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<DIV><FONT face=Arial size=2>Gray, Dean,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>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></DIV>
<DIV><FONT face=Arial size=2>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></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>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></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>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></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Richard</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=gfowler@raytheon.com href="mailto:gfowler@raytheon.com">Gray E
Fowler</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, November 18, 2005 10:57
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Discussion List
(Batteries)</DIV>
<DIV><BR></DIV><BR><FONT face=sans-serif size=2>Richard</FONT> <BR><BR><FONT
face=sans-serif size=2>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>
<BR><FONT face=sans-serif size=2>First, electric airplanes do not exactly
drive the battery market,......even if 50% of the FAI finalists use them. No
other applications </FONT><BR><FONT face=sans-serif size=2>that I am aware of
uses these batteries in the manner that we attempt, which is that massive
current draw. What electric planes do </FONT><BR><FONT face=sans-serif
size=2>to batteries is damaging, as demonstrated by your 25 flights.
</FONT> <BR><FONT face=sans-serif size=2>I would not expect the battery
market to develop a battery capable of long life and extreme current draw
since no one else uses </FONT><BR><FONT face=sans-serif size=2>batteries in
such a manner.</FONT> <BR><BR><FONT face=sans-serif size=2>Invest in bottle of
Windex, clean the oil. </FONT><BR><BR><BR><BR><FONT size=2><TT>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> <BR><FONT face=sans-serif
size=2><BR><BR><BR>Gray Fowler<BR>Principal Chemical Engineer<BR>Composites
Engineering</FONT></BLOCKQUOTE></BODY></HTML>