Connecting the tank vent on RV-4

hcccs · #1 01-08-2013, 03:11 PM

I am installing the tank vent on my RV-4 and trying to figure out how to connect the AL tube coming out from the fuselage with the fitting on the tank. When measuring I find that there is 1-2 inches between the two when the tank is put in place I and don't understand how to connect the two any easy way if at all. I built everything as per plans and now I find it doesn't work - or so I think. How have you RV4 builder done this?

WAM120RV · #2 01-08-2013, 03:56 PM

Hi,

The vent comes out of the tank via a 90 degree fitting which should be facing forward as per plans. The gap between the fuselage hole and the fitting allows enough room to bend soft alum tubing to meet the 90 degree fitting.

There are several photos on my blog where the tubes can be seen bending back behind the front tank mount. Sorry the photos were not taken to show this but you should get the idea from them.

foka4 · #3 01-08-2013, 08:08 PM

I had the same issue on my -4 project. The tanks were assembled by. The previous owner with straight fittings.

I used 04-05800 elbows from aircraft spruce to make everything work out. This part is a 90-degree "street elbow" with AN ends.

These little gems aren't listed with the rest of the AN fittings, so not many people stumble upon them, but they can be a lifesaver in tight spots. You may find a use for one on your mechanical fuel pump as well.

M

foka4 · #4 01-08-2013, 08:16 PM

....now that I think about it, I may have used these fittings elsewhere. I seem to recall that the vents are 1/4", and those elbows are 3/8". I'm 1500 miles away from my RV at the moment, so I can't verify. I guess not everything you read on the Internet can be true.

Sorry,

M

hcccs · #5 01-09-2013, 04:27 AM

Quote:

Originally Posted by WAM120RV

Hi,

The vent comes out of the tank via a 90 degree fitting which should be facing forward as per plans. The gap between the fuselage hole and the fitting allows enough room to bend soft alum tubing to meet the 90 degree fitting.

There are several photos on my blog where the tubes can be seen bending back behind the front tank mount. Sorry the photos were not taken to show this but you should get the idea from them.

I looked through the blog and didn't find the picture you mentioned but I get the idea. Thanks.

Marc DeGirolamo · #6 01-09-2013, 10:43 AM

Quote:

Originally Posted by hcccs

I am installing the tank vent on my RV-4 and trying to figure out how to connect the AL tube coming out from the fuselage with the fitting on the tank. When measuring I find that there is 1-2 inches between the two when the tank is put in place I and don't understand how to connect the two any easy way if at all. I built everything as per plans and now I find it doesn't work - or so I think. How have you RV4 builder done this?

Not sure if this is what you are wondering about ??

hcccs · #7 01-09-2013, 12:00 PM

Quote:

Originally Posted by Marc DeGirolamo

Not sure if this is what you are wondering about ??

Yes, it is. Thanks for the picture.

Derek · #8 01-09-2013, 02:55 PM

Is the vent option in the picture Ive attached better or worse ? To me it looks easier to implement.

fixnflyguy · #9 01-09-2013, 06:24 PM

I am always a fan of good ideas,but I am wondering if the coiled vent has been in operation yet? The vent system per plans puts a point in the loop that runs up the bulkhead much higher than the vent end in the tank.This prevents siphoning in certain attitudes,such as slips and sloped parking...per plans is easy to do, and the root connection is not that hard.

Ironflight · #10 01-09-2013, 06:28 PM

Quote:

Originally Posted by fixnflyguy

I am always a fan of good ideas,but I am wondering if the coiled vent has been in operation yet?

I's in operation in all of the F-1 Rockets out there in the world, and in a number of RV's. I would say that it works "adequately" - has not given us any problems in our RV-3 yet, and if you take a look at the even simpler RV-10 vent, you might be surprised at what you see....