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  #31  
Old 06-25-2022, 05:46 PM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
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Quote:
Originally Posted by David Z View Post
Has anyone come up with a good solution to the accidental overfill problem? Obviously we're going to watch fuel levels and never intentionally over fill the tank. The consequence of doing that is something I worry about. As much as I don't want to vent fuel overboard, I'd much rather vent fuel than rupture a main tank.

Would 1/4" aux transfer line negate any concerns about venting fuel overboard through 1/4" vent lines if an overfill did happen?
I have outboard and inboard tanks, the engine only draws fuel from the inboards. At the low point of the outboards I have two fuel pickups, one is a direct -6 size line to the high point of the inboard, and the other is a -6 size line through a Facet low-pressure fuel pump to the high point of the inboard tank.

In operation, normally as I burn fuel from the inboards it will pull a slight vacuum, and fuel will automatically flow from the outboard to the inboard via the straight pipe. However - this requires that the inboard filler cap is airtight and does not leak - if it does, then no fuel will transfer and I lose access to all the fuel in the outboard tank. To fix that problem I put the second line in place with the pump to force it across if needed. When the inboard tank is full and the pump is still running, then the excess flows back into the outboard tank via the straight pipe -6 sized line, preventing an overpressure on the inboard tank.

My tanks vent from atmosphere into the high point of the outboard tank, via a rocket-style 45-degree vent fitting on the bottom of the wing, and then through the outboard tank into the inboard tank for flow-through venting. I cannot dump fuel overboard, or overpressure the inboard tank, by trying to overfill the inboard tank with this design. It's worked well for me for almost 1100 hours now.
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Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2023 dues paid
N16GN flying 1,250 hrs and counting on 91E10; IO360, SDS, WWRV200, Dynon HDX, IFD440, G5
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
Repeat Offender - 10 empennage in process.

Last edited by airguy : 06-25-2022 at 05:48 PM.
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  #32  
Old 06-25-2022, 06:29 PM
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Dan 57 Dan 57 is online now
 
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Location: LSZF
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Quote:
As much as I don't want to vent fuel overboard, I'd much rather vent fuel than rupture a main tank.
Haven’t read the whole thread and there are, as usual, many different threads all pertaining to the same subject.
I’ve been using my 25USG Turtle tank on most legs of my actual trip, and unfortunately overfilled my right tank twice… yes, I know
No consequences but the lost fuel, and the smell of gas in the cockpit. Depends of course as to where said vents are installed, mine are in the gear leg fairings. The plumbing itself is as follows: a T installed in the R supply line. The OPs: empty the R tank to about half, switch supply to the left whilst transferring from the aux to the R. Works perfect lest you forget to switch off the transfer pump and valve…
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  #33  
Old 06-25-2022, 06:49 PM
David Z David Z is offline
 
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Location: Thunder Bay Ontario
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Dan 57: what transfer pump are using for the fuselage Turtle tank?

I'm assuming 3/8" transfer line from the Turtle tank and typical 1/4" vent lines?
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  #34  
Old 06-25-2022, 07:11 PM
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Dan 57 Dan 57 is online now
 
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David, I’m using the transfer pump as provided by the Turtle tank. Since my tank sits on the pax seat, I had a long thought thinking gravity could be enough to xfer the fuel. Still, ordered the tank with the pump, and very happy with that decision since the transfers have been working without problems. Installed an additional power outlet (merit 10A type) on the panel.
The install is all 3/8, and the big plus of the Turtle is in not needing a vent Fill, try not to have any air left in the tank, install cap, and go fly
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YLL On Tour... the blook:
https://vansairforce.net/community/s...d.php?t=210564

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  #35  
Old 06-25-2022, 08:11 PM
David Z David Z is offline
 
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Location: Thunder Bay Ontario
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Do you happen to know the pressure and flow capabilities of the transfer pump from Turtle Pac? I'm trying to compare it to what I'll be using. Since you can't over-pressure the wing tanks, that's what I'm hoping to replicate.
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Empennage Passed Pre-close Inspection
Wings mostly done
Fuselage assembly, it's a riveting job!
83126
Dash 8 day job is financing the RV8
Donation till September 2023
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  #36  
Old 11-24-2022, 02:36 PM
Staunch111 Staunch111 is offline
 
Join Date: Oct 2013
Location: Sydney
Posts: 202
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Quote:
Originally Posted by airguy View Post
I have outboard and inboard tanks, the engine only draws fuel from the inboards. At the low point of the outboards I have two fuel pickups, one is a direct -6 size line to the high point of the inboard, and the other is a -6 size line through a Facet low-pressure fuel pump to the high point of the inboard tank.

