Rubber band powered aeroplanes are a fun learning project that ends up with a great toy as the result of the whole process. No batteries required, the rubber band will continue to power your aeroplane for as long as it entertains you to wind up the propeller and make it fly. A few simple materials and a little time is all that is required to make this project, and it can serve as an excellent hands-on engineering lesson.
Purchase your propeller through a local hobby shop or online. A source for them is listed in the resource section of this article. You can attempt to create your own with recycled plastic and paper clips, but they are not as strong and resilient as a purchased propeller made for this type of aeroplane model. Purchased propellers in the smaller sizes fit balsa square dowels from 1/8 inch to 3/8 inch. Check the literature on the propeller to see which size it fits before purchasing.
Cut your balsa pieces and lay out before assembling. There are many plans you can follow; the basic shape will be used for this tutorial. A 1/4 inch thick square dowel of balsa about 12 inches long is the centre support for the plane, or fuselage. Thin sheet balsa is cut into two wings, each 2 inches wide by 5 inches long. The wings can be cut in one piece that is 2 inches wide by 10 inches long as well. Cut tail wings that are one fourth the size of the total length of the front wings, in this case 2 1/2 inches each. Cut a rudder that is 1 1/2 inches high to attach to the top back of the plane.
Shape a piece of paper clip section into a small hook with a straight protruding end about 1/2 inch long. Push this into the back section of your balsa dowel, 2 inches in from the end with the hook open side facing the back. Insert 1/4 inch of the extension into the balsa fuselage for stability. Leave another 1/4 inch extended above to keep the rubber band 'floating' and not in contact with the wood. It needs to be deep enough to be able to hold the tension of the rubber band when wound. Place a small bead of glue on the metal before pushing into the balsa for added strength.
Glue the front wings in place on the wood dowel, about 2 inches from the front end. Glue to the top side of the dowel. Place a small strip of balsa beneath the edge of each wing where glued to the dowel to lift the outer end of each wing slightly upward to provide for stable flight. If you get more advanced with your model you can work with different size spacers beneath the wings for different angles and other designs. Now glue the rear wings in place just behind the hook on the top of the balsa dowel, and glue the rudder in place standing up and centred on top of the back wings. Allow to dry.
Mount the propeller on the front of the plane. Be sure the rubber band hook is at the top of the assembly.
Connect your rubber band to the propeller hook, and the hook you placed near the back of the plane. The band should be long enough to be slightly slack at rest. Wind up the propeller clockwise to put moderate tension on the rubber band, and gently glide your aeroplane forward as you release the propeller, launching it to fly on its own.