Tank?

[Chris Fretz]

Hey fellas can you educate me on this tank? What is it, Uniflow? The two lines close together, which do what? Thanks you guys.

[Chris Fretz]

It appears to be a uniflow, with the center tube the uniflow and the one on the left in the photo as the over flow. But then I could be wrong. But I doubt it.

Good to know thanks!  I was going to start off with muffler pressure first,  so I could pressurize the uniflow line? Is there something to the effect that you don't fill with the uniflow line?

[Juan Valentin]

      It looks to me like a uniflow tank where the uniflow line is pressurized with muffler pressure and not vented ,the other line going down is the overflow.
                                                                                                                                                 Juan

[Gerald Arana]

Easy enough to check. Just put some fuel in it (couple ounces) and use your fuel bulb to draw out the fuel with the ship vertical so the wedge is on the bottom. If it draws out, it's the uniflow line and if not, it's the over flow line.

Your welcome, Jerry

[Randy Cuberly]

Good to know thanks!  I was going to start off with muffler pressure first,  so I could pressurize the uniflow line? Is there something to the effect that you don't fill with the uniflow line?

It's perfectly acceptable to fill with the uniflo line.  This looks like a pretty standard commercial uniflo tank and therefore it's safe to assume that the middle line is the uniflo line.  the only caveat is to make sure that the pressure fitting on the muffler is on the top of the muffler when the plane is upright.  otherwise it is likely to fill with oil between flights or storage and interfere with the pressure from the muffler.

Randy Cuberly

[Jim Svitko]

As others have said, it is most likely uniflow with the middle of the three lines the uniflow line.  To verify, take a piece of 1/16 music wire or something similar and slide it into the middle tube.  If it is the uniflow line it will go in only an inch or two and meet resistance.

If you took the back plate off the tank you would see that the uniflow tube is bent and the rear end of it is soldered to the fuel pick up (fuel line to the engine), terminating a short distance from the end of the feed line.  That is, the uniflow line will not reach to the rear of the tank as the pick up/feed line does.

[Chris Fretz]

Easy enough to check. Just put some fuel in it (couple ounces) and use your fuel bulb to draw out the fuel with the ship vertical so the wedge is on the bottom. If it draws out, it's the uniflow line and if not, it's the over flow line.

Your welcome, Jerry

Ill give that a try thanks!

It's perfectly acceptable to fill with the uniflo line.  This looks like a pretty standard commercial uniflo tank and therefore it's safe to assume that the middle line is the uniflo line.  the only caveat is to make sure that the pressure fitting on the muffler is on the top of the muffler when the plane is upright.  otherwise it is likely to fill with oil between flights or storage and interfere with the pressure from the muffler.

Randy Cuberly

Thats interesting bit of information, thanks for sharing. Its on the bottom when the plane is upright.

[Steve Helmick]

Could somebody post a photo showing what to do with the other (inlet) ends of the uniflow and overflow tubes for Mr. #Liner?   Steve

[Randy Cuberly]

Could somebody post a photo showing what to do with the other (inlet) ends of the uniflow and overflow tubes for Mr. #Liner?   Steve

Hmmmmmm...Maybe!

The line leading to the muffler is obviously the uniflo line and it's the top line here and the middle line on the tank.  The bottom line on the tank is the overflow line and is capped for flight and open for filling through the uniflo line.  This plumbing on the tank is called "Figg" style after the fellow that came up with it long ago.  It works very well for most installations and is available from RSM and Brodak.  As you can see the uniflo line is on top of the muffler otherwise it cannot drain when it gets oil or fuel in it!  The fuel tank inside the aircraft ( Gieseke Nobler) is otherwise very much like the one shown in the photo at the top of this thread.

Randy Cuberly

[Chris Fretz]

Hmmmmmm...Maybe!

The line leading to the muffler is obviously the uniflo line and it's the top line here and the middle line on the tank.  The bottom line on the tank is the overflow line and is capped for flight and open for filling through the uniflo line.  This plumbing on the tank is called "Figg" style after the fellow that came up with it long ago.  It works very well for most installations and is available from RSM and Brodak.  As you can see the uniflo line is on top of the muffler otherwise it cannot drain when it gets oil or fuel in it!  The fuel tank inside the aircraft ( Gieseke Nobler) is otherwise very much like the one shown in the photo at the top of this thread.

Randy Cuberly
Wow that's pretty!

