The top is made from one sheet of paper folded in half. I then drew the planform (top view) one one side. Using my fingers, I then formed the sides, making a radius on the top spline slowly widening till it reached the leading edge of the wing. The spline started from almost nothing at the tip, till it was around 1/2" inch. This gave the long nose lift. Now the sides of the long nose are on the same plane as the leading edge of the wings. At this point, you form a wing foil, (this just takes practice, too big, too slow, not enough, no lift). I then took another sheet (I used 110 lb. card stock, and did the same procedure for the rudder. The trick here is to cut the rudder oversized, as you will have to make symmetric foils on each side. This gives the rudder drag, which brings up the nose, and Rudder authority (keeps the glider going straight). When you duplicate the rudder shapes (Mirrored to each other), you then glue the back trailing edges with a flat, depending on the model size, mine were usually 18" inches long, and make a flat around 1/2". glued together, keeping everything symmetric. This will be your rudder.
Find the center of lift by looking own the wing, and seeing where the lift will occur the most, usually just at the highest part of the camber. This is your center of lift. The center of Gravity must be infront of the Center of lift. You get this big making a jig to balance the plane, with the rudder assembly, with the elevator mounted, which can be a single sheet, as long as it has a camber, to give lift. The opening on top of the rudder will allow you to use a good dollop of glue to attach the Elevator, which should be folded, to form a small "V", which will stabillize the craft. The elevator must be big. By sliding the rudder back and forth, with the plain on the center of gravity jig, you place the tail assembly so that the nose is downwarn. This will make the plane nose heavy, and the plabe will fly. At this point, you either angle the tail assembly to make the plane rise, or cut elevators into the tail plane. When you make a few of these, you will get the feel for it. Do not use Canard wings, they mess up the whole airflow characteristics. In short, with what I have just written, you should be able to bang out your first one, and dial it in, till you have a model have flying the way you want. If you throw it, and the nose goes to the left or right, you have too much aileron, or too much of an angle on the Elevator.. To make the bottom, you simply trace out the aircraft on the bottom of the body, on a flat sheet, and glue it to the fuesalage. You do this before you balance the craft's Center of Gravity. I always added doublers on the nose inside, as it can take a beating, but is also easily fixable. God Luck!
