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Date: Tue, 05 Jul 2011 08:39:47 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] generator and dyno prop
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On 07/04/2011 10:51 PM, Ernest Christley wrote:
> I tested the dyno-prop today.  I had been waiting to complete some 
> rework on the Harly-Davidson generator I'm using.  I was trying to 
> pass control back to the pilot by putting a solid-state relay inline 
> with the regulator's output.  The relay appears to have either 
> interfered with the proper operation of the regulator, or caused 
> enough of a voltage drop to make the generator unable to charge the 
> battery.  Either way, the relay is out, and a 80A fusible link is in.  
> I'm now getting 13.5V at 4000rpm.
>
> Which leads me back to the dyno-prop.  I got lazy and didn't cut down 
> the 88mm wide prop I built.  I didn't want to take the time to balance 
> it again.  At 40% throttle, I had the engine up to 4000rpm (1258 at 
> the prop).  That would be 26Hp if the prop was of the correct length.  
> I know I was generating more than that, but I haven't a clue how much 
> more.
>
> OAT was somewhere between 97* and hotter-n-hell.  The logs show the 
> MAT was 103* (measured at the throttle body).  The graph of the 
> coolant temp climbs at a 30 degree angle.  In 50 seconds, I went from 
> 162* to 192*.  That's with a blower stuck into the intake for the 
> single radiator.  Luckily, I think I've reached the point where I can 
> put the cowl on, and start using the second radiator.
>
> -- 
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   
> http://mail.lancaironline.net:81/lists/flyrotary/List.html
>
Hi Earnest,

13.5 V sounds a bit low, unless the regulator is holding voltage 
artificially low. Isn't the HD generator designed for direct drive off 
the HD crank? If so, I'd think that it could make useful voltage & 
current at much lower rpm (think city riding in traffic).

Charlie