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Episode 90: Supersized Myths

  • Supersized Shark
    • Sharks attracted to low frequency noise: busted
    • Sharks afraid of dolphins: plausible
  • Supersized Jet Taxi: This time, with an actual 747, the Jet Taxi Myth was confirmed
  • Supersized Cruise Water Ski: You can wakeboard behind a cruise ship confirmed
  • Supersized Rocket Car (Jet Car JATO Revisit): appropriately supersized (aka, the car blew up)

This episode was a sort of return-to-the-early-days sort of affair, but adding better budget and addressing past failures. The got to return to their pilot episode (Jet Car JATO), Scottie Chapman made a brief return as builder, Adam was given another opportunity to get seasick, and Jamie found himself in the water with sharks once more.

Supersized Shark

See also: Jaws Special

Jamie and Adam shipped their gear to False Bay, South Africa (near Cape Town), where they hired African Shark Eco Charters to take them out into waters infested with great white sharks. Seal Island, located just 5.7 km off the coast, is home to innumerable seals. The huge seal population also attracts the great whites. On an initial site-seeing trip, Adam and Jamie got to see first-hand how many: Jamie couldn't even finish his explanation before a seal decoy they dropped in the water was hit by a great white breaching out of the water. They lured the sharks closer using tuna heads and Jamie went for a closer look inside the shark cage. He got quite a show as a shark got a full nose into the cage and knocked things around. Meanwhile, Adam didn't take enough ginger pills and spent much of the trip seasick.

Adam: "South Africa has been pretty crazy to us so far. We did see an air attack, Jamie almost got eaten, I threw up -- Now we are able to start our tests."

Supersized Shark Myth 1: Sharks attracted to noises

Myth: Sharks are attracted to low-frequency noises (40hz) that sound like an animal thrashing around

The theory is that the great white sharks detect the low frequency noises using lateral lines that run along the length of their body. Jamie supposed that there was some credence to this theory, given that the operators of their shark cruise rap on the side of the boat to attract the great whites.

Jamie once again went in the water along with an underwater speaker system that first blasted the MythBusters theme song to the surrounding sea life.

Jamie (to Adam): "If you're gonna be sick, can you be sick on the other side of the boat, over"

With Jamie in the water, they tried three tests: * 40hz hum for 10 minutes: no sign of sharks * 0-40hz sweep: presuming that 40hz was too precise, they swept the sound from 0-40hz. Still no sign of sharks. * High frequency: they went in the other direction, blasting a high pitched noise instead. A single shark appeared

Not knowing if Jamie was a factor in the sharks (not) appearing, they pulled Jamie out of the water and repeated the same series of tests. This time, no sharks appeared at all.


Supersized Shark Myth 2: Sharks are afraid of dolphins

Myth: Sharks are afraid of dolphins

Marine biologists speculated that dolphins are intelligent enough to be capable of altruistic acts, such as rescuing animals of other species from shark attacks. They MythBusters researchers dug up two incidents from 2004 that seemed to confirm this myth. In New Zealand, lifeguards training on a beach reported a great white appearing on the beach and then swimming away when a dolphin swam up. Similarly, in Australia, a fisherman capsized and was stranded for two days. Great whites approached but were repelled by a dolphin.

Jamie and Adam constructed a foam, animatronic dolphin after studying the swimming motion of Merlin the dolphin at Discovery Kingdom. Adam cut out a dolphin model from a block of upholstery foam. He used a printout of a 3D dolphin model they found online as a guide. Meanwhile, Jamie worked on generating the dolphin tail motion that they figured was crucial to fooling the sharks. He connected an electric drill to an off-centered crank to create the undulations. Bike chain was used as a mechanical spine. When the drill was turned on, the entire rig flapped up and down like a dolphin.

Down in South Africa, they conducted a series of tests to see if the animatronic dolphin was a shark deterrent: * Seal decoy: the seal decoy was hit by a shark within five seconds of being dropped in the water * Seal decoy + animatronic dolphin: the dolphin and seal decoys cruised along the water close together. A great white fin broke the surface between the fake dolphin and seal, but no bite. * Tuna heads + animatronic dolphin: They upped the ante by throwing a tuna head into the water. As a shark approached the tuna head, they pulled the dolphin over -- the shark swam away. They repeated the test again with the same result. * Tuna heads: With the fake dolphin out of the water, the great white went to town on the tuna heads.

