I fixed that other vert stab pic above, and now here's the rudder. It needs to be prepared the same way you did your ailerons. Only, instead of leaving some of the flute for the coro to grab, you have to grind or sand these flutes flat, so all you have left is the inside skin for the hinge. The vertical stab has to fold flat, and if there is any flute left on the rudder, it will be raised on the hinge line, dramatically reducing the effectiveneness of the rudder in flight.

The rudder and elevator halves are the most 'complicated' pieces in the Cor-Star. Be patient, they take a little time to make right. Make sure you weigh them down when gluing, and check often that the poly glue isn't pushing the wooden blocks out of position. Your result will be an extremely stiff and strong rudder. I have landed very hard on the tail of my first Cor-Star (hard enough to snap the wire...TWICE),and the rudder isn't showing any signs of fatigue.

When the rudder is glued, go ahead and glue it's hinge into the vertical stab, glue the vertical stab halves and fold them onto the rudder hinge. Make sure you can move the rudder 45 degrees in both directions. Don't forget to mist with water!