Quick 'n' easy balloon tank

Quick 'n' easy balloon tank
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Quick 'n' easy balloon tank - 5/8/2008 7:44:58 PM

MJD

Posts: 1500
Joined: 5/27/2003
From: Orangeville, ON, CANADA
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The talk about balloon tanks in the “airplane recommendation” thread by maaaarius inspired me to shuffle downstairs and finish something I meant to do ages ago. Gee, it must have taken me 20 minutes to make it, and most of that was taking pictures.

Here is an idea I had for quick and easy balloon tank construction. You need:

- an empty Visine bottle
- a suitable balloon
- a chunk of 1/8” OD tubing (or whatever you choose to use)
- assorted tools you ought to have lying around

Pic1

Visine bottle, balloon, spout (it’s a two piece affair), screw-on cap. Call all your allergy-plagued and/or stoner friends and ask them to save Visine bottles for you.

Pic2

Close-up of the spout and cap. On the spout at left, I have already sliced off the part that push fits into the bottle – it is not needed. I have not yet sliced off the top part of the screw-on cap, it worked well with a singe edge blade. Careful of your fingers.

Pic3

Shows the spout weighing in at 0.87 grams. It has not been drilled out for the fuel outlet tubing yet. I am sure that removed the 0.07 gram part at least.

Pic4

A blurry shot of the screw-on cap at 0.95 grams. The part that projects above the threaded part must be sliced off.

Pic5

Shows a “suitable balloon” weighing in at a whopping 1.35 grams.

Pic6

Shows the two part spout. It has been drilled out to make a push fit for a short section of 1/8” OD tubing – in this case I used some polyurethane tubing I have on hand. It seals beautifully in a push fit hole like this, but so will metallic tubing. Because soft plastics tend to drill undersize, I ended up using a 9/64” drill bit to make a hole that was a nice fit for the 1/8” OD tube. Experiment with what you have beforehand so you don’t screw up too many Visine bottles.

Pic7

Shows the spout components in finished form.

Pic8

Shows the assembled tank. Here’s the cool part – carefully slice the roll-up rim from the balloon’s neck, then slide it over the spout assembly until the neck is just past the threads. Wet the outside of the balloon – your tongue works well, mine did – then carefully screw the cap on to pin the balloon in the threads as you can see here. Works like a charm. Because the spout is a twopart snap together affair, I decided not to tempt fate by using it alone. The tip part snaps pretty aggressively into the other bit, but that would require tying or rubber banding off the tank. I think that using the cap makes the whole affair much simpler, and in addition it is dead nuts simple to change balloons in the field.

As you can see, the completed tank weighs 2.80 grams. That is about 1/10 the weight of a Sullivan one ounce tank, so I figured any weight reduction beyond that was superfluous, but feel free to experiment.

Pic 9

Ta da! The tank is full of water but slack, and with this balloon holds 22 grams of water, aka 22 ml of fuel.

Howzat? Now to mold a lightweight tank compartment cover for the Blink..

Mike D.

attached (hopefully): Pic1 - Pic9

(edit) p.s. if space was an issue you could obviously shorten the balloon neck a bit, and lose just a little capacity. You'll figure it out.

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< Message edited by MJD -- 5/8/2008 8:01:50 PM >

Post #: 1

RE: Quick 'n' easy balloon tank - 5/8/2008 9:13:02 PM

maaaarius

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From: cg, NORWAY
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Hurray, someone took pictures! Thanks a lot

Will it actually be able to pick up fuel even when the plane makes a loop? Why not make the tube long enough to go all the way into the balloon?

Thanks again!

(in reply to MJD)

Post #: 2

RE: Quick 'n' easy balloon tank - 5/8/2008 10:31:03 PM

Jim Thomerson

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From: Austin, TX, USA
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When you fill a balloon tank, you get all the air out, so the pickup is in fuel all the time.

(in reply to maaaarius)

Post #: 3

RE: Quick 'n' easy balloon tank - 5/8/2008 10:55:44 PM

MJD

Posts: 1500
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From: Orangeville, ON, CANADA
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quote:

ORIGINAL: Jim Thomerson

When you fill a balloon tank, you get all the air out, so the pickup is in fuel all the time.

