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Connecting the tank vent on RV-4

hcccs

hcccs

Well Known Member
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?
 
The gaps for a reason.

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.
 
Aircraft Spruce 04-05800

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
 
Uh...

....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
 
WAM120RV said:
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.
Click to expand...

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

hcccs said:
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?
Click to expand...

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

IMG_2729.jpg
 
What about other vent options ?

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


AlternateVent.jpg


ventoption.jpg
 
Last edited:
coiled vent issue

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.
 
fixnflyguy said:
I am always a fan of good ideas,but I am wondering if the coiled vent has been in operation yet?
Click to expand...

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....
 
Thanks for the PIREP Paul, I didn't know that was being used on the Rockets..nice that all the plumbing is in the wing/tank.
 
Derek said:
Is the vent option in the picture Ive attached better or worse ? To me it looks easier to implement.




ventoption.jpg
Click to expand...

Elegant and simple. If it is working well as Ironflight says then I'll change over to using this installation. The left side on my RV4 is really awkward since the linkage from the quadrant in in the way.

It really pays to ask VAF for advice!
 
My brothers RV7a is set up with the coil system also---it has been flying since 2008 and I am not aware of ANY problems with this set up.

Cheers,

db
 
Interconnection

To avoid a problem If a fuel vent would get blocked (insect?) I interconnected the two vent lines behind the panel (2 T's and a bit of tubing, a very small weight penalty). That would not be possible with this set-up.

Regards, Tonny.
 
Sorry for dragging this thread back up. But has anyone done this in a -9A? I'd love to run coiled vent lines, both to keep it out of the fuse and to keep the tank "modular". But there's barely 1/2" of tank skin between the inner rib flange and the skin's wing root edge. Certainly not enough space for a vent.

The best I've read in other threads is to mount the vent on the lower wing root fairing. Just curious if there's any other place I should consider mounting the vent? My current thought is to have the coils inside the tank, with either a short soft aluminum or braided line run from the fitting at the rib to wherever the vent is.

Thanks!
 
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