[Steve Helmick]

FWIW, I feel it is a BIG reliability and ease of use deal to put all the external tubes (Uniflow and Overflow) on the inboard side of the fuselage, as per Randy's photo. Some put the overflow on the bottom, which works, but can also be overlooked when fueling. You need to plug it off for either a standard uniflow or for muffler pressure to the uniflow vent to function. Leave the cap off and your NV setting goes all wonky. Lean, not good! Planning ahead helps improve reliability and reduces operational headaches.    Steve   

[Chris Fretz]

FWIW, I feel it is a BIG reliability and ease of use deal to put all the external tubes (Uniflow and Overflow) on the inboard side of the fuselage, as per Randy's photo. Some put the overflow on the bottom, which works, but can also be overlooked when fueling. You need to plug it off for either a standard uniflow or for muffler pressure to the uniflow vent to function. Leave the cap off and your NV setting goes all wonky. Lean, not good! Planning ahead helps improve reliability and reduces operational headaches.    Steve   

Ok I think I may be confused here. Are you just saying as per Randys picture it just makes it easier to use? It does look pretty awesome and professional. So whats wrong with my set up besides it does not have the ease of use?

Does muffler pressure give you the same run result as running a uniflow without pressure? (I've never used a uniflow before)

[Chris Fretz]

Do you guys drill an tap the bottom side of the E-3030 muffler when mounting a engine upside down to make the pressure port right side up? What do you guys use to plug the existing hole?

[Chris Fretz]

It's perfectly acceptable to fill with the uniflo line.  This looks like a pretty standard commercial uniflo tank and therefore it's safe to assume that the middle line is the uniflo line.  the only caveat is to make sure that the pressure fitting on the muffler is on the top of the muffler when the plane is upright.  otherwise it is likely to fill with oil between flights or storage and interfere with the pressure from the muffler.

Randy Cuberly

Ok got another question.  The pressure fitting on the muffler needing to be on top, does this matter on a standard tank (not a uniflow)?

[Chris Fretz]

Hmmmmmm...Maybe!

The line leading to the muffler is obviously the uniflo line and it's the top line here and the middle line on the tank.  The bottom line on the tank is the overflow line and is capped for flight and open for filling through the uniflo line.  This plumbing on the tank is called "Figg" style after the fellow that came up with it long ago.  It works very well for most installations and is available from RSM and Brodak.  As you can see the uniflo line is on top of the muffler otherwise it cannot drain when it gets oil or fuel in it!  The fuel tank inside the aircraft ( Gieseke Nobler) is otherwise very much like the one shown in the photo at the top of this thread.

Randy Cuberly

What kind of spinners is on that Gieseke?

[Steve Helmick]

Ok I think I may be confused here. Are you just saying as per Randys picture it just makes it easier to use? It does look pretty awesome and professional. So whats wrong with my set up besides it does not have the ease of use?

Does muffler pressure give you the same run result as running a uniflow without pressure? (I've never used a uniflow before)

Some engines like muffler pressure, and apparently, some do not. If you have trouble with your muffler coming loose or leaky tank/hoses, then muffler pressure is not for you. The thing muffler pressure absolutely always fixes is the engine going rich when headed upwind and lean when headed downwind. I like that a lot. It's also easy to put some fuel into the cold engine by simply blocking the muffler outlet, even on a tongue muffler.

The alternative is to run a hose from the uniflow air inlet (setup just like Randy's) into the backplate cavity or similar constant pressure area. I tried pipe pressure on my OS .46VF and didn't like it very well, so rigged a bracket on the backplate to hold a tube in the BP cavity. Brett has posted that he has his plane setup so he can do this if he wants. I just do it all the time. I suspect that the NV setting might change, tho the launch rpm would likely be the same. With low winds, I didn't have the rich/lean problem, but when the wind came up, it was not fun. Others use a restriction on the uniflow air inlet, but it seems to me like it would require more experimenting, and if you lose your restrictor, you're screwed. 

If you don't remember to put that cap on the bottom (overflow), then you'll have accidentally converted your tank from a Uniflow to a standard tank. The engine will run leaner as the fuel load is depleted. Sometimes that's good, but not often IMO. I never liked that. I have forgotten to cap the bottom mounted overflow tube, and that's why I suggest avoiding that setup. When you make a cap for the overflow, either put a BB in a short piece of tubing or use a rivet to plug a piece of tubing. Too many guys use a machine screw. That can leak. Some use those cute little yellow caps...fine for keeping dust out of a tank, but not trustworthy for sealing up a Uniflow tank's overflow.    Steve