[femm] Re: Hi! (re: magnetic launcher)

["David Meeker" <dcm3c@xxxxxxx>]

b00r1s2-@xxxxxxx wrote: 
original article:http://www.egroups.com/group/femm/?start=59
> To whom this may concern,
> I am a freshman High School student, and i am doing a science
project 
> on electromagnets and coils. I am designing a shooting device that
will 
> propel a large payload into orbit. Im writing this letter to see if
you could 
> give me any hints our help on this topic. Thank you for your time.
> 
> Wayne Willyard

It's funny that you should mention this. I have recently been working
in this area. Look into a NASA a program that they call ``Maglifter''.
The idea is to magnetically levitate and propel a rocket up to about
mach 1, eliminating the need for the first (and biggest) stage in the
rocket that propels the payload the rest of the way into orbit. This
will (hopefully) reducing the cost of getting stuff into orbit.

NASA has awarded several contracts to make small, ``proof of concept''
machines, each of which works using a slightly different approach. 
There is a machine built by the University of Sussex (i.e. the late Dr.
Laithwaite) that uses currents induced on the vehicle by stationary
coils to both levitate and propel the vehicle. A US company, PRT
Advanced Maglev, is somehow involved in with this machine as well. I
think that this machine has recently turned up at NASA Marshall in
Huntsville, AL. Check out pictures of the machine at:
http://www1.msfc.nasa.gov/NEWSROOM/news/photos/1998/photos98-190.htm
http://www1.msfc.nasa.gov/NEWSROOM/news/photos/1999/photos99-260.htm


Dr. Post et. al at Livermore Labs have been looking into mounting
arrays of permanent magnets on a rocket sled. The permanent magnets
are driven as a synchronous motor. Lift is created by the magnets
passing over a type of null-flux coil that provides lift while
minimizing magnetic drag.
http://www.popularmechanics.com/popmech/sci/9805STTRM.html
http://www.llnl.gov/str/Post.html

A third machine has been built by Foster-Miller in Waltham, MA. This
machine is propelled by sort of a linear brushless DC motor and
levitated using null flux coils. This test rig brings an approx. 12 lb
vehicle to about 55 mph at the end of a 20' drive section. This scale
model machine uses permanent magnets mounted on the vehicle, but a
larger sized model would use superconducting coils instead of permanent
magnets

Dave.
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