Looking for good places to mount the GSU 25 ADHRS modules, so thought just under the seats may be a good spot. Made a couple plates to clamp to the main cross bars and measured the angle relative to the lower longeron horizontal datum. Turns out 12.5 degrees is what I measured. So I printed some angle blocks from ABS-GF and embedded some AN3 nylock nuts inside. Think it will work well. Very solid mounting and they are within 1 degree of aircraft axes.
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