>>
    >>      If we plan on making a toothed wheel with inductive pickup
   part of
    >> the design then the flywheel style alternator will need to go
   onto the
    >> opposite end of the shaft. The magnetic field of the alternator
   will
    >> interfere with the timing pickup. It looks like Renesis has the
    >> toothed wheel behind the pulley.
    >>      The DIY wind power generators I have seen are very close
   and are
    >> called "axial flux"
    >>      The coils are turned were they look like a bunch of 'O's making
    >> petals to a flower.
    >>
    >>      The places for the axial flux alternator:
    >>         Prop flange
    >>              prop rpm
    >>              part of the split PSU and still in design phase
    >>              moment is large
    >>         between the planet cage and fly wheel
    >>              engine rpm
    >>              part of the split PSU and still in design phase
    >>              moment is large - ~16"
    >>         Pulley side
    >>              Move toothed wheel to flywheel - minimal moment change
    >>              Could be part of an accessory case design
    >>              moment
    >>
    >> --
    >> Blake C. Lewis
    >>
    >>
    >> What do you do about the eddy currents in the aluminum?  There
   is heat
    >> and resistance to power in this housing.  I ask because I have
   designed
    >> motors with aluminum housings.  A proff of this power is to place a
    >> plate of aluminum on a series of "toothpicks" for bearings or
   "wheels".
    >> Rapidly pass a neodymium magnet over it and the aluminum will
   move.  In
    >> a motor or generator that energy develops heat and drag.  Does this
    >> design address that?
    >>
    >> Rick Irwin
    >
    >
    > Rick,
    >    I haven't designed electric motors before. I am assuming that you
    > are referring to the moving magnets as opposed to a moving stator.
    >    A prop flange design would be a way to minimize this problem,
   being
    > that location has the least amount of stationary metal.
    >    I think that the RevMaster and the Harley radial designs both have
    > aluminum housings.
    >    How significant do you think that the heat and drag is in the
    > efficiency of the alternator over a conventional automotive
   design? Do
    > you think that the loss is more or less than that due to belt loading
    > and friction?
    >
    > --
    > Blake C. Lewis

   The magnetic flux will be contained in the iron cores of the coils.
   Eddy currents in the non-ferrous frame will not be an issue.  With this
   type alternator there may be some efficiency issues with the voltage
   regulator, however.  These alternators are usually paired with a shunt
   type regulator.  With this type regulator the alternator is producing
   near full output all the time.  With a 30 amp alternator that would be
   about 360 watts (about 1/2  horsepower net).  There may also be
   mechanical losses because we will probably need to incorporate a fan in
   the structure somewhere to cool the coils and the voltage regulator will
   need to be located in a cool air stream.  The Compu-Fire system that was
   mentioned last week is unique because the Compu-Fire regulator is a
   series-pass type which would save a little energy when the aircraft
   electrical load was low.

   Aubrey


I believe that modern regulators for pm alternators are all series
pass...   The one that is used on the BandC dynamo is
(http://www.bandspecialties.com).  I have this unit on my O-200 Varieze,
and it works great.  The regulator doesn't seem to get very hot (though
it's only producing 12A).

I think the newer motorcycle dynamos are 3phase..


Matt-


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