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Date: Tue, 22 Feb 2005 16:28:59 -0600
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: 2nd battery Re: Amps required to run engine&amp-
 hours available
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Ernest Christley wrote:

> Bobby J. Hughes wrote:
>
>> Found the picture. The catalog seems to be missing.
>> http://www.racemate.com/home.htm
>>
>>
>>  
>>
> There that's better.  The claim that it won't overvoltage is 
> absolutely false.  In the bottom of the picture on the right.  That is 
> the regulator.  It works by dumping excess energy to ground.  It looks 
> like a heat sink, because it IS a heat sink.  If that thing burns out 
> and you rev high enough that the rest of your system can burn off what 
> the generator puts out, you're in an overvoltage situation.
>
> The specs claim 1/3rd Hp to drive it.  That is about 18A at 13.5V.  
> I'll make a big assumption here and assume that they rated that at 
> 5500RPM, the same number they used to compare the pump flows at the 
> bottom of the spec page.  Using this on the end of the crankshaft 
> would be a simple matter of bolting the coil pack to the front housing 
> and the bolting the 'can' that carries the magnets to the end of the 
> shaft.  Many motorcycles use this exact same setup, and you can buy 
> some of those packages for about $100.  I looked at and rejected 
> those, because 18A isn't enough for a replacement; though it will do 
> as a backup.
>
> Harley Davidson makes a similar setup for their Goldwing bikes that is 
> 35A.  That is the one I want to look at.

I'm one of the early speculators/hopefuls about whether the crank angle 
sensor shaft/gear could handle the torque of a small alternator 
supplying just engine electrical power. The eshaft is obviously a safer 
route if no one can do the sensor shaft calcs with confidence.

18 amps should be plenty to run the engine stuff. Start using ship's 
power & switch to the crank mounted alt. automatically (as someone else 
mentioned) as rpm comes up. Use the a/c electrical system (which backs 
up itself at low current demand levels) as backup for the engine's 
power. Now it's triple redundant.

The eshaft thing should be do-able with the little Kubota PM alternators 
if you can rig a little 3 legged support in front of the eshaft pulley & 
bolt a flex coupler to the front of the pulley to drive the alt. shaft.

There's also a crank mounted alt. sold by one of the VW conversion 
houses. I posted a link to it several months ago; I'll try to find it 
again if anyone's interested.

The ideal way to control it would be a switching regulator instead of 
the linear shunt that seems to be common, but I doubt there's an 
off-the-shelf model that would handle the rather wide input voltage 
swing (probably <12v to >60v)  give 14v out.

Charlie