[NSRCA-discussion] Heat Sinks

Mon Aug 4 08:44:41 AKDT 2008

Work expands as the time to completion approaches.  I am "finishing"  
an airplane to fly tomorrow and it's amazing how many of the "little"  
tasks leap out as I seem to get close to done.

Ron VP

On Aug 4, 2008, at 10:03 AM, AtwoodDon at aol.com wrote:

> As in most projects, when you are 99% done, you only have 25% left  
> to do.  That is how most projects in my work environment went.  I  
> always told the project managers that when they reported their  
> project status and I was usually right.  If I was wrong, they had  
> more than 25% left to go.....
>
> Don
>
>
>
> In a message dated 8/4/2008 7:30:18 A.M. Pacific Daylight Time,  
> gfowler at raytheon.com writes:
>
> Anthony
>
> My new plane is 99.5% complete-all I have to do is balance and  
> align the wings-and then "re-learn" to fly. My kid just completed  
> the massive soccer "qualifying" tournament-6 games, two weekends,  
> nothing below 103F, so I am conditioned to start flying again.
>
>
>
>
> Gray Fowler
> Senior Principal Chemical Engineer
> Radomes and Specialty Apertures
> Technical Staff Composites Engineering
> Raytheon
>
>
> Anthony Romano <anthonyr105 at hotmail.com>
> Sent by: nsrca-discussion-bounces at lists.nsrca.org
> 08/04/2008 09:17 AM
> Please respond to
> General pattern discussion <nsrca-discussion at lists.nsrca.org>
>
>
> To
> General pattern discussion <nsrca-discussion at lists.nsrca.org>
> cc
> Subject
> Re: [NSRCA-discussion] Heat Sinks
>
>
>
>
>
> Hi Gray,
> Glad to see you still lurking.
> First, saw that technique to cool the batteries on the moon rover.
>
> Anthony
>
>
>
>
>
> To: nsrca-discussion at lists.nsrca.org
> From: gfowler at raytheon.com
> Date: Mon, 4 Aug 2008 08:51:48 -0500
> Subject: Re: [NSRCA-discussion] Heat Sinks
>
>
> Guys
>
> 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.
>
> 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.
>
> 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.
>
> Just a thought
>
>
>
>
> Gray Fowler
> Senior Principal Chemical Engineer
> Radomes and Specialty Apertures
> Technical Staff Composites Engineering
> Raytheon
>
>
> "Earl Haury" <ejhaury at comcast.net>
> Sent by: nsrca-discussion-bounces at lists.nsrca.org 08/01/2008 04:15 PM
> Please respond to
> General pattern discussion <nsrca-discussion at lists.nsrca.org>
>
>
> To
> <bob at toprudder.com>, "General pattern discussion" <nsrca- 
> discussion at lists.nsrca.org>
> cc
> Subject
> Re: [NSRCA-discussion] Heat Sinks
>
>
>
>
>
>
>
> Bob
>
> 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".
>
> Earl
> ----- Original Message -----
> From: Bob Richards
> To: General pattern discussion
> Sent: Friday, August 01, 2008 3:47 PM
> Subject: Re: [NSRCA-discussion] Heat Sinks
> 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.
>
> 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. ;-)
>
> Bob R
>
> --- On Fri, 8/1/08, Jay Marshall <lightfoot at sc.rr.com> wrote:
> 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.
>
>
>
>
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