The sharks may not have been 'afraid' of the dolphins, but they did seem to be deterred.


Supersized Jet Taxi

Myth: A taxi driver in Rio de Janeiro drove 100ft behind a 747 and was blown over (not actually a myth, as this incident was confirmed)

Previously: Jet Taxi

Jamie and Adam had tried this mythbusting before but were unable to obtain a 747 engine to test with. 747 engines can each generate 54000 lbs of thrust. With a smaller engine they could only push the taxi backwards. In the meantime, the British Show Top Gear one-upped the MythBusters by obtaining a 747 and flipping a car. The MythBusters were not to be outdone, so the build team got access to a Kalitta Air 747 and set to flipping a taxi, bus, and small airplane.

They first stuck Buster in the driver seat of a taxi. The taxi was towed along a line 100 ft behind the 747. As it entered the jet stream, the hood was torn off and the entire cab quickly went airborne, rolling several times before stopping.

Next, they stuck Buster in a bus donated to them by the Oscoda School District. After removing oil and squirrels, they also towed it along a line 100 ft behind the 747. Just like the taxi, the bus went flying into the air and rolled several times.

Their final test was with a small two-seater plane, aka "MythBust Air," that had a missing engine. Afraid of parts flying off the plane, they added 20 ft to the distance, instead pulling it along a line 120 ft behind the 747. The small plane shell was easily flipped over and pushed along the grass. It didn't seem to suffer as much damage as the bus or taxi, whether it was due to the extra distance, aerodynamics, or luck, who knows.


Supersized Rocket Car

The MythBusters at long last have come full circle: the JATO myth, aka MythBusters pilot episode.

Small-scale tests

Adam created multiple scale model vacuum-form molds of the Impala by using a CNC mill to carve out a foam model. They replicated the same rocket structure (roof mounted) and thrust that they used in the pilot episode, at scale, even taking into account the 55/45 front/back balance of the 3700 lb Impala.

With their first tests, which used F-motor rockets, the car flew off the side of the ramp instead of going over. They made two adjustments, switching to K-motors, which have 10x the thrust, as well as remounting the rockets in the trunk instead of on the roof. The car flew flew off the ramp and flipped before landing, then came apart as it spun around in circles.

Full-scale launch

Jamie sold the original Impala, so they went shopping and found a new one named 'Holly.' Based on their scale-model testing, they outfitted it with two steel tubes, one on top of the other, in the trunk along the center-line. 600lbs of weight was added to the front of the car to preserve the weight balance. They contracted with a professional rocket fuel firm to make the ammonium perchlorate rockets, which have a 450 degrees ignition temperature. Their rocket expert projected that they could fly 20 miles in a straight trajectory.

They setup their test in the desert with the Impala rigged to be towed towards a launch ramp by a pickup truck. Scottie Chapman made a temporary return as a MythBuster to create the ramp and drive the pickup. She sliced two shipping containers in half diagonally to form the launch surface. Fiber board was laid across to form the ramp surface. With several test runs and surgical tubing on the steering wheel, Adam was able to dial in the Impala to hit the ramp straight on.

Adam: "It's headed towards the ramp.... or not"

Instead of taking off, the car exploded on ignition. The explosion was brilliant, but the results were not as their effort blew up in their faces.


Jamie: "Well, let's reset"
Adam: "I think someone owes me 10,000 bucks"
Jamie: "Rocket car sucked when it blew up"

appropriately supersized

Supersized Cruise Water Ski

Myth: You can wakeboard behind a cruise ship

The build team setup for this myth by having Tory practice for the stunt with two smaller boats. He was pulled up to speed by one boat and then attempted to transfer to a line trailing behind a second boat. He failed on two out of his first three tries, as the rope was a bit difficult to see in the whitewash.

For the real stunt, they used the 2000-ton Regal Empress, piloted by Capt. Stavros Kontas. 300 ft of brightly colored tow rope was set behind the ship as it cruised along at 14 knots. A crowd of on-lookers watched from the cruise ship deck as Tory got 'over-excited' on the first run and fell down. His second attempt went perfectly and he wake-boarded behind the supersized ship.