Steve,
As you have seen on my website, I run a vent line from the tank to the
top of the Cobra neck area about 2 inches down from the filler neck
(that allows expansion or overfilling to clear out of the Cobra). On
the other side of the neck I run a 1/4 inch line to the vent in the gear
truss well. I believe you are having issues with filling the tank and
the slow fill rate of the Cobra neck. Most of the tank venting will
take the path of least resistance which is vent out of the fuel cap when
filling and will occasionally (always) result in a lovely cool fuel
shower.
Provided your 2 inch boss attaching the rubber hose to the Cobra has
been properly reamed out to allow a full flow. (Some do not trim this
inner molding out to increase the area, which is stronger for those who
over tighten clamps, but reduces the tank inlet diameter.):
Two things will help prevent a blow back of fuel.
First, A 3/8=9D max line (I use 5/16=9D) does help vent the
air out quickly. The problem is where is your vent line run? If it
runs to the Cobra first, you must make sure as you are filling, the vent
line remains clear. Not so easy to do. If the vent is to the top or
bottom of the aircraft direct from the tank, it would be prudent to run
3/8 inch until fairly close to the vent then to the 1/4 inch vent.
Choose your fittings carefully as a 3/8 by 1/8 NPT fitting may only have
a 1/4 inch ID on some brass fittings. Choose wisely.
Second. A short (12=9D) piece of 1 inch ID polyurethane clear
tubing is what I use to attach to the fuel nozzle from the fuel truck.
I place the polyurethane tube on the trucks nozzle and insert the
flexible tube into the Cobra. This does two things. 1. It is a visual
indication of the fuel burping back into the hose allowing me to stop or
reduce flow. I never fuel at a rate that completely fills the clear
tube. When near completely full, the tube fills and holds the fuel
after I stop the nozzle, if the 12 inch line stays full, I retract it
slowly and the remaining fuel in the line tops me to my vent line.
Second, it keeps my tank to Cobra (and sight gauge vent line) clear of
the incoming fuel. No burps unless I go full throttle at 100 GPM that
the truck delivers, then it is fuel bath time.
Jim Brown is to credit for this, he used a 24 inch tube which he would
force down into the Cobra quite far on his mono. He showed me that by
first squirting some fuel in the Cobra to pre lube it, the tube slid in
quite easily and gratifying. He could fill at a much higher rate and
rarely had a burp back. The longer line also allowed him to hold the
nozzle at chest height for more comfortable fuelling. I just like the
12 inch long one as it fits in the headrest easily.
Try the inexpensive 1 inch flexible polyurethane (or similar in the UK)
and a bit of patience and it works for me and the line boys quite well
on our blind filling of the Europa Tank...
Best Regards,
Bud Yerly
Best Regards,
Bud Yerly
From: Steven Pitt
Sent: Monday, July 27, 2015 6:45 PM
Subject: Re: Europa-List: vent pipes
Thanks as ever Graham. Did you make up any of your vent pipe
bosses/fittings that I have seen in photos some while ago?
Steve
----- Original Message -----
From: GRAHAM SINGLETON
To: europa-list@matronics.com
Sent: Monday, July 27, 2015 6:06 PM
Subject: Re: Europa-List: vent pipes
Steve
I would suggest using 3/8 aluminium from tank to the top of the cobra,
then 1/4" to the outside air. That way
any splashing goes back into the tank. I used -6 AN fittings
Graham
On Monday, 27 July 2015, 14:57, Steven Pitt
<steven.pitt2@ntlworld.com> wrote:
<steven.pitt2@ntlworld.com>
I am looking to increase the size of my fuel vent pipes for my
trigear. What
sizes have others used. The Europa supplied
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target="_blank">http://www.bsp; -Matt Dralle, List Admin.
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