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Make a rail gun into a rail motor?

  1. Jan 11, 2010 #1
    I've been thinking about an idea for a while now... what if you take a rail gun set up and instead of shooting something you turn it into a motor. Just make the rails into hoops that almost touch and connect the armature to a point in the center of this. I'm wondering how armature (now a rotor) will react once it picks up speed. Will it go faster and faster because of the speed it gained from its previous revolutions?

    I don't know too much about how much power needs to go into these to produce a useful magnetic field... can anyone elaborate?
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  3. Jan 11, 2010 #2


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  4. Jan 11, 2010 #3
  5. Jan 12, 2010 #4


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    You seem to be describing an induction motor!
  6. Jan 12, 2010 #5
    A rail gun is a motor, albeit a linear one. As for the setup you describe in your post, I don't believe it would work if I'm interpreting it correctly. My knowledge of rail guns is limited but as I understand it, a current flows through the rails and the armature forming a magnetic field, and a Lorentz force accelerates the armature along the rails.

    In the setup you describe, the Lorentz force on both sides of the rotational axis on the armature would push in the same direction due to the magnetic field inside the rails being unidirectional, therefore it would not spin. Instead, the Lorentz force would try to accelerate the armature along the rails as with a normal rail gun setup, but of course it wouldn't move due to it being attached in the middle.

    Excuse me if my terminology is wrong, English is not my first language.
  7. Jan 13, 2010 #6
    This is not a linear motor, maglev, stepper motor, or induction motor. It is closest to a homopolar motor or Faraday motor, and operates at very low voltages and very high currents. The high current causes high resistance losses in the motor and power supply and a lot of wear on the brushes, while there are few advantages...it is not particularly useful as a motor.
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