Yep. The way you do that easily and reliably, maaaarius (is that the right number of "a's"?), is to get yourself a large syringe, 30ml - 60ml or so. You want one that has at least double your intended fuel capacity. Rig the syringe however you wish to, so that it has a fuel tubing nipple on the end of a section of filler line made from flexible tubing long enough to draw fuel from your can. Depress the plunger all the way, then draw in as much fuel as you want to be in the tank plus a few ml more, e.g. 5ml extra. Now, disconnect the fuel line from the engine and connect this to the filler line on the syringe. You must now hold the syringe vertically, filler line down, and pull the plunger back farther - it will now suck out any air from within the tank. This air will bubble up through the fuel in the syringe. and collect at the top of the column. When you have drawn out all the air, depress the plunger to discharge the fuel, which is now at the bottom of the syringe with the air on top, into the bladder. BUT, be careful you do not inject any air into the bladder after the fuel - this is where the extra 5ml of fuel comes in. Discharge the amount wanted in the tank, and stop when only the 5ml of fuel is remaining. Done! Connect the fuel line to the engine again, and take care to keep the nose up a bit from now on as fuel will easily gravity siphon into the engine.

It takes much more time to explain it than to do it. It is extremely simple when you understand what you are trying to accomplish - no air in the system - and how. Make darn sure you are not creating any pressure in the bladder! Know the relaxed capacity of the bladder beforehand. This is a key point of their use - you must fill them only to capacity or you will have some misery either due to bladder pressure or damage to the bladder itself.

This BTW is how you fill Jett and Tettra bubbleless tanks as typically used in pylon racers, and by those that have seen the light with respect to bladder tanks and their miraculous properties. Oddly, many people never try them, yet they are so simple, and so amazingly effective at eliminating fuel system troubles. They are, IMHO, well worth the money and more so in terms of peace of mind, and I have decided I will from this point forward use only bladder tanks of some sort in all my glow aircraft, no matter the aircraft type and purpose.

Hope this is of some help.

MJD

(EDIT) p.s. the fuel will swell the rubber plunger in the syringe, so I keep them empty at all times when not using them, and usually get along okay. If you remove the plunger and let it dry out it will reduce in size again, eventually. A filler I own made by Jett, uses a metal plunger with o-ring seals that are compatible with fuel, so it doesn't have this problem.

< Message edited by MJD -- 5/8/2008 11:00:51 PM >

(in reply to Jim Thomerson)

Post #: 4

RE: Quick 'n' easy balloon tank - 5/9/2008 5:30:40 PM

Mr. Mugen

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From: Ishpeming, MI, USA
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Very nice! Thanks for taking the time to show us. I need to make one for a small boat project I have on the back burner.

_____________________________

Everything electronic runs on smoke.....if you let your smoke out, it''s dead! AMA#378033

(in reply to MJD)

Post #: 5

RE: Quick 'n' easy balloon tank - 5/10/2008 12:02:28 AM

gabe200

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From: baltimore, MD, USA
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so how long can you run an .049 on this bladder tank

(in reply to Mr. Mugen)

Post #: 6

RE: Quick 'n' easy balloon tank - 5/10/2008 3:14:58 AM

MJD

Posts: 1500
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From: Orangeville, ON, CANADA
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quote:

ORIGINAL: gabe200

so how long can you run an .049 on this bladder tank

That depends on the size of the balloon of course, and there is some variety available there. The one in the picture held 23cc of water with the longish neck, and about 21cc when I cut the neck shorter. It looked more sensible once trimmed, and fits with room to spare in a Blink's tank compartment. For those not running pressure of course..

Duration? A Black Widow runs 3-4 minutes on it's 8cc tank according to posts I've read here. From my recollection that sounds right, I think 3:30-3:40 was what I used to see on a 6-3 MAS, but it has been ages since I ever timed a run so I could be OTL. So this bladder would, I guess, run a Black Widow for 8-10 minutes, which is more than enough for me. A Tee Dee a bit less due to higher power output I presume, a Sure Start may run longer depending on it's level of anemia.

MJD

(in reply to gabe200)

Post #: 7

RE: Quick 'n' easy balloon tank - 5/11/2008 8:24:09 PM

maaaarius

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From: cg, NORWAY
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Thanks a lot for the detailed explanation. I had to read it like three times before I fully understood it

Seems like I will try to get some balloons and something similar to that small Visine bottle. Hopefully I can find a usable bottle/tip. Tried my engine today and to my surprise it actually worked. The fuel I have is rather old and one of my cans have brownish fuel in it... not sure if it works. What kind of fuel should I buy? My options are:

Blue Thunder 20% nitro, car
Cool Power HP 30% nitro, heli - High Performance
Power MV 15% nitro 18% oil, heli
Sidewinder 25% nitro 10% oil, car - pro race blend

Not sure if any of those can be used with a cox engine. The higher the nitro the faster? Should it have oil in it?

