Mountain Banshee Card Stock Glider

The mountain banshee, or Ikran, comes from the fictional world of Pandora. As you can see, I have designed a glider based on it.

I've included two versions of the glider. They differ in their wing design. The version with pointed wing tips is photographed in this post, but I believe the version with rounded wing tips is better for flight.

-sheet of medium card stock (80 lb. / 215 gsm) or beige file folder, cut to a standard size (8.5" x 11" / A4)

-large steel paper clip (approx. 2" long)

-pliers

-liquid white glue and glue stick

-scissors and hobby knife

-ruler

Cut out the shapes. I used a vector file and automated cutter, because it makes prototyping so much faster. When cutting out by hand, it's important to go slowly and be as precise as possible. A hobby knife will be helpful for tight corners, but be sure to have a sharp blade and a good mat that won't slide.

Straighten out the paper clip and cut two straight pieces 3 cm long. Add a slight bend at the mid point of each piece. Get the fuselage piece (A) and use liquid glue to secure the pieces to the interior of the nose of the Ikran.

(If you expect to fly mostly in breezy conditions, or want your glider to be better at flying straight and far, make one of the metal pieces 3.5 cm long.)

Use a glue stick for this step. Glue piece C to the top of piece B, making sure it is set back a few millimeters from the leading edges of the wings. Reinforce the next and head by gluing both D pieces to the top of the main piece. Lastly, reinforce tail with piece E.

Use a ruler to establish angles on the tabs of piece A, on the dashed lines. Bend them to 90 degrees. Add liquid glue to one side of A, being careful not to get any on the tabs. Fold A in half and press the sides together, working back and forth (head to tail) until the bond is established.

Apply liquid glue to the tabs of A and attach is to the bottom of the main piece. Make sure it is centered and straight.

Use a glue stick to attach both F pieces to the sides of A.

Use a ruler to establish creases on all the dotted lines. Carefully bend down the tabs of the trailing edges of the wings (flaps and ailerons). The two closest to center should be deflected down about 10 degrees, those in the middle to about 8, and the outermost one barely at all. Raise the wing tips about ten degrees about horizontal. Raise the sides of the horizontal stabilizers to an angle of about 70 degrees, and raise the rudder on the end tail to about 5 degrees of deflection. Curl the inner portion of the leading edges of the wings down slightly, as well at the protruding claws.

Add a bit of washout to each wing by pinching the tip, twisting it forward about 15 degree, then releasing. (This reduces the angel of attack near the wing tips, helping to prevent tip stalls.)

Make sure you've made a crease on the dashed line of the fin (G), worked the rudder side to side, then straightened it. Use a thin bead of liquid glue to attach it to the main piece.

Using an object such as a book, with a slightly round edge, make a soft crease about 12 mm in from each wing tip. This will allow you to bend the wing tips up and form winglets, like those of many airliners.

Check the glider from various angles. Try to work out any imperfections. It is critical that the left and right wings have the same shape and angles.

Damp and humid weather will make the glider too heavy, and may even cause the wings to droop. Hot and dry weather can cause the material to twist and warp. And any amount of breeze will make it hard to test your glider. For those reasons, it is best to test and trim (i.e. make adjustments) indoors. Throw the glider straight, level, and with consistent force. You do not need to throw it hard.

Adjustments should be very small and incremental. If your Ikran noses up, reduce the deflection of the elevator on the tail piece. If it noses down, try raising the elevators on the horizontal stabilizers (secondary wings) by a few degrees; raise the elevator on the tail if this doesn't work. If your Ikran drifts left or right, use the rudders to correct that tendency, starting with the small rudder of the tail fin.

If your Ikran rolls and crashed immediately, the most likely cause is asymmetrical wings. For example, one aileron might be raise several degrees higher than its counterpart on the other wing. Try your best and work out the defects. It will take some persistence and patience, especially if you don't have much experience with gliders.