E386 – Adjusting Declination

The Earth’s magnetic field varies significantly depending on your location relative to the poles. To adjust for the offset in your location, we’ll change the magnetic declination parameter until the heading shown on Mission Planner matches the heading of your plane. To start, power on the R/C transmitter, then power on the E386 – we’ll want to do this with the battery installed as it would be for flight and with the wings plugged in and installed. Be sure not to set it near any large metallic objects as the compass is very sensitive and can be affected by local magnetic disturbances. Once it has initialized, set it on the ground at a known heading.. it can be any direction as long as it’s known. If no directions are known for certain, you can use visual cues that would be visible on Google Earth. For example, you can point the nose to be perpendicular to your street or parallel with the edge of your house. Once that’s decided, connect to the E386 by telemetry in Mission Planner.

Once connected, you’ll see an airplane icon at roughly your current location. If you’re inside, you may need to go near a window or put the E386 outside in order to get a GPS fix. There will be a red line emerging straight forward from the icon, that is the direction the autopilot thinks it’s facing.  Knowing the real direction, we can now adjust and iterate the magnetic declination until the red line is pointing in the same direction we know the E386 to be pointing. To start, take a mental note of approximately how many degrees off the true direction the red line is pointing. Now click on Initial Setup -> Mandatory Hardware -> Compass. If the red line was counterclockwise of the true direction, add the approximate number of degrees you noted before to the current value, type that in and then switch back to Flight Data. Wait at least 30 seconds between iterations, it takes some time for the direction to update. If the red line was spun clockwise relative to the true direction, subtract. Negative values are okay but they should not exceed 180 degrees in either direction.

Initial setting, I’ve set the E386 down lining up with the stack across the parking lot.


Now after adding -4 degrees to the declination value, it’s very close to true heading.




Once the heading in Mission Planner lines up with the E386’s true heading it’s finally time to learn how to Plan a Mapping Mission.