Premier Date: January 30, 2016
In the workshop, Jamie constructed several rough car models by welding together steel cans and piping. These models more accurately reflected the scaled-down thickness of actual body panels than commercial model cars. At a bomb range, Jamie and Adam placed a model on the ground, sandwiched between two steel plates, with a layer of “detasheet” explosive above the top plate to drive it downward. The explosion crushed the model to a height of approximately 1 inch (2.5 cm), or 1/5 of its original height. Further testing with different configurations of plates and explosives often tore the models to pieces. A repeat of the first test with 50% more explosive gave the best result, so this configuration was used in the full-scale test.
Next, a real car was placed on a steel plate, with a second steel plate suspended directly above it. This plate weighed 7,000 pounds (3,200 kg) and was loaded with 1,000 pounds (450 kg) of ANFO. The resulting explosion effectively vaporized the car and threw pieces of the steel gantry 500 feet (150 m) into the air. Adam and Jamie discovered that the blast had punched through the upper plate, generating shrapnel that destroyed the car. They called the myth busted, with Jamie commenting that a steel plate thick enough to withstand the blast would be heavy enough to crush the car simply by being dropped on it.
Adam and Jamie found that a vacuum cleaner with a standard attachment could only lift a 5-pound (2.3 kg) weight, but that its lifting power increased linearly with the cross-sectional area of the attachment. Adam built a suction cup 8 inches (20 cm) in diameter and they used it to easily lift a 50-pound (23 kg) weight. Based on this success, they built 40 such cups, all connected to a single vacuum via a manifold, and hung them from a steel frame that would be lifted by a crane.
On Treasure Island, the suction cups were placed on the hood, roof, and trunk of a 2,800-pound (1,300 kg) car. The first series of lifts looked promising but failed when excessive buckling of the hood caused some of the cups to pop loose. After they replaced the hood with a flat piece of sheet steel to eliminate the buckling, they were able to lift the car only 1 inch (2.5 cm) off the ground before it fell.
Back in the shop, they decided to replace the suction cups with three large plywood boxes, each one contoured to match the car’s surface and fitted with a rubber gasket for a tight seal. The three boxes had a combined area of 4,000 square inches (2.6 m2) and vacuum gauges recorded a vacuum pressure of 6 inches of mercury (20 kPa) for each box when the vacuum cleaner was running. Using this method, the car remained attached while being lifted to the crane’s maximum height, confirming the myth. Adam and Jamie then shut off the vacuum and the car crashed to the ground.
Premier Date: January 23, 2016
Each of the following myths was based on a viral video.
Jamie chose an air cannon to propel the shrimp and built a pneumatic sprayer for the eggs, while Adam designed nozzles to launch and disperse the flour and bread crumbs. The final element was a device that generated a burst of flame to expose the shrimp to a temperature of 500 °F (260 °C). They set up all of the equipment as an assembly-line in an airplane hangar. The first several shrimp they launched disintegrated while leaving the cannon barrel, but fitting them into a paper cup (similar to a sabot on an artillery projectile) allowed them to travel downrange intact.
Once the aim was adjusted to hit the target consistently, they measured a flight time of 392 milliseconds and adjusted the timing on each component in the line. Eventually the shrimp went through each element on time, but at the end none were properly coated or cooked. Next, they replaced the flame rig with a 3 foot (0.9 m) long sword forge running at 2,100 °F (1,150 °C) and fired a fully-prepared shrimp directly through it, but found that its temperature still had not increased significantly. The same result occurred with a 12-foot (3.7 m) long forge, prompting them to declare the myth busted as the shrimp simply did not have enough time to absorb the heat needed for cooking.
Adam and Jamie built a blast-proof tank and filled it with water. They then positioned a shrink-wrapped tomato and a blasting cap near each other in the tank. After they set it off, Jamie was able to insert a straw in the undamaged skin and suck out a mouthful of juice, while Adam was unable to draw any from an intact tomato. They repeated this test several times and found that they could get more juice by moving the blasting cap closer to the tomato, and the tomato skin did not break until the blasting cap was positioned very close. Adam and Jamie ran a tomato through an industrial juicer at the shop and obtained a 62% juice yield based on its original weight. They measured a 33% yield upon draining the juice out of one of the tomatoes from their tests.
To investigate the use of larger amounts of explosive, they set up a new trial at a quarry pond, placing 20 pounds (9.1 kg) of TNT underwater at a depth of 10 feet (3.0 m). They then placed mesh bags containing one each of tomatoes, oranges, cucumbers, and pineapples at various distances from the explosives. After the explosion, they discovered that the surviving samples were either ruptured or tenderized, but they were not able to obtain any juice. They deemed the myth plausible based on the small-scale tests, and Jamie hypothesized that the use of the small tank allowed the shock wave from the explosion to reflect back and forth from the walls, repeatedly striking the tomato and more effectively juicing it.
Premier Date: January 16, 2016
For a demonstration, Adam added a small amount of boiling water to a 1 gallon (3.8 L) metal can, screwed on the cap. As he allowed it to cool, the can slowly buckled. Adam and Jamie then repeated the test with a 55 gallon (210 L) drum; after a tense wait of more than 20 minutes, the container’s side walls suddenly collapsed. They performed a third test, fitting the drum with a vacuum gauge and temperature sensor, and recorded a time to failure of 8 minutes, a peak vacuum of 16 inches of mercury (54 kPa), and a temperature drop from 195 °F (91 °C) to 170 °F (77 °C). When another drum was steam-cleaned to heat it to 203 °F (95 °C), it took 16 minutes to fail; the peak vacuum was 17.5 inches of mercury (59 kPa), and the buckling was more pronounced. Adam and Jamie then built a small-scale tank car out of four drums welded together, and reproduced a similar implosion.
The full-scale tests began at a railroad depot in Boardman, Oregon. They set up a decommissioned tank car measuring 67 feet (20 m) in length and 10 feet (3.0 m) in diameter and with 0.5 inch (13 mm) steel walls, making it the largest prop ever used on MythBusters. After Adam inspected the interior to verify that it was in good condition, they sealed the release valves and attached a vacuum gauge and temperature sensors. The car was steam-cleaned for 3 hours, reaching 209 °F (98 °C), after which the steam was shut off, the hatch was sealed, and a fire hose began to spray water over the car to simulate rain and more quickly cool the car. The vacuum readings peaked at 27 inches of mercury (91 kPa) as the car cooled to 100 °F (38 °C), but no collapse had occurred after 60 minutes and they ended the test at that point.
Theorizing that internal damage or corrosion could make collapse more likely, Adam and Jamie obtained a second, older car. For this test, they used an industrial vacuum pump to achieve the same negative pressures, but much more quickly. Again, the car remained intact after 60 minutes, so they ended the test and vented it to the atmosphere. Finally, to investigate the effect of physical damage, they dropped a 3,200 pound (1,500 kg) concrete block onto the tank car from a height of 30 feet (9.1 m), resulting in a significant dent. When the pressure was pumped down again, the car collapsed at 23 inches of mercury (78 kPa). Adam and Jamie declared the myth-as-stated busted, but noted that it could happen if the tank car is already badly damaged.