[jan]

I just installed OS61 with pump in my new Staudacher. Now I do not need pressure and vent line between the tank and a muffler! But how to vent the tank?
Thanks for a good advice! Jan

[planecrazy]

Jan,
You'll have to have a vent to atmosphere on the tank. Otherwise, the vacuum created in the tank from the engine drawing out the fuel will become too much for the engine and it won't be able to draw fuel anymore. And that'll probably happen at a point when you don't want it to. You know, a go around @ 7 1/2 feet, trying to avoid that 30 ft tree that jumped into your flight path..........

Chris

[jan]

So it looks like I will have to have three tubes. Intake. second for fueling and the third one to vent the tank. Do you think Chris that I should restrict diameter of the end of the vent tube so that it does not spill any fuel during aerobatics or ground handling?

Jan

[4*60]

...

[WildBill]

your feuling tube can be your vent as well, as long as you arn't flying inverted for extended periods of time it should be fine no spillage, other wise you will need a third line.

[Gary Maker]

In my opinion you will still need the third line! If you try fueling through the vent line, then where does the air in the tank go as you fill it! Without the third line the tank will build up a positive pressure and force the fuel through the pump and into the engine causing a massive flooding problem OR there will just be such a build up of pressure that you won't be able to get any fuel into the tank and might even cause damage to the tank. As the tank is being filled the air needs to escape via the third line. And you need the vent to allow air back into the tank as the fuel is used by the engine. When you finish fueling make sure you use a plug to seal the third line while flying and there won't be any fuel spillage!

[JimMoss]

Actually you can get away with a 2 line system ......
Fuel line and vent ...... Just fill through your fuel line with clunk inside tank and vent goes to top of tank inside. if you can get at fuel line that is.

If you can't get to the fuel line ..... forget what I said ....... you will need a third line.

Also if you have an inline fuel filter ...... do not fill through it disconnect at fuel filter than fill, otherwise you will putting any contaminants right into the carb or pump.

HTH

[Gary Maker]

You are right Jim! But I was assuming that with this scale plane with cowel attatched it would be difficult if not impossible to get at the carb fuel line!

The exception would be to use a quick connect fuel filler valve and that third line would not be necessary but the pump would have to be between the carb and the filler valve! For the extra $25 for the valve, it might be worth serious consideration and eliminate a lot of concerns!

[JimMoss]

Gary as you said, a third line in the case of a hard to get fuel line is the easiest fix.

Just use a fuel dot on top of the fuse to the third line and it makes it look like a scale fuel cap as well!

[Flypaper]

An easy way without having to plug any lines is, the filler goes from the top of the cowl, through the tank to the bottom. Vent goes from the top of the tank, through the front of the tank, and out the bottom of the cowl. Won't drain fuel right side up, or upside down. Tank lines go just insde the front of the tank.