<br><font size=2 face="sans-serif">Richard</font>
<br>
<br><font size=2 face="sans-serif">In the world of batteries, modelers
aint nuthin'-especially pattern dudes. In the military, battery applications
are critical, but any application like we use them, that is 60 amps for
8 minutes is a short term disposable application best handled by a chemical-thermal
battery. Military drives such battery technology and it probably is what
the pattern flyers are gloming off of, but the batteries croak simply cuz
they are pushed too hard. If the military or anyone else IS driving the
technology, do you not think that the battery suppliers would pass on such
info as your cool down/heat discharge process to keep pattern dudes from
frying their expensive batteries?</font>
<br>
<br><font size=2 face="sans-serif">My point is that this technology will
not be ready for the average pattern flyer for quite some time(5 years)
if ever.</font>
<br>
<br><font size=2 face="sans-serif">Good luck, it is good to hear honesty
about these batteries. Most people flying them dodge life cycle questions
-"all so new-dont know yet" which reminds me of a Rodney Dangerfield
joke.......</font>
<br>
<br><font size=2 face="sans-serif">I grew up in a tough neighborhood.......a
guy came up to me and my friends once and asked us "how long does
it take to get to the subway from here" our response was...."dont
know....no one's ever made it yet".-tough neighborhood.</font>
<br><font size=2 face="sans-serif"><br>
<br>
<br>
Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</font>
<br>
<br>
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<td width=40%><font size=1 face="sans-serif"><b>"Richard Strickland"
<richard.s@allied-callaway.com></b> </font>
<br><font size=1 face="sans-serif">Sent by: discussion-request@nsrca.org</font>
<p><font size=1 face="sans-serif">11/18/2005 11:58 AM</font>
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<div align=center><font size=1 face="sans-serif">Please respond to<br>
discussion@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"><discussion@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: Discussion List (Batteries)</font></table>
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<br><font size=2 face="Arial">Gray, Dean,</font>
<br><font size=3> </font>
<br><font size=2 face="Arial">While my experience wasn't the greatest--it
really wasn't all that bad once we had the bugs worked out. BTW,
it was a Hacker system like Jason's.</font>
<br><font size=2 face="Arial">One of the issues was to determine how cool
the batteries needed to be before putting them back on charge; another
was to make sure you were not over or under charging. Another was
to make sure they were balanced. But for me it came down to weight
and longevity. Contrary to where your information is coming from,
my understanding is that modeling IS driving this battery segment along
with the military. I'm reasonably confident there will be significant
breakthroughs like that nano-tech unit(Toshiba or some other heavy-hitter
like that) posted earlier this year that will impact the market fairly
shortly. The 3200s were under-sized, but 4000s would be also. The
motors would peak out at 67-69 amps on application of full throttle and
back down to the 63-65 range. This system worked well, but we were
too close to the edge to lose any capacity and complete an FAI flight.
Temps started with a 40-50 degree rise when we started using them
in the upper 70s and 80s and the same and a little more as ambient got
warmer. They got too hot. We also tend to fly out.</font>
<br><font size=3> </font>
<br><font size=2 face="Arial">Realistically, if to get decent mileage out
of these things and have to stay close to 10C; then you've got to have
at least 6000s+ and keep the weight down. I know zip about batteries,
except how to design conveyor systems for them, but they almost need to
act like a capacitor--very high charge, discharge rates, and unlimited
cycles with no damage. I can't imagine there aren't MANY folks working
on that concept.</font>
<br><font size=3> </font>
<br><font size=2 face="Arial">Of course there are other alternatives--lighter
and/or smaller airframes, different motor, ESC, prop combinations--but
if you want unlimited vertical with 11 lbs--then your're going to draw
55-70 amps.</font>
<br><font size=3> </font>
<br><font size=2 face="Arial">Richard</font>
<br><font size=3>----- Original Message ----- </font>
<br><font size=3><b>From:</b> </font><a href=mailto:gfowler@raytheon.com><font size=3 color=blue><u>Gray
E Fowler</u></font></a><font size=3> </font>
<br><font size=3><b>To:</b> </font><a href=mailto:discussion@nsrca.org><font size=3 color=blue><u>discussion@nsrca.org</u></font></a><font size=3>
</font>
<br><font size=3><b>Sent:</b> Friday, November 18, 2005 10:57 AM</font>
<br><font size=3><b>Subject:</b> Re: Discussion List (Batteries)</font>
<br>
<br><font size=2 face="sans-serif"><br>
Richard</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
I am not a battery expert, but like everyone else on the list that does
not stop me from having an opinion about batteries.</font><font size=3>
</font><font size=2 face="sans-serif"><br>
First, electric airplanes do not exactly drive the battery market,......even
if 50% of the FAI finalists use them. No other applications <br>
that I am aware of uses these batteries in the manner that we attempt,
which is that massive current draw. What electric planes do <br>
to batteries is damaging, as demonstrated by your 25 flights. </font><font size=3>
</font><font size=2 face="sans-serif"><br>
I would not expect the battery market to develop a battery capable of long
life and extreme current draw since no one else uses <br>
batteries in such a manner.</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
Invest in bottle of Windex, clean the oil. </font><font size=3><br>
<br>
<br>
</font><font size=2><tt><br>
In fairness to the manufacturers, I don't think they really understood
that<br>
guys potentially would go out and fly 50+ flights per week. When
I finally<br>
got all my infrastructure charging act together and made time to<br>
practice--which wasn't all that much, I still was clicking along at a 35<br>
flight/week pace right up to our first contest in mid June. As you
may<br>
recall, I was using 20C 3200s on a shared cost beta program. At 11
lbs.,<br>
the airplanes were gobbling up 63-68 amps at times and significantly heated<br>
the batteries and shortened their lives. The manufacturer came out
with<br>
some 15C 4000s--but there was still the problem of amp draw and heat. The<br>
consensus at that point is the batteries aren't very happy at much over
10C.<br>
The problem I had/have is anything over the smaller batteries was going
to<br>
blow the weight limit--plus, as more information was coming out from some
of<br>
the top guys that they were getting around 50-60 flights on the larger<br>
packs. Since I'm not a top dog, I would pretty much have to foot
the entire<br>
bill to switch to the larger units. As it appeared to me--the batteries<br>
just aren't quite up to the task for the average guy--so I made an interim<br>
decision to go back to IC for the rest of the season--hoping the battery<br>
guys would come up with something more acceptable for '06.<br>
<br>
That didn't pan out very well either, so I was effectively out for the<br>
season. (Lots of other contributing factors also) What I told
the battery<br>
manufacturer was what a guy really needs is five sets of batteries(with
the<br>
then current stuff) and immediate service for turnaround. Have three
sets<br>
for flying and one or two sets traveling to/from.<br>
<br>
I'm sold on electric--particularly for a guy with limited practice time.
I<br>
could go on and on....<br>
<br>
Richard</tt></font><font size=3> </font><font size=2 face="sans-serif"><br>
<br>
<br>
<br>
Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</font>
<br>