In operation, normally as I burn fuel from the inboards it will pull a slight vacuum, and fuel will automatically flow from the outboard to the inboard via the straight pipe. However - this requires that the inboard filler cap is airtight and does not leak - if it does, then no fuel will transfer and I lose access to all the fuel in the outboard tank. To fix that problem I put the second line in place with the pump to force it across if needed. When the inboard tank is full and the pump is still running, then the excess flows back into the outboard tank via the straight pipe -6 sized line, preventing an overpressure on the inboard tank.

My tanks vent from atmosphere into the high point of the outboard tank, via a rocket-style 45-degree vent fitting on the bottom of the wing, and then through the outboard tank into the inboard tank for flow-through venting. I cannot dump fuel overboard, or overpressure the inboard tank, by trying to overfill the inboard tank with this design. It's worked well for me for almost 1100 hours now.
Hey Airguy,

Apologies in rssurecting an old thread but do you have a build site for your 9? Or do you have a list of all parts for the installation and operation of your outbioard leading edge tanks? I'm building a 7 and I acknowledge the wing difference but am certainly not wanting to reinvent the wheel and in reading your posts it appears your very happy with how the mod turned out. Thanks
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  #37  
Old 11-24-2022, 04:07 PM
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jaradtke jaradtke is offline
 
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Send me your email address and I'll send you all the information Pat Tuckey shared about his ER tanks that Airguy, myself and others have utilized.
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  #38  
Old 11-25-2022, 08:18 AM
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Dan 57 Dan 57 is online now
 
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Quote:
pressure and flow capabilities of the transfer pump from Turtle Pac?
just noticed your query now David...

AFAIK the Pump Kit comprises a Holley 12-927 pump, data in the chart. I have not timed the transfer times, but they were about 4 minutes to refill the 3/4 fuel burned from my right 18USG tank.

As I already mentioned somewhere, the only flaw is human performance affected ops, as in forgetting to switch the pump off, and being awaken by the strong smell of fuel, or letting the pump run dry and seize when operating with a closed shut-off valve
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__________________
- ain't the Destination, but the Journey -

www.aerofun.ch
YLL On Tour... the blook:
https://vansairforce.net/community/s...d.php?t=210564

RV-6.9i #25685, slider, O-360-A3A (carb/dual Lightspeed II), MTV-12-B, HB-YLL owner & lover
RV-4 #2062 HB-YVZ airframe builder
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  #39  
Old 11-27-2022, 09:18 PM
David Z David Z is offline
 
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Location: Thunder Bay Ontario
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That's great thanks. If that pump didn't damage your tanks, then the little Facet ones I'm looking will be okay too.
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Wings mostly done
Fuselage assembly, it's a riveting job!
83126
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Donation till September 2023
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  #40  
Old 11-27-2022, 10:02 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
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Quote:
Originally Posted by Dan 57 View Post
just noticed your query now David...

AFAIK the Pump Kit comprises a Holley 12-927 pump, data in the chart. I have not timed the transfer times, but they were about 4 minutes to refill the 3/4 fuel burned from my right 18USG tank.

As I already mentioned somewhere, the only flaw is human performance affected ops, as in forgetting to switch the pump off, and being awaken by the strong smell of fuel, or letting the pump run dry and seize when operating with a closed shut-off valve
I thought of I were to do a fuel transfer system, I might use a pressure switch that could detect when the pump runs dry, the pressure goes to zero and turns on a light.. something like this set to as light as it can be set..https://www.pegasusautoracing.com/pr...asp?RecID=2980

If there’s not enough pressure in the transfer line to set it off, possibly a restricted fitting could work in the line after the switch..
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Last edited by Taltruda : 11-27-2022 at 10:06 PM.
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