The dihedral angle. We typically glue on the inside piece of wood after it's cut out an basically use it as a template. Then cut everything to it on the bandsaw.
If you run a Hitec into any resistance or binding they're junk. Been through many. Look into Reefs micro 99. Super light and strong. Use them for steering servos on little boats.
Selling my Roadrunner 21. This was the 2nd boat built of the latest design. Has a couple imperfections pictured but never crashed. Added a little width to the front sponsons(also pictured). Comes with servos, tank, flex shaft, and needle valve. $500 shipped in US. Money order please. Thanks...