Discussion List (Batteries)

[Chuck Hochhalter]

In regards to the airframe, I am agreeing with you in a sense that the
planes will e-volve (grin) to be able to compliment the electric setups.
Right now we are adapting current IC airframes.  The advantages of
"braking" with the controllers and larger props may see another swing in
basic design concepts.  Look at Nats Voodoo express, now that may be the
extreme end of design compared to the airframes we see now and what we
evolve to but who knows, could a redesigned curare with slim fuse make a
come back???  
 
Can't wait to see what comes next.
 
Chuck
 
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of Richard Strickland
Sent: Friday, November 18, 2005 11:58 AM
To: discussion at nsrca.org
Subject: Re: Discussion List (Batteries)
 
Gray, Dean,
 
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.
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.
 
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.
 
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.
 
Richard
 
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