Here are some photographs, to see my small FW called "Titine" (translation : "so tiny"...) It was launch with a short bungee, but will fly at slope as well.
A small mixing device (electronic) allow to use a simple 2-channels radio control.
Some (simple) calculation were made, and twist distribution is set according to an accurate function.
This for a constant airfoil.
C = chord
E = span
x = distance along span (x = 0 at root, x = +/- 1 at tips)