By winding a rubber band, it could store enough energy to turn a propeller for a short duration. With a 10 foot model taking the current world record, as you can see in the video below the break ...

The opposite ..nil of the rubber band is ' held in any convenient manner. Naturally the two strips must be wound in opposite directions, so that the two propellers will turn :n opposite directions.

Ever noticed that a rubber band gets warmer when it’s stretched? The bands also get cooler when allowed to snap back to relaxed length? [Ben Krasnow] noticed, and he built a rubber band cooled ...