Tube Climber Objective: To build a device that will climb inside a vertical plastic tube. Permitted Materials 1. A battery powered electric motor (one or two AA cells). 2. Parts may be used from commercial objects (toys, models, etc.) but the frame holding the device together must be constructed, not purchased whole. There are no limitations on the types of materials used in the construction of the device. Other Constraints 1. No energy sources other than the AA batteries may be used. 2. The device must fit completely in a tube 10 inches long with a 4-inch internal diameter. 3. The device may not scratch or pit the internal surface of the competition tube while in operation. Here is what I've come up with so far, but I think that they are to complicated, also I'm not sure the 3rd would be allowed because the spring needed to hold the wheels on the side of the tube would have stored energy. Hopefully these drawings are clear. This would have wheels perpendicular to the view point helping to keep it upright int he tube. I like the idea of using rubber tank tracks but have not designed anything yet. I'd like to hear your thoughts, and flaws. If you guys could help me makes these designs (or your own) more simple (lighter) I'd appreciate it.