Premier Date: May 12, 2010
Adam and Jamie began by applying force to the middle of a strip of duct tape in order to determine its breaking strength. Finding a result of 67.3 lb, they built up strands from layers of tape and Adam experimented with weaving them together to strengthen the design. They settled on a rope bridge with a 10-layer walkway, two handrails, and two stabilizing rails.
They took the bridge to Mare Island Naval Shipyard, where they could set it up across a 104-foot gap with a 50-foot drop. During test runs to pre-stretch the parts and reduce the tape’s elasticity, they decided to connect the walkway and handrails with struts in hopes of reducing the wobble. A total of 196 rolls of tape were used to build the finished bridge, which was connected to steel frames on opposite ends of the gap. Adam and Jamie both made the crossing successfully, though Jamie had a much harder time keeping his balance due to his fear of heights and/or the stress of Adam’s previous crossing. Jamie commented that the elastic nature of the tape made it a poor choice for building bridges.
Kari tore apart a car’s body and frame with the help of a squad of San Francisco firefighters. Grant and Tory then reassembled it with tape, and the Build Team took it to Naval Air Station Alameda, where they set up an obstacle course on the runway to put as much stress on the car as possible. With Kari driving 40-60 miles per hour, the car held together through 10 laps. Next they did some off-road driving in the rain; the engine stalled after several minutes, but the tape did not fail.
The Build Team hooked a force meter between a car’s rear bumper and a telephone pole, and found that the car could pull with a force of 1300 pounds. Based on the breaking strength data from the bridge testing, they wrapped five rolls of tape around the car and pole to bind the two together. When Grant stepped on the gas, the car stayed in place even as the tires began to smoke, with only one strip of tape breaking.
The Build Team placed two concrete barricades on the Alameda runway and used one roll of tape to make a single thick strand strung between them. Driving at 40 miles per hour, Tory was able to break through easily. For further tests, the team used 100 rolls of tape to make a 3-inch-thick wall, which they hung between the barricades, and towed the car into it while Grant steered remotely. On the first test, a problem with the tow cable caused the car to hit one of the barricades; the tape took a glancing blow, but did not break. The second test ended with one of the wall’s anchor points breaking loose, while the wall itself remained intact. In the third and final test, the car hit the wall dead center and broke through, but not before the tape had stretched nearly 6 feet. Based on the amount of time and material that would be needed to construct a workable car stopper, the team declared the myth busted.