[NSRCA-discussion] [NSRCA-discussion ]Coke bottle tanks

[Stuart Chale]

I would suspect that a coke bottle tank as long as the stopper is secure
would be very durable.  After all it has to stand up to pressurized water in
it no matte how hard you shake it :)

Way back when I was running round shampoo bottles in YS 60 pumped pattern
planes.  In fact I still have an Atlanta with one in it.  The ones I used
were a long cylinder shape which allowed it to fit right over the CG in
those relatively narrow fuses.  Except for the flat bottom the cylinder
shape was perfect for pressurization.  Just think of the propane truck's
tank shape.

A comment on Kraft tanks:
They are seamed or at least they used to be and a pressurized system will
split them quite easily.  Luckily I learned this on a test stand and not in
a model.

Stuart


-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ed Miller
Sent: Saturday, January 28, 2006 10:10 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] AAA NimH batterys

Making weight isn't a problem. My EMC2 currently weighs 4815 grams. Just 
looking for that elusive 4799 marker and keep plane durable and maintenance 
free. Tank is already light, Kraft 16oz at 57 grams and don't want the 
possibility of filling the fuse with fuel in the event the coke bottle tank 
leaks.  I'll leave my 5 cell, 2/3A, 1100mah NimH in place. I think I've 
found an area I can get those last 16 grams.......Thanks to all that 
convinced me the AAA NimH pack is not the way to go.
Ed M.
----- Original Message ----- 
From: <jivey61 at bellsouth.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Saturday, January 28, 2006 8:49 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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