X-8 Leveling Reference Point

As of the more recent versions of ArduPlane, the firmware no longer does an automatic level on startup.  Instead, that has become one of the initial startup steps when installing it in a new plane.

In the past, I have glued a bubble sight onto the rear spar enclosure and used that as "level".  Recently, someone else said they use the inside floor near the CG line.  Both seem ok, but both are different. I just looked at the wing and the underside is angled slightly node-down with my bubble level technique.

Does anyone have, or want to offer, their way of determining X-8 airframe "level" for the purpose of setting up the APM?


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  • I've found the best airframe performance (trim and efficiency) to be slightly nose high, about 3 or 4 degrees AoA. I just put the x8 on a level surface and put the lid under the nose to lift it about 1 inch, that gives a few degrees nose up and it flies perfectly at that setting with standard CoG.

  • Moderator

    As I understand it, the new levelling procedure uses 6 reference points to find level (of the APM) hence the 'level dance' we're all doing now. You can do it with the APM outside the plane or copter as it's APM specific rather than airframe specific. Then you mount the APM on a flat horizontal surface within the airframe and adjust AHRS_TRIM_X and Y if your plane doesn't fly level.

    As said that's how I understand it at the moment, but I'm open to correction.

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