Make a rail gun into a rail motor?

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Discussion Overview

The discussion revolves around the concept of transforming a rail gun setup into a motor by modifying the configuration of the rails and the armature. Participants explore the feasibility of this idea, comparing it to existing motor technologies and examining the underlying physics involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes modifying a rail gun to create a motor by using hoops instead of straight rails, questioning how the armature would behave as it gains speed.
  • Another participant suggests that the concept resembles how a mag-lev train operates, referencing linear motors.
  • There is a suggestion that the proposed design might be similar to a stepper motor.
  • Another participant argues that the setup could be interpreted as an induction motor.
  • One participant asserts that the proposed motor would not function as intended, explaining that the Lorentz force would not cause the armature to spin due to the unidirectional magnetic field.
  • A later reply clarifies that the design is more akin to a homopolar or Faraday motor, noting the inefficiencies and limitations associated with such a configuration.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and classification of the proposed motor design, with no consensus reached on its viability or effectiveness.

Contextual Notes

Participants mention various types of motors and their operational principles, but there are unresolved questions about the specific mechanics and power requirements of the proposed setup.

Mr 4738
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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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You seem to be describing an induction motor!
 
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.
 
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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