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rowlandcarson(at)gmail.co
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 Posted: Wed May 04, 2016 7:27 am Post subject: fuel vent query |
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I’m installing the type of fuel vent described by Graham Singleton and others, where the vent pipe goes up to a syphon break at the top of the F18 filler neck then down to reach atmospheric pressure underneath the fuselage. I’m using 1/4” soft aluminium pipe with AN fittings.
It’s probably not very important, but I wondered if there was any conventional wisdom on the ideal shape for the bottom end of the vent pipe. I believe I’ve seen vents that are chamfered like A & B in the diagram attached below, but am not sure if that would create an undesirable increase (A) or decrease (B) pressure in the vent pipe.
It seems desirable (to prevent accidental damage etc) that the vent should protrude as little as possible below the fuselage, so the diagrams show an exaggerated length for clarity. Instead of a straight cut pipe as at C, would there be any downside to terminating the pipe in an AN bulkhead fitting with the outer end cut off, to make it look rather like a large static port? This seems the most robust and elegant way to do it, but I’m concerned that it may cause problems I hadn’t thought of.
Anyone have any relevant experience or knowledge of the shapes of fuel vents?
in friendship
Rowland
| Rowland Carson ... that's Rowland with a 'w' ...| <rowlandcarson(at)gmail.com (rowlandcarson(at)gmail.com)> http://www.rowlandcarson.org.uk| Skype, Twitter: rowland_carson Facebook: Rowland Carson| pictures: http://picasaweb.google.com/rowlandcarson
[img]cid:05AA331A-80BC-4473-B39D-FA5C86DFFC5D(at)home[/img]
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budyerly(at)msn.com
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| Posted: Wed May 04, 2016 2:07 pm Post subject: fuel vent query |
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Rowland,
For the last 10 years I’ve been putting the vent on the bottom. I use 1/4 inch OD tube (although others have gone with larger) and extended the tube below the fuselage some two inches minimum to be in clean air bent forward. Typically on the Starboard side and use a break in the cobra neck. Drill the two holes at the base of the tube as in the Europa top mounts should mud or grass get flung into the tip. A clogged vent will starve the engine eventually as the vacuum of the fuel being used will be greater than the pumps capability to draw fuel...
Find a convenient place in the trigear well or on a mono it can be behind the bulkhead or glued to the wood supports, being sure to clear the flaps. I put it on the forward side of the bulkhead and glassed and floxed it in. Just scuff the tube and install. It is very rugged and light. I made my tube from stainless. It is a bit hard to drill, but very stiff and strong. Use either rubber, tygon or polyurethane tubing with appropriate clamps.
On my website is how I plumb the unit which is similar to Grahams. I don’t use AN fittings as it is a vent system and not worth the fittings.
See photo attached and www.customflightcreations.com and hit the techniques tab.
Regards,
Bud Yerly
From: Rowland Carson (rowlandcarson(at)gmail.com)
Sent: Wednesday, May 04, 2016 11:26 AM
To: Europa e-mail list (europa-list(at)matronics.com)
Subject: fuel vent query
I’m installing the type of fuel vent described by Graham Singleton and others, where the vent pipe goes up to a syphon break at the top of the F18 filler neck then down to reach atmospheric pressure underneath the fuselage. I’m using 1/4” soft aluminium pipe with AN fittings.
It’s probably not very important, but I wondered if there was any conventional wisdom on the ideal shape for the bottom end of the vent pipe. I believe I’ve seen vents that are chamfered like A & B in the diagram attached below, but am not sure if that would create an undesirable increase (A) or decrease (B) pressure in the vent pipe.
It seems desirable (to prevent accidental damage etc) that the vent should protrude as little as possible below the fuselage, so the diagrams show an exaggerated length for clarity. Instead of a straight cut pipe as at C, would there be any downside to terminating the pipe in an AN bulkhead fitting with the outer end cut off, to make it look rather like a large static port? This seems the most robust and elegant way to do it, but I’m concerned that it may cause problems I hadn’t thought of.
Anyone have any relevant experience or knowledge of the shapes of fuel vents?
in friendship
Rowland
| Rowland Carson ... that's Rowland with a 'w' ...
| <rowlandcarson(at)gmail.com (rowlandcarson(at)gmail.com)> http://www.rowlandcarson.org.uk
| Skype, Twitter: rowland_carson Facebook: Rowland Carson
| pictures: http://picasaweb.google.com/rowlandcarson
[img]cid:9EA5A946743744EFB4D227BB4CA191E5(at)PCADMIN13[/img]
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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