Even if the revmaster alternator (dynamo) won't work as it sits, this
design seems very easy to copy.  The RPM issue is not a real concern
since the magnets are the only part of the assembly that's exposed to
high rpm load.  If one were really concerned about reliability, an
alternator like this could be constructed at each end of the engine,
or two nested on one end, probably even driving by a single set of
magnets..

I suspect that the alternator magnetic pickups are divided into two sets
just like the CDI energy coils. I know that GAMI was working on an
engine electrical system that electronically combined the output of two
alternators to provide redundancy(*); there's no reason that RevMaster
couldn't have copied that concept.

Whoever talks to RevMaster about this beast please ask about that.

Russell Kent

(*) On the theory that solid state circuits are orders of magnitude more
reliable than mechanical drive line parts.

---------------------------------------------------------

Just talked to Joe and he said the coils are in two groups of five. Two
separate alternators with rectifiers. 30 amps total. He feels it might go to 7000 RPM
but he will sell just the magnets and stator coils and we can do our own
carbon reinforced flywheel. He has the magnets cast for that radius.
He also says the neodymium magnets saturate at 4500 to 5000 RPM but there is no real
problem running it higher. You can reduce the saturation by moving the coils
radially inward if necessary.

"Neodymium magnets offer the best value when comparing performance, size and cost.
They are moderate in price, very strong magnetically, and typically allow for dimensional reductions. They have poor resistance to corrosion and should have a coating or
plating applied. Consideration should be given to the grade of alloy when exposing
Neodymium magnets to temperatures above ambient room. Neodymium Iron Boron has good
resistance to external demagnetization fields because of its high Intrinsic Coercive
Force (Hci) . This resistance makes Neodymium magnets an excellent choice for
electromechanical applications."

Paul Lamar ...No rotor no motor.

That unit looks great.

The magnets saturate or the coils saturate?  My electro-understanding says it's the coils.  At any rate that can be taken care of if we are designing for an rpm limit of 8000-8500.  It's probably not be an issue for a 6000 rpm cruise.  Did he say what the design normal operating rpm is for this unit?  What is the diameter of the magnet ring?

It's a great looking unit.  If we rolled our own and gave up the CDI coils it could be mounted on the prop flange with a little compromise to the airplane's C.G.  The redundant ignition is a nice idea though.  Could provide a limp home mode of some sort.

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2

(sorry 'bout that I was behind on my email)  Got the dimensions and
the rest of the story from a previous post.


Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2


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