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Windell writes - "After trying out our simple demonstration of magnetohydrodynamic (MHD) propulsion, you might want to make something a little more "practical." Here's how to build a simple little boat that moves through salt water (at a snail's pace) via MHD propulsion.
The craft is not designed for performance; it's designed to demonstrate a functional MHD craft with made with inexpensive, easily available materials. While it may move slowly, hey, it moves, and you can make it in about five minutes. " - Link.
A review of the simple design shows that you might use a bit of silicone sealant to hold the electrodes in place and insulate the outsides of the coins for better effect.
In fact, there are a lot of efficiency gains that can be experimented with, including magnet size, shape, and placement, different metals for electrodes (the coins), and experimenting with different voltage and amperage circuits.
I suppose you could add a solar panel and use rechargeable batteries or a newer ultracapcitor to make it self-sustaining.
I also think the magnet could be moved (rotated) for steering. Conceptually, it should change course, but I don't know how well it would work in practice.
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I agree completely; there is a lot of room for gains in efficiency. Sealing the outsides of the electrodes would be a good start. =)
The reason that I went with a 9 V was that it was easy to connect to and something that people are likely to have laying around. I'm afraid that I don't know many other good ways to hook up a battery for high-current usage without soldering, a battery box, or requiring specialized batteries. The big disadvantage is that the energy capacity of a 9V is pretty small, they drain very quickly.
For steering, I think that a good way would be to put two of these drive units side by side and control it like a tank. It might work particulary well because occasionally reversing the current would help to remove oxide build-up on the electrodes, keeping the current high. I might do it that way for my next RC MHD boat.
-Windell.
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Using multiple drives like tanks do is certainly the most effective and practicle solution, but I suspect that you could alter the properties of the megnetic interaction to create a torsion effect like turning a rudder.
The point to my post was that thier is lots of opportunity to experiement with this basic design as a science fair entry. I think the basic design concept is outstanding - it would have never occured to me that one could create a MHD drive so simply. Thanks for the contribution!
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now all we have to do is attach one to a typhoon class submarine.
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