Indoor model airplanes, the graceful ballerinas of the model aviation world, are craft and hobby, form with function, for those who build and fly them. Indeed, within the dozen or so official classes of airplanes, the variety of styles is astonishing. Some are precision scale models of real planes and some are sculptural creations born of fantasy. None weighs more than a few ounces and some are so light, less than .035 of a gram, that a small hand gesture can destroy them. Each model is a hand-crafted original.
Traditional materials are thin strips of balsa wood and tissue paper.
Newer, high-tech materials such as carbon fibers that are thinner than a strand of hair and transparent film so light that it cannot be touched without damaging it are increasingly popular in ultralight classes. But no matter the beauty of design or accuracy of detail, the real purpose of these planes, like all flying machines, is to stay aloft. To fly as long as they can. Keeping an airplane in the air is the job of its motor. On an indoor model airplane, the motor is a rubber band.