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Date: Sun, 05 Dec 2004 19:03:06 -0600
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: gear drive for distributor and oil metering pump
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Ernest Christley wrote:

> David Carter wrote:
>
>> Wonder if "we" could come up with an alternator to drop into that hole -
>> some back-up "juice" for our "electrically dependent engines".
>>
>> David
>>
>
> That is exactly what I've been thinking, David.  Steve stopped by to 
> look at my project last week, and we were discussing it. Thanks to Mr. 
> Leonard over there, I now know what to look for.
>
> I need to find a 2/3HP or 500W or 30Amp generator/DC PM motor.  It'll 
> be 3" or 4" in diameter, with a couple inches of shaft sticking out.  
> I'm thinking it would be easy enough to key the shaft to fit as a 
> direct replacement for the metering pump.
>
> I don't have the numbers with me, but I was doodling with them a while 
> back.  I figured something like a couple of in.lb. of torque on the 
> worm gear to produce 500W at 6000RPM.  I now know the gear would turn 
> at half that, so it is still less that 5in.lb. on the gear.  The 
> upshot is that 3000RPM motors are much more abundant that 6000RPM motors.
>
> I'm trying to source a part.  I'm also thinking that a standard 
> alternator can be made to fit by cutting down the housing.
>
Try your John Deere dealer. I know 20A versions are available, & I think 
that there's a 30A version as well. They are also found on Yanmar (sp?) 
tractors. The 20A one is not much bigger than the Mazda crank angle sensor.

I've been asking about using that shaft for an alt. drive for a while 
but this is the 1st interest I've seen from others. I like the idea of 
using it to run the engine electronics independently with the aircraft 
electrical system as backup.

The questions are: will the shaft take the load, & will the alt. make 
enough current at cruise to supply the engine's needs?

Charlie