Tube Climber


To build a device that will climb inside a vertical plastic tube.

Permitted Materials
  1. 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. The batteries must be carried along with the device as it climbs the tube.
  3. The only parts of the device that are allowed to contact the tube are drive and guide wheels. There is no limit on the number or size of wheels as long as the size limitation (above) is met. The wheels must not scratch or pit the internal surface of the competition tube while in operation.
Testing Procedure
  1. A transparent plastic tube four inches in internal diameter and six feet long will be mounted vertically at the edge of a table. One foot from each end, laser diodes and photo detectors, on opposite sides of the tube, will be mounted to start and stop timing the motion of the climbing device. Contestants will place their climbing device in the first foot of the tube and turn on the battery powered motor. Timing will commence when the first laser beam is broken and stopped when the second laser beam is broken.
  2. Each contestant will be given three attempts. Batteries must be provided by the contestants and may be replaced between tests. The best score (shortest time) of the three will be used as the final score. The three attempts will be scheduled consecutively; however, contestants may opt to delay the third attempt to make minor repairs or adjustments.
  3. In the event of a tie, the second best of the three attempts will be the tie breaker. If none of the entries reach the top, the one climbing the highest will win.
  4. Each contestant may have up to two practice runs in the competition tube during the hour prior to the competition. The practice runs will not be timed and will not count as part of the competition.
  5. To test the device in your own school a section of four inch diameter plastic sewer pipe, available at most hardware stores, will be nearly the same as our transparent tube. Stated tube diameters may vary slightly, so it is important that the device can be adjusted to match different four inch tubes.
Testing Equipment – Timer
College of Saint Benedict
Saint John’s University

Jim Crumley
Chair, Physics Department
SJU PEngl 107
Physics Department