Some of you are old enough to remember a pre-30 Rock Alec Baldwin trying to wrangle Sean Connery's rogue Russian submarine captain and his top-secret magnetohydrodynamic propulsion system in The Hunt for Red October. The system doesn't exist, in reality, but you can make a teacup version of it, using some basic materials. Bring the Red October home.
Top image: ~Precons on Deviant Art
The other day we covered the homopolar motor, a way to make a simple electric motor with just a few pieces of wire, a magnet, a battery, and a screw. Now it's time to get high tech — with a teacup and some salt. The reason this is high tech is, it was fictionalized in The Hunt for Red October, a spy film in which the Red October is a Typhoon-class submarine commanded by a defecting Russian. Played by Sean Connery, he tries to signal to the CIA agent played by Alec Baldwin that he's willing to come in peacefully. He's a prize not only for his own knowledge, but because he brings with him the sub's top secret 'caterpillar drive,' a magnetohydrodynamic system. It can run silently, as you're about to see.
The caterpillar engine is quiet because the only thing that moves is the water. So how do you recreate this marvel? First grab a teacup, one of the handle-less ceramic white ones often found in Chinese restaurants. Put some water in it, and salt the water. Then pour in some pepper to make the motion of the water visible. Set the tea cup on top of the disk magnet. Grab thick pieces of wire (thin ones will heat up and burn you) and press them to either side of the battery. Lower them into the water. You'll see the water churn and spin between the wires.
This is the same thing that happened in the homopolar engine. Electrons traveling through a magnetic field feel a push at right angles to both the magnetic field and the direction of their travel. Since the electrons are traveling between the two wires, they're traveling horizontally. The magnetic field lines are vertical. And so the water is pushed forward and backward. The entire thing churns the water like a propeller — and it does so silently, without any machinery.
The Typhoon class submarines did and do exist, but their drivers weren't magnetohydrodynamic engines. Although caterpillar drives are used in submarine prototypes, no one has found a way to make them practical for widespread use. No wonder the Red October was so valuable.
Top Image: Department of Defense
Via Evil Mad Scientist.