UStik,

The Taurus originally has balsa spars, 1/4 x 1/2 so that is no weight.
The balsa nose sheeting and the shear webs both use a surface to glue the connection if I want to make the D. And that are the balsa spars.
In that case I probably am going to use 8 x 8 mm spars.
BTW, we do not know the internals of the old Taurus wing with the 3 ailerons thread hangings.
It is clear that with a 19 % wing the silk and dope covering makes the wing strong and with less wood light.
I always want to use the D tube beause it fixes the total wing before covering.

Cees