's aligned to the same reading. It was only off be a degree. Confirmed with my expensive compass. So now the ADAHRS is within a tenth in roll & pitch and within less than a degree in yaw. Should calibrate fine.
Sorry, but I get pretty OCD about this kind of stuff.

 

[sahrens]

No reason to be sorry

Build the airplane you want!

 

[wirejock]

Follow up
Forget about the cell completely. The cell was way off North compared to the compass.
Bad enough it's horribly inaccurate, but it also generated a magnetic field strong enough to throw off my compass.
I was using the camera to read the compass and couldn't make sense of the wild readings. Then I saw the compass swing as the cell got closer. Doh!
I couldn't get exact readings because of the location but from what I could read with a mirror, it's within a degree of the airplane yaw centerline. Hopefully the system will calibrate the deviation.

By the way, the flap weldment really sings with a strong magnetic field. It really moves my compass whithin avout 12". Thankfully it's quite a way from the ADAHRS.