If I am building at 2.4" to 1' and smaller I use Aphaltic resin type glue and
drag simulated stiches across the rib.
In either case I then cut strips of Coverite and iron them over the stiches (I
find a rotary knife to be the most effective tool for this job).
As far as spacing goes I'll have to check at home to confirm the distance.
Both top and bottom wings used the same spacing and the only varition occurred
within the areas covered by the propeller arc here the spacing was cut in half
because of the increased pressure within the slip stream. I have noted that
rib stiching systems varied from country to country and may have even varied
from one manufacturer to the next and my information is based on RFC/RAF
practices.
Tally Ho
Guy