Matt,

I've measured both the method that you've described above and Andy's suggested method and for me they do not come out the same as you suggested. If I shim the tail 33.5 mm then the height of the top of the chin cowl is closer to 40 mm below the centerline of the stab tube.

Are you sure these two methods are supposed to be the same? If so, please explain.

Thanks,
KeithB


If you blocked the flat chin area such that it is parallel to your flat surface, and the bottom of the fuse just touching the surface, then the tail post sits 33.5 mm above the surface. Then reference your stab at zero and wing at +0.25 with the fuse blocked up this way.

If you decide to lower the tail, say 10 mm or more, the model will likely pitch to U/C on knife edge. If you raise the tail 10 mm or more, then it will likely pitch to canopy. Remember knife egde pitching is largely a function of where on the vertical stab the CP is located.

Good luck

MattK