Some of the funnest episodes of MYTHBUSTERS have involved toying with cars. Dropping them off cliffs. Pushing them with rockets into concrete barriers. And blowing them up. In this week’s new episode, “Driven to Destruction,” the MYTHBUSTERS capped our auto experience by testing two amazing myths: Crushing a car with explosives and lifting a car with a single vacuum cleaner.
Sucking It Up
It was Adam Savage’s idea to test the power of a single vacuum cleaner against the weight of a car. He began by simply sticking the end of a vacuum hose against a five-pound weight and trying to lift it, and it worked. Then he scaled up the experiment. Reasoning that it was a question of increasing the surface area to match the increase in weight, Adam built a larger suction cup attaching it to the vacuum hose through a manifold and tested it on a 50-pound weight, and that worked. Once again, it was time to scale up the experiment.
The car Adam wanted to lift weighed 2,600 pounds, so he created 40 suction cups providing 1,500 square inches of suction. He attached the suction cups to a cradle, which were suspended from a crane. The crane would lift the cradle, but it was the vacuum cleaner providing suction through the suction cups that would actually lift the car. Placing cups on the trunk lid, the roof, and the front hood of the car, Jamie Hyneman turned on the vacuum cleaner. Just as it seemed like the car would lift, a couple of the suction cups popped off the car and the car didn’t lift. Adam was bouncing with excitement, but he soon fell limp with disappointment as the suction cups failed. Turns out the sheet metal in the hood didn’t have structural integrity and the hood buckled.
Adam and Jamie realigned the suction cups and tried again, but the cups still didn’t hold. So they replaced the hood with a piece of sheet steel for more structure and tried the experiment again. That lifted the car a full inch before the suction cups released. While the idea of the experiment was to lift the car to the top of the crane, and this failed to do that, it did lift the car off the ground. There was a basis to the idea. The next step was to rethink their “suction cups.”
Instead of using what Adam called an octopus of 40 suction cups, the MYTHBUSTERS crew decided to try three large suction boxes made of Fin plywood, contoured to fit the shape of the car, and using rubber gasket seals on the bottoms. Once again, the boxes were attached to the cradle and connected to the vacuum cleaner with hoses and a manifold. This time, however, they put vacuum gauges on each box to ensure they were getting a suction before they lifted the cradle with the crane. Showing six inches of mercury of pressure, it was time to lift the cradle with the crane, and up it went, the suction of the single vacuum cleaner holding the car to the boxes. With great drama, Adam and Jamie watched as not only did the car lift above the one-inch mark, it went higher, and higher, and higher, as high as the crane could lift.
At the top of the crane, Jamie shut off the power to the vacuum cleaner and the suction let loose, and the car fell to the ground to Adam’s delight. “Like clockwork,” said Jamie. “I love, love, love doing car myths,” said Adam. “But this was my favorite! Next time someone tells you MYTHBUSTERS sucks, tell them, ‘Damn straight!'”
Note: The vacuum cleaner used for the initial scale tests looked like one of those home cyclone models. The model used in the field for the actual car lift looked like a shop wet/dry vac.
- Conclusion: Confirmed
Crushing It
You know Jamie – Jamie wants a boom. Only this time, rather than to simply use explosives to blow something up, Jamie wanted to use explosives to test a myth. And that he did. His idea for a car myth experiment was to flatten a car with explosives.
He began with a scale model test. But scale model cars don’t scale down properly for the materials, so to do the experiment properly, Jamie created his own model combining thin-sheet steel cans and pipes. The MYTHBUSTERS crew took Jamie’s scaled down models to their favorite bomb range in Alameda County and sandwiched it between two steel plates and used a single sheet of deta sheet explosive. The explosion gave Jamie a nice, satisfying boom and flattened the car model to less than an inch, which was one-fifth its original size.
Next, Jamie tried varying the number of sheets of steel above the scaled model, but that not only didn’t flatten the car, it also broke and melted some of the model pieces. To try the model experiment again, they went back to a simpler plate configuration, but tried 50 percent more explosives. And that squashed the car more aggressively, fusing what would have been its engine into the car’s body.
Satisfied that he had an experiment he could scale up to full size, Jamie headed with Adam to the mother of all explosion test sites in New Mexico. Using two massive steel plates – one embedded in the ground and one suspended above – they created a life-sized sandwich around a 1987 Yugo, a decrepit-looking car with a poor reputation, made in Yogoslavia; while it was still working they felt it clearly deserved to be flattened. Because the deta sheet explosive had torn up the scaled-down model, Jamie decided to use 1,000 pounds of ANFO, because it pushes with universal pressure instead of breaking things apart.
Jamie and Adam headed to an underground bunker for safety and then proceeded with the usual MYTHBUSTERS countdown. Five, four, three, two, one… BOOM! “That was very intense,” said an amazed Jamie. “Energetic,” said a shocked Adam. The explosion was so big, it sent the 3,000-pound gantry over 500 feet into the air. And the Yugo? It was gone. Not flattened — gone! The ANFO had punched a hole through the steel plate and blown the Yugo into bits, sending hunks of shrapnel hundreds of feet in every direction, landing one large chunk into a rental car. The shock wave cracked a windshield.
This experiment would clearly require some rethinking. They could have used larger sheets of steel plating, but they would have crushed the car just by their own weight, and that wasn’t the point of the experiment. So the only thing left to do was walk away.
- Conclusion: Busted.
MYTHBUSTERS have made 48 cars go bye-bye since 2002. This episode was one of them. If you missed it, the program repeats Wednesday on the Science Channel at 9:00 p.m. ET (6:00 p.m. PT) and midnight ET (9:00 p.m. PT).