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<DIV>I've had a chance to fly Dean's set-up recently and battery/motor temps were relatively low....on the order of 105-110F, which is just warm to touch. Weather was moderate at around 60F, but I've witnessed the model flown in 90F heat with a just a slight increase in powerplant temp. Folks inclined to run electrics would do well to study Dean's photo in an earlier email. This is definitely a good way to do it, is lightweight and balsa sheet is cheap.</DIV>
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<DIV>MattK</DIV>
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<DIV>In a message dated 12/18/2006 8:09:53 PM Eastern Standard Time, bob@toprudder.com writes:</DIV>
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<DIV>Dean,</DIV>
<DIV> </DIV>
<DIV>I was thinking that proper ducting would be a lot easier than trying to engineer a way to force the air through the spinner.</DIV>
<DIV> </DIV>
<DIV>KISS.</DIV>
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<DIV>Bob R.</DIV>
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<DIV><BR><B><I>Dean Pappas <d.pappas@kodeos.com></I></B> wrote:</DIV>
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<DIV><SPAN class=822123515-18122006>Hi Jim,</SPAN></DIV>
<DIV><SPAN class=822123515-18122006>I have fiddled with this a fair bit, and the setup I am using now produces very modest temperature rises on the AXI.</SPAN></DIV>
<DIV><SPAN class=822123515-18122006>I see less than 15C rise after a P-07 with 84 A W.O.T. current draw at the beginning of the flight. After the flight, static W.O.T is more like 75 or 76 A.</SPAN></DIV>
<DIV><SPAN class=822123515-18122006></SPAN> </DIV>
<DIV><SPAN class=822123515-18122006>The inlets total up to just about 1 square inch, which is ducted straight to an airbox that surrounds the front of the motor. The inlet airbox is about 5/8" deep from front to back, and has plenty of volume, just because it needs to evvelop the front of the motor and the cowl inlets. The airbox has a hole through wich the motor can passes, and the hole is extended with a sleeve that runs back to near the aft end of the rotating part of the motor.</SPAN></DIV>
<DIV><SPAN class=822123515-18122006>The wrapped balsa sleeve has maybe 1/8" clearance around the motor. The high pressure air in the inlet airbox is forced to either flow closely over the outside of the motor or through the holes in the motor. </SPAN></DIV>
<DIV><SPAN class=822123515-18122006>For motors such as the Pletty, where the prop drive does not stand proud of the front of the motor can, a drive extender washer maybe 1/2" long will improve cooling by providing some volume inside the inlet airbox, and allowing the air to "turn" to flow along the motor axis. This is actually important.</SPAN></DIV>
<DIV><SPAN class=822123515-18122006></SPAN> </DIV>
<DIV><SPAN class=822123515-18122006>The warm air then dumps into the aft end of the motor compartment, which is segregated from the rest of the cooling pathg to the batteries.</SPAN></DIV>
<DIV><SPAN class=822123515-18122006>An separate outlet gets rid of this air. In my case, it is simply a hole in the bottom of the "scale" cowl of the Funtana. Ideally, the aft end of the cheeks that everybody seems to be putting into their designs would be an ideal low pressure-high velocity outlet, but everybody belnds them into the fuse instead of leaving a back end exit like the Pylon guys.</SPAN></DIV>
<DIV><SPAN class=822123515-18122006>You could just have the motor sleeve dump into the fuse above the batteries, but rear-facing exhaust stacks or a fake turbo-prop exhaust would look cool and be functional. I'll try to post some low-res pictures on the list.</SPAN></DIV>
<DIV><SPAN class=822123515-18122006></SPAN> </DIV>
<DIV><SPAN class=822123515-18122006>later,</SPAN></DIV>
<DIV><SPAN class=822123515-18122006>Dean</SPAN></DIV>
<DIV><SPAN class=822123515-18122006></SPAN> </DIV>
<DIV> </DIV>
<DIV><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT face="Times New Roman">Kodeos Communications</FONT> <BR><FONT face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT face="Times New Roman">d.pappas@kodeos.com</FONT> </DIV>
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<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma>-----Original Message-----<BR><B>From:</B> nsrca-discussion-bounces@lists.nsrca.org [mailto:nsrca-discussion-bounces@lists.nsrca.org]<B>On Behalf Of </B>J.Oddino<BR><B>Sent:</B> Friday, December 15, 2006 7:13 PM<BR><B>To:</B> NSRCA Mailing List<BR><B>Subject:</B> [NSRCA-discussion] Cooling outrunners<BR><BR></FONT></DIV>
<DIV>It would seem the best way to cool outrunners that have holes in the case on the end that faces the nose ring, would be to bring air in through the spinner and through holes in the backplate. Wondering if anyone has really thought about the optimum design. I can picture internal vanes but perhaps cutting off the nose of the spinner and leaving a big hole would be adequate. Anyone tried anything like this?</DIV>
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<DIV>Jim O</DIV></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></DIV>
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