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Apr 20, 2019, 09:55 AM
I'm a pilot, 100 yrs too late
Thermalin's Avatar
Thread OP
Question

Glow Fuel Tank Plumbing Question


Considered putting this under engines but it's not engine related per say .

Most of my planes are open engine access so access to carb line to fuel up is not an issue. Current build is cowled and I think I'm needing a 3rd line to simplify access which I haven't really used before, just 2 line, vent\pressure and carb\fill.

I attached a couple pics, each with different takes.
1st shows a fuel \ de-fuel line which makes sense.
2nd shows the fueling port but not way to empty tank later if needed.

I assume I want to go with pic #1 as the best solution?
I understand I need to cap off that fill line to close off the system as a whole.

Is the 1st pic the standard setup or are there many ways to approach this? Of course I'm looking for simple, least problematic solution, nothing fancy like fuel port \ access points, etc. that can be purchased.
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Apr 20, 2019, 10:03 AM
Registered User
I do the dual clunk method. Works and is easy.
Edwin
Apr 21, 2019, 10:30 AM
Registered User
I usually use the two line system also but for a cowled engine where you can't get to the pick-up tube easily you are going to need a three line system. The easiest way is to have a line that goes to the bottom of the tank with a short piece of tubing on it (you don't need a second clunk) and use that line to fill and empty the tank. Plane needs to sit level to empty tank. In your second diagram just flip the filler tube down and add a piece of tubing to the bottom of the tank.
Apr 21, 2019, 10:59 AM
Build a scale plane already!!!
scale_only's Avatar
Correct,, in the second pic,, that's what it looks like as you are putting in in the tank,, simply rotate the pick up line to the bottom of the tank,, been doing it that way as long as I can remember,, never used a second clunk either
Apr 21, 2019, 02:57 PM
I'm a pilot, 100 yrs too late
Thermalin's Avatar
Thread OP
Thanks....
I should take stock in K&S as I hate bending tubing and seem to go through a lot of it.

I'm assuming it's this?

https://www.amazon.com/Soft-Brass-Fu...gateway&sr=8-2
Last edited by Thermalin; Apr 21, 2019 at 03:06 PM.
Apr 21, 2019, 04:52 PM
Registered User
Quote:
Originally Posted by Thermalin
Thanks....
I should take stock in K&S as I hate bending tubing and seem to go through a lot of it.

I'm assuming it's this?

https://www.amazon.com/Soft-Brass-Fu...gateway&sr=8-2
The soft tubing is the best but that seems kinda expensive. Do you have a hobby store or Ace Hardware near you? Regular brass tubing does crack sometimes.
Apr 22, 2019, 06:15 AM
Build a scale plane already!!!
scale_only's Avatar
Quote:
Originally Posted by jimbopilotfl
the soft tubing is the best but that seems kinda expensive. Do you have a hobby store or ace hardware near you? Regular brass tubing does crack sometimes.

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Apr 22, 2019, 07:03 AM
A man with a plan
Balsaworkbench's Avatar
Rather than adding a third line that hangs out of the cowl and has a plug in the end, you could just route the clunk-to-carb line so it exits and reenters the cowl, and put a joint in it. Take the joint apart to fuel and defuel, and then put it back together. The joint doesn't have to be anything more complicated than a little piece of brass or nylon tubing.
Apr 22, 2019, 11:53 AM
Registered User
Quote:
Originally Posted by Balsaworkbench
Rather than adding a third line that hangs out of the cowl and has a plug in the end, you could just route the clunk-to-carb line so it exits and reenters the cowl, and put a joint in it. Take the joint apart to fuel and defuel, and then put it back together. The joint doesn't have to be anything more complicated than a little piece of brass or nylon tubing.
...but when you try to fuel the plane it will flood and drip fuel out of the carb and when you try and take fuel out of the tank you will suck air through the carburetor unless you close the needle valve or close the venturi with a choke and make sure the engine is on the compression stroke and the valves are closed. Please don't ask how I know.

It is easier to add a third line to the bottom of the tank to fuel and empty the tank.
Apr 22, 2019, 12:32 PM
A man with a plan
Balsaworkbench's Avatar
Maybe I wasn't clear. Here's a diagram.

The fuel line comes out a hole in the cowl, then goes back into another hole. The joint is in the part that's outside the cowl. To fuel the plane, just take the joint apart and pump the fuel into the tank as you normally would. When the joint is taken apart during fueling and defueling, the carburetor isn't connected to anything.

Some people would complain about the fuel line hanging out of the cowl, but I say it's just as good as having a third line hanging out of the cowl.
Apr 22, 2019, 01:02 PM
I'm a pilot, 100 yrs too late
Thermalin's Avatar
Thread OP
I did this once before but forgotten what I'd done till I saw your pic. Since my cylinder head opening is a bit extra I could push it and out of the cowl as needed.

If I go with a third line, do the fuel dot's stay put? What's the odds of the fill\defill line which I assume will hang down and below the tank losing it's fuel dot from vibration of whatever and then fuel begins to siphon out during flight.?
Apr 22, 2019, 01:05 PM
Build a scale plane already!!!
scale_only's Avatar
I like to use the ones that screw in,,, they work better IMO
Apr 22, 2019, 02:03 PM
Registered User
I just let it dangle down low. I use roofing nails cut off to about 1/2" long. There's serrations right under the nail head that help grip. Been doing this on a third line for a couple of decades.
Edwin
Last edited by edwin1; Apr 22, 2019 at 02:11 PM.
Apr 22, 2019, 05:55 PM
Registered User

Refueling


On my ME109 I just soldered in the middle a couple of pieces of brass tubing to a short piece of brass plate.I plumed the rear fitting to the tank and the front fitting to the engine. On the outside I just used a loop of fuel line to join the two. To refuel Just pull the loop off of the front fitting. The loop line has to be just the right length so it does not kink.

Kip
Apr 22, 2019, 06:14 PM
Registered User
Quote:
Originally Posted by Balsaworkbench
Maybe I wasn't clear. Here's a diagram.

The fuel line comes out a hole in the cowl, then goes back into another hole. The joint is in the part that's outside the cowl. .
Oh yeah, that will work but it does lengthen the pick-up tubing considerably. I still think it is easier and cleaner to have a dedicated fill/empty fitting.


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