<WOB> re: Electric Supercharger

[Knute Ream <knute@xxxxxxxxx>]

Chris Bourk wrote:
>I'm REALLY interested in knowing where you got a 12 volt electric motor
>capable of pulling 30 amps coupled to a fan that connects via copper wires
>WITH electronic controllers that  weights less than 1 lb.  PLEASE,  tell us...

Well, though I don't necessarily agree with the concept of an electric
supercharger, I do have such a motor sitting on my kitchen table.  The
current state of the art is brushless motors (turned inside out so that the
fixed magnet is on the spinning armature, and the electronics are on the
outside; no brushes means less friction, and no arcing when pushed to
phenomenal currents)  Anyway:  the Astroflight .05 brushless motor
(intended for ducted fans) that I am today splicing into my
radio-controlled electric helicopter (Ikarus ECO-8) weighs 4.5oz total
weight _including controller and wiring harness_ and draws up to 300W of
power at 12V with an output efficiency of up to 92%.  That means that even
under full load, it's still only warm to the touch and requires no
heatsinks...  (Traditional DC motors are considered very efficient at any
number above about 60%, a number that measures how much energy is dumped in
the form of heat instead of mechanical work)

I don't know the backpressure numbers on the ducted fan applications of
these types of motors, but a 4" diam ducted fan (WeMoTec or equivalent)
will generate a couple of pounds of static pressure at an exhaust velocity
of 170mph on the bench.

There are bigger ones that the one I'm using, such as the Aveox units, that
supply more power at similar efficiency, up to 1000W or so, and are still
on the shy side of 1 lb.

You asked!

- -Knute

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