Top view:
Illustrated with 2 x 6 dimensional lumber construction on the main dome,
X1 struts are 2 x 4, and slant base struts are 2 x 8.
A pictorial view in perspective mode:
In this next image, FI boards are added, shown in light blue color and
and X1 and FI struts join at main dome struts (green) approx. 24" on center
on the 26'-6" diameter dome.