D180 magnetometer tilt?

[pierre smith]

Mornin' guys,
I was helping a buddy install his magnetometer in his -4 yesterday and the instructions said to tilt it the same amount as the D180. It worked out to 10 degrees but is it really necessary? If so, why? The other axes also are required to be aligned with the D180 as well, and this make sense.

Thanks,

[Kevin Horton]

The lines of force in the earth's magnetic field are sloped. The magnetometer measures the 3 components of those lines of force, and the calculations need to know the pitch angle of the magnetometer. The calculations assume that the pitch angle of the magnetometer is the same as the EFIS. If you don't put them at the same angle, expect errors in the heading.

[az_gila]

Aren't the RV-6 panels at an 8 degree tilt (not 10 degrees) to the longeron reference line?

UPDATE

Oops... I see you have the -6 not the one you measured - a -4 .....

gil in Tucson

[pierre smith]

Yes Gil,
The panel tilt is 8 deg to the longerons. However, the longerons take a downward bend forward of where the airplane's level point is by about 2 degrees. The math is....well, y' know. Our 6 does this too.

You're observant, eh??