Discussion List (Batteries)

[Keith Black]

Excellent point Chuck about the high drag fuses. With that electric brake on the front the thinner fuse (and lighter) planes may slow just as well. 

However, I must say, I really like the looks of the newer beefier planes.

Keith
  ----- Original Message ----- 
  From: Chuck Hochhalter 
  To: discussion at nsrca.org 
  Sent: Friday, November 18, 2005 12:14 PM
  Subject: RE: Discussion List (Batteries)


  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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