A Design with Teeth (Viewpoint Feature)1 Nov, 2008 By: Eddie Paul
With help from AutoCAD, I built a fully submersible shark.
In my Hollywood career I've worked as a stuntman, stunt driver, special effects coordinator, and custom car fabricator. I've built a lot of weird stuff for movies, including 48 cars for Grease, Mask, Cobra, Miracle Mile, Wild at Heart, The Fast and the Furious, 2 Fast 2 Furious, xXx, Taxi, and about a hundred other movies. I recreated antique flying machines and made miniature submarines and two full-sized mechanical horses that jumped off a bridge in The Mask of Zorro. I built a 7' great barracuda that was used by the television show Rescue 911. Outside Hollywood, I created lightweight portable pumping equipment for fire departments, a backpack biological decontamination unit for soldiers in Iraq, and airborne laser weapon systems for the U.S. Department of Defense.
Despite all that, I believe my 17' great white shark ranks as one of the strangest projects ever. It was not my first shark, but it was one of the most challenging, because this massive metal monster of the sea would carry Jean-Michel Cousteau's son Fabien as its pilot and cargo as he swam with the creatures for the television special Shark: Mind of a Demon.
AutoCAD was the main tool I used on each and every part of the construction of the shark submersible, from design to building and even for the support equipment used for moving and lifting the shark in and out of the water.
It was May 2004. I had roughly one month to design and build the swimming great white, so I sat down at my computer, fired up AutoCAD, and started laying out rough designs, sizes, and placement of the required mechanical inner workings of the shark. By drawing each of the components at full size, I found it easy to move and place my mechanical assets in the most beneficial locations for the best leverage and buoyancy advantages possible. I then calculated the specific gravity of each component, adding it with text to that part in the drawing, then moving it toward the front or rear — fore and aft, if you are so inclined — to help me adjust and keep track of the center of buoyancy of the shark submarine through the entire design phase. Each of these components was absolutely required to make the shark function safely underwater. I had to ensure that each and every one of them was at least somewhat neutrally buoyant, or I would ultimately wind up with a very expensive air mattress — or worse yet, an anchor. Each component also had to be salt-water compatible, or the shark would be reduced to a worthless oxide in no time.
I whipped out a set of drawings and printed them at full size for the many templates that I required and transferred them into plastic or metal, which was cut out and used for the main polycarbonate spine or the many mechanical components to make the shark swim. On this main spine I attached approximately 30 2"-diameter stainless steel tube ribs that had been previously bent to shape and plugged at each end with a set of custom-machined plastic plugs. This plugging made each of the ribs a flotation tank that could make up for some of the unavoidable negative buoyancy. The shark was an equilibrium of positive and negative components being placed at precise points to balance each other. Most of this work was being done on my computer screen using AutoCAD and a spreadsheet program; I used the List command to get the areas for calculations or the area that could then be converted into volumes to calculate the weight of the particular part as it compared with the same volume of water. I could adjust for each part depending on whether it was positive, neutral, or negative in salt water.
The shark's tail was swept through its power stroke by two air cylinders connected from the tail by cables to a scuba tank through a four-way air valve. Fabien simply had to tilt the air-control–valve lever whichever way he wanted the tail to move, and it would respond.
The hollowed-out fiberglass head allowed room for the air cylinder and the bell crank.
We finished the shark on time and within a budget of $200,000 and some tradeout. It was a masterpiece of materials massaged into a real-life, counterfeit shark that fooled even the resident great whites every time it was lowered into the icy seas near Guadalupe Island in Mexico.
Editor's note: "Viewpoint" is an occasional feature that invites guest authors to express opinions about CAD-related topics.
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