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Building Tips and technical articles. => 1/2 A building. => Topic started by: Larry Renger on March 07, 2009, 11:07:49 PM

Title: Baggie tank progress!
Post by: Larry Renger on March 07, 2009, 11:07:49 PM

Thanks to Ray Copeland and Clancy Arnold, I have some 2 mil plastic bags to play with.  I made a couple of tanks with them and flew one today.  The performance was excellent.  Now I need to fly it for several weeks to evaluate durability.

Those of you with calipers or micrometers, sneak into the kitchen and measure all your wife's baggies!  We need brand names and specific items listed by film weight.

Clancy sent me some 1.5 mil bags, and I will also try them out.  Lighter is better, of course since the fuel will drain more evenly and conform to the container better. 

My Nelson Head/Brodak .049 does the full pattern on 25cc of 15% Nitro on 46' lines with a Master Airscrew 6x3 prop, just for reference.

Title: Re: Baggie tank progress!
Post by: Bill Heher on March 08, 2009, 11:18:05 AM

Ziploc brand sandwich bags with pink zipper = .0020"    This is for double thickness at bottom of bag
Ziploc Double Zipper gallon size Heavy Duty freezer bag = .0045"
Great Value brand ( Target store ) Quart Freezer = .0030

That's all we had on hand- and she just came in and looked at me at the table with her bags and a digital caliper - "what are you?? - oh never mind I don't want to know"

I love that woman!!

Title: Re: Baggie tank progress!
Post by: Larry Renger on March 08, 2009, 12:29:53 PM

Great input, thanks!  Keep those numbers rolling in, folks.   y1

Title: Re: Baggie tank progress!
Post by: bob werle on April 20, 2009, 06:05:01 PM

Larry

McMaster-Carr has some tear-off bags on a roll in both 1.5 and 2 mil thickness. Sizws starting at 3x5 material is polyethylene..  Found on page 1533 of their on line catalog.

Title: Re: Baggie tank progress!
Post by: sleepy gomez on April 23, 2009, 08:22:23 PM

I have used non-latex condoms FOR THE FUEL SYSTEM!.  Works good.

Title: Re: Baggie tank progress!
Post by: david beazley on April 24, 2009, 02:56:46 PM

I disassembled a Jett Engineering bubbless tank that we used in RC Pylon racing, once.  I came to find out that the inner bladder was a baby bottle liner.  Thickness unknown but worked for a couple of years racing until its untimely demise.

Title: Re: Baggie tank progress!
Post by: Larry Renger on April 24, 2009, 10:17:30 PM

So far, I am still having a leakage problem.  If I overpressure the tank at all, it springs a leak.  No margin for error it seems with incompressable fluids.  I am also having a problem that the heavy baggies take up too much room and allow less fuel in the tank compartment because they don't seem to unfold all the way.  I may have to make a clear plastic box to see what is really going on.

For the contest tomorrow, I am going back to balloons!  One trick I do with them is to blow them up with air and leave them for a day.  They end up much thinner wall and larger capacity, but seem to retain adequate toughness.  Kind of like breaking in a rubber motor on a free-flight. 

Title: Re: Baggie tank progress!
Post by: minnesotamodeler on April 25, 2009, 06:06:41 AM

that's a good thought; I'll try it. Not so much for capacity as for "collapsibility".  Thanks for the idea.

Also the baby bottle liners sounds like a possibility.