Q-500 Racing Discuss AMA 428, AMA 424, and any other variants of Quickie 500 racing

Jett Boubbless tank

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Old 10-19-2010, 08:49 AM
  #1
flyreel
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Default Jett Boubbless tank

How do you fuel the Jett Boubbless tank? It says on the web dont use a hand or electric pump. Then how do you fill it?
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Old 10-19-2010, 08:54 AM
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Default RE: Jett Boubbless tank

You use a syringe, its called a Jett Tanker on their website. You put about 6 oz of fuel in the Syringe and hook up to the tank. Pull all of the air out of the fuel tank and it will bubble up through the fuel in the syringe. Once you have it completely empty push the fuel into the tank until it is full. Keep the back end of the tanker point up so you are just pushing fuel into the tank. Clamp off the fuel line and unhook the tanker. When you are ready to fly, unhook the fuel line clamp and start it up.
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Old 10-19-2010, 10:09 AM
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Default RE: Jett Boubbless tank

Hi!
As Daven says! But! You can of course fill it using an electric or manual fuel pump too. I have for a dozen of years.
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Old 10-19-2010, 02:03 PM
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Default RE: Jett Boubbless tank

Jaka- are you using a three line system?
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Old 10-19-2010, 02:12 PM
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Default RE: Jett Boubbless tank

He would have to be to get the air out.
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Old 10-19-2010, 02:27 PM
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Default RE: Jett Boubbless tank

Must be a Tettra tank - don't the Jett tanks come with two lines? All of the ones I have did.
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Old 10-19-2010, 06:18 PM
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Default RE: Jett Boubbless tank

The Jett tank does come with only 2 lines (pressure and fill). I have used a manual pump by filling the tank slightly and then drawing out the air and some of the fuel, then filling it up. It is more difficult to get a feel of the pressure in the tank then by using the syringe. But it works in a pinch.
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Old 10-19-2010, 06:24 PM
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Default RE: Jett Boubbless tank


Davin is, as usual right on. Its always best to follow the insrtuctions, but yes, you can get away with the electric pump. You still have to pull the existing air out of the tank, or pressure the air out from the other line. Lots of ways to skin the cat in a emergency including sucking it out with your mouth as a last resort. But, why not just do it right to start from. When you have 60 seconds on the clock to get ready, one will do some strange things.
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Old 10-19-2010, 11:59 PM
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Default RE: Jett Boubbless tank

The tetra bubbless tanks can be setup 2 or three line. Both are described in the instructions I received. If you go 3 line you fill through the line to carb and open vent line that goes to top of tank. Using a manual or electric pump this purges the air out of the top. When done filling close off vent. When emptying, empty from carb line with vent line closed. The pressure tap that comes with the tank is into the hard tank outside of the bladder, so air is not introduced there. I have used this for sport club racing since we are not allowed any syringe fillers (there was an incident of someone adding something to the tank) as we use club provided fuel and everyone fills at a common can with pump.

This method seems to work very well. Try it outside of the plane and you'll see how the air comes out so there is no air left. Not as bullet proof as 2 line and syringe I am guessing, so I guess that is why pylon racers generally go that route.

- Joe.
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Old 10-20-2010, 12:58 AM
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Default RE: Jett Boubbless tank

The whole purpose of using a bubbless is to have no air in the fuel so it can't foam. If you use an electric pump, it is very difficult to get all of the air out of the tank. Having a little fuel in before you attempt to suck the air out is of no use. It is not until all of the fuel is removed that you start removing the rest of the air. The tube inside the tank is in the center of the bag, not on the bottom as with a clunk. You don't have to have to have used all the fuel before air can get to the tube. Any air in the bag will cause an opportunity for foam. Seems silly to buy a bubbless tank and then not fill it properly. Also, using pressure on the pressure line to force the air out of the bag is taking a chance on loosing the seal where the pressure line enters the tank. It is not designed to withstand more pressure than the exhaust normally puts out.

If you are going to use a Bubble-Jett Tank, buy the Bubble-Jett tanker so you can fill it properly. Any other method is taking a chance on leaning out at the end of your run. Isn't that why you bought a Bubble-Jett tank? I hear that the three line Tetra will work well with an electric pump. If you don't want to use the tanker, you should probably think about a three line Tetra.

Blessings, Terry
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Old 10-20-2010, 07:12 AM
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Default RE: Jett Boubbless tank

Terry, I agree, I use two lines because it is one less line to leak, and filling this way is not an issue.

I will say that Multiple World Champ Chris Callow uses 3 lines in his F3D planes, so it must work as well.
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Old 10-20-2010, 09:23 AM
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Default RE: Jett Boubbless tank


To clarify, I am not suggesting using the pressure line to force anything out.

