Topic: Series on Magnetism by Eric Laithwaite

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- 09/07/20 @ 1:21am EDT #102049 test
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  boris8826 Reply to Author,
  boris79@nym.hush.com
  
  The Imperial College of London published a series of video lectures by the late Professor Eric Laithwaite. There are several lectures on there, all uploaded to YouTube around 2015. The lectures were recorded between late 60s and early 80s.
  
  Eric Laithwaite invented a motor that is not in the shape of a cylinder but in the shape of a planar track. In a series of lectures he explains, using visual props and apparatuses, how he arrived at his motor. He shows the process of the scientific method, of inductive reasoning in action. He shows avenues taken that did not lead anywhere. Moreover, his explanations are so simple that they can be understood by a child. Each lecture is arranged in a logical progression, with every minute of it rich in content.
  
  An amazing thing he has discovered is that if there is an alternating current flowing through an electromagnet, then the presence of a piece of aluminium beside it generates a new phenomenon. He calls that new thing a “moving magnetic flux.”
  
  The magnetic levitation trains in Japan are built according to his discovery and invention. Relying on the magnetic aspects means that no electricity is flowing where a human can accidentally touch something and get electrocuted. The current is only flowing in electromagnets, not in something that’s exposed to touch. Each wire is insulated, and the whole thing is further insulated by being placed in a box.
  
  With a guiding rail, one can propel a car without any mechanical action! Nothing is rubbing, there are no wheels on the ground, there’s no loss to friction. I predict that we will see many more engineering applications of his discoveries. Moreover, I have a hunch that more discoveries are waiting to be made by tinkering with magnetism.
  
  Here is the link to the 1968 lecture: https://www.youtube.com/watch?v=0tJfqMYHaQw
  
  /sb
- 09/08/20 @ 11:53pm EDT #132443 test
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  Harry Binswanger Reply to Author,
  hb@alum.mit.edu
  
  Re: Boris Reitman’s post 102049 of 9/7/20
  
  Is this any different from the idea which was not new in the 60s of a “coil gun” or of a “rail gun”?
  
  I had the idea (which I highly doubt was original) in about ’62 of a train floated above a track that would, as it traveled, switch off the electromagnet behind it and turn on the one ahead of it, so that it always experienced the pull of the magnetic field. It’s like the above except the coil is continuous and the train carries two armatures, one in front and one behind to switch on or off parts of that coil.
  
  *sb
- 09/09/20 @ 2:07am EDT #132448 test
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  boris8826 Reply to Author,
  boris79@nym.hush.com
  
  Re: Harry Binswanger’s post 132443 of 9/8/20
  
  In one of those lectures, Eric Laithwaite discussed this design, right before switching to the one that he preferred. He didn’t give a reason. I think that the reason is that such design for the train would be more costly to produce because the magnet must encircle all of the train, for the whole track. So the whole track must be a tunnel. (Otherwise the train, running at 300 miles per hour, won’t be stable.)
  
  It turns out that when Laithwaite was tasked to solve this issue, there was already a solution for the magnetic trains that was built and deployed: the train saddled an aluminum guide rail, and propelled itself magnetically along it. However, while that solution looked good on paper, it failed in practice. The model assumed that a long aluminum guide could be produced as one piece. In practice, the miles-long guide was built from sections, and that created a weak point at the connections. At high speeds, there was a shearing force that broke the connections and could lead to a catastrophe.
  
  Laithwaite then looked for a design that would keep the magnetic drive, but didn’t have such downsides. He solved it by putting the guide rail under the train. He discovered, partly by chance, a magnetic solution that would levitate the train above the track, propel the train, and also hold it stably within the track.
  
  /sb
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