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Air Cylinder of Death. In the Jaws Special, the Exploding Scuba Tank segment proved that a scuba tank doesn't really explode so much as they take off like a rocket. So what happens if you purposely shear the valve off of such a tank? Can you make a rocket out of one that will go through a brick wall? There's only one way to find out.

As Myth-tern Jess greases up the rails, Adam and Jamie build a device to knock the valve off the tank. The only problem is that when they drop it, it doesn't work. It only dislodges it. So instead of a rocket, they get a big whoosh of air. Back to the drawing board. After adding some more weight to the guillotine and some grease to make it slide better, another try proves more successful than could be imagined. The tank goes through the temporary wall built for testing and then puts a crack in the building wall six feet beyond. Confirmed.

Since there was so much power in the tank, Adam and Jamie decide to rig up a rocket-powered speed boat with a couple of full-size cylinders to see what happens. Unfortunately, the answer is "not much". The first run produces a top speed of only 5 knots or so, and Jamie only travels about 100 feet. After rethinking their design, they lower the nozzles into the water and try again, and the speed drops even further, as does the distance. Oh well.

Black Gun Powder Engine. Grant, Kari and Tory are tasked with the glamorous job of making an engine that runs on black powder. It is well known that black powder contains more energy than gasoline, so it seems like a reasonable idea. But no one else has managed to get it to happen, so perhaps there is more to this idea than it seems. The build team finds three famous minds that had plans for black powder engines and will test each one to see if they can produce a result.

First up, a design from Christiaan Huygens, who lived in the 17th century. This engine is one of the earliest (perhaps the earliest that involved a piston, like those we have today in automobile engines. So it seems like a sound idea. The problem in assembling it is that even with today's tools, it is impossible to get a vacuum, and without a vacuum, the compression doesn't work right. Busted.

The next engine is a similar design, but instead of the piston model, it's a simpler method from Sir George Cayley in the 18th century. His engine had a piston-like design, but did not require the vacuum. Even better, his engine had a reloading mechanism - something lacking in the first design, and essential for continued operation. Once it's set up, however, the design doesn't seem capable of actually getting a second load of black powder into the chamber. The action is just too violent. Busted.

The third design comes from Thomas Payne, who lived in the late 18th and early 19th century. His design is along the lines of a water wheel, and rather than being an internal combustion engine, it is more of an external combustion model - a step backwards, but if it works, perhaps it will do the trick. This model uses scoops attached to a wheel that will catch the force of powder fired at it. As the wheel turns, it catches the next blast, and so forth. However, as with the prior model, the machine can't reload - and to make matters worse, the wheel doesn't turn anyway. Tory makes a modification to try and get things to work and only manages to make the whole thing backfire and burn the entire payload. Busted.

Finally, Grant builds an air injection system to use on a lawnmower engine, and using a drill to start the engine, attempts to feed the mixture directly into a standard gasoline engine. No go. The black powder turns into a nasty gunk which won't ignite. After draining out all the oil, they try again, but still it won't ignite. In a last, desperate attempt, they load some black powder directly into the engine, and get it to fire - but it won't keep running. Busted.