The 3 line approach has two lines in the bladder. One is the feed line set up same as 2 line approach, simply fuel tubing in middle of bladder. The pressure line goes to the provided pressure line tap in the outside casing of the tank, same as two line approach. The 3rd line is a vent that goes to the top to one of the little humps in the top of the tank inside the bladder. As you fill, air rises to the top and vents out. Eventually all air is theoretically displaced by the fuel and comes out the vent line until it is full of fuel. The the fuel causes the bladder to expand theoretically. I agree there is a practical chance that some air may not come out or the bladder may not expand completely and you'll get a less than full tank. One way to see the practical performance vs. theoretical is to actually try it outside of the plane. I have multiple times as that is how my engine test stand is set up and it seems to work. I also use this in my stock T-34 racers initially for the rule reasons I mentioned (no syringe fueling allowed) and since it worked well for that, I use it even when not required by the rules.

- Joe.
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Old 10-20-2010, 10:20 AM
  #13
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Default RE: Jett Boubbless tank

Hi!
Yes! three line system.
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Old 10-20-2010, 05:01 PM
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Default RE: Jett Boubbless tank

Quote:
ORIGINAL: delateurj


To clarify, I am not suggesting using the pressure line to force anything out.

The 3 line approach has two lines in the bladder. One is the feed line set up same as 2 line approach, simply fuel tubing in middle of bladder. The pressure line goes to the provided pressure line tap in the outside casing of the tank, same as two line approach. The 3rd line is a vent that goes to the top to one of the little humps in the top of the tank inside the bladder. As you fill, air rises to the top and vents out. Eventually all air is theoretically displaced by the fuel and comes out the vent line until it is full of fuel. The the fuel causes the bladder to expand theoretically. I agree there is a practical chance that some air may not come out or the bladder may not expand completely and you'll get a less than full tank. One way to see the practical performance vs. theoretical is to actually try it outside of the plane. I have multiple times as that is how my engine test stand is set up and it seems to work. I also use this in my stock T-34 racers initially for the rule reasons I mentioned (no syringe fueling allowed) and since it worked well for that, I use it even when not required by the rules.

- Joe.
I said that about someone using the pressure line to pressurize the part of the tank outside the bladder in an attempt to force out all of the air in the bladder. It will work in theory, but the pressure line on the Jett tank is siliconed in and the seal could fail if too much pressure is applied.

Why is syringe filling not allowed? How could that possibly give anyone an advantage? Sometimes we get a little carried away with rules.

Blessings, Terry
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Old 10-20-2010, 05:16 PM
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Default RE: Jett Boubbless tank

Hi Terry,

Don't know the background. Rule was in place before I started racing in the stock classes using standard fuel which have the fueling restriction.

Agree 2 line has less chance for leaks and air getting into the tank.

- Joe.
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Old 10-23-2010, 10:13 AM
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Default RE: Jett Boubbless tank


Quote:
ORIGINAL: delateurj

Hi Terry,

Don't know the background. Rule was in place before I started racing in the stock classes using standard fuel which have the fueling restriction.

Agree 2 line has less chance for leaks and air getting into the tank.

- Joe.
Weird. Maybe they are afraid someone will sneak a little nitro into the syringe before they fill it, if it's only not allowed in the events where the fuel is controlled. there is no real speed advantage to a bladder tank other than it reduces the chance of leaning out at the end of a run.

Blessings, Terry
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Old 10-23-2010, 10:57 PM
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Default RE: Jett Boubbless tank

Hi Terry,

Yeah, my guess is someone was caught adding nitro. But that is purely a guess.

"if it's only not allowed in the events where the fuel is controlled. there is no real speed advantage to a bladder tank other than it reduces the chance of leaning out at the end of a run."

I want to make sure I don't cause confusion on the rules and I am not which it you mean when you say "it's only not allowed". I assume you mean a syringe and that is correct. Syringes are not allowed at the fueling station in the stock classes. Tettra Bubbleless tanks are allowed in all classes.

Regards,
Joe.
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Old 10-24-2010, 12:45 AM
  #18
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Default RE: Jett Boubbless tank

Yes, I meant the syringe. The only stock class we fly at our club is Club 40 racing. Participants are encouraged to use the stock tank which is so large that a bubbless tank is not necessary. The race only last about 3 minutes and you can fly 10 minutes easily on that much fuel. The club furnishes the fuel so I guess it might me a little awkward if someone needed to use Syringe at the fueling station.


Blessings, Terry
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