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Building Tips and technical articles. => 1/2 A building. => Topic started by: John Rist on June 03, 2009, 03:57:03 PM

Title: Balloon tank
Post by: John Rist on June 03, 2009, 03:57:03 PM

I am going to build my first balloon tank.  The balloons I found at Wall-Mart are a little bigger that I would like.  It shouldn't matter as long as I keep the air out of it.  Also I saw a great "how to build" article somewhere. Does anyone have the link.

Next question is how do you fill one with no air inside.  I guessing with a syringe 1/2 full you suck on the balloon untill all of the air is out and then push in the fuel - making sure the syringe dosen't push in any air..
 H^^

Title: Re: Balloon tank
Post by: minnesotamodeler on June 03, 2009, 08:02:54 PM

Exactly right, John.  Draw out all the air with the syringe, then turn the syringe point down so all you inject is fuel.  Don't overfill the balloon, to the stretch point, it isn't intended to be a pressure tank. 

I posted a series of pix showing how I construct a balloon tank for 1/2A.  Not sure where it is now.  Let's see if I can re-create it.

Title: Re: Balloon tank
Post by: Larry Renger on June 04, 2009, 09:23:26 AM

I do a couple of things differently.  First, I cut the fuel hose at the location where the balloon will be tied off, and insert some brass tubing.  Second, I blow the balloon up as hard as I dare and leave it tied off for a day before using it (this makes the capacity greater and the walls thinner for a better run at the end of the flight).  Finally, I use the same brass wire from line wraps to tie the balloon to the hose.

Title: Re: Balloon tank
Post by: john e. holliday on June 04, 2009, 10:06:13 AM

How far into the ballon do you put the fuel line?  DOC Holliday

Title: Re: Balloon tank
Post by: Chris Keller on June 04, 2009, 10:15:17 AM

This is a good idea, but I just don't like the looks of a big black fils canister on the plane. I may have to try this with standard tank that is gutted and has a removeable end. Or maybe build a cowling around the balloon with a removeable cover or something

Title: Re: Balloon tank
Post by: john e. holliday on June 04, 2009, 10:18:07 AM

The Fire Baby had the ballon tank under the canopy behind the firewall.  DOC Holliday

Title: Re: Balloon tank
Post by: John Castle on June 04, 2009, 10:23:37 AM

I use a 3" plastic nyrod type tube and insert it about an inch into the fuel tubing. The remaining 2" that will be in the balloon I drill several holes crosswise. Blow up the balloon a few times to get it soft, insert the tube into the balloon and by pulling on the balloon the neck will constrict around the fuel tube, then wrap it with a rubber band to seal the neck. This takes less than 5 minutes tops.  :)

John

Title: Re: Balloon tank
Post by: minnesotamodeler on June 04, 2009, 04:35:10 PM

On some of my planes I do use a fuelproofed inner compartment, no ugly canister. 

Title: Re: Balloon tank
Post by: Larry Renger on June 04, 2009, 11:12:28 PM

Balloon tanks are included with the Sky Sport kit.

Title: Re: Balloon tank
Post by: Mark Misegadis on October 12, 2009, 03:59:11 PM

Larry Renger,

Where is that first photo you posted taken?

Mark

Title: Re: Balloon tank
Post by: Larry Renger on October 12, 2009, 06:25:36 PM

That is the site at Whittier Narrows.