Need some advice on a vent line.

I built a Jetmach 60 and am wondering how to put the vent line in. Can I double back the vent link back on the tank like gassers do?

On my past jets I just vented to the bottom directly from the tank, but always had to deal with fuel spilling everywhere all the time. Are there any advantages/disadvantages of venting like the "gassers" ?
Thanks in advance

On all 4 of my jets i have just routed vent from top of tank straight down and out also have done to the side but what I do make is a right angle fitting so the vent faces forward with airstream going over an open pipe at 90deg that makes for negative suction on vent (venturi effect) not want you want. That's how I have ran mine and never had a fuel issue ever.

When I did the vent for my EF Yak 54 88" that's how I was advised to do the vent route similar to yours in the pic but never done jets that way.

Alan

I do mine just like you have in the pictures of your gasser. Has worked fine up to this point.

I understand about the venturi efffect, I'm just inquiring about the vent line spilling gas when the gas in the tank "sloshes" around while taxiing, flying, or while carrying, or transporting the jet.

Thanks

Use a festo shut off valve, when you aren't flying shut it off
The trick is to always remember to turn it on before starting[:@]

Yea ... don't forget to open the value before filling. If not, you will have a ruptured tank and a plane full of fuel (don't ask me how I know) </p>

I would personally NEVER use such a valve because I know, I just KNOW I'd forget it and make the internal mess discussed above above.

Rather, I use a simple plug in the vent line and attach this [link=http://dreamworksrc.com/catalog/product_info.php?products_id=1451]flag[/link] or this [link=http://dreamworksrc.com/catalog/product_info.php?products_id=197]flag[/link] to the plug with a bit of safety wire. Makes it difficult to miss the fact that the plug is still in, and when I did get ahead of myself during fueling just the other day, forgetting to pull it, the plug popped out all on it's own. No fuse mess from my forgetfullness, thank goodness.

On one recently completed jet I ran the vent straight out of the tail. If it exits at the bottom/aft end of the fuse there's little or no leakage in any attitude and what does dribble out does not tend to come into contact with the airframe.

It's good to have some sort of loop in the vent line, similar to the picture in post #1. It's not unusual for a little bit of fuel to get into the vent line during loops, rolls, etc. Once the plane rights itself fuel in the horizontal section of the vent line will migrate back to the tank.

I also put a forward facing bevel at the end of the vent tube to create a bit of positive pressure to help keep fuel from exiting.

Joe