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"  Don&amp;#039;t underestimate 20,000 pounds of pure bite force, especially when it comes from an 8-foot wide, 8000-pound set of steel shark jaws. MythBuster Grant Imahara did, and he took an unexpected flight because of it.  It&amp;#039;s June 11, and we&amp;#039;re on hand to watch the MythBusters filming &amp;quot;Sharkzilla,&amp;quot; a Discovery Channel special that will air next week during the 25th anniversary of Shark Week. On this particular afternoon, Imahara and fellow MythBusters Tory Belleci and Kari Byron are on the beach in Ventura, Calif., messing around with a 52-foot-long mechanical shark and its choppers. &amp;quot;Imagine the back end of a dump truck, except it has shark teeth,&amp;quot; Belleci says. &amp;quot;Basically a giant crushing, destroying machine\u2026 in the shape of a shark. It&amp;#039;s awesome.&amp;quot;  The shark in question, lying on a platform above the beach, is a robotic version of the megalodon, a prehistoric behemouth that grew to more than 50 feet in length\u2014almost three times bigger than a great white. The MythBusters built it to solve a curious incident nicknamed the &amp;quot;Miocene Crime Scene,&amp;quot; discovered by Sean and Lisa Tohill, owners of Shark Tooth Hill in Bakersfield. The Tohills found a near-perfect baleen whale fossil with a huge missing piece: its head. In its place was a bevy of megalodon teeth. So the question is simple: Could this unfathomably big prehistoric predator, nicknamed Sharkzilla, actually have bitten the head clean off a whale?  &amp;quot;We&amp;#039;ve done Shark Week a couple of times in the past but trying to find new shark myths is difficult,&amp;quot; Belleci says. &amp;quot;So to have this integration where we can come back and be a part of Shark Week, especially on the 25th anniversary, is such an honor.&amp;quot;  Over the course of this sunny California afternoon, the producers have lined up a number of increasingly challenging obstacles for this huge mechanical Sharkzilla to chomp through, leading up to its final test: a 10-foot-long by 4-foot-wide blue cylinder filled with different types of foam and intended to closely resemble a hunk of whale. First up, though, is a simple rectangular piece of foam designed to see how many square feet Sharkzilla can bite at once (30, it turns out). The MythBusters help lift the foam into the robot&amp;#039;s enormous steel jaws and hold it in place as the jaws slowly clench down. The 20,000 pounds of force generated sends Imahara flying off the platform, down to the beach 4 feet below. He&amp;#039;s okay, but everyone, including the crowd that&amp;#039;s gathered around, knows that Sharkzilla is not to be taken lightly. Next up is a series of wood constructs. For each test, the Mythbusters vary the number of vertical shafts supporting the horizontal ones, increasing bite forces in increments of 5000 pounds. Sharkzilla easily crushes the 10,000- and 15,000-pound constructions, and even crunches through the 20,000 pound one. But the grand finale was yet to come.      How to Build a Megalodon Recreating an enormous ancient animal is no easy feat, especially when all that remains of megalodon after millions of years are its teeth. A team from the engineering house Technifex, lead by Jim Sharits, created the life-size working model currently obliterating things on the beach. &amp;quot;It&amp;#039;s a prehistoric creature and that means it&amp;#039;s a prehistoric scale,&amp;quot; Imahara told PM. &amp;quot;It&amp;#039;s pretty far outside of what we would normally build on our show.&amp;quot;  The Technifex team began with a nearly 1-foot-long tooth found earlier this year near the Miocene Crime Scene at Shark Tooth Hill. They recruited scientists, including Chuck Ciampaglio from Wright State University, to help extrapolate from that evidence and create a creature that&amp;#039;s as accurate as possible. The dimensions they came up with were big enough to fit an average man inside: jaws about 8 feet wide and 6 feet tall. It&amp;#039;s not just size; the correct motions matter, too. &amp;quot;It&amp;#039;s not just a straightforward chomp, chomp, chomp,&amp;quot; Imahara says. &amp;quot;They really tried to get it technically accurate to what the researchers think the actual megalodon jaw looks like.&amp;quot;  The keyword being think. &amp;quot;There&amp;#039;s nothing existing out there that really tells us what the megalodon jaws were because there is nothing intact\u2014they were made out of cartilage,&amp;quot; Sharits says. &amp;quot;The closest analog, if you will, is the great white because it&amp;#039;s very similar in structure. At least in theory.&amp;quot; So his team upscaled a great white jaw to megalodon size and went to a foundry. Using a sand-cast system similar to a teeth mold, they hoped they could create the intricate jaw structure in two casts. It took thirteen. When it was done, they poured a steel alloy into the molds to create the two huge pieces of jaw, and endured a similar process for the 92 teeth. Next, Technifex had to make sure the jaws could generate the necessary force without snapping. After a month of research and a week of engineering, the team built a main pivot shaft stretching from each corner of the mouth linked to two hydraulic rams with a 4-inch bore and a 2-inch shaft. &amp;quot;With a 4-inch bore, the area of the piston and the amount of fluid behind it gives you the increased pressure,&amp;quot; Sharits says. &amp;quot;Two thousand psi of hydraulic fluid pressure go to the lines, and that&amp;#039;s delivered into the two hydraulic rams and the larger bore. That much area in the pistons is delivering exponentially more power.&amp;quot; Back to the beach and the mystery at hand. After Sharkzilla bites through the 20,000-pound wood construct, the team lifts the huge whale mockup onto the stage and places it between the jaws. Slowly, Sharkzilla begins to bite down\u2014until, a few inches in, everything stops. Can mechanical megalodon do it? Or will the miocene murder go unsolved? Tune into &amp;quot;Sharkzilla&amp;quot; to find out. It airs Aug. 13 at 9 pm Eastern on Discovery Channel. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/science/a8041/how-it-works-the-mythbusters-mechanical-sharkzilla-11479532/>