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Q & A: Maglev track design

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Most recent answer: 10/22/2007
Q:
Hi-I’m intrested in making a mini-maglev train. I would like to know how i could do this and what would be the best way to shape the tracks. You i make them into a "V" shape so the train sits in the middle and levitates, or should i make a track that is a "T" shape and the train shaped like a hat for the "T" so the train doesn’t go too high or low.Example of each track: "V": /--\ <-------Train \\ /====\ // \\________// <-- Track "T": The "- | =" are the trainThe "**" are the track /========------------ || ****** || -- ** -- ** ** Thank you for your time.
- Steve Denham (age 17)
Winter Park, FL, USA
A:
Hi Steve,

Good luck making the mini-maglev train! Making a
practical magnetically levitated transportation vehicle
would help fuel economy and speed passengers to their destinations.
The design criteria to worry about for a real transportation
system (not all of these are necessary for making a gee-whiz
model, however) are (and I may be missing a few along the way):


1) It has to be safe. This means it has to be stable, easy to
control (start, stop, hard to derail).

2) It has to have low friction. A magnetically levitated
vehicle should not mechanically touch anything.

3) It should tolerate weather and random conditions.
Leaves and sticks that fall on the track should not
stop the train! So if your train hovers a fraction
of an inch over the track, that might not be good enough.

4) It should be economical
a) It shouldn't cost too much to build.
b) It shouldn't cost too much to operate.
(that is, it shouldn't take huge amounts of electrical
power, and thousands of miles of cryogenic equipment
might be expensive!)

Hard to judge: 5) People shouldn't be afraid of it.
I saw a proposal where the vehicle hangs below the track.
People with a fear of heights may be afraid to ride in such things.


Now it turns out that variants of your "V" and "T"-shaped proposals
exist and are being prototyped today. There is a proposal for
building a maglev train from Baltimore, MD to Washington,
DC, using a German "T" design:
.
This design is complicated because the support magnets are under
the rail and attract each other. This situation is unstable,
as you can convince yourself by experimenting with a few small
permanent magnets. The magnets want to stick together and do not
like to hover, balancing gravity out. This problem is solved by
installng electronic feedback mechanisms in the train. The train
contains sensors to detect how far the support magnets are apart,
and applies the necessary adjustments in the electrical current
to compensate for any deviations found. You also need guidance
magnets on the sides of your "T" with similar feedback to keep
the train from sliding to the side, and to keep it on the track
in a turn.


An alternative design is based on repulsive magnets
and uses superconducting materials to achieve the stability. The
has some description and lots of pictures, but I found
more readable.
It describes both your "V" and "T" designs. Here is a newer
idea of how to make maglev track
called "inductrack" which uses permanent magnets on the train
and coils in the track. So, the short answers are: Both
designs will work, but both will cost quit a lot of money
to build. You can work to improve the designs so they better
fulfill the requirements above. If you can do a good job of
that, try entering your design in
.
There's a link on the web site to find kits even!


Good luck!


Tom

(published on 10/22/2007)

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