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Old Apr 14, 2012, 08:42 AM
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first time inverted engine

I have been building a corsair 60 ARF and am running a evo.61NX Engine that is mounted inverted..Got it running for the first time the other day and tuned seems to run awesome...But as i was putting the plane away i noticed that if you roll the plane to far to the right (the side which the exhaust is on) then fuel just pores out the exhuast..i guess this will be a major problem while flying but im still kinda new to this... any thoughts?
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Old Apr 14, 2012, 08:50 AM
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The "fuel" pouring out of the exhaust is just unburned oil. Think of it as a good thing, unless someone with more experience knows better.
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Old Apr 14, 2012, 11:42 AM
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It is most likely that your muffler outlet is not rotated to a low point and oil accumulates there until you turn the plane on it's side. It is not a problem and will not affect how the engine runs. Only problem is if it drips on your carpet a wife can become very unhappy.
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Old Apr 15, 2012, 07:09 AM
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This is not just a drip though..I only held it on its side for a moment but its like a steady stream..seems a bit much for just some unburned oil..
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Old Apr 15, 2012, 07:39 AM
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Just need to be sure, did you fully drain your tank?
Edwin
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Old Apr 15, 2012, 08:21 AM
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Sounds like some fuel had drained out of the fuel tank and collected in the muffler. It can easily happen when you have the plane inverted, and you are removing the wing or something, while there is still fuel in the fuel tank.
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Old Apr 15, 2012, 11:39 AM
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I see this all the time. Turn the plane on its side and fuel pours out of the muffler. Many reasons possible. 1 When filling the tank if you doun't take the line off the muffler it will get lots of fuel in there . 2 If the muffler outlet is not at the bottom, with the plane upright it will accumulate liquid that will drain (A LOT) when the plane is turned to the side. 3 The engine is running very rich and will fill the muffler with fluid. 4 Turning the plane over with fuel in the tank can cause the muffler tube to allow fuel to flow into the muffler, and then it will drain out. 5 There are lots of possabilities. NONE of which will affect the way it runs/flies. Just residule fuel/oil that drains all over your wifes carpet. Enjoy your plane.
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Old Apr 15, 2012, 08:36 PM
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With a tank (typically) more than 1/2 full, your vent tube will become submerged when the plane is rolled on its side (or inverted), which can allow siphoning to occur.
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Old Apr 16, 2012, 07:08 AM
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Quote:
Originally Posted by NACA0012 View Post
With a tank (typically) more than 1/2 full, your vent tube will become submerged when the plane is rolled on its side (or inverted), which can allow siphoning to occur.
Ditto...I fly three aircraft with inverted engines...one leaked as yours.It was the vent siphoning at that angle
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Old Apr 16, 2012, 04:34 PM
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Ok im thinking its the vent tube i am just worried that from turning and banking while flying i will loose the majority of my fuel and cut my fiight times drastically..
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Old Apr 16, 2012, 05:25 PM
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Originally Posted by stevolution View Post
Ok im thinking its the vent tube i am just worried that from turning and banking while flying i will loose the majority of my fuel and cut my fiight times drastically..
That won't happen.....when the engine is running,there's a bit of pressure at that fitting where the vent is attached....as long as the engine is running,the fuel is kept in that line by the pressure.
The line is put there to keep some positive pressure in the tank to help supply fuel to the engine.
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Old Apr 16, 2012, 05:49 PM
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+1 As long as the engine is running it is impossible for fuel to run out the vent tube, since this tube is there to provide pressure to the tank FROM the muffler. DON"T WORRY. This is NOT a problem . Enjoy your plane.
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Old Apr 16, 2012, 07:02 PM
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I was experimenting with a uniflow set up where the muffler pressure fuel tube is as long as the fuel pick up line, inside the tank, both had clunks on them.
While running full throttle on the ground, if I chopped the throttle to idle it would spew raw fuel out of the muffler.
I went back the the normal fuel line setup after that.

Jeff
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Old Apr 16, 2012, 07:32 PM
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Normally, the Uniflow vent is NOT attached to the muffler. When you did that, you positively pressurized the tank like blowing up a balloon, so when that high speed pressurization ceased at idle, the "balloon" released its pressure out the handiest least resistance source - the submerged uniflow vent and shot the fuel out.

A simple check valve, or simply using Uniflow as it was intended (if your engine has enough fuel draw to handle uniflow's slight negative tank pressure). Not every engine has enough fuel draw to tolerate uniflow as it was intended. K&B .40's and OS Max "H" .40 are two examples I've encountered that aren't happy with proper Uniflow. The LA's seem OK with it.
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Old Apr 17, 2012, 05:24 PM
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Thanks for the help guys im still pretty new to this and am doing my best to learn..

Not sure if it matters in this case but i did forget to mention that i am running a fuel dot.

Has anybody in this room flown this plane my maiden will hopefully be this weekend weather permitting and this is my first war bird so i wanted someones first hand experience..
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