hi ive just got a spitfire im building, and having only flown electric aircraft before i came across a problem.
3 fuel lines, and i have no idea which should be going where![:'(]
the tank has 2 lines that are next to each other, and then a line about midway down the tank?
im assuming the top two are the pressure and fill lines and the middle one is the fuel line to the engine?
[&:] very confused,
CG

You only need two fuel lines coming out of the tank...

When the aircraft is sitting upright one of them will be higher than the other. The high one with the metal tubing bent towards the top of the fuel tank will go to the outlet on the exhaust to provide back pressure.

The other one will go to the engine's carburator to provide fuel. The copper tubing on this line will extend about 1/3 of the way into the tank. Then were will be fuel tubing with a "clunk" on the end. While holding the fuel tank vertical (the outlets on top) the clunk should be very close to the bottom of the tank, but not touching.

This ought to get you started...

I used to have links to some really great diagrams on the web for setting them up, but I can't find anything now. Anybody have those?

i see where your coming from, ill get a piccie of the tank in question and post again tomorrow...see if you can tell me what wants to go where

Hold the tank up to a strong light.

Which ever nipple from the tank has a fuel line and clunk on it goes to the carb. Odds are it will be the middle line - the one closest to the center of the tank.

Now look at the 2 nipples together. If one of them has a piece of metal tubing angled up towards the top of the tank, that is for your muffler pressure. (Chances are one of them will have something angled towards the top of the tank, otherwise the 3 nipples are usually all be in a row vertically ). If neither one has anything angled up to the top of the tank it will make no difference which you choose for muffler pressure and which one for fueling/defueling.

The third one (with nothing attached to it ) is the one for fueling/defueling the plane. On that one you will need to run the fuel line to the outside of the plane and install a fuel dot of some type (Take a look at DuBro Fuel-It http://www2.towerhobbies.com/cgi-bin...?&I=LXAHE1&P=7 as an example of one type of fuel dot ) I use the Dubro system and am very happy with it, especially for cowled planes or those engines that are a pain to get at the fuel line (OS 46 FX ). If you decide you do not want to run the 3rd line, you will need to plug that nipple off - I suggest a short piece of fuel line with the end melted closed so it is air tight.

If the 3 nipples were in a vertical position, the bottom one (closest to the middle of the tank ) is usually the fuel line to the carb, the top one is for muffler pressure and the middle one for fueling/defueling.

In either case, when you defuel the plane, you will need to stand the plane on its nose so you can get the fuel out of the tank.

Goose - one thing I have done on all my planes is to run the 3 hose system. Like the guys said, the one with the brass tube going to the top of the tank internally is normally the pressure line running back from the muffler. Where I vary a little bit are the other two lines. I put clunks on each nipple in the tank with equal lengths of fuel line. I use one to go to the carb/needle valve and the other goes to a fuel dot. I personally like the fuel dots from SlimLine. What this does is allow you to de-fuel the plane without putting it on it's nose. I have never had a clunk in any of the planes get wrapped up or tangled up with each other. Your only adding a few ounces of weight.

I might get a little grief for telling you how I do this , but you should also test your tank for any airleaks by submerging it in a sink of water with two of the lines tied together with a single hose, and then you use the other hose end to blow into to apply some positive pressure to the tank. Just looking for bubbles.... What I do that I said I probably shouldn't tell about is -- I use one of the compressed air cans you can buy at the the computer stores to blow off your keyboards to give the tank a little pressure test. The small plastic tube that comes with most of these cans of compressed air just happens to be the exact right size to fit into the fuel line. I hold the tank in my hand underwater in a way that allows me to feel a slight increase in size from the airpressure. I hold that for a about 20 seconds, remove the tank, and then remove the tube out of the fuel line to release the pressure. Test is complete as long as I haven't seen any bubble escaping

The danger in this is getting carried away with your air pressure and blowing a seam out of your fuel tank while it's submerged and making for a little clean up in the bathroom [X(] I've tested probably about 25 or 30 tanks this way and have not blown one up yet, knock on wood

I use a three line tank system too On every engine thats covered by a cowling. I also double clunk my two fuel lines. If you don't clunk your fill line it's impossible to de-fuel your tank.
so 1 more time 1 line is pressure from the muffler 1 line to the carb 1 line is for fill.

SNOW SHOULD BE ILLEGAL ON FLYIN DAYS

gotcha, cheers guys should have the plane finished early next year, ill post when she's done

"Fuel Dots" are a great way to keep the filler line in place.

http://www.pspmfg.com/FuelDotsRegular.html