Level ADAHRS and Mag 236?

[jnmeade]

I am upgrading my D100/120 system to D1000 in my Flight Design CTSW.
I am deciding where to mount the ADAHRS 200/201 dual stack. I am using the mounting boss in the left wing for the MAG 236.
How do I know the MAG 236 is 0° in all axes and how to I make sure the ADAHRS is congruent with the MAG 236?

 

[Dynon101]

Making sure that the boxes are level left/right /forward /backwards is as simple as placing a digital angle finder on the top surface of the unit in each axis... if they are not the same getting them trued up is the hard part.

My strategy is to use place the airplane on jacks and then use a water tube to make sure that the airplane is level... then use the same water tube to level a flat plate on my workbench and then calibrate my digital angle finder.

Then my ADAHRS (stack) is mounted on an aluminum tray that is attached to the fuselage with three threaded rods so I can then true up the ADAHRS to the airplane.

Getting the three boxes aligned with the longitudinal axis is still a challenge because it is difficult to measure.

 

[jnmeade]

Yes, the yaw axis orientation is part of my original question. The other axes of the ADAHRS are trivial, as you point out. Accessing the MAG 236 in the wing is extremely difficult and I'd be obliged for any suggestions on how to do that. Is there some kind of sensor I can attach to it and then read the sensor orientation?

 

[swatson999]

Getting the three boxes aligned with the longitudinal axis is still a challenge because it is difficult to measure.

What kind of plane?

 

[Dynon101]

I am in the same boat (...errr airplane).

I cannot do this on my airplane however I have heard of some builders making an oval hatch in the bottom surface of their wing and mounting the SV-MAG on the top surface of the hatch. The nut plates are going to have to be steel however you can use brass #10-32 screws to attach the SV-MAG to the hatch and then the hatch to the airframe. If you need to service the unit you simply unscrew 8 screws and the hatch falls down with the SV-MAG attached to it. Leave long enough wires.

My airplane I will have to take the wing off to get to it...Grrr.

 

[jnmeade]

Plane per OP is Flight Design CTSW.
I think I'm going to start by assuming:
1. Wing sits on fuselage square - 90° - I'll see if I can find a way to get some point of reference inside the wing to set the yaw axis based on that. That may be challenging.
2. Dihedral is about 1.7°. I can verify that and set the mount so that the MAG is down 1.7° on the outboard side. Do that outside on the bench. That will help with the roll axis as a start point.
3. Pitch axis I have a friend with a similar plane. I may be able to measure his reference the inside of the wing and set a start point for pitch.
Pretty coarse way to approach it.
I was hoping there was a way to set the ADAHRS and have a remote that would transfer that orientation to the MAG. Access is extremely cramped.

 

[swatson999]

Plane per OP is Flight Design CTSW. 
I think I'm going to start by assuming:
1.  Wing sits on fuselage square - 90° - I'll see if I can find a way to get some point of reference inside the wing to set the yaw axis based on that.  That may be challenging.
2.  Dihedral is about 1.7°.  I can verify that and set the mount so that the MAG is down 1.7° on the outboard side. Do that outside on the bench. That will help with the roll axis as a start point.
3.  Pitch axis I have a friend with a similar plane.  I may be able to measure his reference the inside of the wing and set a start point for pitch.
Pretty coarse way to approach it.
I was hoping there was a way to set the ADAHRS and have a remote that would transfer that orientation to the MAG.  Access is extremely cramped.

Yaw axis should be okay if it's close...you have to "swing" the compass, per the procedure, which should take out any remaining difference between the plane's yaw axis and the AHRS.

For roll and pitch, there must be *some* reference lines in the airframe which can be used. E.g., in an RV, the pitch can be determined by leveling the plane using the deck which covers the longerons along the side of the cockpit, and the roll angle can be determined using the top of the spar carry-through mid-cockpit.

There must be some similar reference locations in your plane. Once you have those you can either level them and then set the AHRS level, or determine the angles and set the AHRS to match.

 

[jnmeade]

You are missing the main point. I can get the ADAHRS pretty much right.
How do I get the MAG 236 congruent with the ADAHRS?