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DIY Magnetohydrodynamic Thruster
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A Homemade
Magnetohydrodynamic Thruster (MHDT)

A Homemade MagnetoHydrodynamic ThrusterBased on the image on the left, it is possible to make a simple MHD thruster, just powerful enough to propel a toy boat.

This type of thruster generates magnetic fields by passing an electric current through a liquid conductor, such as sea water. Using another magnetic field, the liquid can be pushed in a chosen direction, therefore generating thrust. You can easily make one of these devices from household materials and a couple of neodymium magnets. In the diagram below the small arrows represent the intersecting electric and magnetic fields. the large blue arrow represents the flow of water.

Two opposing inner faces of a rectangular plastic tube are covered by metal strips. These are the main electrodes and should have a connection for a battery. Magnets are attached on the outside of the tube so that they are attracting each other, and are at 90° to the electrodes.

The metal strips here are cut from a thin Aluminium sheet, but you can just use foil although it wont last as long. The electrolysis and salt water corrosion soon eats away at the metal, but foil should last just long enough to see it working. The best sort of electrode would possibly be made from carbon. A good power source for this device would be a pulse width modulated supply such as our power pulse modulator. This would allow you to adjust the frequency and width of electical pulses so that you could get the optimum thrust from your design.

To learn how a MagnetoHydroDynamic thruster works, see the Propulsion section.

MagnetoHydrodynamic Thruster In ActionThis setup shows the electrodes closer together than the magnets. The combination of magnets used in this device were not strong enough to move the electrified water with any decent force. At only 1.5V in salty water, large amounts of electrolysis occurs, but the water does generally flow in one direction.

The key to getting the best performance it to have the strongest magnetic field you can get across the gap between the electrodes.

Also make sure the magnets are behind the plastic or insulated somehow. You don't want them shorting out the electric current in the water.

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Questions and Comments on the DIY MagnetoHydroDynamic Thruster

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The information provided here can not be guaranteed as accurate or correct. Always check with an alternate source before following any suggestions made here.
JetManSaturday, 29th April 2006 8:24pm - No.23
Thats cool! I never knew that something with such a complicated name could be so easy to make. To the workshop! I'm gonna make myself a Magnetohydrodynamic thruster propelled boat. :)
 
SpammistMonday, 4th September 2006 9:39am - No.226
OMG I LOVE U GUYS! YOU JUST SOLVED MY HIGH SCHOOL PROJECT! IM GONNA BEAT ALL MY CLASSMATES IN SCHOOL YAY!
 
JohnFriday, 13th April 2007 3:47pm - No.1153
I am thirteen and just wanted to say Thanks for the plans on this i think i am going to make one.
 
JordanTuesday, 22nd May 2007 4:51am - No.1324
Will this propulsion device only work in salt water?
 
RMCyberneticsTuesday, 22nd May 2007 1:23pm - No.1327
It will work in any electrically conductive fluid.
 
MonoMonday, 9th July 2007 2:45am - No.1421
first off, stainless steel is a much better choice for a conductor as is non-corrosive. and secondly, why not take this design a step further and ignite the the Oxy-Hydrogen gas your creating as a by-product of the electrolysis? it could be drawn off and redirected thru stationary thrusters or used to fuel the generator. of course i dont believe the governments of the world are ready to release the truth about water as fuel, but it works.
 
RMCyberneticsMonday, 9th July 2007 9:10am - No.1422
Stainless steel would still be corroded by electrolysis but at a much lower rate than Aluminium. Ignigting the gas could be quite an interesting mod to the design.
 
JimSunday, 28th October 2007 7:44pm - No.2071
Stainless Steel would tend to block the magnetic field from the gap, I think. The electrodes need to be made of a non-magnetic material such as aluminum or copper. Is this not right?
 
ChuckyThursday, 1st November 2007 4:09am - No.2101
Good quality stainless is non-magnetic
 
IMMonday, 31st December 2007 8:13am - No.2381
Hi, I have some 1x1/8" neodymium magnets
I am planning to use for the MHDT. How wide should I make
the tube?

Thanks,
IM
 
RMCyberneticsFriday, 4th January 2008 3:12am - No.2390
I don't know. You should experiment with different dimensions, you will learn more.
 

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