X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wf-out-1314.google.com ([209.85.200.168] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3632316 for flyrotary@lancaironline.net; Tue, 05 May 2009 03:10:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.200.168; envelope-from=bartrim@gmail.com Received: by wf-out-1314.google.com with SMTP id 28so3297470wff.25 for ; Tue, 05 May 2009 00:09:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:subject:from:to:in-reply-to :references:content-type:date:message-id:mime-version:x-mailer; bh=h894Qg9HIQ9yC3bdQMRTZhkjvK80nCRxonqI+TvfDDc=; b=CNHpaE9hcxVLxpy+cibk8rcs/cHbtqJVw4fW2hHrYVNW/T2DBoLsbbr5Ckpeg1Y3mk h8zqPqfAP2w9lerLMe7QkECYR2MBmNAmRMSzbhaT+4fMctGWjPAcHWLzhY/MSrePR1NO qteM6CAj9AfxVRVFtlqn/8ShAWykXE5Gt3znQ= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:in-reply-to:references:content-type:date:message-id :mime-version:x-mailer; b=oaLyky2zM8jP1Q5LTbrOV1yaAcRSR8M4aESh7vHAS21YjIgWmj3tn+eYphdXe7BwDb 0Lnf7lYQuKZioaPZQYQ7AdFlNgguTMKN8VOPMq75ApICfqVbx3Etaz48YU3d0ya3HP4F T4VMjFbY/x0XcKtbZAd5rm1LmtWCHhJ5Arc+0= Received: by 10.142.239.11 with SMTP id m11mr2450109wfh.120.1241507366341; Tue, 05 May 2009 00:09:26 -0700 (PDT) Return-Path: Received: from ?192.168.1.64? (d154-5-222-193.bchsia.telus.net [154.5.222.193]) by mx.google.com with ESMTPS id 30sm3547204wfd.1.2009.05.05.00.09.15 (version=SSLv3 cipher=RC4-MD5); Tue, 05 May 2009 00:09:23 -0700 (PDT) Subject: Re: [FlyRotary] Re: Harley Davidson Generator From: Todd Bartrim To: Rotary motors in aircraft In-Reply-To: References: Content-Type: multipart/alternative; boundary="=-AyIiPXiT8WRAfjqokV3b" Date: Tue, 05 May 2009 00:07:41 -0700 Message-Id: <1241507261.9116.3.camel@Endurance> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 --=-AyIiPXiT8WRAfjqokV3b Content-Type: text/plain Content-Transfer-Encoding: 7bit Thanks for the youtube link Bob; That was interesting. It's quite unlikely that I'd reach anywhere near 300F, so it should be fine. Todd C-FSTB On Mon, 2009-05-04 at 07:46 -0600, Bob White wrote: > You are looking for Curie temperature. For Neodymium magnets, they > start loosing strength at around 300F and the curie temperature is 590F > (according to a web site). > http://www.matchrockets.com/ether/magfaqs.html > > Here is an interesting YouTube video of the phenomenon. > http://www.youtube.com/watch?v=X8ZHQQUusGo > > Bob W. > > On Mon, 4 May 2009 19:40:21 +1000 > "George Lendich" wrote: > > > Todd, > > The heat actually affects the rare earth magnets, a search on the internet should confirm this. I just can't remember the details. I guess the glue is another matter. > > George (down under) > > Hi Ernest; > > From Georges comment, I gather that the heat sensitivity would likely be due to the glue that bonds the magnets to the inside of the rotor. This makes sense and also means that I shouldn't have much of an issue if no air blows under the rotor and onto the stator. Air movement around the rotor should be enough. > > I really am a lot less satisfied with "should" than I used to be. > > > > Todd > > C-FSTB > > > > > > > > On Sun, 2009-05-03 at 21:01 -0400, Ernest Christley wrote: > > Todd Bartrim wrote: > > > I'm thinking about the cooling issue that you are addressing with fan > > > blades. How much heat do you think it will generate? I'm > > > thinking/hoping not much. I don't know about the original Harley > > > install, but as this is commonly used source of power, I got to > > > looking at my Ski-Doo, ATV and dirt bike. In everyone of them the > > > stator/rotor is completely sealed up and is not liquid or oil cooled. > > > And I've never had issues with them. It would be a simple matter for > > > me to put a small baffle at the exit of one of the evap cores that I > > > use for cooling and direct some of the air over the rotor, but due to > > > the tight fit, not much air would find it's way under to the stator. > > I don't know what sort of heat load it'll generate, but it is almost > > immaterial to my installation. For me, he intake air will be flowing > > over it regardless. I've been told that PM alternators are only 50% > > efficient. I find that hard to believe; that would be a 500W heat > > source for a 40A generator. But even at that worst case, it isn't an > > issue for me. > > > > > > --=-AyIiPXiT8WRAfjqokV3b Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: 7bit Thanks for the youtube link Bob;
    That was interesting. It's quite unlikely that I'd reach anywhere near 300F, so it should be fine.

Todd       
C-FSTB

On Mon, 2009-05-04 at 07:46 -0600, Bob White wrote: 
You are looking for Curie temperature.  For Neodymium magnets, they
start loosing strength at around 300F and the curie temperature is 590F
(according to a web site).
http://www.matchrockets.com/ether/magfaqs.html

Here is an interesting YouTube video of the phenomenon.
http://www.youtube.com/watch?v=X8ZHQQUusGo

Bob W.

On Mon, 4 May 2009 19:40:21 +1000
"George Lendich" <lendich@aanet.com.au> wrote:

> Todd,
> The heat actually affects the rare earth magnets, a search on the internet should confirm this. I just can't remember the details. I guess the glue is another matter.
> George (down under)
>   Hi Ernest;
>       From Georges comment, I gather that the heat sensitivity would likely be due to the glue that bonds the magnets to the inside of the rotor. This makes sense and also means that I shouldn't have much of an issue if no air blows under the rotor and onto the stator. Air movement around the rotor should be enough.
>        I really am a lot less satisfied with "should" than I used to be.
> 
>   Todd
>   C-FSTB
> 
>        
> 
>   On Sun, 2009-05-03 at 21:01 -0400, Ernest Christley wrote: 
> Todd Bartrim wrote:
> > I'm thinking about the cooling issue that you are addressing with fan 
> > blades. How much heat do you think it will generate? I'm 
> > thinking/hoping not much. I don't know about the original Harley 
> > install, but as this is commonly used source of power, I got to 
> > looking at my Ski-Doo, ATV and dirt bike. In everyone of them the 
> > stator/rotor is completely sealed up and is not liquid or oil cooled. 
> > And I've never had issues with them. It would be a simple matter for 
> > me to put a small baffle at the exit of one of the evap cores that I 
> > use for cooling and direct some of the air over the rotor, but due to 
> > the tight fit, not much air would find it's way under to the stator.
> I don't know what sort of heat load it'll generate, but it is almost 
> immaterial to my installation.  For me, he intake air will be flowing 
> over it regardless.  I've been told that PM alternators are only 50% 
> efficient.  I find that hard to believe;  that would be a 500W heat 
> source for a 40A generator.  But even at that worst case, it isn't an 
> issue for me.
> 
>
--=-AyIiPXiT8WRAfjqokV3b--