<br><font size=2 face="sans-serif">Guys</font>
<br>
<br><font size=2 face="sans-serif">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 size=2 face="sans-serif">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 size=2 face="sans-serif">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 size=2 face="sans-serif">Just a thought<br>
</font>
<br><font size=2 face="sans-serif"><br>
<br>
<br>
Gray Fowler<br>
Senior Principal Chemical Engineer<br>
Radomes and Specialty Apertures<br>
Technical Staff Composites Engineering<br>
Raytheon</font>
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<td width=40%><font size=1 face="sans-serif"><b>"Earl Haury"
<ejhaury@comcast.net></b> </font>
<br><font size=1 face="sans-serif">Sent by: nsrca-discussion-bounces@lists.nsrca.org</font>
<p><font size=1 face="sans-serif">08/01/2008 04:15 PM</font>
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<div align=center><font size=1 face="sans-serif">Please respond to<br>
General pattern discussion <nsrca-discussion@lists.nsrca.org></font></div></table>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif"><bob@toprudder.com>, "General
pattern discussion" <nsrca-discussion@lists.nsrca.org></font>
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<div align=right><font size=1 face="sans-serif">cc</font></div>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: [NSRCA-discussion] Heat Sinks</font></table>
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<br><font size=3>Bob</font>
<br><font size=3> </font>
<br><font size=3 face="Arial">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 size=3 face="Arial">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 size=3 color=blue><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 size=3 color=blue><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>
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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>
<p><font size=2 color=#000080 face="Arial">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>
<p><font size=3 face="Times New Roman"> </font>
<p><font size=3> </font></table>
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