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<body class='hmmessage'>Hi Gray,<BR>
Glad to see you still lurking.<BR>
First, saw that technique to cool the batteries on the moon rover.<BR>
<BR>
Anthony<BR><BR><BR><BR><BR>
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To: nsrca-discussion@lists.nsrca.org<BR>From: gfowler@raytheon.com<BR>Date: Mon, 4 Aug 2008 08:51:48 -0500<BR>Subject: Re: [NSRCA-discussion] Heat Sinks<BR><BR><BR><FONT face=sans-serif size=2>Guys</FONT> <BR><BR><FONT face=sans-serif size=2>Considering that I do not fly E, this may not work, but here is a trick from the missile world where the electronics generate massive heat in a small package (no air cooling at mach 3!!) that must be dissapated.</FONT> <BR><BR><FONT face=sans-serif size=2>Heat sinks work well but rely on intimate contact with the heat source, which can be the actual problem-how to get the battery heat into the sink with the odd shape of the battery packs and the flatness of the aluminum. Since you guys know the operating temperature of the dischaging batteries, choose a wax that melts just below your target temperature. Cast the wax around the battery pack (you need a container or tub-super thin aluminum). Then have the cooling fins-heat sink on top. When the batteries heat up the wax will melt. This phase change will cool the batteries-then the viscous liquid wax will also efficiently transfer the heat to the aluminum tub and the aluminum heat sink. The heat sink will cool the wax which then cool the batteries.</FONT> <BR><BR><FONT face=sans-serif size=2>After recharging, the batteries cool, the wax resolidifies and it is ready to go all over again. Wax is light weight, the aluminum tub-heatsink would need to be custom fabbed and very thin-and basically sealed. Wax can be easily cleaned from the batteries if needed.</FONT> <BR><BR><FONT face=sans-serif size=2>Just a thought<BR></FONT><BR><FONT face=sans-serif size=2><BR><BR><BR>Gray Fowler<BR>Senior Principal Chemical Engineer<BR>Radomes and Specialty Apertures<BR>Technical Staff Composites Engineering<BR>Raytheon</FONT> <BR><BR><BR><BR>
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<TD width="40%"><FONT face=sans-serif size=1><B>"Earl Haury" <ejhaury@comcast.net></B> </FONT><BR><FONT face=sans-serif size=1>Sent by: nsrca-discussion-bounces@lists.nsrca.org</FONT>
<FONT face=sans-serif size=1>08/01/2008 04:15 PM</FONT>
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<DIV align=center><FONT face=sans-serif size=1>Please respond to<BR>General pattern discussion <nsrca-discussion@lists.nsrca.org></FONT></DIV></TR></TBODY></TABLE><BR><BR>
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<DIV align=right><FONT face=sans-serif size=1>To</FONT></DIV>
<TD><FONT face=sans-serif size=1><bob@toprudder.com>, "General pattern discussion" <nsrca-discussion@lists.nsrca.org></FONT>
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<TD><FONT face=sans-serif size=1>Re: [NSRCA-discussion] Heat Sinks</FONT></TR></TBODY></TABLE><BR>
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<TD></TR></TBODY></TABLE><BR></TR></TBODY></TABLE><BR><BR><BR><FONT size=3>Bob</FONT> <BR><FONT size=3> </FONT> <BR><FONT face=Arial size=3>My thought is that packs setting on something thermally conductive rather than insulating seems better. Love your CO2 cartridge idea - wonder if AMA would consider that a "gaseous boost".</FONT> <BR><FONT size=3> </FONT> <BR><FONT face=Arial size=3>Earl</FONT><FONT size=3> </FONT><BR><FONT size=3>----- Original Message ----- </FONT><BR><FONT size=3><B>From:</B> </FONT><A href="mailto:bob@toprudder.com"><FONT color=blue size=3><U>Bob Richards</U></FONT></A><FONT size=3> </FONT><BR><FONT size=3><B>To:</B> </FONT><A href="mailto:nsrca-discussion@lists.nsrca.org"><FONT color=blue size=3><U>General pattern discussion</U></FONT></A><FONT size=3> </FONT><BR><FONT size=3><B>Sent:</B> Friday, August 01, 2008 3:47 PM</FONT> <BR><FONT size=3><B>Subject:</B> Re: [NSRCA-discussion] Heat Sinks</FONT> <BR>
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<TD><FONT size=3>I've been thinking about this, and I think the best way would be sandwich thin pieces of aluminum between the cells and extend past the edge of the pack. But I'm not sure I like the idea of placing anything electrically conductive between the cells. Best to provide an air space between the cells and duct the cooling air between them.</FONT> <BR><FONT size=3> </FONT> <BR><FONT size=3>Of course, if you really want some wow-factor in the setup, you would have a thermostatically controlled cowl flap that only opens up once the pack starts to go beyond the optimum temperature. Maybe even an emergency cooling system - a small CO2 cartridge from an air rifle might do. ;-)<BR><BR>Bob R<BR><BR>--- On <B>Fri, 8/1/08, Jay Marshall <I><lightfoot@sc.rr.com></I></B> wrote:</FONT> <BR>
<FONT face=Arial color=#000080 size=2>The idea of a real heat sink, maybe with the fins as part of the skin of the plane and in the airstream, and the LiPo cell edges bonded to the sink with thermal compound, has some merit and may require some investigation – if cooling is what we really want.</FONT>
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