[NSRCA-discussion] AAA NimH batterys to Coke bootle fuel tanks

Mon Jan 30 14:47:59 AKST 2006

Actually there is shrinkage with 15%, though I'm not sure it's that big of a
deal, unless of course the bottle gets brittle and cracks.

As to the plasticizer (sp?) getting into the fuel, I don't think this is
much of a worry because after probably 75 flights my tank was only a couple
of grams lighter that it was to begin with, though it was noticeably smaller
(probably 10% to 20% smaller).

Keith

----- Original Message ----- 
From: <jivey61 at bellsouth.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Saturday, January 28, 2006 2:16 PM
Subject: Re: [NSRCA-discussion] AAA NimH batterys to Coke bootle fuel tanks

> Wayne
>  Yes I am convinced the hi nitro is causing the plastic to shrink. Good to
> hear that 15% has little effect.
>
> Jim Ivey
> ----- Original Message ----- 
> From: "Wayne Galligan" <wgalligan at texasairnet.com>
> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> Sent: Saturday, January 28, 2006 10:24 AM
> Subject: Re: [NSRCA-discussion] AAA NimH batterys to Coke bootle fuel
tanks
>
>
> > Jim and all,
> >
> > So far I have I had excellent service with my Coke bottle fuel tank.
Now
> > granted, I am using 15% Cool Power and running an OS 1.40 that sips fuel
> and
> > others that have experienced tank shrinkage have been using higher nitro
> > content and running YS's.  Since the NAT's I have only changed my tank
> once.
> > It only takes a quick rinse of the bottle with some fuel and you can be
> back
> > in the air in about 5 minutes. So for the quick weight fix it would OK
> even
> > if you had to change tanks every day at a contest.
> >
> > Advantage that I have found with the Coke bottle shape is it keeps the
> clunk
> > in the fuel better. Since changing from a DuBro tank the engine no
longer
> > sucks air when low on fuel and a 16.9oz bottle delivers just as much
> flying
> > time as a 20oz Dubro did because of this.
> >
> >  As for the 750mil 3A NiMh packs... keep them for your small airplanes
and
> > not a $2500 airship. I think you'd be better off using Li-Ion or Li-Po's
> if
> > making weight is an issue.
> >
> > Wayne Galligan
> >
> > ----- Original Message ----- 
> > From: <jivey61 at bellsouth.net>
> > To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> > Sent: Saturday, January 28, 2006 7:49 AM
> > Subject: Re: [NSRCA-discussion] AAA NimH batterys
> >
> >
> > > All.......
> > > You are sacrificing safety for weight.....not good. Stick with a good
> > > capacity battery and remove the on-off switch and harness this will
save
> > you
> > > 1 oz +.I did this just for Nats for 6 flights......made weight and it
is
> > > safe.
> > > By the way I am still experimenting with coke bottle tanks.These save
> > 1-1/2
> > > oz versus tettra.  I have a 32 oz bottle filled with fuel in the
> shrinking
> > > process,for 2 months now. It has shrunk 1/4 inch in diameter.My hopes
> are
> > > that when it stops shrinking it will be 24-26 fluid oz which works
with
> > the
> > > thirsty DZ. Hope it doesnt leak and I will tell results later.
> > >
> > > Jim Ivey
> > > ----- Original Message ----- 
> > > From: "Jerry Budd" <jerry at buddengineering.com>
> > > To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> > > Sent: Saturday, January 28, 2006 4:02 AM
> > > Subject: Re: [NSRCA-discussion] AAA NimH batterys
> > >
> > >
> > > > For the 2002 Nats I switched to a AAA 700 mAh NiMH battery pack to
> > > > make weight.  While practicing at the Kokomo field I discovered that
> > > > the pack was good for about 1-1/2 flights (don't ask me how I know
> > > > that!).
> > > >
> > > > Fortunately, I got control back (well - partially) after the 1-1/2
> > > > downline snap and was able to coax the plane back onto the ground.
> > > > Not fun.
> > > >
> > > > At the post-flight debrief I figured out that the AAA cells simply
> > > > had too high of an internal impedance to deliver enough current to
> > > > keep the voltage above the receiver/servo cut-off level when all the
> > > > servos needed to move at once.  I was using JR 7000 Super Servos for
> > > > aileron which went slow/shut off at 4.6V whereas the other JR servos
> > > > kept on working down to 4.2V.
> > > >
> > > > Jerry
> > > >
> > > >
> > > > >Ed is right.  The smaller the cells the higher the internal
> resistance.
> > > Run
> > > > >them down to 20% remaining capacity and put a heavy load, like 5
Amps
> > on
> > > > >them and read the voltage.  You will probably not like what you
see.
> > > > >
> > > > >Jim O
> > > > >
> > > > >
> > > > >----- Original Message -----
> > > > >From: "Ed Alt" <ed_alt at hotmail.com>
> > > > >To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> > > > >Sent: Thursday, January 26, 2006 3:06 PM
> > > > >Subject: Re: [NSRCA-discussion] AAA NimH batterys
> > > > >
> > > > >
> > > > >>  Ed:
> > > > >>  You might get disappointing results due to the inherently high
> > > internal
> > > > >>  resistance of NiMH.  Going with AAA cella and such a low
capacity
> > > might
> > > > >mean
> > > > >>  that you don't get as many flights as you expect before a
voltage
> > test
> > > > >under
> > > > >>  load dips below an acceptable value.
> > > > >>
> > > > >>  Ed
> > > > >>  ----- Original Message -----
> > > > >>  From: "Ed Miller" <edbon85 at charter.net>
> > > > >>  To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> > > > >>  Sent: Thursday, January 26, 2006 9:05 AM
> > > > >>  Subject: [NSRCA-discussion] AAA NimH batterys
> > > > >>
> > > > >>
> > > > >>  > Is anyone using AAA NimH batteries for a RX pack ??. I am
> looking
> > at
> > > > >>  > Batteries America ( EHYOST ) and they seem to have AAA NimH's
in
> > > 720,
> > > > >800
> > > > >>  > and 900mah ratings. I currently use their 2/3A 5 cell NimH
pack
> at
> > > > >1100mah
> > > > >>  > and a weight of 3.85 ounces complete with the long lead I have
> on
> > > the
> > > > >>  > pack.
> > > > >>  > Going to their AAA 5 cell pack looks like I can save about an
> > ounce
> > > or
> > > > >so.
> > > > >>  > Mah isn't an issue, I can get in excess of 7 to 8 flights on
the
> > > 1100mah
> > > > >>  > pack I use now before charging so going to 900mah shouldn't be
a
> > big
> > > > >hit.
> > > > >>  > Don't suggest Lithium anything as lighter, want to continue to
> use
> > > my
> > > > >>  > Alpha
> > > > >>  > 4 charger and am not convinced those new batteries are safe.
> > > > >  > > Ed M.
> > > >
> > > > -- 
> > > > ___________
> > > > Jerry Budd
> > > > Budd Engineering
> > > > (661) 722-5669 Voice/Fax
> > > > (661) 435-0358 Cell Phone
> > > > mailto:jerry at buddengineering.com
> > > > http://www.buddengineering.com
> > > > _______________________________________________
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> > >
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