If you have the Hobbico Avistar ARF, which requires you to glue the dihedral braces into the pockets, you MUST do that step. Unless the spar caps are glued to the plywood brace, and the center ribs glued to each other with no gaps, and the leading and trailing edges glued to each other, the wing just isn't strong enough across the center. Glued, all the elements support each other.

We've seen wings with broken ply dihedral braces becaue the facing ribs weren't glued much at all. This allowed the two wing halves to twist a bit in relation to each other, and this twisting eventually breaks the plywood dihedral brace. Properly-glued, the wing is strong enough to take whatever the modeler can dish out in the air.

The Avistar Select RTF comes with the steel rod for the center brace, and anti-rotation pins at the trailing edge. This wing has also proven to be strong enough for the normal in-air forces the model will encounter.

The designs of these models are not lightly thought-out, but developed with a very large number of hours of testing by very experienced R/C builders and fliers.