@MDJ: Yes, that is the correct number of a's, but you can feel free to use any number you like, although I do prefer one simple a

< Message edited by maaaarius -- 5/11/2008 8:25:00 PM >

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Post #: 8

RE: Quick 'n' easy balloon tank - 5/11/2008 9:14:07 PM

Jim Thomerson

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From: Austin, TX, USA
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Designman had an article a couple of months back in Flying Models where he showed how to make a two layer balloon tank. Muffler pressure went into the outer balloon and fuel (of course) into the inner balloon. Looked pretty neat.

(in reply to maaaarius)

Post #: 9

RE: Quick 'n' easy balloon tank - 5/12/2008 3:01:32 AM

MJD

Posts: 1500
Joined: 5/27/2003
From: Orangeville, ON, CANADA
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quote:

ORIGINAL: Jim Thomerson

Designman had an article a couple of months back in Flying Models where he showed how to make a two layer balloon tank. Muffler pressure went into the outer balloon and fuel (of course) into the inner balloon. Looked pretty neat.

LOL! I was going to try that sometime as the next step in balloontanking. Seems it's always been done before by someone

(in reply to Jim Thomerson)

Post #: 10

RE: Quick 'n' easy balloon tank - 5/12/2008 3:08:26 AM

MJD

Posts: 1500
Joined: 5/27/2003
From: Orangeville, ON, CANADA
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quote:

ORIGINAL: maaaarius

Blue Thunder 20% nitro, car
Cool Power HP 30% nitro, heli - High Performance
Power MV 15% nitro 18% oil, heli
Sidewinder 25% nitro 10% oil, car - pro race blend

Not sure if any of those can be used with a cox engine. The higher the nitro the faster? Should it have oil in it?

One thing that is pretty important with Coxes is to have a reasonable percentage of castor oil in the fuel. It's been ceovered here a few times, but basically a good Cox 1/2A fuel:

- contains a minimum of 15% nitromethane. They start to run smoothly at 15% and run great on anything from 25-35% in general. Forget what's high for a .40 or .60 - an .049 likes 25% nitro like a .46 likes 10%.
- contains a minimum of 20% total oil content of which 50% at least should be castor.

That said, if all you can find is some 15% syn/cas blend with 18% oil, it will run on that and not too badly. Overall, the service life will likely be shorter, but it won't fall apart before your eyes.

SIG Champion is good fuel is you can find some.

(in reply to maaaarius)

Post #: 11

RE: Quick 'n' easy balloon tank - 5/13/2008 3:52:25 AM

gabe200

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From: baltimore, MD, USA
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i use sig 1/2a fuel with added castor oil

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Post #: 12

RE: Quick 'n' easy balloon tank - 5/13/2008 1:27:39 PM

maaaarius

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From: cg, NORWAY
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I'm trying to find suitable fuel in Norway, but it's not easy. Is it ok to buy a 25% nitro fuel and add 20% oil? Does it have to be castor oil? I'll still try to hunt for more proper fuel, but it's possible that I will have to "make" my own.

< Message edited by maaaarius -- 5/14/2008 3:13:49 PM >

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Post #: 13

RE: Quick 'n' easy balloon tank - 5/13/2008 2:10:31 PM

MJD

Posts: 1500
Joined: 5/27/2003
From: Orangeville, ON, CANADA
Status: offline

quote:

ORIGINAL: maaaarius

I'm trying to find suitable fuel in Norway, but it's not easy. Is it ok to buy a 25% nitro fuel and add 20% oil? Does it have to be castor oil? I'll still try to hunt for more proper fuel, but it's possible that I will have to "made" my own.

If you have 25% fuel available, find out what the oil content is, and the type of oil - synthetic, castor, or synthetic/castor blend, or at least the brand and type. You won't need to add 20% oil, there is already oil in there, but you may need to add some castor oil to bring the total oil and castor oil amounts up to suitable levels.

(in reply to maaaarius)

&nbs